gpgscm: Move files to a gpgscm subdirectory.

--

Note that we used

  git filter-branch --subdirectory-filter tests/gpgscm

in gnupg master to filter out the gpgscm part.  This commit merely
moves these files to a subdirectory which will be used in libgpg-error
for gpgscm.

Signed-off-by: Werner Koch <wk@gnupg.org>

25 files changed, 12880 insertions, 0 deletions

diff --git a/gpgscm/LICENSE.TinySCHEME b/gpgscm/LICENSE.TinySCHEME
new file mode 100644
index 0000000..23a7e85
--- /dev/null
+++ b/gpgscm/LICENSE.TinySCHEME
@@ -0,0 +1,31 @@
+                         LICENSE TERMS
+
+Copyright (c) 2000, Dimitrios Souflis
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+Redistributions of source code must retain the above copyright notice,
+this list of conditions and the following disclaimer.
+
+Redistributions in binary form must reproduce the above copyright
+notice, this list of conditions and the following disclaimer in the
+documentation and/or other materials provided with the distribution.
+
+Neither the name of Dimitrios Souflis nor the names of the
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR
+CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/gpgscm/Makefile.am b/gpgscm/Makefile.am
new file mode 100644
index 0000000..44d7b3f
--- /dev/null
+++ b/gpgscm/Makefile.am
@@ -0,0 +1,64 @@
+# TinyScheme-based test driver.
+#
+# Copyright (C) 2016 g10 Code GmbH
+#
+# This file is part of GnuPG.
+#
+# GnuPG is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# GnuPG is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, see <https://www.gnu.org/licenses/>.
+
+EXTRA_DIST = \
+	LICENSE.TinySCHEME \
+	Manual.txt \
+	ffi.scm \
+	init.scm \
+	lib.scm \
+	makefile.scm \
+	repl.scm \
+	t-child.scm \
+	xml.scm \
+	tests.scm \
+	gnupg.scm \
+	time.scm
+
+AM_CPPFLAGS = -I$(top_srcdir)/common
+include $(top_srcdir)/am/cmacros.am
+
+AM_CFLAGS =
+
+CLEANFILES =
+
+bin_PROGRAMS = gpgscm
+noinst_PROGRAMS = t-child
+
+common_libs = ../$(libcommon)
+commonpth_libs = ../$(libcommonpth)
+
+gpgscm_CFLAGS = -imacros scheme-config.h \
+	$(LIBGCRYPT_CFLAGS) $(LIBASSUAN_CFLAGS) $(GPG_ERROR_CFLAGS)
+gpgscm_SOURCES = main.c private.h ffi.c ffi.h ffi-private.h \
+	scheme-config.h scheme.c scheme.h scheme-private.h \
+	opdefines.h small-integers.h
+gpgscm_LDADD = $(LDADD) $(common_libs) \
+	$(NETLIBS) $(LIBICONV) $(LIBREADLINE) $(LIBINTL) \
+	$(LIBGCRYPT_LIBS) $(GPG_ERROR_LIBS)
+
+t_child_SOURCES = t-child.c
+
+# Make sure that all libs are build before we use them.  This is
+# important for things like make -j2.
+$(PROGRAMS): $(common_libs)
+
+check-local: gpgscm$(EXEEXT) t-child$(EXEEXT)
+	EXEEXT=$(EXEEXT) GPGSCM_PATH=$(srcdir) \
+		./gpgscm$(EXEEXT) $(srcdir)/t-child.scm
diff --git a/gpgscm/Manual.txt b/gpgscm/Manual.txt
new file mode 100644
index 0000000..b146926
--- /dev/null
+++ b/gpgscm/Manual.txt
@@ -0,0 +1,444 @@
+
+
+                       TinySCHEME Version 1.41
+
+                    "Safe if used as prescribed"
+                    -- Philip K. Dick, "Ubik"
+
+This software is open source, covered by a BSD-style license.
+Please read accompanying file COPYING.
+-------------------------------------------------------------------------------
+
+     This Scheme interpreter is based on MiniSCHEME version 0.85k4
+     (see miniscm.tar.gz in the Scheme Repository)
+     Original credits in file MiniSCHEMETribute.txt.
+
+     D. Souflis (dsouflis@acm.org)
+
+-------------------------------------------------------------------------------
+     What is TinyScheme?
+     -------------------
+
+     TinyScheme is a lightweight Scheme interpreter that implements as large
+     a subset of R5RS as was possible without getting very large and
+     complicated. It is meant to be used as an embedded scripting interpreter
+     for other programs. As such, it does not offer IDEs or extensive toolkits
+     although it does sport a small top-level loop, included conditionally.
+     A lot of functionality in TinyScheme is included conditionally, to allow
+     developers freedom in balancing features and footprint.
+
+     As an embedded interpreter, it allows multiple interpreter states to
+     coexist in the same program, without any interference between them.
+     Programmatically, foreign functions in C can be added and values
+     can be defined in the Scheme environment. Being a quite small program,
+     it is easy to comprehend, get to grips with, and use.
+
+     Known bugs
+     ----------
+
+     TinyScheme is known to misbehave when memory is exhausted.
+
+
+     Things that keep missing, or that need fixing
+     ---------------------------------------------
+
+     There are no hygienic macros. No rational or
+     complex numbers. No unwind-protect and call-with-values.
+
+     Maybe (a subset of) SLIB will work with TinySCHEME...
+
+     Decent debugging facilities are missing. Only tracing is supported
+     natively.
+
+
+     Scheme Reference
+     ----------------
+
+     If something seems to be missing, please refer to the code and
+     "init.scm", since some are library functions.  Refer to the MiniSCHEME
+     readme as a last resort.
+
+          Environments
+     (interaction-environment)
+     See R5RS. In TinySCHEME, immutable list of association lists.
+
+     (current-environment)
+     The environment in effect at the time of the call. An example of its
+     use and its utility can be found in the sample code that implements
+     packages in "init.scm":
+
+          (macro (package form)
+               `(apply (lambda ()
+                         ,@(cdr form)
+                         (current-environment))))
+
+     The environment containing the (local) definitions inside the closure
+     is returned as an immutable value.
+
+     (defined? <symbol>) (defined? <symbol> <environment>)
+     Checks whether the given symbol is defined in the current (or given)
+     environment.
+
+          Symbols
+     (gensym)
+     Returns a new interned symbol each time. Will probably move to the
+     library when string->symbol is implemented.
+
+          Directives
+     (gc)
+     Performs garbage collection immediately.
+
+     (gc-verbose) (gc-verbose <bool>)
+     The argument (defaulting to #t) controls whether GC produces
+     visible outcome.
+
+     (quit) (quit <num>)
+     Stops the interpreter and sets the 'retcode' internal field (defaults
+     to 0). When standalone, 'retcode' is returned as exit code to the OS.
+
+     (tracing <num>)
+     1, turns on tracing. 0 turns it off. (Only when USE_TRACING is 1).
+
+          Mathematical functions
+     Since rationals and complexes are absent, the respective functions
+     are also missing.
+     Supported: exp, log, sin, cos, tan, asin, acos, atan, floor, ceiling,
+     trunc, round and also sqrt and expt when USE_MATH=1.
+     Number-theoretical quotient, remainder and modulo, gcd, lcm.
+     Library: exact?, inexact?, odd?, even?, zero?, positive?, negative?,
+     exact->inexact. inexact->exact is a core function.
+
+          Type predicates
+     boolean?,eof-object?,symbol?,number?,string?,integer?,real?,list?,null?,
+     char?,port?,input-port?,output-port?,procedure?,pair?,environment?',
+     vector?. Also closure?, macro?.
+
+          Types
+     Types supported:
+
+          Numbers (integers and reals)
+          Symbols
+          Pairs
+          Strings
+          Characters
+          Ports
+          Eof object
+          Environments
+          Vectors
+
+          Literals
+     String literals can contain escaped quotes \" as usual, but also
+     \n, \r, \t, \xDD (hex representations) and \DDD (octal representations).
+     Note also that it is possible to include literal newlines in string
+     literals, e.g.
+
+          (define s "String with newline here
+          and here
+          that can function like a HERE-string")
+
+     Character literals contain #\space and #\newline and are supplemented
+     with #\return and #\tab, with obvious meanings. Hex character
+     representations are allowed (e.g. #\x20 is #\space).
+     When USE_ASCII_NAMES is defined, various control characters can be
+     referred to by their ASCII name.
+     0	     #\nul	       17       #\dc1
+     1	     #\soh             18       #\dc2
+     2	     #\stx             19       #\dc3
+     3	     #\etx             20       #\dc4
+     4	     #\eot             21       #\nak
+     5	     #\enq             22       #\syn
+     6	     #\ack             23       #\etv
+     7	     #\bel             24       #\can
+     8	     #\bs              25       #\em
+     9	     #\ht              26       #\sub
+     10	     #\lf              27       #\esc
+     11	     #\vt              28       #\fs
+     12	     #\ff              29       #\gs
+     13	     #\cr              30       #\rs
+     14	     #\so              31       #\us
+     15	     #\si
+     16	     #\dle             127      #\del
+
+     Numeric literals support #x #o #b and #d. Flonums are currently read only
+     in decimal notation. Full grammar will be supported soon.
+
+          Quote, quasiquote etc.
+     As usual.
+
+          Immutable values
+     Immutable pairs cannot be modified by set-car! and set-cdr!.
+     Immutable strings cannot be modified via string-set!
+
+          I/O
+     As per R5RS, plus String Ports (see below).
+     current-input-port, current-output-port,
+     close-input-port, close-output-port, input-port?, output-port?,
+     open-input-file, open-output-file.
+     read, write, display, newline, write-char, read-char, peek-char.
+     char-ready? returns #t only for string ports, because there is no
+     portable way in stdio to determine if a character is available.
+     Also open-input-output-file, set-input-port, set-output-port (not R5RS)
+     Library: call-with-input-file, call-with-output-file,
+     with-input-from-file, with-output-from-file and
+     with-input-output-from-to-files, close-port and input-output-port?
+     (not R5RS).
+     String Ports: open-input-string, open-output-string, get-output-string,
+     open-input-output-string. Strings can be used with I/O routines.
+
+          Vectors
+     make-vector, vector, vector-length, vector-ref, vector-set!, list->vector,
+     vector-fill!, vector->list, vector-equal? (auxiliary function, not R5RS)
+
+          Strings
+     string, make-string, list->string, string-length, string-ref, string-set!,
+     substring, string->list, string-fill!, string-append, string-copy.
+     string=?, string<?, string>?, string>?, string<=?, string>=?.
+     (No string-ci*? yet). string->number, number->string. Also atom->string,
+     string->atom (not R5RS).
+
+          Symbols
+     symbol->string, string->symbol
+
+          Characters
+     integer->char, char->integer.
+     char=?, char<?, char>?, char<=?, char>=?.
+     (No char-ci*?)
+
+          Pairs & Lists
+     cons, car, cdr, list, length, map, for-each, foldr, list-tail,
+     list-ref, last-pair, reverse, append.
+     Also member, memq, memv, based on generic-member, assoc, assq, assv
+     based on generic-assoc.
+
+          Streams
+     head, tail, cons-stream
+
+          Control features
+     Apart from procedure?, also macro? and closure?
+     map, for-each, force, delay, call-with-current-continuation (or call/cc),
+     eval, apply. 'Forcing' a value that is not a promise produces the value.
+     There is no call-with-values, values, nor dynamic-wind. Dynamic-wind in
+     the presence of continuations would require support from the abstract
+     machine itself.
+
+          Property lists
+     TinyScheme inherited from MiniScheme property lists for symbols.
+     put, get.
+
+          Dynamically-loaded extensions
+     (load-extension <filename without extension>)
+     Loads a DLL declaring foreign procedures. On Unix/Linux, one can make use
+     of the ld.so.conf file or the LD_RUN_PATH system variable in order to place
+     the library in a directory other than the current one. Please refer to the
+     appropriate 'man' page.
+
+          Esoteric procedures
+     (oblist)
+     Returns the oblist, an immutable list of all the symbols.
+
+     (macro-expand <form>)
+     Returns the expanded form of the macro call denoted by the argument
+
+     (define-with-return (<procname> <args>...) <body>)
+     Like plain 'define', but makes the continuation available as 'return'
+     inside the procedure. Handy for imperative programs.
+
+     (new-segment <num>)
+     Allocates more memory segments.
+
+     defined?
+     See "Environments"
+
+     (get-closure-code <closure>)
+     Gets the code as scheme data.
+
+     (make-closure <code> <environment>)
+     Makes a new closure in the given environment.
+
+          Obsolete procedures
+     (print-width <object>)
+
+     Programmer's Reference
+     ----------------------
+
+     The interpreter state is initialized with "scheme_init".
+     Custom memory allocation routines can be installed with an alternate
+     initialization function: "scheme_init_custom_alloc".
+     Files can be loaded with "scheme_load_file". Strings containing Scheme
+     code can be loaded with "scheme_load_string". It is a good idea to
+     "scheme_load" init.scm before anything else.
+
+     External data for keeping external state (of use to foreign functions)
+     can be installed with "scheme_set_external_data".
+     Foreign functions are installed with "assign_foreign". Additional
+     definitions can be added to the interpreter state, with "scheme_define"
+     (this is the way HTTP header data and HTML form data are passed to the
+     Scheme script in the Altera SQL Server). If you wish to define the
+     foreign function in a specific environment (to enhance modularity),
+     use "assign_foreign_env".
+
+     The procedure "scheme_apply0" has been added with persistent scripts in
+     mind. Persistent scripts are loaded once, and every time they are needed
+     to produce HTTP output, appropriate data are passed through global
+     definitions and function "main" is called to do the job. One could
+     add easily "scheme_apply1" etc.
+
+     The interpreter state should be deinitialized with "scheme_deinit".
+
+     DLLs containing foreign functions should define a function named
+     init_<base-name>. E.g. foo.dll should define init_foo, and bar.so
+     should define init_bar. This function should assign_foreign any foreign
+     function contained in the DLL.
+
+     The first dynamically loaded extension available for TinyScheme is
+     a regular expression library. Although it's by no means an
+     established standard, this library is supposed to be installed in
+     a directory mirroring its name under the TinyScheme location.
+
+
+     Foreign Functions
+     -----------------
+
+     The user can add foreign functions in C. For example, a function
+     that squares its argument:
+
+          pointer square(scheme *sc, pointer args) {
+           if(args!=sc->NIL) {
+               if(sc->isnumber(sc->pair_car(args))) {
+                    double v=sc->rvalue(sc->pair_car(args));
+                    return sc->mk_real(sc,v*v);
+               }
+           }
+           return sc->NIL;
+          }
+
+   Foreign functions are now defined as closures:
+
+   sc->interface->scheme_define(
+        sc,
+        sc->global_env,
+        sc->interface->mk_symbol(sc,"square"),
+        sc->interface->mk_foreign_func(sc, square));
+
+
+     Foreign functions can use the external data in the "scheme" struct
+     to implement any kind of external state.
+
+     External data are set with the following function:
+          void scheme_set_external_data(scheme *sc, void *p);
+
+     As of v.1.17, the canonical way for a foreign function in a DLL to
+     manipulate Scheme data is using the function pointers in sc->interface.
+
+     Standalone
+     ----------
+
+     Usage: tinyscheme -?
+     or:    tinyscheme [<file1> <file2> ...]
+     followed by
+	       -1 <file> [<arg1> <arg2> ...]
+	       -c <Scheme commands> [<arg1> <arg2> ...]
+     assuming that the executable is named tinyscheme.
+
+     Use - in the place of a filename to denote stdin.
+     The -1 flag is meant for #! usage in shell scripts. If you specify
+          #! /somewhere/tinyscheme -1
+     then tinyscheme will be called to process the file. For example, the
+     following script echoes the Scheme list of its arguments.
+
+	       #! /somewhere/tinyscheme -1
+	       (display *args*)
+
+     The -c flag permits execution of arbitrary Scheme code.
+
+
+     Error Handling
+     --------------
+
+     Errors are recovered from without damage. The user can install his
+     own handler for system errors, by defining *error-hook*. Defining
+     to '() gives the default behavior, which is equivalent to "error".
+     USE_ERROR_HOOK must be defined.
+
+     A simple exception handling mechanism can be found in "init.scm".
+     A new syntactic form is introduced:
+
+          (catch <expr returned exceptionally>
+               <expr1> <expr2> ... <exprN>)
+
+     "Catch" establishes a scope spanning multiple call-frames
+     until another "catch" is encountered.
+
+     Exceptions are thrown with:
+
+          (throw "message")
+
+     If used outside a (catch ...), reverts to (error "message").
+
+     Example of use:
+
+          (define (foo x) (write x) (newline) (/ x 0))
+
+          (catch (begin (display "Error!\n") 0)
+               (write "Before foo ... ")
+               (foo 5)
+               (write "After foo"))
+
+     The exception mechanism can be used even by system errors, by
+
+          (define *error-hook* throw)
+
+     which makes use of the error hook described above.
+
+     If necessary, the user can devise his own exception mechanism with
+     tagged exceptions etc.
+
+
+     Reader extensions
+     -----------------
+
+     When encountering an unknown character after '#', the user-specified
+     procedure *sharp-hook* (if any), is called to read the expression.
+     This can be used to extend the reader to handle user-defined constants
+     or whatever. It should be a procedure without arguments, reading from
+     the current input port (which will be the load-port).
+
+
+     Colon Qualifiers - Packages
+     ---------------------------
+
+     When USE_COLON_HOOK=1:
+     The lexer now recognizes the construction <qualifier>::<symbol> and
+     transforms it in the following manner (T is the transformation function):
+
+          T(<qualifier>::<symbol>) = (*colon-hook* 'T(<symbol>) <qualifier>)
+
+     where <qualifier> is a symbol not containing any double-colons.
+
+     As the definition is recursive, qualifiers can be nested.
+     The user can define his own *colon-hook*, to handle qualified names.
+     By default, "init.scm" defines *colon-hook* as EVAL. Consequently,
+     the qualifier must denote a Scheme environment, such as one returned
+     by (interaction-environment). "Init.scm" defines a new syntantic form,
+     PACKAGE, as a simple example. It is used like this:
+
+          (define toto
+               (package
+                    (define foo 1)
+                    (define bar +)))
+
+          foo                                     ==>  Error, "foo" undefined
+          (eval 'foo)                             ==>  Error, "foo" undefined
+          (eval 'foo toto)                        ==>  1
+          toto::foo                               ==>  1
+          ((eval 'bar toto) 2 (eval 'foo toto))   ==>  3
+          (toto::bar 2 toto::foo)                 ==>  3
+          (eval (bar 2 foo) toto)                 ==>  3
+
+     If the user installs another package infrastructure, he must define
+     a new 'package' procedure or macro to retain compatibility with supplied
+     code.
+
+     Note: Older versions used ':' as a qualifier. Unfortunately, the use
+     of ':' as a pseudo-qualifier in existing code (i.e. SLIB) essentially
+     precludes its use as a real qualifier.
diff --git a/gpgscm/ffi-private.h b/gpgscm/ffi-private.h
new file mode 100644
index 0000000..037da56
--- /dev/null
+++ b/gpgscm/ffi-private.h
@@ -0,0 +1,148 @@
+/* FFI interface for TinySCHEME.
+ *
+ * Copyright (C) 2016 g10 code GmbH
+ *
+ * This file is part of GnuPG.
+ *
+ * GnuPG is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * GnuPG is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef GPGSCM_FFI_PRIVATE_H
+#define GPGSCM_FFI_PRIVATE_H
+
+#include <gpg-error.h>
+#include "scheme.h"
+#include "scheme-private.h"
+
+#define FFI_PROLOG()						\
+  unsigned int ffi_arg_index GPGRT_ATTR_UNUSED = 1;		\
+  int err GPGRT_ATTR_UNUSED = 0					\
+
+int ffi_bool_value (scheme *sc, pointer p);
+
+#define CONVERSION_number(SC, X) (SC)->vptr->ivalue (X)
+#define CONVERSION_string(SC, X) (SC)->vptr->string_value (X)
+#define CONVERSION_character(SC, X) (SC)->vptr->charvalue (X)
+#define CONVERSION_list(SC, X)	(X)
+#define CONVERSION_bool(SC, X)	ffi_bool_value ((SC), (X))
+#define CONVERSION_path(SC, X)	(((SC)->vptr->is_string (X)	  \
+				  ? (SC)->vptr->string_value	  \
+				  : (SC)->vptr->symname) (X))
+
+#define IS_A_number(SC, X)	(SC)->vptr->is_number (X)
+#define IS_A_string(SC, X)	(SC)->vptr->is_string (X)
+#define IS_A_character(SC, X)	(SC)->vptr->is_character (X)
+#define IS_A_list(SC, X)	(SC)->vptr->is_list ((SC), X)
+#define IS_A_bool(SC, X)	((X) == (SC)->F || (X) == (SC)->T)
+#define IS_A_path(SC, X)	((SC)->vptr->is_string (X)	\
+				 || (SC)->vptr->is_symbol (X))
+
+#define FFI_ARG_OR_RETURN(SC, CTYPE, TARGET, WANT, ARGS)		\
+  do {									\
+  if ((ARGS) == (SC)->NIL)						\
+    return (SC)->vptr->mk_string ((SC),					\
+				  "too few arguments: want "		\
+				  #TARGET "("#WANT"/"#CTYPE")\n");	\
+  if (! IS_A_##WANT ((SC), pair_car (ARGS))) {				\
+    char ffi_error_message[256];					\
+    snprintf (ffi_error_message, sizeof ffi_error_message,		\
+	      "argument %d must be: " #WANT "\n", ffi_arg_index);	\
+    return  (SC)->vptr->mk_string ((SC), ffi_error_message);		\
+  }									\
+  TARGET = CONVERSION_##WANT (SC, pair_car (ARGS));			\
+  ARGS = pair_cdr (ARGS);						\
+  ffi_arg_index += 1;							\
+  } while (0)
+
+#define FFI_ARGS_DONE_OR_RETURN(SC, ARGS)                               \
+  do {									\
+  if ((ARGS) != (SC)->NIL)						\
+    return (SC)->vptr->mk_string ((SC), "too many arguments");		\
+  } while (0)
+
+#define FFI_RETURN_ERR(SC, ERR)					\
+  return _cons ((SC), mk_integer ((SC), (ERR)), (SC)->NIL, 1)
+
+#define FFI_RETURN(SC)	FFI_RETURN_ERR (SC, err)
+
+#define FFI_RETURN_POINTER(SC, X)					\
+  return _cons ((SC), mk_integer ((SC), err),				\
+		_cons ((SC), (X), (SC)->NIL, 1), 1)
+#define FFI_RETURN_INT(SC, X)						\
+  FFI_RETURN_POINTER ((SC), mk_integer ((SC), (X)))
+#define FFI_RETURN_STRING(SC, X)			\
+  FFI_RETURN_POINTER ((SC), mk_string ((SC), (X)))
+
+char *ffi_schemify_name (const char *s, int macro);
+
+void ffi_scheme_eval (scheme *sc, const char *format, ...)
+  GPGRT_ATTR_PRINTF (2, 3);
+pointer ffi_sprintf (scheme *sc, const char *format, ...)
+  GPGRT_ATTR_PRINTF (2, 3);
+
+#define ffi_define_function_name(SC, NAME, F)				\
+  do {									\
+    char *_fname = ffi_schemify_name ("__" #F, 0);                      \
+    scheme_define ((SC),						\
+		   (SC)->global_env,					\
+		   mk_symbol ((SC), _fname),                            \
+		   mk_foreign_func ((SC), (do_##F)));			\
+    ffi_scheme_eval ((SC),						\
+		     "(define (%s . a) (ffi-apply \"%s\" %s a))",	\
+		     (NAME), (NAME), _fname);                           \
+    free (_fname);                                                      \
+  } while (0)
+
+#define ffi_define_function(SC, F)                                      \
+  do {									\
+    char *_name = ffi_schemify_name (#F, 0);                            \
+    ffi_define_function_name ((SC), _name, F);                          \
+    free (_name);                                                       \
+  } while (0)
+
+#define ffi_define_constant(SC, C)					\
+  do {									\
+    char *_name = ffi_schemify_name (#C, 1);                            \
+    scheme_define ((SC),                                                \
+                   (SC)->global_env,					\
+                   mk_symbol ((SC), _name),                             \
+                   mk_integer ((SC), (C)));                             \
+    free (_name);                                                       \
+  } while (0)
+
+#define ffi_define(SC, SYM, EXP)					\
+  scheme_define ((SC), (SC)->global_env, mk_symbol ((SC), (SYM)), EXP)
+
+#define ffi_define_variable_pointer(SC, C, P)				\
+  do {									\
+    char *_name = ffi_schemify_name (#C, 0);                            \
+    scheme_define ((SC),                                                \
+                   (SC)->global_env,					\
+                   mk_symbol ((SC), _name),                             \
+                   (P));                                                \
+    free (_name);                                                       \
+  } while (0)
+
+#define ffi_define_variable_integer(SC, C)				\
+  ffi_define_variable_pointer ((SC), C, (SC)->vptr->mk_integer ((SC), C))
+
+#define ffi_define_variable_string(SC, C)				\
+  ffi_define_variable_pointer ((SC), C, (SC)->vptr->mk_string ((SC), C ?: ""))
+
+gpg_error_t ffi_list2argv (scheme *sc, pointer list,
+			   char ***argv, size_t *len);
+gpg_error_t ffi_list2intv (scheme *sc, pointer list,
+			   int **intv, size_t *len);
+
+#endif /* GPGSCM_FFI_PRIVATE_H */
diff --git a/gpgscm/ffi.c b/gpgscm/ffi.c
new file mode 100644
index 0000000..dde5b52
--- /dev/null
+++ b/gpgscm/ffi.c
@@ -0,0 +1,1470 @@
+/* FFI interface for TinySCHEME.
+ *
+ * Copyright (C) 2016 g10 code GmbH
+ *
+ * This file is part of GnuPG.
+ *
+ * GnuPG is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * GnuPG is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+
+#include <assert.h>
+#include <ctype.h>
+#include <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <gpg-error.h>
+#include <limits.h>
+#include <stdarg.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#if HAVE_LIBREADLINE
+#define GNUPG_LIBREADLINE_H_INCLUDED
+#include <readline/readline.h>
+#include <readline/history.h>
+#endif
+
+#include "../../common/util.h"
+#include "../../common/exechelp.h"
+#include "../../common/sysutils.h"
+
+#include "private.h"
+#include "ffi.h"
+#include "ffi-private.h"
+
+/* For use in nice error messages.  */
+static const char *
+ordinal_suffix (int n)
+{
+  switch (n)
+    {
+    case 1: return "st";
+    case 2: return "nd";
+    case 3: return "rd";
+    default: return "th";
+    }
+  assert (! "reached");
+}
+
+
+
+int
+ffi_bool_value (scheme *sc, pointer p)
+{
+  return ! (p == sc->F);
+}
+
+
+
+static pointer
+do_logand (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  unsigned int v, acc = ~0;
+  while (args != sc->NIL)
+    {
+      FFI_ARG_OR_RETURN (sc, unsigned int, v, number, args);
+      acc &= v;
+    }
+  FFI_RETURN_INT (sc, acc);
+}
+
+static pointer
+do_logior (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  unsigned int v, acc = 0;
+  while (args != sc->NIL)
+    {
+      FFI_ARG_OR_RETURN (sc, unsigned int, v, number, args);
+      acc |= v;
+    }
+  FFI_RETURN_INT (sc, acc);
+}
+
+static pointer
+do_logxor (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  unsigned int v, acc = 0;
+  while (args != sc->NIL)
+    {
+      FFI_ARG_OR_RETURN (sc, unsigned int, v, number, args);
+      acc ^= v;
+    }
+  FFI_RETURN_INT (sc, acc);
+}
+
+static pointer
+do_lognot (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  unsigned int v;
+  FFI_ARG_OR_RETURN (sc, unsigned int, v, number, args);
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+  FFI_RETURN_INT (sc, ~v);
+}
+
+/* User interface.  */
+
+static pointer
+do_flush_stdio (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+  fflush (stdout);
+  fflush (stderr);
+  FFI_RETURN (sc);
+}
+
+
+int use_libreadline;
+
+/* Read a string, and return a pointer to it.  Returns NULL on EOF. */
+char *
+rl_gets (const char *prompt)
+{
+  static char *line = NULL;
+  char *p;
+  xfree (line);
+
+#if HAVE_LIBREADLINE
+    {
+      line = readline (prompt);
+      if (line && *line)
+        add_history (line);
+    }
+#else
+    {
+      size_t max_size = 0xff;
+      printf ("%s", prompt);
+      fflush (stdout);
+      line = xtrymalloc (max_size);
+      if (line != NULL)
+        fgets (line, max_size, stdin);
+    }
+#endif
+
+  /* Strip trailing whitespace.  */
+  if (line && strlen (line) > 0)
+    for (p = &line[strlen (line) - 1]; isspace (*p); p--)
+      *p = 0;
+
+  return line;
+}
+
+static pointer
+do_prompt (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  const char *prompt;
+  const char *line;
+  FFI_ARG_OR_RETURN (sc, const char *, prompt, string, args);
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+  line = rl_gets (prompt);
+  if (! line)
+    FFI_RETURN_POINTER (sc, sc->EOF_OBJ);
+
+  FFI_RETURN_STRING (sc, line);
+}
+
+static pointer
+do_sleep (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  unsigned int seconds;
+  FFI_ARG_OR_RETURN (sc, unsigned int, seconds, number, args);
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+  sleep (seconds);
+  FFI_RETURN (sc);
+}
+
+static pointer
+do_usleep (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  useconds_t microseconds;
+  FFI_ARG_OR_RETURN (sc, useconds_t, microseconds, number, args);
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+  usleep (microseconds);
+  FFI_RETURN (sc);
+}
+
+static pointer
+do_chdir (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  char *name;
+  FFI_ARG_OR_RETURN (sc, char *, name, path, args);
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+  if (chdir (name))
+    FFI_RETURN_ERR (sc, errno);
+  FFI_RETURN (sc);
+}
+
+static pointer
+do_strerror (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  int error;
+  FFI_ARG_OR_RETURN (sc, int, error, number, args);
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+  FFI_RETURN_STRING (sc, gpg_strerror (error));
+}
+
+static pointer
+do_getenv (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  char *name;
+  char *value;
+  FFI_ARG_OR_RETURN (sc, char *, name, string, args);
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+  value = getenv (name);
+  FFI_RETURN_STRING (sc, value ? value : "");
+}
+
+static pointer
+do_setenv (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  char *name;
+  char *value;
+  int overwrite;
+  FFI_ARG_OR_RETURN (sc, char *, name, string, args);
+  FFI_ARG_OR_RETURN (sc, char *, value, string, args);
+  FFI_ARG_OR_RETURN (sc, int, overwrite, bool, args);
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+  if (gnupg_setenv (name, value, overwrite))
+    FFI_RETURN_ERR (sc, gpg_error_from_syserror ());
+  FFI_RETURN (sc);
+}
+
+static pointer
+do_exit (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  int retcode;
+  FFI_ARG_OR_RETURN (sc, int, retcode, number, args);
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+  exit (retcode);
+}
+
+/* XXX: use gnupgs variant b/c mode as string */
+static pointer
+do_open (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  int fd;
+  char *pathname;
+  int flags;
+  mode_t mode = 0;
+  FFI_ARG_OR_RETURN (sc, char *, pathname, path, args);
+  FFI_ARG_OR_RETURN (sc, int, flags, number, args);
+  if (args != sc->NIL)
+    FFI_ARG_OR_RETURN (sc, mode_t, mode, number, args);
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+
+  fd = open (pathname, flags, mode);
+  if (fd == -1)
+    FFI_RETURN_ERR (sc, gpg_error_from_syserror ());
+  FFI_RETURN_INT (sc, fd);
+}
+
+static pointer
+do_fdopen (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  FILE *stream;
+  int fd;
+  char *mode;
+  int kind;
+  FFI_ARG_OR_RETURN (sc, int, fd, number, args);
+  FFI_ARG_OR_RETURN (sc, char *, mode, string, args);
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+
+  stream = fdopen (fd, mode);
+  if (stream == NULL)
+    FFI_RETURN_ERR (sc, gpg_error_from_syserror ());
+
+  if (setvbuf (stream, NULL, _IONBF, 0) != 0)
+    FFI_RETURN_ERR (sc, gpg_error_from_syserror ());
+
+  kind = 0;
+  if (strchr (mode, 'r'))
+    kind |= port_input;
+  if (strchr (mode, 'w'))
+    kind |= port_output;
+
+  FFI_RETURN_POINTER (sc, sc->vptr->mk_port_from_file (sc, stream, kind));
+}
+
+static pointer
+do_close (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  int fd;
+  FFI_ARG_OR_RETURN (sc, int, fd, number, args);
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+  FFI_RETURN_ERR (sc, close (fd) == 0 ? 0 : gpg_error_from_syserror ());
+}
+
+static pointer
+do_seek (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  int fd;
+  off_t offset;
+  int whence;
+  FFI_ARG_OR_RETURN (sc, int, fd, number, args);
+  FFI_ARG_OR_RETURN (sc, off_t, offset, number, args);
+  FFI_ARG_OR_RETURN (sc, int, whence, number, args);
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+  FFI_RETURN_ERR (sc, lseek (fd, offset, whence) == (off_t) -1
+                  ? gpg_error_from_syserror () : 0);
+}
+
+static pointer
+do_get_temp_path (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+#ifdef HAVE_W32_SYSTEM
+  char buffer[MAX_PATH+1];
+#endif
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+
+#ifdef HAVE_W32_SYSTEM
+  if (GetTempPath (MAX_PATH+1, buffer) == 0)
+    FFI_RETURN_STRING (sc, "/temp");
+  FFI_RETURN_STRING (sc, buffer);
+#else
+  FFI_RETURN_STRING (sc, "/tmp");
+#endif
+}
+
+static pointer
+do_mkdtemp (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  char *template;
+#ifdef PATH_MAX
+  char buffer[PATH_MAX];
+#else
+  char buffer[1024];
+#endif
+  char *name;
+  FFI_ARG_OR_RETURN (sc, char *, template, string, args);
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+
+  if (strlen (template) > sizeof buffer - 1)
+    FFI_RETURN_ERR (sc, EINVAL);
+  strncpy (buffer, template, sizeof buffer);
+
+  name = gnupg_mkdtemp (buffer);
+  if (name == NULL)
+    FFI_RETURN_ERR (sc, gpg_error_from_syserror ());
+  FFI_RETURN_STRING (sc, name);
+}
+
+static pointer
+do_unlink (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  char *name;
+  FFI_ARG_OR_RETURN (sc, char *, name, string, args);
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+  if (unlink (name) == -1)
+    FFI_RETURN_ERR (sc, gpg_error_from_syserror ());
+  FFI_RETURN (sc);
+}
+
+static gpg_error_t
+unlink_recursively (const char *name)
+{
+  gpg_error_t err = 0;
+  struct stat st;
+
+  if (stat (name, &st) == -1)
+    return gpg_error_from_syserror ();
+
+  if (S_ISDIR (st.st_mode))
+    {
+      DIR *dir;
+      struct dirent *dent;
+
+      dir = opendir (name);
+      if (dir == NULL)
+        return gpg_error_from_syserror ();
+
+      while ((dent = readdir (dir)))
+        {
+          char *child;
+
+          if (strcmp (dent->d_name, ".") == 0
+              || strcmp (dent->d_name, "..") == 0)
+            continue;
+
+          child = xtryasprintf ("%s/%s", name, dent->d_name);
+          if (child == NULL)
+            {
+              err = gpg_error_from_syserror ();
+              goto leave;
+            }
+
+          err = unlink_recursively (child);
+          xfree (child);
+          if (err == gpg_error_from_errno (ENOENT))
+            err = 0;
+          if (err)
+            goto leave;
+        }
+
+    leave:
+      closedir (dir);
+      if (! err)
+        rmdir (name);
+      return err;
+    }
+  else
+    if (unlink (name) == -1)
+      return gpg_error_from_syserror ();
+  return 0;
+}
+
+static pointer
+do_unlink_recursively (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  char *name;
+  FFI_ARG_OR_RETURN (sc, char *, name, string, args);
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+  err = unlink_recursively (name);
+  FFI_RETURN (sc);
+}
+
+static pointer
+do_rename (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  char *old;
+  char *new;
+  FFI_ARG_OR_RETURN (sc, char *, old, string, args);
+  FFI_ARG_OR_RETURN (sc, char *, new, string, args);
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+  if (rename (old, new) == -1)
+    FFI_RETURN_ERR (sc, gpg_error_from_syserror ());
+  FFI_RETURN (sc);
+}
+
+static pointer
+do_getcwd (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  pointer result;
+  char *cwd;
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+  cwd = gnupg_getcwd ();
+  if (cwd == NULL)
+    FFI_RETURN_ERR (sc, gpg_error_from_syserror ());
+  result = sc->vptr->mk_string (sc, cwd);
+  xfree (cwd);
+  FFI_RETURN_POINTER (sc, result);
+}
+
+static pointer
+do_mkdir (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  char *name;
+  char *mode;
+  FFI_ARG_OR_RETURN (sc, char *, name, string, args);
+  FFI_ARG_OR_RETURN (sc, char *, mode, string, args);
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+  if (gnupg_mkdir (name, mode) == -1)
+    FFI_RETURN_ERR (sc, gpg_error_from_syserror ());
+  FFI_RETURN (sc);
+}
+
+static pointer
+do_rmdir (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  char *name;
+  FFI_ARG_OR_RETURN (sc, char *, name, string, args);
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+  if (rmdir (name) == -1)
+    FFI_RETURN_ERR (sc, gpg_error_from_syserror ());
+  FFI_RETURN (sc);
+}
+
+static pointer
+do_get_isotime (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  gnupg_isotime_t timebuf;
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+  gnupg_get_isotime (timebuf);
+  FFI_RETURN_STRING (sc, timebuf);
+}
+
+static pointer
+do_get_time (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+  FFI_RETURN_INT (sc, gnupg_get_time ());
+}
+
+static pointer
+do_getpid (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+  FFI_RETURN_INT (sc, getpid ());
+}
+
+static pointer
+do_srandom (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  int seed;
+  FFI_ARG_OR_RETURN (sc, int, seed, number, args);
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+  srand (seed);
+  FFI_RETURN (sc);
+}
+
+static int
+random_scaled (int scale)
+{
+  int v;
+#ifdef HAVE_RAND
+  v = rand ();
+#else
+  v = random ();
+#endif
+
+#ifndef RAND_MAX   /* for SunOS */
+#define RAND_MAX 32767
+#endif
+
+  return ((int) (1 + (int) ((float) scale * v / (RAND_MAX + 1.0))) - 1);
+}
+
+static pointer
+do_random (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  int scale;
+  FFI_ARG_OR_RETURN (sc, int, scale, number, args);
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+  FFI_RETURN_INT (sc, random_scaled (scale));
+}
+
+static pointer
+do_make_random_string (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  int size;
+  pointer chunk;
+  char *p;
+  FFI_ARG_OR_RETURN (sc, int, size, number, args);
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+  if (size < 0)
+    return ffi_sprintf (sc, "size must be positive");
+
+  chunk = sc->vptr->mk_counted_string (sc, NULL, size);
+  if (sc->no_memory)
+    FFI_RETURN_ERR (sc, ENOMEM);
+
+  for (p = sc->vptr->string_value (chunk); size; p++, size--)
+    *p = (char) random_scaled (256);
+  FFI_RETURN_POINTER (sc, chunk);
+}
+
+
+
+/* estream functions.  */
+
+struct es_object_box
+{
+  estream_t stream;
+  int closed;
+};
+
+static void
+es_object_finalize (scheme *sc, void *data)
+{
+  struct es_object_box *box = data;
+  (void) sc;
+
+  if (! box->closed)
+    es_fclose (box->stream);
+  xfree (box);
+}
+
+static void
+es_object_to_string (scheme *sc, char *out, size_t size, void *data)
+{
+  struct es_object_box *box = data;
+  (void) sc;
+
+  snprintf (out, size, "#estream %p", box->stream);
+}
+
+static struct foreign_object_vtable es_object_vtable =
+  {
+    es_object_finalize,
+    es_object_to_string,
+  };
+
+static pointer
+es_wrap (scheme *sc, estream_t stream)
+{
+  struct es_object_box *box = xmalloc (sizeof *box);
+  if (box == NULL)
+    return sc->NIL;
+
+  box->stream = stream;
+  box->closed = 0;
+  return sc->vptr->mk_foreign_object (sc, &es_object_vtable, box);
+}
+
+static struct es_object_box *
+es_unwrap (scheme *sc, pointer object)
+{
+  (void) sc;
+
+  if (! is_foreign_object (object))
+    return NULL;
+
+  if (sc->vptr->get_foreign_object_vtable (object) != &es_object_vtable)
+    return NULL;
+
+  return sc->vptr->get_foreign_object_data (object);
+}
+
+#define CONVERSION_estream(SC, X)	es_unwrap (SC, X)
+#define IS_A_estream(SC, X)		es_unwrap (SC, X)
+
+static pointer
+do_es_fclose (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  struct es_object_box *box;
+  FFI_ARG_OR_RETURN (sc, struct es_object_box *, box, estream, args);
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+  err = es_fclose (box->stream);
+  if (! err)
+    box->closed = 1;
+  FFI_RETURN (sc);
+}
+
+static pointer
+do_es_read (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  struct es_object_box *box;
+  size_t bytes_to_read;
+
+  pointer result;
+  void *buffer;
+  size_t bytes_read;
+
+  FFI_ARG_OR_RETURN (sc, struct es_object_box *, box, estream, args);
+  FFI_ARG_OR_RETURN (sc, size_t, bytes_to_read, number, args);
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+
+  buffer = xtrymalloc (bytes_to_read);
+  if (buffer == NULL)
+    FFI_RETURN_ERR (sc, ENOMEM);
+
+  err = es_read (box->stream, buffer, bytes_to_read, &bytes_read);
+  if (err)
+    FFI_RETURN_ERR (sc, err);
+
+  result = sc->vptr->mk_counted_string (sc, buffer, bytes_read);
+  xfree (buffer);
+  FFI_RETURN_POINTER (sc, result);
+}
+
+static pointer
+do_es_feof (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  struct es_object_box *box;
+  FFI_ARG_OR_RETURN (sc, struct es_object_box *, box, estream, args);
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+
+  FFI_RETURN_POINTER (sc, es_feof (box->stream) ? sc->T : sc->F);
+}
+
+static pointer
+do_es_write (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  struct es_object_box *box;
+  const char *buffer;
+  size_t bytes_to_write, bytes_written;
+
+  FFI_ARG_OR_RETURN (sc, struct es_object_box *, box, estream, args);
+  /* XXX how to get the length of the string buffer?  scheme strings
+     may contain \0.  */
+  FFI_ARG_OR_RETURN (sc, const char *, buffer, string, args);
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+
+  bytes_to_write = strlen (buffer);
+  while (bytes_to_write > 0)
+    {
+      err = es_write (box->stream, buffer, bytes_to_write, &bytes_written);
+      if (err)
+        break;
+      bytes_to_write -= bytes_written;
+      buffer += bytes_written;
+    }
+
+  FFI_RETURN (sc);
+}
+
+
+
+/* Process handling.  */
+
+static pointer
+do_spawn_process (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  pointer arguments;
+  char **argv;
+  size_t len;
+  unsigned int flags;
+
+  estream_t infp;
+  estream_t outfp;
+  estream_t errfp;
+  pid_t pid;
+
+  FFI_ARG_OR_RETURN (sc, pointer, arguments, list, args);
+  FFI_ARG_OR_RETURN (sc, unsigned int, flags, number, args);
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+
+  err = ffi_list2argv (sc, arguments, &argv, &len);
+  if (err == gpg_error (GPG_ERR_INV_VALUE))
+    return ffi_sprintf (sc, "%luth element of first argument is "
+                        "neither string nor symbol",
+                        (unsigned long) len);
+  if (err)
+    FFI_RETURN_ERR (sc, err);
+
+  if (verbose > 1)
+    {
+      char **p;
+      fprintf (stderr, "Executing:");
+      for (p = argv; *p; p++)
+        fprintf (stderr, " '%s'", *p);
+      fprintf (stderr, "\n");
+    }
+
+  err = gnupg_spawn_process (argv[0], (const char **) &argv[1],
+                             NULL,
+                             NULL,
+                             flags,
+                             &infp, &outfp, &errfp, &pid);
+  xfree (argv);
+#define IMC(A, B)                                                       \
+  _cons (sc, sc->vptr->mk_integer (sc, (unsigned long) (A)), (B), 1)
+#define IMS(A, B)                                                       \
+  _cons (sc, es_wrap (sc, (A)), (B), 1)
+  FFI_RETURN_POINTER (sc, IMS (infp,
+                              IMS (outfp,
+                                   IMS (errfp,
+                                        IMC (pid, sc->NIL)))));
+#undef IMS
+#undef IMC
+}
+
+static pointer
+do_spawn_process_fd (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  pointer arguments;
+  char **argv;
+  size_t len;
+  int infd, outfd, errfd;
+
+  pid_t pid;
+
+  FFI_ARG_OR_RETURN (sc, pointer, arguments, list, args);
+  FFI_ARG_OR_RETURN (sc, int, infd, number, args);
+  FFI_ARG_OR_RETURN (sc, int, outfd, number, args);
+  FFI_ARG_OR_RETURN (sc, int, errfd, number, args);
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+
+  err = ffi_list2argv (sc, arguments, &argv, &len);
+  if (err == gpg_error (GPG_ERR_INV_VALUE))
+    return ffi_sprintf (sc, "%luth element of first argument is "
+                        "neither string nor symbol",
+                        (unsigned long) len);
+  if (err)
+    FFI_RETURN_ERR (sc, err);
+
+  if (verbose > 1)
+    {
+      char **p;
+      fprintf (stderr, "Executing:");
+      for (p = argv; *p; p++)
+        fprintf (stderr, " '%s'", *p);
+      fprintf (stderr, "\n");
+    }
+
+  err = gnupg_spawn_process_fd (argv[0], (const char **) &argv[1],
+                                infd, outfd, errfd, &pid);
+  xfree (argv);
+  FFI_RETURN_INT (sc, pid);
+}
+
+static pointer
+do_wait_process (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  const char *name;
+  pid_t pid;
+  int hang;
+
+  int retcode;
+
+  FFI_ARG_OR_RETURN (sc, const char *, name, string, args);
+  FFI_ARG_OR_RETURN (sc, pid_t, pid, number, args);
+  FFI_ARG_OR_RETURN (sc, int, hang, bool, args);
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+  err = gnupg_wait_process (name, pid, hang, &retcode);
+  if (err == GPG_ERR_GENERAL)
+    err = 0;	/* Let the return code speak for itself.  */
+
+  FFI_RETURN_INT (sc, retcode);
+}
+
+
+static pointer
+do_wait_processes (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  pointer list_names;
+  char **names;
+  pointer list_pids;
+  size_t i, count;
+  pid_t *pids;
+  int hang;
+  int *retcodes;
+  pointer retcodes_list = sc->NIL;
+
+  FFI_ARG_OR_RETURN (sc, pointer, list_names, list, args);
+  FFI_ARG_OR_RETURN (sc, pointer, list_pids, list, args);
+  FFI_ARG_OR_RETURN (sc, int, hang, bool, args);
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+
+  if (sc->vptr->list_length (sc, list_names)
+      != sc->vptr->list_length (sc, list_pids))
+    return
+      sc->vptr->mk_string (sc, "length of first two arguments must match");
+
+  err = ffi_list2argv (sc, list_names, &names, &count);
+  if (err == gpg_error (GPG_ERR_INV_VALUE))
+    return ffi_sprintf (sc, "%lu%s element of first argument is "
+                        "neither string nor symbol",
+                        (unsigned long) count,
+                        ordinal_suffix ((int) count));
+  if (err)
+    FFI_RETURN_ERR (sc, err);
+
+  err = ffi_list2intv (sc, list_pids, (int **) &pids, &count);
+  if (err == gpg_error (GPG_ERR_INV_VALUE))
+    return ffi_sprintf (sc, "%lu%s element of second argument is "
+                        "not a number",
+                        (unsigned long) count,
+                        ordinal_suffix ((int) count));
+  if (err)
+    FFI_RETURN_ERR (sc, err);
+
+  retcodes = xtrycalloc (sizeof *retcodes, count);
+  if (retcodes == NULL)
+    {
+      xfree (names);
+      xfree (pids);
+      FFI_RETURN_ERR (sc, gpg_error_from_syserror ());
+    }
+
+  err = gnupg_wait_processes ((const char **) names, pids, count, hang,
+                              retcodes);
+  if (err == GPG_ERR_GENERAL)
+    err = 0;	/* Let the return codes speak.  */
+  if (err == GPG_ERR_TIMEOUT)
+    err = 0;	/* We may have got some results.  */
+
+  for (i = 0; i < count; i++)
+    retcodes_list =
+      (sc->vptr->cons) (sc,
+                        sc->vptr->mk_integer (sc,
+                                              (long) retcodes[count-1-i]),
+                        retcodes_list);
+
+  xfree (names);
+  xfree (pids);
+  xfree (retcodes);
+  FFI_RETURN_POINTER (sc, retcodes_list);
+}
+
+
+static pointer
+do_pipe (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  int filedes[2];
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+  err = gnupg_create_pipe (filedes);
+#define IMC(A, B)                                                       \
+  _cons (sc, sc->vptr->mk_integer (sc, (unsigned long) (A)), (B), 1)
+  FFI_RETURN_POINTER (sc, IMC (filedes[0],
+                              IMC (filedes[1], sc->NIL)));
+#undef IMC
+}
+
+static pointer
+do_inbound_pipe (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  int filedes[2];
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+  err = gnupg_create_inbound_pipe (filedes, NULL, 0);
+#define IMC(A, B)                                                       \
+  _cons (sc, sc->vptr->mk_integer (sc, (unsigned long) (A)), (B), 1)
+  FFI_RETURN_POINTER (sc, IMC (filedes[0],
+                              IMC (filedes[1], sc->NIL)));
+#undef IMC
+}
+
+static pointer
+do_outbound_pipe (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  int filedes[2];
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+  err = gnupg_create_outbound_pipe (filedes, NULL, 0);
+#define IMC(A, B)                                                       \
+  _cons (sc, sc->vptr->mk_integer (sc, (unsigned long) (A)), (B), 1)
+  FFI_RETURN_POINTER (sc, IMC (filedes[0],
+                              IMC (filedes[1], sc->NIL)));
+#undef IMC
+}
+
+
+
+/* Test helper functions.  */
+static pointer
+do_file_equal (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  pointer result = sc->F;
+  char *a_name, *b_name;
+  int binary;
+  const char *mode;
+  FILE *a_stream = NULL, *b_stream = NULL;
+  struct stat a_stat, b_stat;
+#define BUFFER_SIZE	1024
+  char a_buf[BUFFER_SIZE], b_buf[BUFFER_SIZE];
+#undef BUFFER_SIZE
+  size_t chunk;
+
+  FFI_ARG_OR_RETURN (sc, char *, a_name, string, args);
+  FFI_ARG_OR_RETURN (sc, char *, b_name, string, args);
+  FFI_ARG_OR_RETURN (sc, int, binary, bool, args);
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+
+  mode = binary ? "rb" : "r";
+  a_stream = fopen (a_name, mode);
+  if (a_stream == NULL)
+    goto errout;
+
+  b_stream = fopen (b_name, mode);
+  if (b_stream == NULL)
+    goto errout;
+
+  if (fstat (fileno (a_stream), &a_stat) < 0)
+    goto errout;
+
+  if (fstat (fileno (b_stream), &b_stat) < 0)
+    goto errout;
+
+  if (binary && a_stat.st_size != b_stat.st_size)
+    {
+      if (verbose)
+        fprintf (stderr, "Files %s and %s differ in size %lu != %lu\n",
+                 a_name, b_name, (unsigned long) a_stat.st_size,
+                 (unsigned long) b_stat.st_size);
+
+      goto out;
+    }
+
+  while (! feof (a_stream))
+    {
+      chunk = sizeof a_buf;
+
+      chunk = fread (a_buf, 1, chunk, a_stream);
+      if (chunk == 0 && ferror (a_stream))
+        goto errout;	/* some error */
+
+      if (fread (b_buf, 1, chunk, b_stream) < chunk)
+        {
+          if (feof (b_stream))
+            goto out;	/* short read */
+          goto errout;	/* some error */
+        }
+
+      if (chunk > 0 && memcmp (a_buf, b_buf, chunk) != 0)
+        goto out;
+    }
+
+  fread (b_buf, 1, 1, b_stream);
+  if (! feof (b_stream))
+    goto out;	/* b is longer */
+
+  /* They match.  */
+  result = sc->T;
+
+ out:
+  if (a_stream)
+    fclose (a_stream);
+  if (b_stream)
+    fclose (b_stream);
+  FFI_RETURN_POINTER (sc, result);
+ errout:
+  err = gpg_error_from_syserror ();
+  goto out;
+}
+
+static pointer
+do_splice (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  int source;
+  char buffer[1024];
+  ssize_t bytes_read;
+  pointer sinks, sink;
+  FFI_ARG_OR_RETURN (sc, int, source, number, args);
+  sinks = args;
+  if (sinks == sc->NIL)
+    return ffi_sprintf (sc, "need at least one sink");
+  for (sink = sinks; sink != sc->NIL; sink = pair_cdr (sink), ffi_arg_index++)
+    if (! sc->vptr->is_number (pair_car (sink)))
+      return ffi_sprintf (sc, "%d%s argument is not a number",
+                          ffi_arg_index, ordinal_suffix (ffi_arg_index));
+
+  while (1)
+    {
+      bytes_read = read (source, buffer, sizeof buffer);
+      if (bytes_read == 0)
+        break;
+      if (bytes_read < 0)
+        FFI_RETURN_ERR (sc, gpg_error_from_syserror ());
+
+      for (sink = sinks; sink != sc->NIL; sink = pair_cdr (sink))
+        {
+          int fd = sc->vptr->ivalue (pair_car (sink));
+          char *p = buffer;
+          ssize_t left = bytes_read;
+
+          while (left)
+            {
+              ssize_t written = write (fd, p, left);
+              if (written < 0)
+                FFI_RETURN_ERR (sc, gpg_error_from_syserror ());
+              assert (written <= left);
+              left -= written;
+              p += written;
+            }
+        }
+    }
+  FFI_RETURN (sc);
+}
+
+static pointer
+do_string_index (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  char *haystack;
+  char needle;
+  ssize_t offset = 0;
+  char *position;
+  FFI_ARG_OR_RETURN (sc, char *, haystack, string, args);
+  FFI_ARG_OR_RETURN (sc, char, needle, character, args);
+  if (args != sc->NIL)
+    {
+      FFI_ARG_OR_RETURN (sc, ssize_t, offset, number, args);
+      if (offset < 0)
+        return ffi_sprintf (sc, "offset must be positive");
+      if (offset > strlen (haystack))
+        return ffi_sprintf (sc, "offset exceeds haystack");
+    }
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+
+  position = strchr (haystack+offset, needle);
+  if (position)
+    FFI_RETURN_INT (sc, position - haystack);
+  else
+    FFI_RETURN_POINTER (sc, sc->F);
+}
+
+static pointer
+do_string_rindex (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  char *haystack;
+  char needle;
+  ssize_t offset = 0;
+  char *position;
+  FFI_ARG_OR_RETURN (sc, char *, haystack, string, args);
+  FFI_ARG_OR_RETURN (sc, char, needle, character, args);
+  if (args != sc->NIL)
+    {
+      FFI_ARG_OR_RETURN (sc, ssize_t, offset, number, args);
+      if (offset < 0)
+        return ffi_sprintf (sc, "offset must be positive");
+      if (offset > strlen (haystack))
+        return ffi_sprintf (sc, "offset exceeds haystack");
+    }
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+
+  position = strrchr (haystack+offset, needle);
+  if (position)
+    FFI_RETURN_INT (sc, position - haystack);
+  else
+    FFI_RETURN_POINTER (sc, sc->F);
+}
+
+static pointer
+do_string_contains (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  char *haystack;
+  char *needle;
+  FFI_ARG_OR_RETURN (sc, char *, haystack, string, args);
+  FFI_ARG_OR_RETURN (sc, char *, needle, string, args);
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+  FFI_RETURN_POINTER (sc, strstr (haystack, needle) ? sc->T : sc->F);
+}
+
+
+
+static pointer
+do_get_verbose (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+  FFI_RETURN_INT (sc, verbose);
+}
+
+static pointer
+do_set_verbose (scheme *sc, pointer args)
+{
+  FFI_PROLOG ();
+  int new_verbosity, old;
+  FFI_ARG_OR_RETURN (sc, int, new_verbosity, number, args);
+  FFI_ARGS_DONE_OR_RETURN (sc, args);
+
+  old = verbose;
+  verbose = new_verbosity;
+
+  FFI_RETURN_INT (sc, old);
+}
+
+
+gpg_error_t
+ffi_list2argv (scheme *sc, pointer list, char ***argv, size_t *len)
+{
+  int i;
+
+  *len = sc->vptr->list_length (sc, list);
+  *argv = xtrycalloc (*len + 1, sizeof **argv);
+  if (*argv == NULL)
+    return gpg_error_from_syserror ();
+
+  for (i = 0; sc->vptr->is_pair (list); list = sc->vptr->pair_cdr (list))
+    {
+      if (sc->vptr->is_string (sc->vptr->pair_car (list)))
+        (*argv)[i++] = sc->vptr->string_value (sc->vptr->pair_car (list));
+      else if (sc->vptr->is_symbol (sc->vptr->pair_car (list)))
+        (*argv)[i++] = sc->vptr->symname (sc->vptr->pair_car (list));
+      else
+        {
+          xfree (*argv);
+          *argv = NULL;
+          *len = i;
+          return gpg_error (GPG_ERR_INV_VALUE);
+        }
+    }
+  (*argv)[i] = NULL;
+  return 0;
+}
+
+gpg_error_t
+ffi_list2intv (scheme *sc, pointer list, int **intv, size_t *len)
+{
+  int i;
+
+  *len = sc->vptr->list_length (sc, list);
+  *intv = xtrycalloc (*len, sizeof **intv);
+  if (*intv == NULL)
+    return gpg_error_from_syserror ();
+
+  for (i = 0; sc->vptr->is_pair (list); list = sc->vptr->pair_cdr (list))
+    {
+      if (sc->vptr->is_number (sc->vptr->pair_car (list)))
+        (*intv)[i++] = sc->vptr->ivalue (sc->vptr->pair_car (list));
+      else
+        {
+          xfree (*intv);
+          *intv = NULL;
+          *len = i;
+          return gpg_error (GPG_ERR_INV_VALUE);
+        }
+    }
+
+  return 0;
+}
+
+
+char *
+ffi_schemify_name (const char *s, int macro)
+{
+  /* Fixme: We should use xtrystrdup and return NULL.  However, this
+   * requires a lot more changes.  Simply returning S as done
+   * originally is not an option.  */
+  char *n = xstrdup (s), *p;
+  /* if (n == NULL) */
+  /*   return s; */
+
+  for (p = n; *p; p++)
+    {
+      *p = (char) tolower (*p);
+       /* We convert _ to - in identifiers.  We allow, however, for
+	  function names to start with a leading _.  The functions in
+	  this namespace are not yet finalized and might change or
+	  vanish without warning.  Use them with care.	*/
+      if (! macro
+	  && p != n
+	  && *p == '_')
+	*p = '-';
+    }
+  return n;
+}
+
+pointer
+ffi_sprintf (scheme *sc, const char *format, ...)
+{
+  pointer result;
+  va_list listp;
+  char *expression;
+  int size, written;
+
+  va_start (listp, format);
+  size = vsnprintf (NULL, 0, format, listp);
+  va_end (listp);
+
+  expression = xtrymalloc (size + 1);
+  if (expression == NULL)
+    return NULL;
+
+  va_start (listp, format);
+  written = vsnprintf (expression, size + 1, format, listp);
+  va_end (listp);
+
+  assert (size == written);
+
+  result = sc->vptr->mk_string (sc, expression);
+  xfree (expression);
+  return result;
+}
+
+void
+ffi_scheme_eval (scheme *sc, const char *format, ...)
+{
+  va_list listp;
+  char *expression;
+  int size, written;
+
+  va_start (listp, format);
+  size = vsnprintf (NULL, 0, format, listp);
+  va_end (listp);
+
+  expression = xtrymalloc (size + 1);
+  if (expression == NULL)
+    return;
+
+  va_start (listp, format);
+  written = vsnprintf (expression, size + 1, format, listp);
+  va_end (listp);
+
+  assert (size == written);
+
+  sc->vptr->load_string (sc, expression);
+  xfree (expression);
+}
+
+gpg_error_t
+ffi_init (scheme *sc, const char *argv0, const char *scriptname,
+          int argc, const char **argv)
+{
+  int i;
+  pointer args = sc->NIL;
+
+  /* bitwise arithmetic */
+  ffi_define_function (sc, logand);
+  ffi_define_function (sc, logior);
+  ffi_define_function (sc, logxor);
+  ffi_define_function (sc, lognot);
+
+  /* libc.  */
+  ffi_define_constant (sc, O_RDONLY);
+  ffi_define_constant (sc, O_WRONLY);
+  ffi_define_constant (sc, O_RDWR);
+  ffi_define_constant (sc, O_CREAT);
+  ffi_define_constant (sc, O_APPEND);
+#ifndef O_BINARY
+# define O_BINARY	0
+#endif
+#ifndef O_TEXT
+# define O_TEXT		0
+#endif
+  ffi_define_constant (sc, O_BINARY);
+  ffi_define_constant (sc, O_TEXT);
+  ffi_define_constant (sc, STDIN_FILENO);
+  ffi_define_constant (sc, STDOUT_FILENO);
+  ffi_define_constant (sc, STDERR_FILENO);
+  ffi_define_constant (sc, SEEK_SET);
+  ffi_define_constant (sc, SEEK_CUR);
+  ffi_define_constant (sc, SEEK_END);
+
+  ffi_define_function (sc, sleep);
+  ffi_define_function (sc, usleep);
+  ffi_define_function (sc, chdir);
+  ffi_define_function (sc, strerror);
+  ffi_define_function (sc, getenv);
+  ffi_define_function (sc, setenv);
+  ffi_define_function_name (sc, "_exit", exit);
+  ffi_define_function (sc, open);
+  ffi_define_function (sc, fdopen);
+  ffi_define_function (sc, close);
+  ffi_define_function (sc, seek);
+  ffi_define_function (sc, get_temp_path);
+  ffi_define_function_name (sc, "_mkdtemp", mkdtemp);
+  ffi_define_function (sc, unlink);
+  ffi_define_function (sc, unlink_recursively);
+  ffi_define_function (sc, rename);
+  ffi_define_function (sc, getcwd);
+  ffi_define_function (sc, mkdir);
+  ffi_define_function (sc, rmdir);
+  ffi_define_function (sc, get_isotime);
+  ffi_define_function (sc, get_time);
+  ffi_define_function (sc, getpid);
+
+  /* Random numbers.  */
+  ffi_define_function (sc, srandom);
+  ffi_define_function (sc, random);
+  ffi_define_function (sc, make_random_string);
+
+  /* Process management.  */
+  ffi_define_function (sc, spawn_process);
+  ffi_define_function (sc, spawn_process_fd);
+  ffi_define_function (sc, wait_process);
+  ffi_define_function (sc, wait_processes);
+  ffi_define_function (sc, pipe);
+  ffi_define_function (sc, inbound_pipe);
+  ffi_define_function (sc, outbound_pipe);
+
+  /* estream functions.  */
+  ffi_define_function_name (sc, "es-fclose", es_fclose);
+  ffi_define_function_name (sc, "es-read", es_read);
+  ffi_define_function_name (sc, "es-feof", es_feof);
+  ffi_define_function_name (sc, "es-write", es_write);
+
+  /* Test helper functions.  */
+  ffi_define_function (sc, file_equal);
+  ffi_define_function (sc, splice);
+  ffi_define_function (sc, string_index);
+  ffi_define_function (sc, string_rindex);
+  ffi_define_function_name (sc, "string-contains?", string_contains);
+
+  /* User interface.  */
+  ffi_define_function (sc, flush_stdio);
+  ffi_define_function (sc, prompt);
+
+  /* Configuration.  */
+  ffi_define_function_name (sc, "*verbose*", get_verbose);
+  ffi_define_function_name (sc, "*set-verbose!*", set_verbose);
+
+  ffi_define (sc, "*argv0*", sc->vptr->mk_string (sc, argv0));
+  ffi_define (sc, "*scriptname*", sc->vptr->mk_string (sc, scriptname));
+  for (i = argc - 1; i >= 0; i--)
+    {
+      pointer value = sc->vptr->mk_string (sc, argv[i]);
+      args = (sc->vptr->cons) (sc, value, args);
+    }
+  ffi_define (sc, "*args*", args);
+
+#if _WIN32
+  ffi_define (sc, "*pathsep*", sc->vptr->mk_character (sc, ';'));
+#else
+  ffi_define (sc, "*pathsep*", sc->vptr->mk_character (sc, ':'));
+#endif
+
+  ffi_define (sc, "*win32*",
+#if _WIN32
+              sc->T
+#else
+              sc->F
+#endif
+              );
+
+  ffi_define (sc, "*maintainer-mode*",
+#if MAINTAINER_MODE
+              sc->T
+#else
+              sc->F
+#endif
+              );
+
+  ffi_define (sc, "*run-all-tests*",
+#if RUN_ALL_TESTS
+              sc->T
+#else
+              sc->F
+#endif
+              );
+
+
+  ffi_define (sc, "*stdin*",
+              sc->vptr->mk_port_from_file (sc, stdin, port_input));
+  ffi_define (sc, "*stdout*",
+              sc->vptr->mk_port_from_file (sc, stdout, port_output));
+  ffi_define (sc, "*stderr*",
+              sc->vptr->mk_port_from_file (sc, stderr, port_output));
+
+  return 0;
+}
diff --git a/gpgscm/ffi.h b/gpgscm/ffi.h
new file mode 100644
index 0000000..eba6282
--- /dev/null
+++ b/gpgscm/ffi.h
@@ -0,0 +1,30 @@
+/* FFI interface for TinySCHEME.
+ *
+ * Copyright (C) 2016 g10 code GmbH
+ *
+ * This file is part of GnuPG.
+ *
+ * GnuPG is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * GnuPG is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef GPGSCM_FFI_H
+#define GPGSCM_FFI_H
+
+#include <gpg-error.h>
+#include "scheme.h"
+
+gpg_error_t ffi_init (scheme *sc, const char *argv0, const char *scriptname,
+		      int argc, const char **argv);
+
+#endif /* GPGSCM_FFI_H */
diff --git a/gpgscm/ffi.scm b/gpgscm/ffi.scm
new file mode 100644
index 0000000..051c2c2
--- /dev/null
+++ b/gpgscm/ffi.scm
@@ -0,0 +1,51 @@
+;; FFI interface for TinySCHEME.
+;;
+;; Copyright (C) 2016 g10 Code GmbH
+;;
+;; This file is part of GnuPG.
+;;
+;; GnuPG is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation; either version 3 of the License, or
+;; (at your option) any later version.
+;;
+;; GnuPG is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+;;
+;; You should have received a copy of the GNU General Public License
+;; along with this program; if not, see <http://www.gnu.org/licenses/>.
+
+;; Foreign function wrapper.  Expects F to return a list with the
+;; first element being the `error_t' value returned by the foreign
+;; function.  The error is thrown, or the cdr of the result is
+;; returned.
+(define (ffi-apply name f args)
+  (let ((result (apply f args)))
+    (cond
+     ((string? result)
+      (ffi-fail name args result))
+     ((not (= (car result) 0))
+      (ffi-fail name args (strerror (car result))))
+     ((and (= (car result) 0) (pair? (cdr result))) (cadr result))
+     ((= (car result) 0) '())
+     (else
+      (throw (list "Result violates FFI calling convention: " result))))))
+
+(define (ffi-fail name args message)
+  (let ((args' (open-output-string)))
+    (write (cons (string->symbol name) args) args')
+    (throw (get-output-string args') message)))
+
+;; Pseudo-definitions for foreign functions.  Evaluates to no code,
+;; but serves as documentation.
+(macro (ffi-define form))
+
+;; Runtime support.
+
+;; Low-level mechanism to terminate the process.
+(ffi-define (_exit status))
+
+;; Get the current time in seconds since the epoch.
+(ffi-define (get-time))
diff --git a/gpgscm/gnupg.scm b/gpgscm/gnupg.scm
new file mode 100644
index 0000000..5fcf9fd
--- /dev/null
+++ b/gpgscm/gnupg.scm
@@ -0,0 +1,44 @@
+;; Common definitions for executing gpg and related tools.
+;;
+;; Copyright (C) 2016, 2017 g10 Code GmbH
+;;
+;; This file is part of GnuPG.
+;;
+;; GnuPG is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation; either version 3 of the License, or
+;; (at your option) any later version.
+;;
+;; GnuPG is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+;;
+;; You should have received a copy of the GNU General Public License
+;; along with this program; if not, see <http://www.gnu.org/licenses/>.
+
+;; Evaluate a sequence of expressions with the given home directory.
+(define-macro (with-home-directory gnupghome . expressions)
+  (let ((original-home-directory (gensym)))
+    `(let ((,original-home-directory (getenv "GNUPGHOME")))
+       (dynamic-wind
+	   (lambda () (setenv "GNUPGHOME" ,gnupghome #t))
+	   (lambda () ,@expressions)
+	   (lambda () (setenv "GNUPGHOME" ,original-home-directory #t))))))
+
+;; Evaluate a sequence of expressions with an ephemeral home
+;; directory.
+(define-macro (with-ephemeral-home-directory setup-fn . expressions)
+  (let ((original-home-directory (gensym))
+	(ephemeral-home-directory (gensym))
+	(setup (gensym)))
+    `(let ((,original-home-directory (getenv "GNUPGHOME"))
+	   (,ephemeral-home-directory (mkdtemp))
+	   (,setup (delay (,setup-fn))))
+       (finally (unlink-recursively ,ephemeral-home-directory)
+	 (dynamic-wind
+	     (lambda ()
+	       (setenv "GNUPGHOME" ,ephemeral-home-directory #t)
+	       (with-working-directory ,ephemeral-home-directory (force ,setup)))
+	     (lambda () ,@expressions)
+	     (lambda () (setenv "GNUPGHOME" ,original-home-directory #t)))))))
diff --git a/gpgscm/init.scm b/gpgscm/init.scm
new file mode 100644
index 0000000..66bec0f
--- /dev/null
+++ b/gpgscm/init.scm
@@ -0,0 +1,823 @@
+;    Initialization file for TinySCHEME 1.41
+
+; Per R5RS, up to four deep compositions should be defined
+(define (caar x) (car (car x)))
+(define (cadr x) (car (cdr x)))
+(define (cdar x) (cdr (car x)))
+(define (cddr x) (cdr (cdr x)))
+(define (caaar x) (car (car (car x))))
+(define (caadr x) (car (car (cdr x))))
+(define (cadar x) (car (cdr (car x))))
+(define (caddr x) (car (cdr (cdr x))))
+(define (cdaar x) (cdr (car (car x))))
+(define (cdadr x) (cdr (car (cdr x))))
+(define (cddar x) (cdr (cdr (car x))))
+(define (cdddr x) (cdr (cdr (cdr x))))
+(define (caaaar x) (car (car (car (car x)))))
+(define (caaadr x) (car (car (car (cdr x)))))
+(define (caadar x) (car (car (cdr (car x)))))
+(define (caaddr x) (car (car (cdr (cdr x)))))
+(define (cadaar x) (car (cdr (car (car x)))))
+(define (cadadr x) (car (cdr (car (cdr x)))))
+(define (caddar x) (car (cdr (cdr (car x)))))
+(define (cadddr x) (car (cdr (cdr (cdr x)))))
+(define (cdaaar x) (cdr (car (car (car x)))))
+(define (cdaadr x) (cdr (car (car (cdr x)))))
+(define (cdadar x) (cdr (car (cdr (car x)))))
+(define (cdaddr x) (cdr (car (cdr (cdr x)))))
+(define (cddaar x) (cdr (cdr (car (car x)))))
+(define (cddadr x) (cdr (cdr (car (cdr x)))))
+(define (cdddar x) (cdr (cdr (cdr (car x)))))
+(define (cddddr x) (cdr (cdr (cdr (cdr x)))))
+
+;;;; Utility to ease macro creation
+(define (macro-expand form)
+     ((eval (get-closure-code (eval (car form)))) form))
+
+(define (macro-expand-all form)
+   (if (macro? form)
+      (macro-expand-all (macro-expand form))
+      form))
+
+(define *compile-hook* macro-expand-all)
+
+
+(macro (unless form)
+     `(if (not ,(cadr form)) (begin ,@(cddr form))))
+
+(macro (when form)
+     `(if ,(cadr form) (begin ,@(cddr form))))
+
+; DEFINE-MACRO Contributed by Andy Gaynor
+(macro (define-macro dform)
+  (if (symbol? (cadr dform))
+    `(macro ,@(cdr dform))
+    (let ((form (gensym)))
+      `(macro (,(caadr dform) ,form)
+         (apply (lambda ,(cdadr dform) ,@(cddr dform)) (cdr ,form))))))
+
+; Utilities for math. Notice that inexact->exact is primitive,
+; but exact->inexact is not.
+(define exact? integer?)
+(define (inexact? x) (and (real? x) (not (integer? x))))
+(define (even? n) (= (remainder n 2) 0))
+(define (odd? n) (not (= (remainder n 2) 0)))
+(define (zero? n) (= n 0))
+(define (positive? n) (> n 0))
+(define (negative? n) (< n 0))
+(define complex? number?)
+(define rational? real?)
+(define (abs n) (if (>= n 0) n (- n)))
+(define (exact->inexact n) (* n 1.0))
+(define (<> n1 n2) (not (= n1 n2)))
+
+; min and max must return inexact if any arg is inexact; use (+ n 0.0)
+(define (max . lst)
+  (foldr (lambda (a b)
+           (if (> a b)
+             (if (exact? b) a (+ a 0.0))
+             (if (exact? a) b (+ b 0.0))))
+         (car lst) (cdr lst)))
+(define (min . lst)
+  (foldr (lambda (a b)
+           (if (< a b)
+             (if (exact? b) a (+ a 0.0))
+             (if (exact? a) b (+ b 0.0))))
+         (car lst) (cdr lst)))
+
+(define (succ x) (+ x 1))
+(define (pred x) (- x 1))
+(define gcd
+  (lambda a
+    (if (null? a)
+      0
+      (let ((aa (abs (car a)))
+            (bb (abs (cadr a))))
+         (if (= bb 0)
+              aa
+              (gcd bb (remainder aa bb)))))))
+(define lcm
+  (lambda a
+    (if (null? a)
+      1
+      (let ((aa (abs (car a)))
+            (bb (abs (cadr a))))
+         (if (or (= aa 0) (= bb 0))
+             0
+             (abs (* (quotient aa (gcd aa bb)) bb)))))))
+
+
+(define (string . charlist)
+     (list->string charlist))
+
+(define (list->string charlist)
+     (let* ((len (length charlist))
+            (newstr (make-string len))
+            (fill-string!
+               (lambda (str i len charlist)
+                    (if (= i len)
+                         str
+                         (begin (string-set! str i (car charlist))
+                         (fill-string! str (+ i 1) len (cdr charlist)))))))
+          (fill-string! newstr 0 len charlist)))
+
+(define (string-fill! s e)
+     (let ((n (string-length s)))
+          (let loop ((i 0))
+               (if (= i n)
+                    s
+                    (begin (string-set! s i e) (loop (succ i)))))))
+
+(define (string->list s)
+     (let loop ((n (pred (string-length s))) (l '()))
+          (if (= n -1)
+               l
+               (loop (pred n) (cons (string-ref s n) l)))))
+
+(define (string-copy str)
+     (string-append str))
+
+(define (string->anyatom str pred)
+     (let* ((a (string->atom str)))
+       (if (pred a) a
+         (error "string->xxx: not a xxx" a))))
+
+(define (string->number str . base)
+    (let ((n (string->atom str (if (null? base) 10 (car base)))))
+        (if (number? n) n #f)))
+
+(define (anyatom->string n pred)
+  (if (pred n)
+      (atom->string n)
+      (error "xxx->string: not a xxx" n)))
+
+(define (number->string n . base)
+    (atom->string n (if (null? base) 10 (car base))))
+
+
+(define (char-cmp? cmp a b)
+     (cmp (char->integer a) (char->integer b)))
+(define (char-ci-cmp? cmp a b)
+     (cmp (char->integer (char-downcase a)) (char->integer (char-downcase b))))
+
+(define (char=? a b) (char-cmp? = a b))
+(define (char<? a b) (char-cmp? < a b))
+(define (char>? a b) (char-cmp? > a b))
+(define (char<=? a b) (char-cmp? <= a b))
+(define (char>=? a b) (char-cmp? >= a b))
+
+(define (char-ci=? a b) (char-ci-cmp? = a b))
+(define (char-ci<? a b) (char-ci-cmp? < a b))
+(define (char-ci>? a b) (char-ci-cmp? > a b))
+(define (char-ci<=? a b) (char-ci-cmp? <= a b))
+(define (char-ci>=? a b) (char-ci-cmp? >= a b))
+
+; Note the trick of returning (cmp x y)
+(define (string-cmp? chcmp cmp a b)
+     (let ((na (string-length a)) (nb (string-length b)))
+          (let loop ((i 0))
+               (cond
+                    ((= i na)
+                         (if (= i nb) (cmp 0 0) (cmp 0 1)))
+                    ((= i nb)
+                         (cmp 1 0))
+                    ((chcmp = (string-ref a i) (string-ref b i))
+                         (loop (succ i)))
+                    (else
+                         (chcmp cmp (string-ref a i) (string-ref b i)))))))
+
+
+(define (string=? a b) (string-cmp? char-cmp? = a b))
+(define (string<? a b) (string-cmp? char-cmp? < a b))
+(define (string>? a b) (string-cmp? char-cmp? > a b))
+(define (string<=? a b) (string-cmp? char-cmp? <= a b))
+(define (string>=? a b) (string-cmp? char-cmp? >= a b))
+
+(define (string-ci=? a b) (string-cmp? char-ci-cmp? = a b))
+(define (string-ci<? a b) (string-cmp? char-ci-cmp? < a b))
+(define (string-ci>? a b) (string-cmp? char-ci-cmp? > a b))
+(define (string-ci<=? a b) (string-cmp? char-ci-cmp? <= a b))
+(define (string-ci>=? a b) (string-cmp? char-ci-cmp? >= a b))
+
+(define (list . x) x)
+
+(define (foldr f x lst)
+     (if (null? lst)
+          x
+          (foldr f (f x (car lst)) (cdr lst))))
+
+(define (unzip1-with-cdr . lists)
+  (unzip1-with-cdr-iterative lists '() '()))
+
+(define (unzip1-with-cdr-iterative lists cars cdrs)
+  (if (null? lists)
+      (cons cars cdrs)
+      (let ((car1 (caar lists))
+            (cdr1 (cdar lists)))
+        (unzip1-with-cdr-iterative
+          (cdr lists)
+          (append cars (list car1))
+          (append cdrs (list cdr1))))))
+
+(define (map proc . lists)
+  (if (null? lists)
+      (apply proc)
+      (if (null? (car lists))
+        '()
+        (let* ((unz (apply unzip1-with-cdr lists))
+               (cars (car unz))
+               (cdrs (cdr unz)))
+          (cons (apply proc cars) (apply map (cons proc cdrs)))))))
+
+(define (for-each proc . lists)
+  (if (null? lists)
+      (apply proc)
+      (if (null? (car lists))
+        #t
+        (let* ((unz (apply unzip1-with-cdr lists))
+               (cars (car unz))
+               (cdrs (cdr unz)))
+          (apply proc cars) (apply map (cons proc cdrs))))))
+
+(define (list-tail x k)
+    (if (zero? k)
+        x
+        (list-tail (cdr x) (- k 1))))
+
+(define (list-ref x k)
+    (car (list-tail x k)))
+
+(define (last-pair x)
+    (if (pair? (cdr x))
+        (last-pair (cdr x))
+        x))
+
+(define (head stream) (car stream))
+
+(define (tail stream) (force (cdr stream)))
+
+(define (vector-equal? x y)
+     (and (vector? x) (vector? y) (= (vector-length x) (vector-length y))
+          (let ((n (vector-length x)))
+               (let loop ((i 0))
+                    (if (= i n)
+                         #t
+                         (and (equal? (vector-ref x i) (vector-ref y i))
+                              (loop (succ i))))))))
+
+(define (list->vector x)
+     (apply vector x))
+
+(define (vector-fill! v e)
+     (let ((n (vector-length v)))
+          (let loop ((i 0))
+               (if (= i n)
+                    v
+                    (begin (vector-set! v i e) (loop (succ i)))))))
+
+(define (vector->list v)
+     (let loop ((n (pred (vector-length v))) (l '()))
+          (if (= n -1)
+               l
+               (loop (pred n) (cons (vector-ref v n) l)))))
+
+;; The following quasiquote macro is due to Eric S. Tiedemann.
+;;   Copyright 1988 by Eric S. Tiedemann; all rights reserved.
+;;
+;; Subsequently modified to handle vectors: D. Souflis
+
+(macro
+ quasiquote
+ (lambda (l)
+   (define (mcons f l r)
+     (if (and (pair? r)
+              (eq? (car r) 'quote)
+              (eq? (car (cdr r)) (cdr f))
+              (pair? l)
+              (eq? (car l) 'quote)
+              (eq? (car (cdr l)) (car f)))
+         (if (or (procedure? f) (number? f) (string? f))
+               f
+               (list 'quote f))
+         (if (eqv? l vector)
+               (apply l (eval r))
+               (list 'cons l r)
+               )))
+   (define (mappend f l r)
+     (if (or (null? (cdr f))
+             (and (pair? r)
+                  (eq? (car r) 'quote)
+                  (eq? (car (cdr r)) '())))
+         l
+         (list 'append l r)))
+   (define (foo level form)
+     (cond ((not (pair? form))
+               (if (or (procedure? form) (number? form) (string? form))
+                    form
+                    (list 'quote form))
+               )
+           ((eq? 'quasiquote (car form))
+            (mcons form ''quasiquote (foo (+ level 1) (cdr form))))
+           (#t (if (zero? level)
+                   (cond ((eq? (car form) 'unquote) (car (cdr form)))
+                         ((eq? (car form) 'unquote-splicing)
+                          (error "Unquote-splicing wasn't in a list:"
+                                 form))
+                         ((and (pair? (car form))
+                               (eq? (car (car form)) 'unquote-splicing))
+                          (mappend form (car (cdr (car form)))
+                                   (foo level (cdr form))))
+                         (#t (mcons form (foo level (car form))
+                                         (foo level (cdr form)))))
+                   (cond ((eq? (car form) 'unquote)
+                          (mcons form ''unquote (foo (- level 1)
+                                                     (cdr form))))
+                         ((eq? (car form) 'unquote-splicing)
+                          (mcons form ''unquote-splicing
+                                      (foo (- level 1) (cdr form))))
+                         (#t (mcons form (foo level (car form))
+                                         (foo level (cdr form)))))))))
+   (foo 0 (car (cdr l)))))
+
+;;;;;Helper for the dynamic-wind definition.  By Tom Breton (Tehom)
+(define (shared-tail x y)
+   (let ((len-x (length x))
+         (len-y (length y)))
+      (define (shared-tail-helper x y)
+         (if
+            (eq? x y)
+            x
+            (shared-tail-helper (cdr x) (cdr y))))
+
+      (cond
+         ((> len-x len-y)
+            (shared-tail-helper
+               (list-tail x (- len-x len-y))
+               y))
+         ((< len-x len-y)
+            (shared-tail-helper
+               x
+               (list-tail y (- len-y len-x))))
+         (#t (shared-tail-helper x y)))))
+
+;;;;;Dynamic-wind by Tom Breton (Tehom)
+
+;;Guarded because we must only eval this once, because doing so
+;;redefines call/cc in terms of old call/cc
+(unless (defined? 'dynamic-wind)
+   (let
+      ;;These functions are defined in the context of a private list of
+      ;;pairs of before/after procs.
+      (  (*active-windings* '())
+         ;;We'll define some functions into the larger environment, so
+         ;;we need to know it.
+         (outer-env (current-environment)))
+
+      ;;Poor-man's structure operations
+      (define before-func car)
+      (define after-func  cdr)
+      (define make-winding cons)
+
+      ;;Manage active windings
+      (define (activate-winding! new)
+         ((before-func new))
+         (set! *active-windings* (cons new *active-windings*)))
+      (define (deactivate-top-winding!)
+         (let ((old-top (car *active-windings*)))
+            ;;Remove it from the list first so it's not active during its
+            ;;own exit.
+            (set! *active-windings* (cdr *active-windings*))
+            ((after-func old-top))))
+
+      (define (set-active-windings! new-ws)
+         (unless (eq? new-ws *active-windings*)
+            (let ((shared (shared-tail new-ws *active-windings*)))
+
+               ;;Define the looping functions.
+               ;;Exit the old list.  Do deeper ones last.  Don't do
+               ;;any shared ones.
+               (define (pop-many)
+                  (unless (eq? *active-windings* shared)
+                     (deactivate-top-winding!)
+                     (pop-many)))
+               ;;Enter the new list.  Do deeper ones first so that the
+               ;;deeper windings will already be active.  Don't do any
+               ;;shared ones.
+               (define (push-many new-ws)
+                  (unless (eq? new-ws shared)
+                     (push-many (cdr new-ws))
+                     (activate-winding! (car new-ws))))
+
+               ;;Do it.
+               (pop-many)
+               (push-many new-ws))))
+
+      ;;The definitions themselves.
+      (eval
+         `(define call-with-current-continuation
+             ;;It internally uses the built-in call/cc, so capture it.
+             ,(let ((old-c/cc call-with-current-continuation))
+                 (lambda (func)
+                    ;;Use old call/cc to get the continuation.
+                    (old-c/cc
+                       (lambda (continuation)
+                          ;;Call func with not the continuation itself
+                          ;;but a procedure that adjusts the active
+                          ;;windings to what they were when we made
+                          ;;this, and only then calls the
+                          ;;continuation.
+                          (func
+                             (let ((current-ws *active-windings*))
+                                (lambda (x)
+                                   (set-active-windings! current-ws)
+                                   (continuation x)))))))))
+         outer-env)
+      ;;We can't just say "define (dynamic-wind before thunk after)"
+      ;;because the lambda it's defined to lives in this environment,
+      ;;not in the global environment.
+      (eval
+         `(define dynamic-wind
+             ,(lambda (before thunk after)
+                 ;;Make a new winding
+                 (activate-winding! (make-winding before after))
+                 (let ((result (thunk)))
+                    ;;Get rid of the new winding.
+                    (deactivate-top-winding!)
+                    ;;The return value is that of thunk.
+                    result)))
+         outer-env)))
+
+(define call/cc call-with-current-continuation)
+
+
+;;;;; atom? and equal? written by a.k
+
+;;;; atom?
+(define (atom? x)
+  (not (pair? x)))
+
+;;;;    equal?
+(define (equal? x y)
+     (cond
+          ((pair? x)
+               (and (pair? y)
+                    (equal? (car x) (car y))
+                    (equal? (cdr x) (cdr y))))
+          ((vector? x)
+               (and (vector? y) (vector-equal? x y)))
+          ((string? x)
+               (and (string? y) (string=? x y)))
+          (else (eqv? x y))))
+
+;;;; (do ((var init inc) ...) (endtest result ...) body ...)
+;;
+(macro do
+  (lambda (do-macro)
+    (apply (lambda (do vars endtest . body)
+             (let ((do-loop (gensym)))
+               `(letrec ((,do-loop
+                           (lambda ,(map (lambda (x)
+                                           (if (pair? x) (car x) x))
+                                      `,vars)
+                             (if ,(car endtest)
+                               (begin ,@(cdr endtest))
+                               (begin
+                                 ,@body
+                                 (,do-loop
+                                   ,@(map (lambda (x)
+                                            (cond
+                                              ((not (pair? x)) x)
+                                              ((< (length x) 3) (car x))
+                                              (else (car (cdr (cdr x))))))
+                                       `,vars)))))))
+                  (,do-loop
+                    ,@(map (lambda (x)
+                             (if (and (pair? x) (cdr x))
+                               (car (cdr x))
+                               '()))
+                        `,vars)))))
+      do-macro)))
+
+;;;; generic-member
+(define (generic-member cmp obj lst)
+  (cond
+    ((null? lst) #f)
+    ((cmp obj (car lst)) lst)
+    (else (generic-member cmp obj (cdr lst)))))
+
+(define (memq obj lst)
+     (generic-member eq? obj lst))
+(define (memv obj lst)
+     (generic-member eqv? obj lst))
+(define (member obj lst)
+     (generic-member equal? obj lst))
+
+;;;; generic-assoc
+(define (generic-assoc cmp obj alst)
+     (cond
+          ((null? alst) #f)
+          ((cmp obj (caar alst)) (car alst))
+          (else (generic-assoc cmp obj (cdr alst)))))
+
+(define (assq obj alst)
+     (generic-assoc eq? obj alst))
+(define (assv obj alst)
+     (generic-assoc eqv? obj alst))
+(define (assoc obj alst)
+     (generic-assoc equal? obj alst))
+
+(define (acons x y z) (cons (cons x y) z))
+
+;;;; Handy for imperative programs
+;;;; Used as: (define-with-return (foo x y) .... (return z) ...)
+(macro (define-with-return form)
+     `(define ,(cadr form)
+          (call/cc (lambda (return) ,@(cddr form)))))
+
+;; Print the given history.
+(define (vm-history-print history)
+  (let loop ((n 0) (skip 0) (frames history))
+    (cond
+     ((null? frames)
+      #t)
+     ((> skip 0)
+      (loop 0 (- skip 1) (cdr frames)))
+     (else
+      (let ((f (car frames)))
+	(display n)
+	(display ": ")
+	(let ((tag (get-tag f)))
+	  (when (and (pair? tag) (string? (car tag)) (number? (cdr tag)))
+		(display (basename (car tag)))
+		(display ":")
+		(display (+ 1 (cdr tag)))
+		(display ": ")))
+	(write f))
+	(newline)
+	(loop (+ n 1) skip (cdr frames))))))
+
+;;;; Simple exception handling
+;
+;    Exceptions are caught as follows:
+;
+;         (catch (do-something to-recover and-return meaningful-value)
+;              (if-something goes-wrong)
+;              (with-these calls))
+;
+;    "Catch" establishes a scope spanning multiple call-frames until
+;    another "catch" is encountered.  Within the recovery expression
+;    the thrown exception is bound to *error*.  Errors can be rethrown
+;    using (rethrow *error*).
+;
+;    Finalization can be expressed using "finally":
+;
+;         (finally (finalize-something called-purely-for side-effects)
+;              (whether-or-not something goes-wrong)
+;              (with-these calls))
+;
+;    The final expression is executed purely for its side-effects,
+;    both when the function exits successfully, and when an exception
+;    is thrown.
+;
+;    Exceptions are thrown with:
+;
+;         (throw "message")
+;
+;    If used outside a (catch ...), reverts to (error "message")
+
+(define *handlers* (list))
+
+(define (push-handler proc)
+     (set! *handlers* (cons proc *handlers*)))
+
+(define (pop-handler)
+     (let ((h (car *handlers*)))
+          (set! *handlers* (cdr *handlers*))
+          h))
+
+(define (more-handlers?)
+     (pair? *handlers*))
+
+;; This throws an exception.
+(define (throw message . args)
+  (throw' message args (cdr (*vm-history*))))
+
+;; This is used by the vm to throw exceptions.
+(define (throw' message args history)
+  (cond
+   ((and args (list? args) (= 2 (length args))
+	 (equal? *interpreter-exit* (car args)))
+    (*run-atexit-handlers*)
+    (quit (cadr args)))
+   ((more-handlers?)
+    ((pop-handler) message args history))
+   (else
+    (display message)
+    (when (and args (not (null? args)))
+	  (display ": ")
+	  (if (and (pair? args) (string? (car args)))
+	      (begin (display (car args))
+		     (unless (null? (cdr args))
+			     (newline)
+			     (write (cdr args))))
+	      (write args)))
+    (newline)
+    (vm-history-print history)
+    (quit 1))))
+
+;; Convenience function to rethrow the error.
+(define (rethrow e)
+  (apply throw' e))
+
+(macro (catch form)
+     (let ((label (gensym)))
+          `(call/cc (lambda (**exit**)
+               (push-handler (lambda *error* (**exit** ,(cadr form))))
+               (let ((,label (begin ,@(cddr form))))
+                    (pop-handler)
+                    ,label)))))
+
+(define-macro (finally final-expression . expressions)
+  (let ((result (gensym)))
+    `(let ((,result (catch (begin ,final-expression (rethrow *error*))
+			   ,@expressions)))
+       ,final-expression
+       ,result)))
+
+;; Make the vm use throw'.
+(define *error-hook* throw')
+
+
+
+;; High-level mechanism to terminate the process is to throw an error
+;; of the form (*interpreter-exit* status).  This gives automatic
+;; resource management a chance to clean up.
+(define *interpreter-exit* (gensym))
+
+;; Terminate the process returning STATUS to the parent.
+(define (exit status)
+  (throw "interpreter exit" *interpreter-exit* status))
+
+;; A list of functions run at interpreter shutdown.
+(define *atexit-handlers* (list))
+
+;; Execute all these functions.
+(define (*run-atexit-handlers*)
+  (unless (null? *atexit-handlers*)
+	  (let ((proc (car *atexit-handlers*)))
+	    ;; Drop proc from the list so that it will not get
+	    ;; executed again even if it raises an exception.
+	    (set! *atexit-handlers* (cdr *atexit-handlers*))
+	    (proc)
+	    (*run-atexit-handlers*))))
+
+;; Register a function to be run at interpreter shutdown.
+(define (atexit proc)
+  (set! *atexit-handlers* (cons proc *atexit-handlers*)))
+
+
+
+;;;;; Definition of MAKE-ENVIRONMENT, to be used with two-argument EVAL
+
+(macro (make-environment form)
+     `(apply (lambda ()
+               ,@(cdr form)
+               (current-environment))))
+
+(define-macro (eval-polymorphic x . envl)
+  (display envl)
+  (let* ((env (if (null? envl) (current-environment) (eval (car envl))))
+         (xval (eval x env)))
+    (if (closure? xval)
+      (make-closure (get-closure-code xval) env)
+      xval)))
+
+; Redefine this if you install another package infrastructure
+; Also redefine 'package'
+(define *colon-hook* eval)
+
+(macro (package form)
+  `(apply (lambda ()
+	    ,@(cdr form)
+	    (current-environment))))
+
+(define-macro (export name . expressions)
+  `(define ,name
+     (begin
+       ,@expressions)))
+
+;;;;; I/O
+
+(define (input-output-port? p)
+     (and (input-port? p) (output-port? p)))
+
+(define (close-port p)
+     (cond
+          ((input-output-port? p) (close-input-port p) (close-output-port p))
+          ((input-port? p) (close-input-port p))
+          ((output-port? p) (close-output-port p))
+          (else (throw "Not a port" p))))
+
+(define (call-with-input-file s p)
+     (let ((inport (open-input-file s)))
+          (if (eq? inport #f)
+               #f
+               (let ((res (p inport)))
+                    (close-input-port inport)
+                    res))))
+
+(define (call-with-output-file s p)
+     (let ((outport (open-output-file s)))
+          (if (eq? outport #f)
+               #f
+               (let ((res (p outport)))
+                    (close-output-port outport)
+                    res))))
+
+(define (with-input-from-file s p)
+     (let ((inport (open-input-file s)))
+          (if (eq? inport #f)
+               #f
+               (let ((prev-inport (current-input-port)))
+                    (set-input-port inport)
+                    (let ((res (p)))
+                         (close-input-port inport)
+                         (set-input-port prev-inport)
+                         res)))))
+
+(define (with-output-to-file s p)
+     (let ((outport (open-output-file s)))
+          (if (eq? outport #f)
+               #f
+               (let ((prev-outport (current-output-port)))
+                    (set-output-port outport)
+                    (let ((res (p)))
+                         (close-output-port outport)
+                         (set-output-port prev-outport)
+                         res)))))
+
+(define (with-input-output-from-to-files si so p)
+     (let ((inport (open-input-file si))
+           (outport (open-input-file so)))
+          (if (not (and inport outport))
+               (begin
+                    (close-input-port inport)
+                    (close-output-port outport)
+                    #f)
+               (let ((prev-inport (current-input-port))
+                     (prev-outport (current-output-port)))
+                    (set-input-port inport)
+                    (set-output-port outport)
+                    (let ((res (p)))
+                         (close-input-port inport)
+                         (close-output-port outport)
+                         (set-input-port prev-inport)
+                         (set-output-port prev-outport)
+                         res)))))
+
+; Random number generator (maximum cycle)
+(define *seed* 1)
+(define (random-next)
+     (let* ((a 16807) (m 2147483647) (q (quotient m a)) (r (modulo m a)))
+          (set! *seed*
+               (-   (* a (- *seed*
+                         (* (quotient *seed* q) q)))
+                    (* (quotient *seed* q) r)))
+          (if (< *seed* 0) (set! *seed* (+ *seed* m)))
+          *seed*))
+;; SRFI-0
+;; COND-EXPAND
+;; Implemented as a macro
+(define *features* '(srfi-0 tinyscheme))
+
+(define-macro (cond-expand . cond-action-list)
+  (cond-expand-runtime cond-action-list))
+
+(define (cond-expand-runtime cond-action-list)
+  (if (null? cond-action-list)
+      #t
+      (if (cond-eval (caar cond-action-list))
+          `(begin ,@(cdar cond-action-list))
+          (cond-expand-runtime (cdr cond-action-list)))))
+
+(define (cond-eval-and cond-list)
+  (foldr (lambda (x y) (and (cond-eval x) (cond-eval y))) #t cond-list))
+
+(define (cond-eval-or cond-list)
+  (foldr (lambda (x y) (or (cond-eval x) (cond-eval y))) #f cond-list))
+
+(define (cond-eval condition)
+  (cond
+    ((symbol? condition)
+       (if (member condition *features*) #t #f))
+    ((eq? condition #t) #t)
+    ((eq? condition #f) #f)
+    (else (case (car condition)
+            ((and) (cond-eval-and (cdr condition)))
+            ((or) (cond-eval-or (cdr condition)))
+            ((not) (if (not (null? (cddr condition)))
+                     (error "cond-expand : 'not' takes 1 argument")
+                     (not (cond-eval (cadr condition)))))
+            (else (error "cond-expand : unknown operator" (car condition)))))))
+
+(gc-verbose #f)
diff --git a/gpgscm/lib.scm b/gpgscm/lib.scm
new file mode 100644
index 0000000..258f692
--- /dev/null
+++ b/gpgscm/lib.scm
@@ -0,0 +1,307 @@
+;; Additional library functions for TinySCHEME.
+;;
+;; Copyright (C) 2016 g10 Code GmbH
+;;
+;; This file is part of GnuPG.
+;;
+;; GnuPG is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation; either version 3 of the License, or
+;; (at your option) any later version.
+;;
+;; GnuPG is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+;;
+;; You should have received a copy of the GNU General Public License
+;; along with this program; if not, see <http://www.gnu.org/licenses/>.
+
+(macro (assert form)
+  (let ((tag (get-tag form)))
+    `(if (not ,(cadr form))
+	 (throw ,(if (and (pair? tag) (string? (car tag)) (number? (cdr tag)))
+		     `(string-append ,(car tag) ":"
+				     ,(number->string (+ 1 (cdr tag)))
+				     ": Assertion failed: ")
+		     "Assertion failed: ")
+		(quote ,(cadr form))))))
+(assert #t)
+(assert (not #f))
+
+;; Trace displays and returns the given value.  A debugging aid.
+(define (trace x)
+  (display x)
+  (newline)
+  x)
+
+;; Stringification.
+(define (stringify expression)
+  (let ((p (open-output-string)))
+    (write expression p)
+    (get-output-string p)))
+
+(define (filter pred lst)
+  (cond ((null? lst) '())
+        ((pred (car lst))
+         (cons (car lst) (filter pred (cdr lst))))
+        (else (filter pred (cdr lst)))))
+
+(define (any p l)
+  (cond ((null? l) #f)
+        ((p (car l)) #t)
+        (else (any p (cdr l)))))
+
+(define (all p l)
+  (cond ((null? l) #t)
+        ((not (p (car l))) #f)
+        (else (all p (cdr l)))))
+
+;; Return the first element of a list.
+(define first car)
+
+;; Return the last element of a list.
+(define (last lst)
+  (if (null? (cdr lst))
+      (car lst)
+      (last (cdr lst))))
+
+;; Compute the powerset of a list.
+(define (powerset set)
+  (if (null? set)
+      '(())
+      (let ((rst (powerset (cdr set))))
+        (append (map (lambda (x) (cons (car set) x))
+                     rst)
+                rst))))
+
+;; Is PREFIX a prefix of S?
+(define (string-prefix? s prefix)
+  (and (>= (string-length s) (string-length prefix))
+       (string=? prefix (substring s 0 (string-length prefix)))))
+(assert (string-prefix? "Scheme" "Sch"))
+
+;; Is SUFFIX a suffix of S?
+(define (string-suffix? s suffix)
+  (and (>= (string-length s) (string-length suffix))
+       (string=? suffix (substring s (- (string-length s)
+					(string-length suffix))
+				   (string-length s)))))
+(assert (string-suffix? "Scheme" "eme"))
+
+;; Locate the first occurrence of needle in haystack starting at offset.
+(ffi-define (string-index haystack needle [offset]))
+(assert (= 2 (string-index "Hallo" #\l)))
+(assert (= 3 (string-index "Hallo" #\l 3)))
+(assert (equal? #f (string-index "Hallo" #\.)))
+
+;; Locate the last occurrence of needle in haystack starting at offset.
+(ffi-define (string-rindex haystack needle [offset]))
+(assert (= 3 (string-rindex "Hallo" #\l)))
+(assert (equal? #f (string-rindex "Hallo" #\a 2)))
+(assert (equal? #f (string-rindex "Hallo" #\.)))
+
+;; Split HAYSTACK at each character that makes PREDICATE true at most
+;; N times.
+(define (string-split-pln haystack predicate lookahead n)
+  (let ((length (string-length haystack)))
+    (define (split acc offset n)
+      (if (>= offset length)
+	  (reverse! acc)
+	  (let ((i (lookahead haystack offset)))
+	    (if (or (eq? i #f) (= 0 n))
+		(reverse! (cons (substring haystack offset length) acc))
+		(split (cons (substring haystack offset i) acc)
+		       (+ i 1) (- n 1))))))
+    (split '() 0 n)))
+
+(define (string-indexp haystack offset predicate)
+  (cond
+   ((= (string-length haystack) offset)
+    #f)
+   ((predicate (string-ref haystack offset))
+    offset)
+   (else
+    (string-indexp haystack (+ 1 offset) predicate))))
+
+;; Split HAYSTACK at each character that makes PREDICATE true at most
+;; N times.
+(define (string-splitp haystack predicate n)
+  (string-split-pln haystack predicate
+		    (lambda (haystack offset)
+		      (string-indexp haystack offset predicate))
+		    n))
+(assert (equal? '("a" "b") (string-splitp "a b" char-whitespace? -1)))
+(assert (equal? '("a" "b") (string-splitp "a\tb" char-whitespace? -1)))
+(assert (equal? '("a" "" "b") (string-splitp "a \tb" char-whitespace? -1)))
+
+;; Split haystack at delimiter at most n times.
+(define (string-splitn haystack delimiter n)
+  (string-split-pln haystack
+		    (lambda (c) (char=? c delimiter))
+		    (lambda (haystack offset)
+		      (string-index haystack delimiter offset))
+		    n))
+(assert (= 2 (length (string-splitn "foo:bar:baz" #\: 1))))
+(assert (string=? "foo" (car (string-splitn "foo:bar:baz" #\: 1))))
+(assert (string=? "bar:baz" (cadr (string-splitn "foo:bar:baz" #\: 1))))
+
+;; Split haystack at delimiter.
+(define (string-split haystack delimiter)
+  (string-splitn haystack delimiter -1))
+(assert (= 3 (length (string-split "foo:bar:baz" #\:))))
+(assert (string=? "foo" (car (string-split "foo:bar:baz" #\:))))
+(assert (string=? "bar" (cadr (string-split "foo:bar:baz" #\:))))
+(assert (string=? "baz" (caddr (string-split "foo:bar:baz" #\:))))
+
+;; Split haystack at newlines.
+(define (string-split-newlines haystack)
+  (if *win32*
+      (map (lambda (line) (if (string-suffix? line "\r")
+			      (substring line 0 (- (string-length line) 1))
+			      line))
+	   (string-split haystack #\newline))
+      (string-split haystack #\newline)))
+
+;; Trim the prefix of S containing only characters that make PREDICATE
+;; true.
+(define (string-ltrim predicate s)
+  (if (string=? s "")
+      ""
+      (let loop ((s' (string->list s)))
+	(if (predicate (car s'))
+	    (loop (cdr s'))
+	    (list->string s')))))
+(assert (string=? "" (string-ltrim char-whitespace? "")))
+(assert (string=? "foo" (string-ltrim char-whitespace? "  foo")))
+
+;; Trim the suffix of S containing only characters that make PREDICATE
+;; true.
+(define (string-rtrim predicate s)
+  (if (string=? s "")
+      ""
+      (let loop ((s' (reverse! (string->list s))))
+	(if (predicate (car s'))
+	    (loop (cdr s'))
+	    (list->string (reverse! s'))))))
+(assert (string=? "" (string-rtrim char-whitespace? "")))
+(assert (string=? "foo" (string-rtrim char-whitespace? "foo 	")))
+
+;; Trim both the prefix and suffix of S containing only characters
+;; that make PREDICATE true.
+(define (string-trim predicate s)
+  (string-ltrim predicate (string-rtrim predicate s)))
+(assert (string=? "" (string-trim char-whitespace? "")))
+(assert (string=? "foo" (string-trim char-whitespace? " 	foo 	")))
+
+;; Check if needle is contained in haystack.
+(ffi-define (string-contains? haystack needle))
+(assert (string-contains? "Hallo" "llo"))
+(assert (not (string-contains? "Hallo" "olla")))
+
+;; Translate characters.
+(define (string-translate s from to)
+  (list->string (map (lambda (c)
+		       (let ((i (string-index from c)))
+			 (if i (string-ref to i) c))) (string->list s))))
+(assert (equal? (string-translate "foo/bar" "/" ".") "foo.bar"))
+
+;; Read a word from port P.
+(define (read-word . p)
+  (list->string
+   (let f ()
+     (let ((c (apply peek-char p)))
+       (cond
+	((eof-object? c) '())
+	((char-alphabetic? c)
+	 (apply read-char p)
+	 (cons c (f)))
+	(else
+	 (apply read-char p)
+	 '()))))))
+
+(define (list->string-reversed lst)
+  (let* ((len (length lst))
+	 (str (make-string len)))
+    (let loop ((i (- len 1))
+	       (l lst))
+      (if (< i 0)
+	  (begin
+	    (assert (null? l))
+	    str)
+	  (begin
+	    (string-set! str i (car l))
+	    (loop (- i 1) (cdr l)))))))
+
+;; Read a line from port P.
+(define (read-line . p)
+  (let loop ((acc '()))
+    (let ((c (apply peek-char p)))
+      (cond
+       ((eof-object? c)
+	(if (null? acc)
+	    c ;; #eof
+	    (list->string-reversed acc)))
+       ((char=? c #\newline)
+	(apply read-char p)
+	(list->string-reversed acc))
+       (else
+	(apply read-char p)
+	(loop (cons c acc)))))))
+
+;; Read everything from port P.
+(define (read-all . p)
+  (let loop ((acc (open-output-string)))
+    (let ((c (apply peek-char p)))
+      (cond
+       ((eof-object? c) (get-output-string acc))
+       (else
+	(write-char (apply read-char p) acc)
+	(loop acc))))))
+
+;;
+;; Windows support.
+;;
+
+;; Like call-with-input-file but opens the file in 'binary' mode.
+(define (call-with-binary-input-file filename proc)
+  (letfd ((fd (open filename (logior O_RDONLY O_BINARY))))
+	 (proc (fdopen fd "rb"))))
+
+;; Like call-with-output-file but opens the file in 'binary' mode.
+(define (call-with-binary-output-file filename proc)
+  (letfd ((fd (open filename (logior O_WRONLY O_CREAT O_BINARY) #o600)))
+	 (proc (fdopen fd "wb"))))
+
+;;
+;; Libc functions.
+;;
+
+;; Change the read/write offset.
+(ffi-define (seek fd offset whence))
+
+;; Constants for WHENCE.
+(ffi-define SEEK_SET)
+(ffi-define SEEK_CUR)
+(ffi-define SEEK_END)
+
+;; Get our process id.
+(ffi-define (getpid))
+
+;; Copy data from file descriptor SOURCE to every file descriptor in
+;; SINKS.
+(ffi-define (splice source . sinks))
+
+;;
+;; Random numbers.
+;;
+
+;; Seed the random number generator.
+(ffi-define (srandom seed))
+
+;; Get a pseudo-random number between 0 (inclusive) and SCALE
+;; (exclusive).
+(ffi-define (random scale))
+
+;; Create a string of the given SIZE containing pseudo-random data.
+(ffi-define (make-random-string size))
diff --git a/gpgscm/main.c b/gpgscm/main.c
new file mode 100644
index 0000000..5540ac3
--- /dev/null
+++ b/gpgscm/main.c
@@ -0,0 +1,359 @@
+/* TinyScheme-based test driver.
+ *
+ * Copyright (C) 2016 g10 code GmbH
+ *
+ * This file is part of GnuPG.
+ *
+ * GnuPG is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * GnuPG is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+
+#include <assert.h>
+#include <ctype.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <gcrypt.h>
+#include <gpg-error.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#if HAVE_MMAP
+#include <sys/mman.h>
+#endif
+
+#include "private.h"
+#include "scheme.h"
+#include "scheme-private.h"
+#include "ffi.h"
+#include "../common/i18n.h"
+#include "../../common/argparse.h"
+#include "../../common/init.h"
+#include "../../common/logging.h"
+#include "../../common/strlist.h"
+#include "../../common/sysutils.h"
+#include "../../common/util.h"
+
+/* The TinyScheme banner.  Unfortunately, it isn't in the header
+   file.  */
+#define ts_banner "TinyScheme 1.41"
+
+int verbose;
+
+
+
+/* Constants to identify the commands and options. */
+enum cmd_and_opt_values
+  {
+    aNull	= 0,
+    oVerbose	= 'v',
+  };
+
+/* The list of commands and options. */
+static ARGPARSE_OPTS opts[] =
+  {
+    ARGPARSE_s_n (oVerbose, "verbose", N_("verbose")),
+    ARGPARSE_end (),
+  };
+
+char *scmpath = "";
+size_t scmpath_len = 0;
+
+/* Command line parsing.  */
+static void
+parse_arguments (ARGPARSE_ARGS *pargs, ARGPARSE_OPTS *popts)
+{
+  int no_more_options = 0;
+
+  while (!no_more_options && optfile_parse (NULL, NULL, NULL, pargs, popts))
+    {
+      switch (pargs->r_opt)
+        {
+        case oVerbose:
+          verbose++;
+          break;
+
+        default:
+	  pargs->err = 2;
+	  break;
+	}
+    }
+}
+
+/* Print usage information and provide strings for help. */
+static const char *
+my_strusage( int level )
+{
+  const char *p;
+
+  switch (level)
+    {
+    case 11: p = "gpgscm (@GNUPG@)";
+      break;
+    case 13: p = VERSION; break;
+    case 17: p = PRINTABLE_OS_NAME; break;
+    case 19: p = _("Please report bugs to <@EMAIL@>.\n"); break;
+
+    case 1:
+    case 40:
+      p = _("Usage: gpgscm [options] [file] (-h for help)");
+      break;
+    case 41:
+      p = _("Syntax: gpgscm [options] [file]\n"
+            "Execute the given Scheme program, or spawn interactive shell.\n");
+      break;
+
+    default: p = NULL; break;
+    }
+  return p;
+}
+
+
+
+static int
+path_absolute_p (const char *p)
+{
+#if _WIN32
+  return ((strlen (p) > 2 && p[1] == ':' && (p[2] == '\\' || p[2] == '/'))
+          || p[0] == '\\' || p[0] == '/');
+#else
+  return p[0] == '/';
+#endif
+}
+
+
+/* Load the Scheme program from FILE_NAME.  If FILE_NAME is not an
+   absolute path, and LOOKUP_IN_PATH is given, then it is qualified
+   with the values in scmpath until the file is found.  */
+static gpg_error_t
+load (scheme *sc, char *file_name,
+      int lookup_in_cwd, int lookup_in_path)
+{
+  gpg_error_t err = 0;
+  size_t n;
+  const char *directory;
+  char *qualified_name = file_name;
+  int use_path;
+  FILE *h = NULL;
+
+  use_path =
+    lookup_in_path && ! (path_absolute_p (file_name) || scmpath_len == 0);
+
+  if (path_absolute_p (file_name) || lookup_in_cwd || scmpath_len == 0)
+    {
+      h = fopen (file_name, "r");
+      if (! h)
+        err = gpg_error_from_syserror ();
+    }
+
+  if (h == NULL && use_path)
+    for (directory = scmpath, n = scmpath_len; n;
+         directory += strlen (directory) + 1, n--)
+      {
+        if (asprintf (&qualified_name, "%s/%s", directory, file_name) < 0)
+          return gpg_error_from_syserror ();
+
+        h = fopen (qualified_name, "r");
+        if (h)
+          {
+            err = 0;
+            break;
+          }
+
+        if (n > 1)
+          {
+            free (qualified_name);
+            continue; 	/* Try again!  */
+          }
+
+        err = gpg_error_from_syserror ();
+      }
+
+  if (h == NULL)
+    {
+      /* Failed and no more elements in scmpath to try.  */
+      fprintf (stderr, "Could not read %s: %s.\n",
+               qualified_name, gpg_strerror (err));
+      if (lookup_in_path)
+        fprintf (stderr,
+                 "Consider using GPGSCM_PATH to specify the location "
+                 "of the Scheme library.\n");
+      goto leave;
+    }
+  if (verbose > 2)
+    fprintf (stderr, "Loading %s...\n", qualified_name);
+
+#if HAVE_MMAP
+  /* Always try to mmap the file.  This allows the pages to be shared
+   * between processes.  If anything fails, we fall back to using
+   * buffered streams.  */
+  if (1)
+    {
+      struct stat st;
+      void *map;
+      size_t len;
+      int fd = fileno (h);
+
+      if (fd < 0)
+        goto fallback;
+
+      if (fstat (fd, &st))
+        goto fallback;
+
+      len = (size_t) st.st_size;
+      if ((off_t) len != st.st_size)
+        goto fallback;	/* Truncated.  */
+
+      map = mmap (NULL, len, PROT_READ, MAP_SHARED, fd, 0);
+      if (map == MAP_FAILED)
+        goto fallback;
+
+      scheme_load_memory (sc, map, len, qualified_name);
+      munmap (map, len);
+    }
+  else
+  fallback:
+#endif
+    scheme_load_named_file (sc, h, qualified_name);
+  fclose (h);
+
+  if (sc->retcode && sc->nesting)
+    {
+      fprintf (stderr, "%s: Unbalanced parenthesis\n", qualified_name);
+      err = gpg_error (GPG_ERR_GENERAL);
+    }
+
+ leave:
+  if (file_name != qualified_name)
+    free (qualified_name);
+  return err;
+}
+
+
+
+int
+main (int argc, char **argv)
+{
+  int retcode;
+  gpg_error_t err;
+  char *argv0;
+  ARGPARSE_ARGS pargs;
+  scheme *sc;
+  char *p;
+#if _WIN32
+  char pathsep = ';';
+#else
+  char pathsep = ':';
+#endif
+  char *script = NULL;
+
+  /* Save argv[0] so that we can re-exec.  */
+  argv0 = argv[0];
+
+  /* Parse path.  */
+  if (getenv ("GPGSCM_PATH"))
+    scmpath = getenv ("GPGSCM_PATH");
+
+  p = scmpath = strdup (scmpath);
+  if (p == NULL)
+    return 2;
+
+  if (*p)
+    scmpath_len++;
+  for (; *p; p++)
+    if (*p == pathsep)
+      *p = 0, scmpath_len++;
+
+  set_strusage (my_strusage);
+  log_set_prefix ("gpgscm", GPGRT_LOG_WITH_PREFIX);
+
+  /* Make sure that our subsystems are ready.  */
+  i18n_init ();
+  init_common_subsystems (&argc, &argv);
+
+  if (!gcry_check_version (NEED_LIBGCRYPT_VERSION))
+    {
+      fputs ("libgcrypt version mismatch\n", stderr);
+      exit (2);
+    }
+
+  /* Parse the command line. */
+  pargs.argc  = &argc;
+  pargs.argv  = &argv;
+  pargs.flags = 0;
+  parse_arguments (&pargs, opts);
+
+  if (log_get_errorcount (0))
+    exit (2);
+
+  sc = scheme_init_new_custom_alloc (gcry_malloc, gcry_free);
+  if (! sc) {
+    fprintf (stderr, "Could not initialize TinyScheme!\n");
+    return 2;
+  }
+  scheme_set_input_port_file (sc, stdin);
+  scheme_set_output_port_file (sc, stderr);
+
+  if (argc)
+    {
+      script = argv[0];
+      argc--, argv++;
+    }
+
+  err = load (sc, "init.scm", 0, 1);
+  if (! err)
+    err = load (sc, "ffi.scm", 0, 1);
+  if (! err)
+    err = ffi_init (sc, argv0, script ? script : "interactive",
+                    argc, (const char **) argv);
+  if (! err)
+    err = load (sc, "lib.scm", 0, 1);
+  if (! err)
+    err = load (sc, "repl.scm", 0, 1);
+  if (! err)
+    err = load (sc, "xml.scm", 0, 1);
+  if (! err)
+    err = load (sc, "tests.scm", 0, 1);
+  if (! err)
+    err = load (sc, "gnupg.scm", 0, 1);
+  if (err)
+    {
+      fprintf (stderr, "Error initializing gpgscm: %s.\n",
+               gpg_strerror (err));
+      exit (2);
+    }
+
+  if (script == NULL)
+    {
+      /* Interactive shell.  */
+      fprintf (stderr, "gpgscm/"ts_banner".\n");
+      scheme_load_string (sc, "(interactive-repl)");
+    }
+  else
+    {
+      err = load (sc, script, 1, 1);
+      if (err)
+        log_fatal ("%s: %s", script, gpg_strerror (err));
+    }
+
+  retcode = sc->retcode;
+  scheme_load_string (sc, "(*run-atexit-handlers*)");
+  scheme_deinit (sc);
+  xfree (sc);
+  return retcode;
+}
diff --git a/gpgscm/makefile.scm b/gpgscm/makefile.scm
new file mode 100644
index 0000000..32fae3a
--- /dev/null
+++ b/gpgscm/makefile.scm
@@ -0,0 +1,76 @@
+;; Support for parsing Makefiles
+;;
+;; Copyright (C) 2016 g10 Code GmbH
+;;
+;; This file is part of GnuPG.
+;;
+;; GnuPG is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation; either version 3 of the License, or
+;; (at your option) any later version.
+;;
+;; GnuPG is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+;;
+;; You should have received a copy of the GNU General Public License
+;; along with this program; if not, see <http://www.gnu.org/licenses/>.
+
+(define (parse-makefile port key)
+  (define (is-continuation? tokens)
+    (string=? (last tokens) "\\"))
+  (define (valid-token? s)
+    (< 0 (string-length s)))
+  (define (drop-continuations tokens)
+    (let loop ((acc '()) (tks tokens))
+      (if (null? tks)
+	  (reverse acc)
+	  (loop (if (string=? "\\" (car tks))
+		    acc
+		    (cons (car tks) acc)) (cdr tks)))))
+  (let next ((acc '()) (found #f))
+    (let ((line (read-line port)))
+      (if (eof-object? line)
+	  acc
+	  (let ((tokens (filter valid-token?
+				(string-splitp (string-trim char-whitespace?
+							    line)
+					       char-whitespace? -1))))
+	    (cond
+	     ((or (null? tokens)
+		  (string-prefix? (car tokens) "#")
+		  (and (not found) (not (and (string=? key (car tokens))
+					     (string=? "=" (cadr tokens))))))
+	      (next acc found))
+	     ((not found)
+	      (assert (and (string=? key (car tokens))
+			   (string=? "=" (cadr tokens))))
+	      (if (is-continuation? tokens)
+		  (next (drop-continuations (cddr tokens)) #t)
+		  (drop-continuations (cddr tokens))))
+	     (else
+	      (assert found)
+	      (if (is-continuation? tokens)
+		  (next (append acc (drop-continuations tokens)) found)
+		  (append acc (drop-continuations tokens))))))))))
+
+(define (parse-makefile-expand filename expand key)
+  (define (variable? v)
+    (and (string-prefix? v "$(") (string-suffix? v ")")))
+
+  (let expand-all ((values (parse-makefile (open-input-file filename) key)))
+    (if (any variable? values)
+	(expand-all
+	 (let expand-one ((acc '()) (v values))
+	   (cond
+	    ((null? v)
+	     acc)
+	    ((variable? (car v))
+	     (let ((makefile (open-input-file filename))
+		   (key (substring (car v) 2 (- (string-length (car v)) 1))))
+	       (expand-one (append acc (expand filename makefile key))
+			   (cdr v))))
+	    (else
+	     (expand-one (append acc (list (car v))) (cdr v))))))
+	values)))
diff --git a/gpgscm/opdefines.h b/gpgscm/opdefines.h
new file mode 100644
index 0000000..61f7971
--- /dev/null
+++ b/gpgscm/opdefines.h
@@ -0,0 +1,205 @@
+_OP_DEF("load",                           1,  1,       TST_STRING,                      OP_LOAD             )
+_OP_DEF(0,                                0,  0,       0,                               OP_T0LVL            )
+_OP_DEF(0,                                0,  0,       0,                               OP_T1LVL            )
+_OP_DEF(0,                                0,  0,       0,                               OP_READ_INTERNAL    )
+_OP_DEF("gensym",                         0,  0,       0,                               OP_GENSYM           )
+_OP_DEF(0,                                0,  0,       0,                               OP_VALUEPRINT       )
+_OP_DEF(0,                                0,  0,       0,                               OP_EVAL             )
+#if USE_TRACING
+_OP_DEF(0,                                0,  0,       0,                               OP_REAL_EVAL        )
+#endif
+_OP_DEF(0,                                0,  0,       0,                               OP_E0ARGS           )
+_OP_DEF(0,                                0,  0,       0,                               OP_E1ARGS           )
+#if USE_HISTORY
+_OP_DEF(0,                                0,  0,       0,                               OP_CALLSTACK_POP    )
+#endif
+_OP_DEF(0,                                0,  0,       0,                               OP_APPLY_CODE       )
+_OP_DEF(0,                                0,  0,       0,                               OP_APPLY            )
+#if USE_TRACING
+_OP_DEF(0,                                0,  0,       0,                               OP_REAL_APPLY       )
+_OP_DEF("tracing",                        1,  1,       TST_NATURAL,                     OP_TRACING          )
+#endif
+_OP_DEF(0,                                0,  0,       0,                               OP_DOMACRO          )
+_OP_DEF(0,                                0,  0,       0,                               OP_LAMBDA           )
+_OP_DEF(0,                                0,  0,       0,                               OP_LAMBDA1          )
+_OP_DEF("make-closure",                   1,  2,       TST_PAIR TST_ENVIRONMENT,        OP_MKCLOSURE        )
+_OP_DEF(0,                                0,  0,       0,                               OP_QUOTE            )
+_OP_DEF(0,                                0,  0,       0,                               OP_DEF0             )
+_OP_DEF(0,                                0,  0,       0,                               OP_DEF1             )
+_OP_DEF("defined?",                       1,  2,       TST_SYMBOL TST_ENVIRONMENT,      OP_DEFP             )
+_OP_DEF(0,                                0,  0,       0,                               OP_BEGIN            )
+_OP_DEF(0,                                0,  0,       0,                               OP_IF0              )
+_OP_DEF(0,                                0,  0,       0,                               OP_IF1              )
+_OP_DEF(0,                                0,  0,       0,                               OP_SET0             )
+_OP_DEF(0,                                0,  0,       0,                               OP_SET1             )
+_OP_DEF(0,                                0,  0,       0,                               OP_LET0             )
+_OP_DEF(0,                                0,  0,       0,                               OP_LET1             )
+_OP_DEF(0,                                0,  0,       0,                               OP_LET2             )
+_OP_DEF(0,                                0,  0,       0,                               OP_LET0AST          )
+_OP_DEF(0,                                0,  0,       0,                               OP_LET1AST          )
+_OP_DEF(0,                                0,  0,       0,                               OP_LET2AST          )
+_OP_DEF(0,                                0,  0,       0,                               OP_LET0REC          )
+_OP_DEF(0,                                0,  0,       0,                               OP_LET1REC          )
+_OP_DEF(0,                                0,  0,       0,                               OP_LET2REC          )
+_OP_DEF(0,                                0,  0,       0,                               OP_COND0            )
+_OP_DEF(0,                                0,  0,       0,                               OP_COND1            )
+_OP_DEF(0,                                0,  0,       0,                               OP_DELAY            )
+_OP_DEF(0,                                0,  0,       0,                               OP_AND0             )
+_OP_DEF(0,                                0,  0,       0,                               OP_AND1             )
+_OP_DEF(0,                                0,  0,       0,                               OP_OR0              )
+_OP_DEF(0,                                0,  0,       0,                               OP_OR1              )
+_OP_DEF(0,                                0,  0,       0,                               OP_C0STREAM         )
+_OP_DEF(0,                                0,  0,       0,                               OP_C1STREAM         )
+_OP_DEF(0,                                0,  0,       0,                               OP_MACRO0           )
+_OP_DEF(0,                                0,  0,       0,                               OP_MACRO1           )
+_OP_DEF(0,                                0,  0,       0,                               OP_CASE0            )
+_OP_DEF(0,                                0,  0,       0,                               OP_CASE1            )
+_OP_DEF(0,                                0,  0,       0,                               OP_CASE2            )
+_OP_DEF("eval",                           1,  2,       TST_ANY TST_ENVIRONMENT,         OP_PEVAL            )
+_OP_DEF("apply",                          1,  INF_ARG, TST_NONE,                        OP_PAPPLY           )
+_OP_DEF("call-with-current-continuation", 1,  1,       TST_NONE,                        OP_CONTINUATION     )
+#if USE_MATH
+_OP_DEF("inexact->exact",                 1,  1,       TST_NUMBER,                      OP_INEX2EX          )
+_OP_DEF("exp",                            1,  1,       TST_NUMBER,                      OP_EXP              )
+_OP_DEF("log",                            1,  1,       TST_NUMBER,                      OP_LOG              )
+_OP_DEF("sin",                            1,  1,       TST_NUMBER,                      OP_SIN              )
+_OP_DEF("cos",                            1,  1,       TST_NUMBER,                      OP_COS              )
+_OP_DEF("tan",                            1,  1,       TST_NUMBER,                      OP_TAN              )
+_OP_DEF("asin",                           1,  1,       TST_NUMBER,                      OP_ASIN             )
+_OP_DEF("acos",                           1,  1,       TST_NUMBER,                      OP_ACOS             )
+_OP_DEF("atan",                           1,  2,       TST_NUMBER,                      OP_ATAN             )
+_OP_DEF("sqrt",                           1,  1,       TST_NUMBER,                      OP_SQRT             )
+_OP_DEF("expt",                           2,  2,       TST_NUMBER,                      OP_EXPT             )
+_OP_DEF("floor",                          1,  1,       TST_NUMBER,                      OP_FLOOR            )
+_OP_DEF("ceiling",                        1,  1,       TST_NUMBER,                      OP_CEILING          )
+_OP_DEF("truncate",                       1,  1,       TST_NUMBER,                      OP_TRUNCATE         )
+_OP_DEF("round",                          1,  1,       TST_NUMBER,                      OP_ROUND            )
+#endif
+_OP_DEF("+",                              0,  INF_ARG, TST_NUMBER,                      OP_ADD              )
+_OP_DEF("-",                              1,  INF_ARG, TST_NUMBER,                      OP_SUB              )
+_OP_DEF("*",                              0,  INF_ARG, TST_NUMBER,                      OP_MUL              )
+_OP_DEF("/",                              1,  INF_ARG, TST_NUMBER,                      OP_DIV              )
+_OP_DEF("quotient",                       1,  INF_ARG, TST_INTEGER,                     OP_INTDIV           )
+_OP_DEF("remainder",                      2,  2,       TST_INTEGER,                     OP_REM              )
+_OP_DEF("modulo",                         2,  2,       TST_INTEGER,                     OP_MOD              )
+_OP_DEF("car",                            1,  1,       TST_PAIR,                        OP_CAR              )
+_OP_DEF("cdr",                            1,  1,       TST_PAIR,                        OP_CDR              )
+_OP_DEF("cons",                           2,  2,       TST_NONE,                        OP_CONS             )
+_OP_DEF("set-car!",                       2,  2,       TST_PAIR TST_ANY,                OP_SETCAR           )
+_OP_DEF("set-cdr!",                       2,  2,       TST_PAIR TST_ANY,                OP_SETCDR           )
+_OP_DEF("char->integer",                  1,  1,       TST_CHAR,                        OP_CHAR2INT         )
+_OP_DEF("integer->char",                  1,  1,       TST_NATURAL,                     OP_INT2CHAR         )
+_OP_DEF("char-upcase",                    1,  1,       TST_CHAR,                        OP_CHARUPCASE       )
+_OP_DEF("char-downcase",                  1,  1,       TST_CHAR,                        OP_CHARDNCASE       )
+_OP_DEF("symbol->string",                 1,  1,       TST_SYMBOL,                      OP_SYM2STR          )
+_OP_DEF("atom->string",                   1,  2,       TST_ANY TST_NATURAL,             OP_ATOM2STR         )
+_OP_DEF("string->symbol",                 1,  1,       TST_STRING,                      OP_STR2SYM          )
+_OP_DEF("string->atom",                   1,  2,       TST_STRING TST_NATURAL,          OP_STR2ATOM         )
+_OP_DEF("make-string",                    1,  2,       TST_NATURAL TST_CHAR,            OP_MKSTRING         )
+_OP_DEF("string-length",                  1,  1,       TST_STRING,                      OP_STRLEN           )
+_OP_DEF("string-ref",                     2,  2,       TST_STRING TST_NATURAL,          OP_STRREF           )
+_OP_DEF("string-set!",                    3,  3,       TST_STRING TST_NATURAL TST_CHAR, OP_STRSET           )
+_OP_DEF("string-append",                  0,  INF_ARG, TST_STRING,                      OP_STRAPPEND        )
+_OP_DEF("substring",                      2,  3,       TST_STRING TST_NATURAL,          OP_SUBSTR           )
+_OP_DEF("vector",                         0,  INF_ARG, TST_NONE,                        OP_VECTOR           )
+_OP_DEF("make-vector",                    1,  2,       TST_NATURAL TST_ANY,             OP_MKVECTOR         )
+_OP_DEF("vector-length",                  1,  1,       TST_VECTOR,                      OP_VECLEN           )
+_OP_DEF("vector-ref",                     2,  2,       TST_VECTOR TST_NATURAL,          OP_VECREF           )
+_OP_DEF("vector-set!",                    3,  3,       TST_VECTOR TST_NATURAL TST_ANY,  OP_VECSET           )
+_OP_DEF("not",                            1,  1,       TST_NONE,                        OP_NOT              )
+_OP_DEF("boolean?",                       1,  1,       TST_NONE,                        OP_BOOLP            )
+_OP_DEF("eof-object?",                    1,  1,       TST_NONE,                        OP_EOFOBJP          )
+_OP_DEF("null?",                          1,  1,       TST_NONE,                        OP_NULLP            )
+_OP_DEF("=",                              2,  INF_ARG, TST_NUMBER,                      OP_NUMEQ            )
+_OP_DEF("<",                              2,  INF_ARG, TST_NUMBER,                      OP_LESS             )
+_OP_DEF(">",                              2,  INF_ARG, TST_NUMBER,                      OP_GRE              )
+_OP_DEF("<=",                             2,  INF_ARG, TST_NUMBER,                      OP_LEQ              )
+_OP_DEF(">=",                             2,  INF_ARG, TST_NUMBER,                      OP_GEQ              )
+_OP_DEF("symbol?",                        1,  1,       TST_ANY,                         OP_SYMBOLP          )
+_OP_DEF("number?",                        1,  1,       TST_ANY,                         OP_NUMBERP          )
+_OP_DEF("string?",                        1,  1,       TST_ANY,                         OP_STRINGP          )
+_OP_DEF("integer?",                       1,  1,       TST_ANY,                         OP_INTEGERP         )
+_OP_DEF("real?",                          1,  1,       TST_ANY,                         OP_REALP            )
+_OP_DEF("char?",                          1,  1,       TST_ANY,                         OP_CHARP            )
+#if USE_CHAR_CLASSIFIERS
+_OP_DEF("char-alphabetic?",               1,  1,       TST_CHAR,                        OP_CHARAP           )
+_OP_DEF("char-numeric?",                  1,  1,       TST_CHAR,                        OP_CHARNP           )
+_OP_DEF("char-whitespace?",               1,  1,       TST_CHAR,                        OP_CHARWP           )
+_OP_DEF("char-upper-case?",               1,  1,       TST_CHAR,                        OP_CHARUP           )
+_OP_DEF("char-lower-case?",               1,  1,       TST_CHAR,                        OP_CHARLP           )
+#endif
+_OP_DEF("port?",                          1,  1,       TST_ANY,                         OP_PORTP            )
+_OP_DEF("input-port?",                    1,  1,       TST_ANY,                         OP_INPORTP          )
+_OP_DEF("output-port?",                   1,  1,       TST_ANY,                         OP_OUTPORTP         )
+_OP_DEF("procedure?",                     1,  1,       TST_ANY,                         OP_PROCP            )
+_OP_DEF("pair?",                          1,  1,       TST_ANY,                         OP_PAIRP            )
+_OP_DEF("list?",                          1,  1,       TST_ANY,                         OP_LISTP            )
+_OP_DEF("environment?",                   1,  1,       TST_ANY,                         OP_ENVP             )
+_OP_DEF("vector?",                        1,  1,       TST_ANY,                         OP_VECTORP          )
+_OP_DEF("eq?",                            2,  2,       TST_ANY,                         OP_EQ               )
+_OP_DEF("eqv?",                           2,  2,       TST_ANY,                         OP_EQV              )
+_OP_DEF("force",                          1,  1,       TST_ANY,                         OP_FORCE            )
+_OP_DEF(0,                                0,  0,       0,                               OP_SAVE_FORCED      )
+_OP_DEF("write",                          1,  2,       TST_ANY TST_OUTPORT,             OP_WRITE            )
+_OP_DEF("write-char",                     1,  2,       TST_CHAR TST_OUTPORT,            OP_WRITE_CHAR       )
+_OP_DEF("display",                        1,  2,       TST_ANY TST_OUTPORT,             OP_DISPLAY          )
+_OP_DEF("newline",                        0,  1,       TST_OUTPORT,                     OP_NEWLINE          )
+_OP_DEF("error",                          1,  INF_ARG, TST_NONE,                        OP_ERR0             )
+_OP_DEF(0,                                0,  0,       0,                               OP_ERR1             )
+_OP_DEF("reverse",                        1,  1,       TST_LIST,                        OP_REVERSE          )
+_OP_DEF("reverse!",                       1,  1,       TST_LIST,                        OP_REVERSE_IN_PLACE )
+_OP_DEF("list*",                          1,  INF_ARG, TST_NONE,                        OP_LIST_STAR        )
+_OP_DEF("append",                         0,  INF_ARG, TST_NONE,                        OP_APPEND           )
+#if USE_PLIST
+_OP_DEF("set-symbol-property!",           3,  3,       TST_SYMBOL TST_SYMBOL TST_ANY,   OP_SET_SYMBOL_PROPERTY )
+_OP_DEF("symbol-property",                2,  2,       TST_SYMBOL TST_SYMBOL,           OP_SYMBOL_PROPERTY  )
+#endif
+_OP_DEF(0,                                0,  0,       TST_NONE,                        OP_TAG_VALUE        )
+_OP_DEF("make-tagged-value",              2,  2,       TST_ANY TST_PAIR,                 OP_MK_TAGGED        )
+_OP_DEF("get-tag",                        1,  1,       TST_ANY,                         OP_GET_TAG          )
+_OP_DEF("quit",                           0,  1,       TST_NUMBER,                      OP_QUIT             )
+_OP_DEF("gc",                             0,  0,       0,                               OP_GC               )
+_OP_DEF("gc-verbose",                     0,  1,       TST_NONE,                        OP_GCVERB           )
+_OP_DEF("new-segment",                    0,  1,       TST_NUMBER,                      OP_NEWSEGMENT       )
+_OP_DEF("oblist",                         0,  0,       0,                               OP_OBLIST           )
+_OP_DEF("current-input-port",             0,  0,       0,                               OP_CURR_INPORT      )
+_OP_DEF("current-output-port",            0,  0,       0,                               OP_CURR_OUTPORT     )
+_OP_DEF("open-input-file",                1,  1,       TST_STRING,                      OP_OPEN_INFILE      )
+_OP_DEF("open-output-file",               1,  1,       TST_STRING,                      OP_OPEN_OUTFILE     )
+_OP_DEF("open-input-output-file",         1,  1,       TST_STRING,                      OP_OPEN_INOUTFILE   )
+#if USE_STRING_PORTS
+_OP_DEF("open-input-string",              1,  1,       TST_STRING,                      OP_OPEN_INSTRING    )
+_OP_DEF("open-input-output-string",       1,  1,       TST_STRING,                      OP_OPEN_INOUTSTRING )
+_OP_DEF("open-output-string",             0,  1,       TST_STRING,                      OP_OPEN_OUTSTRING   )
+_OP_DEF("get-output-string",              1,  1,       TST_OUTPORT,                     OP_GET_OUTSTRING    )
+#endif
+_OP_DEF("close-input-port",               1,  1,       TST_INPORT,                      OP_CLOSE_INPORT     )
+_OP_DEF("close-output-port",              1,  1,       TST_OUTPORT,                     OP_CLOSE_OUTPORT    )
+_OP_DEF("interaction-environment",        0,  0,       0,                               OP_INT_ENV          )
+_OP_DEF("current-environment",            0,  0,       0,                               OP_CURR_ENV         )
+_OP_DEF("read",                           0,  1,       TST_INPORT,                      OP_READ             )
+_OP_DEF("read-char",                      0,  1,       TST_INPORT,                      OP_READ_CHAR        )
+_OP_DEF("peek-char",                      0,  1,       TST_INPORT,                      OP_PEEK_CHAR        )
+_OP_DEF("char-ready?",                    0,  1,       TST_INPORT,                      OP_CHAR_READY       )
+_OP_DEF("set-input-port",                 1,  1,       TST_INPORT,                      OP_SET_INPORT       )
+_OP_DEF("set-output-port",                1,  1,       TST_OUTPORT,                     OP_SET_OUTPORT      )
+_OP_DEF(0,                                0,  0,       0,                               OP_RDSEXPR          )
+_OP_DEF(0,                                0,  0,       0,                               OP_RDLIST           )
+_OP_DEF(0,                                0,  0,       0,                               OP_RDDOT            )
+_OP_DEF(0,                                0,  0,       0,                               OP_RDQUOTE          )
+_OP_DEF(0,                                0,  0,       0,                               OP_RDQQUOTE         )
+_OP_DEF(0,                                0,  0,       0,                               OP_RDQQUOTEVEC      )
+_OP_DEF(0,                                0,  0,       0,                               OP_RDUNQUOTE        )
+_OP_DEF(0,                                0,  0,       0,                               OP_RDUQTSP          )
+_OP_DEF(0,                                0,  0,       0,                               OP_RDVEC            )
+_OP_DEF(0,                                0,  0,       0,                               OP_P0LIST           )
+_OP_DEF(0,                                0,  0,       0,                               OP_P1LIST           )
+_OP_DEF(0,                                0,  0,       0,                               OP_PVECFROM         )
+_OP_DEF("length",                         1,  1,       TST_LIST,                        OP_LIST_LENGTH      )
+_OP_DEF("assq",                           2,  2,       TST_NONE,                        OP_ASSQ             )
+_OP_DEF("get-closure-code",               1,  1,       TST_NONE,                        OP_GET_CLOSURE      )
+_OP_DEF("closure?",                       1,  1,       TST_NONE,                        OP_CLOSUREP         )
+_OP_DEF("macro?",                         1,  1,       TST_NONE,                        OP_MACROP           )
+_OP_DEF("*vm-history*",                   0,  0,       TST_NONE,                        OP_VM_HISTORY       )
+
+#undef _OP_DEF
diff --git a/gpgscm/private.h b/gpgscm/private.h
new file mode 100644
index 0000000..6e330e0
--- /dev/null
+++ b/gpgscm/private.h
@@ -0,0 +1,26 @@
+/* TinyScheme-based test driver.
+ *
+ * Copyright (C) 2016 g10 code GmbH
+ *
+ * This file is part of GnuPG.
+ *
+ * GnuPG is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * GnuPG is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GPGSCM_PRIVATE_H__
+#define __GPGSCM_PRIVATE_H__
+
+extern int verbose;
+
+#endif /* __GPGSCM_PRIVATE_H__ */
diff --git a/gpgscm/repl.scm b/gpgscm/repl.scm
new file mode 100644
index 0000000..833ec0d
--- /dev/null
+++ b/gpgscm/repl.scm
@@ -0,0 +1,69 @@
+;; A read-evaluate-print-loop for gpgscm.
+;;
+;; Copyright (C) 2016 g10 Code GmbH
+;;
+;; This file is part of GnuPG.
+;;
+;; GnuPG is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation; either version 3 of the License, or
+;; (at your option) any later version.
+;;
+;; GnuPG is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+;;
+;; You should have received a copy of the GNU General Public License
+;; along with this program; if not, see <http://www.gnu.org/licenses/>.
+
+;; Interactive repl using 'prompt' function.  P must be a function
+;; that given the current entered prefix returns the prompt to
+;; display.
+(define (repl p environment)
+  (call/cc
+   (lambda (exit)
+     (let loop ((prefix ""))
+       (let ((line (prompt (p prefix))))
+	 (if (and (not (eof-object? line)) (= 0 (string-length line)))
+	     (exit (loop prefix)))
+	 (if (not (eof-object? line))
+	     (let* ((next (string-append prefix line))
+		    (c (catch (begin (echo "Parse error:" *error*)
+				     (loop prefix))
+			      (read (open-input-string next)))))
+	       (if (not (eof-object? c))
+		   (begin
+		     (catch (begin
+			      (display (car *error*))
+			      (when (and (cadr *error*)
+					 (not (null? (cadr *error*))))
+				    (display ": ")
+				    (write (cadr *error*)))
+			      (newline)
+			      (vm-history-print (caddr *error*)))
+			    (echo "    ===>" (eval c environment)))
+		     (exit (loop ""))))
+	       (exit (loop next)))))))))
+
+(define (prompt-append-prefix prompt prefix)
+  (string-append prompt (if (> (string-length prefix) 0)
+			    (string-append prefix "...")
+			    "> ")))
+
+;; Default repl run by main.c.
+(define (interactive-repl . environment)
+  (repl (lambda (p) (prompt-append-prefix "gpgscm " p))
+	(if (null? environment) (interaction-environment) (car environment))))
+
+;; Ask a yes/no question.
+(define (prompt-yes-no? question default)
+  (let ((answer (prompt (string-append question "? ["
+				       (if default "Y/n" "y/N") "] "))))
+    (cond
+     ((= 0 (string-length answer))
+      default)
+     ((or (equal? "y" answer) (equal? "Y" answer))
+      #t)
+     (else
+      #f))))
diff --git a/gpgscm/scheme-config.h b/gpgscm/scheme-config.h
new file mode 100644
index 0000000..15ca969
--- /dev/null
+++ b/gpgscm/scheme-config.h
@@ -0,0 +1,32 @@
+/* TinyScheme configuration.
+ *
+ * Copyright (C) 2016 g10 code GmbH
+ *
+ * This file is part of GnuPG.
+ *
+ * GnuPG is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * GnuPG is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses/>.
+ */
+
+#define STANDALONE		0
+#define USE_MATH		0
+#define USE_CHAR_CLASSIFIERS	1
+#define USE_ASCII_NAMES		1
+#define USE_STRING_PORTS	1
+#define USE_ERROR_HOOK		1
+#define USE_TRACING		1
+#define USE_COLON_HOOK		1
+#define USE_DL			0
+#define USE_PLIST		0
+#define USE_INTERFACE		1
+#define SHOW_ERROR_LINE		1
diff --git a/gpgscm/scheme-private.h b/gpgscm/scheme-private.h
new file mode 100644
index 0000000..7f92bda
--- /dev/null
+++ b/gpgscm/scheme-private.h
@@ -0,0 +1,274 @@
+/* scheme-private.h */
+
+#ifndef _SCHEME_PRIVATE_H
+#define _SCHEME_PRIVATE_H
+
+#include <stdint.h>
+#include "scheme.h"
+/*------------------ Ugly internals -----------------------------------*/
+/*------------------ Of interest only to FFI users --------------------*/
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+enum scheme_port_kind {
+  port_free=0,
+  port_file=1,
+  port_string=2,
+  port_srfi6=4,
+  port_input=16,
+  port_output=32,
+  port_saw_EOF=64
+};
+
+typedef struct port {
+  unsigned char kind;
+  union {
+    struct {
+      FILE *file;
+      int closeit;
+    } stdio;
+    struct {
+      char *start;
+      char *past_the_end;
+      char *curr;
+    } string;
+  } rep;
+#if SHOW_ERROR_LINE
+  pointer curr_line;
+  pointer filename;
+#endif
+} port;
+
+/* cell structure */
+struct cell {
+  uintptr_t _flag;
+  union {
+    num _number;
+    struct {
+      char   *_svalue;
+      int   _length;
+    } _string;
+    port *_port;
+    foreign_func _ff;
+    struct {
+      struct cell *_car;
+      struct cell *_cdr;
+    } _cons;
+    struct {
+      size_t _length;
+      pointer _elements[0];
+    } _vector;
+    struct {
+         char *_data;
+         const foreign_object_vtable *_vtable;
+    } _foreign_object;
+  } _object;
+};
+
+#if USE_HISTORY
+/* The history is a two-dimensional ring buffer.  A donut-shaped data
+ * structure.  This data structure is inspired by MIT/GNU Scheme.  */
+struct history {
+  /* Number of calls to store.  Must be a power of two.  */
+  size_t N;
+
+  /* Number of tail-calls to store in each call frame.  Must be a
+   * power of two.  */
+  size_t M;
+
+  /* Masks for fast index calculations.  */
+  size_t mask_N;
+  size_t mask_M;
+
+  /* A vector of size N containing calls.  */
+  pointer callstack;
+
+  /* A vector of size N containing vectors of size M containing tail
+   * calls.  */
+  pointer tailstacks;
+
+  /* Our current position.  */
+  size_t n;
+  size_t *m;
+};
+#endif
+
+struct scheme {
+/* arrays for segments */
+func_alloc malloc;
+func_dealloc free;
+
+/* return code */
+int retcode;
+int tracing;
+
+
+#ifndef CELL_SEGSIZE
+#define CELL_SEGSIZE    5000  /* # of cells in one segment */
+#endif
+
+/* If less than # of cells are recovered in a garbage collector run,
+ * allocate a new cell segment to avoid fruitless collection cycles in
+ * the near future.  */
+#ifndef CELL_MINRECOVER
+#define CELL_MINRECOVER    (CELL_SEGSIZE >> 2)
+#endif
+struct cell_segment *cell_segments;
+
+/* We use 4 registers. */
+pointer args;            /* register for arguments of function */
+pointer envir;           /* stack register for current environment */
+pointer code;            /* register for current code */
+pointer dump;            /* stack register for next evaluation */
+pointer frame_freelist;
+
+#if USE_HISTORY
+struct history history;  /* we keep track of the call history for
+                          * error messages */
+#endif
+
+int interactive_repl;    /* are we in an interactive REPL? */
+
+struct cell _sink;
+pointer sink;            /* when mem. alloc. fails */
+struct cell _NIL;
+pointer NIL;             /* special cell representing empty cell */
+struct cell _HASHT;
+pointer T;               /* special cell representing #t */
+struct cell _HASHF;
+pointer F;               /* special cell representing #f */
+struct cell _EOF_OBJ;
+pointer EOF_OBJ;         /* special cell representing end-of-file object */
+pointer oblist;          /* pointer to symbol table */
+pointer global_env;      /* pointer to global environment */
+pointer c_nest;          /* stack for nested calls from C */
+
+/* global pointers to special symbols */
+pointer LAMBDA;               /* pointer to syntax lambda */
+pointer QUOTE;           /* pointer to syntax quote */
+
+pointer QQUOTE;               /* pointer to symbol quasiquote */
+pointer UNQUOTE;         /* pointer to symbol unquote */
+pointer UNQUOTESP;       /* pointer to symbol unquote-splicing */
+pointer FEED_TO;         /* => */
+pointer COLON_HOOK;      /* *colon-hook* */
+pointer ERROR_HOOK;      /* *error-hook* */
+pointer SHARP_HOOK;  /* *sharp-hook* */
+#if USE_COMPILE_HOOK
+pointer COMPILE_HOOK;  /* *compile-hook* */
+#endif
+
+pointer free_cell;       /* pointer to top of free cells */
+long    fcells;          /* # of free cells */
+size_t  inhibit_gc;      /* nesting of gc_disable */
+size_t  reserved_cells;  /* # of reserved cells */
+#ifndef NDEBUG
+int     reserved_lineno;   /* location of last reservation */
+#endif
+
+pointer inport;
+pointer outport;
+pointer save_inport;
+pointer loadport;
+
+#ifndef MAXFIL
+#define MAXFIL 64
+#endif
+port load_stack[MAXFIL];     /* Stack of open files for port -1 (LOADing) */
+int nesting_stack[MAXFIL];
+int file_i;
+int nesting;
+
+char    gc_verbose;      /* if gc_verbose is not zero, print gc status */
+char    no_memory;       /* Whether mem. alloc. has failed */
+
+#ifndef LINESIZE
+#define LINESIZE 1024
+#endif
+char    linebuff[LINESIZE];
+#ifndef STRBUFFSIZE
+#define STRBUFFSIZE 256
+#endif
+char    *strbuff;
+size_t strbuff_size;
+FILE *tmpfp;
+int tok;
+int print_flag;
+pointer value;
+unsigned int flags;
+
+void *ext_data;     /* For the benefit of foreign functions */
+long gensym_cnt;
+
+const struct scheme_interface *vptr;
+};
+
+/* operator code */
+enum scheme_opcodes {
+#define _OP_DEF(A,B,C,D,OP) OP,
+#include "opdefines.h"
+  OP_MAXDEFINED
+};
+
+
+#define cons(sc,a,b) _cons(sc,a,b,0)
+#define immutable_cons(sc,a,b) _cons(sc,a,b,1)
+
+int is_string(pointer p);
+char *string_value(pointer p);
+int is_number(pointer p);
+num nvalue(pointer p);
+long ivalue(pointer p);
+double rvalue(pointer p);
+int is_integer(pointer p);
+int is_real(pointer p);
+int is_character(pointer p);
+long charvalue(pointer p);
+int is_vector(pointer p);
+
+int is_port(pointer p);
+
+int is_pair(pointer p);
+pointer pair_car(pointer p);
+pointer pair_cdr(pointer p);
+pointer set_car(pointer p, pointer q);
+pointer set_cdr(pointer p, pointer q);
+
+int is_symbol(pointer p);
+char *symname(pointer p);
+int hasprop(pointer p);
+
+int is_syntax(pointer p);
+int is_proc(pointer p);
+int is_foreign(pointer p);
+char *syntaxname(pointer p);
+int is_closure(pointer p);
+#ifdef USE_MACRO
+int is_macro(pointer p);
+#endif
+pointer closure_code(pointer p);
+pointer closure_env(pointer p);
+
+int is_continuation(pointer p);
+int is_promise(pointer p);
+int is_environment(pointer p);
+int is_immutable(pointer p);
+void setimmutable(pointer p);
+
+int is_foreign_object(pointer p);
+const foreign_object_vtable *get_foreign_object_vtable(pointer p);
+void *get_foreign_object_data(pointer p);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+
+/*
+Local variables:
+c-file-style: "k&r"
+End:
+*/
diff --git a/gpgscm/scheme.c b/gpgscm/scheme.c
new file mode 100644
index 0000000..4384841
--- /dev/null
+++ b/gpgscm/scheme.c
@@ -0,0 +1,6028 @@
+/* T I N Y S C H E M E    1 . 4 1
+ *   Dimitrios Souflis (dsouflis@acm.org)
+ *   Based on MiniScheme (original credits follow)
+ * (MINISCM)               coded by Atsushi Moriwaki (11/5/1989)
+ * (MINISCM)           E-MAIL :  moriwaki@kurims.kurims.kyoto-u.ac.jp
+ * (MINISCM) This version has been modified by R.C. Secrist.
+ * (MINISCM)
+ * (MINISCM) Mini-Scheme is now maintained by Akira KIDA.
+ * (MINISCM)
+ * (MINISCM) This is a revised and modified version by Akira KIDA.
+ * (MINISCM)    current version is 0.85k4 (15 May 1994)
+ *
+ */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#define _SCHEME_SOURCE
+#include "scheme-private.h"
+#ifndef WIN32
+# include <unistd.h>
+#endif
+#ifdef WIN32
+#define snprintf _snprintf
+#endif
+#if USE_DL
+# include "dynload.h"
+#endif
+#if USE_MATH
+# include <math.h>
+#endif
+
+#include <assert.h>
+#include <limits.h>
+#include <stdint.h>
+#include <float.h>
+#include <ctype.h>
+
+#if USE_STRCASECMP
+#include <strings.h>
+# ifndef __APPLE__
+#  define stricmp strcasecmp
+# endif
+#endif
+
+/* Used for documentation purposes, to signal functions in 'interface' */
+#define INTERFACE
+
+#define TOK_EOF     (-1)
+#define TOK_LPAREN  0
+#define TOK_RPAREN  1
+#define TOK_DOT     2
+#define TOK_ATOM    3
+#define TOK_QUOTE   4
+#define TOK_COMMENT 5
+#define TOK_DQUOTE  6
+#define TOK_BQUOTE  7
+#define TOK_COMMA   8
+#define TOK_ATMARK  9
+#define TOK_SHARP   10
+#define TOK_SHARP_CONST 11
+#define TOK_VEC     12
+
+#define BACKQUOTE '`'
+#define DELIMITERS  "()\";\f\t\v\n\r "
+
+/*
+ *  Basic memory allocation units
+ */
+
+#define banner "TinyScheme 1.41"
+
+#include <string.h>
+#include <stddef.h>
+#include <stdlib.h>
+
+#ifdef __APPLE__
+static int stricmp(const char *s1, const char *s2)
+{
+  unsigned char c1, c2;
+  do {
+    c1 = tolower(*s1);
+    c2 = tolower(*s2);
+    if (c1 < c2)
+      return -1;
+    else if (c1 > c2)
+      return 1;
+    s1++, s2++;
+  } while (c1 != 0);
+  return 0;
+}
+#endif /* __APPLE__ */
+
+#if USE_STRLWR && !defined(HAVE_STRLWR)
+static const char *strlwr(char *s) {
+  const char *p=s;
+  while(*s) {
+    *s=tolower(*s);
+    s++;
+  }
+  return p;
+}
+#endif
+
+#ifndef prompt
+# define prompt "ts> "
+#endif
+
+#ifndef InitFile
+# define InitFile "init.scm"
+#endif
+
+#ifndef FIRST_CELLSEGS
+# define FIRST_CELLSEGS 3
+#endif
+
+
+
+/* All types have the LSB set.  The garbage collector takes advantage
+ * of that to identify types.  */
+enum scheme_types {
+  T_STRING =		 1 << 1 | 1,
+  T_NUMBER =		 2 << 1 | 1,
+  T_SYMBOL =		 3 << 1 | 1,
+  T_PROC =		 4 << 1 | 1,
+  T_PAIR =		 5 << 1 | 1,
+  T_CLOSURE =		 6 << 1 | 1,
+  T_CONTINUATION =	 7 << 1 | 1,
+  T_FOREIGN =		 8 << 1 | 1,
+  T_CHARACTER =		 9 << 1 | 1,
+  T_PORT =		10 << 1 | 1,
+  T_VECTOR =		11 << 1 | 1,
+  T_MACRO =		12 << 1 | 1,
+  T_PROMISE =		13 << 1 | 1,
+  T_ENVIRONMENT =	14 << 1 | 1,
+  T_FOREIGN_OBJECT =	15 << 1 | 1,
+  T_BOOLEAN =		16 << 1 | 1,
+  T_NIL =		17 << 1 | 1,
+  T_EOF_OBJ =		18 << 1 | 1,
+  T_SINK =		19 << 1 | 1,
+  T_FRAME =		20 << 1 | 1,
+  T_LAST_SYSTEM_TYPE =	20 << 1 | 1
+};
+
+static const char *
+type_to_string (enum scheme_types typ)
+{
+     switch (typ)
+     {
+     case T_STRING: return "string";
+     case T_NUMBER: return "number";
+     case T_SYMBOL: return "symbol";
+     case T_PROC: return "proc";
+     case T_PAIR: return "pair";
+     case T_CLOSURE: return "closure";
+     case T_CONTINUATION: return "continuation";
+     case T_FOREIGN: return "foreign";
+     case T_CHARACTER: return "character";
+     case T_PORT: return "port";
+     case T_VECTOR: return "vector";
+     case T_MACRO: return "macro";
+     case T_PROMISE: return "promise";
+     case T_ENVIRONMENT: return "environment";
+     case T_FOREIGN_OBJECT: return "foreign object";
+     case T_BOOLEAN: return "boolean";
+     case T_NIL: return "nil";
+     case T_EOF_OBJ: return "eof object";
+     case T_SINK: return "sink";
+     case T_FRAME: return "frame";
+     }
+     assert (! "not reached");
+}
+
+/* ADJ is enough slack to align cells in a TYPE_BITS-bit boundary */
+#define TYPE_BITS	6
+#define ADJ		(1 << TYPE_BITS)
+#define T_MASKTYPE      (ADJ - 1)
+                              /* 0000000000111111 */
+#define T_TAGGED      1024    /* 0000010000000000 */
+#define T_FINALIZE    2048    /* 0000100000000000 */
+#define T_SYNTAX      4096    /* 0001000000000000 */
+#define T_IMMUTABLE   8192    /* 0010000000000000 */
+#define T_ATOM       16384    /* 0100000000000000 */   /* only for gc */
+#define CLRATOM      49151    /* 1011111111111111 */   /* only for gc */
+#define MARK         32768    /* 1000000000000000 */
+#define UNMARK       32767    /* 0111111111111111 */
+
+
+static num num_add(num a, num b);
+static num num_mul(num a, num b);
+static num num_div(num a, num b);
+static num num_intdiv(num a, num b);
+static num num_sub(num a, num b);
+static num num_rem(num a, num b);
+static num num_mod(num a, num b);
+static int num_eq(num a, num b);
+static int num_gt(num a, num b);
+static int num_ge(num a, num b);
+static int num_lt(num a, num b);
+static int num_le(num a, num b);
+
+#if USE_MATH
+static double round_per_R5RS(double x);
+#endif
+static int is_zero_double(double x);
+static INLINE int num_is_integer(pointer p) {
+  return ((p)->_object._number.is_fixnum);
+}
+
+static const struct num num_zero = { 1, {0} };
+static const struct num num_one  = { 1, {1} };
+
+/* macros for cell operations */
+#define typeflag(p)      ((p)->_flag)
+#define type(p)          (typeflag(p)&T_MASKTYPE)
+#define settype(p, typ)  (typeflag(p) = (typeflag(p) & ~T_MASKTYPE) | (typ))
+
+INTERFACE INLINE int is_string(pointer p)     { return (type(p)==T_STRING); }
+#define strvalue(p)      ((p)->_object._string._svalue)
+#define strlength(p)        ((p)->_object._string._length)
+
+INTERFACE static int is_list(scheme *sc, pointer p);
+INTERFACE INLINE int is_vector(pointer p)    { return (type(p)==T_VECTOR); }
+/* Given a vector, return it's length.  */
+#define vector_length(v)	(v)->_object._vector._length
+/* Given a vector length, compute the amount of cells required to
+ * represent it.  */
+#define vector_size(len)	(1 + ((len) - 1 + 2) / 3)
+INTERFACE static void fill_vector(pointer vec, pointer obj);
+INTERFACE static pointer *vector_elem_slot(pointer vec, int ielem);
+INTERFACE static pointer vector_elem(pointer vec, int ielem);
+INTERFACE static pointer set_vector_elem(pointer vec, int ielem, pointer a);
+INTERFACE INLINE int is_number(pointer p)    { return (type(p)==T_NUMBER); }
+INTERFACE INLINE int is_integer(pointer p) {
+  if (!is_number(p))
+      return 0;
+  if (num_is_integer(p) || (double)ivalue(p) == rvalue(p))
+      return 1;
+  return 0;
+}
+
+INTERFACE INLINE int is_real(pointer p) {
+  return is_number(p) && (!(p)->_object._number.is_fixnum);
+}
+
+INTERFACE INLINE int is_character(pointer p) { return (type(p)==T_CHARACTER); }
+INTERFACE INLINE char *string_value(pointer p) { return strvalue(p); }
+INLINE num nvalue(pointer p)       { return ((p)->_object._number); }
+INTERFACE long ivalue(pointer p)      { return (num_is_integer(p)?(p)->_object._number.value.ivalue:(long)(p)->_object._number.value.rvalue); }
+INTERFACE double rvalue(pointer p)    { return (!num_is_integer(p)?(p)->_object._number.value.rvalue:(double)(p)->_object._number.value.ivalue); }
+#define ivalue_unchecked(p)       ((p)->_object._number.value.ivalue)
+#define rvalue_unchecked(p)       ((p)->_object._number.value.rvalue)
+#define set_num_integer(p)   (p)->_object._number.is_fixnum=1;
+#define set_num_real(p)      (p)->_object._number.is_fixnum=0;
+INTERFACE  long charvalue(pointer p)  { return ivalue_unchecked(p); }
+
+INTERFACE INLINE int is_port(pointer p)     { return (type(p)==T_PORT); }
+INTERFACE INLINE int is_inport(pointer p)  { return is_port(p) && p->_object._port->kind & port_input; }
+INTERFACE INLINE int is_outport(pointer p) { return is_port(p) && p->_object._port->kind & port_output; }
+
+INTERFACE INLINE int is_pair(pointer p)     { return (type(p)==T_PAIR); }
+#define car(p)           ((p)->_object._cons._car)
+#define cdr(p)           ((p)->_object._cons._cdr)
+INTERFACE pointer pair_car(pointer p)   { return car(p); }
+INTERFACE pointer pair_cdr(pointer p)   { return cdr(p); }
+INTERFACE pointer set_car(pointer p, pointer q) { return car(p)=q; }
+INTERFACE pointer set_cdr(pointer p, pointer q) { return cdr(p)=q; }
+
+INTERFACE INLINE int is_symbol(pointer p)   { return (type(p)==T_SYMBOL); }
+INTERFACE INLINE char *symname(pointer p)   { return strvalue(car(p)); }
+#if USE_PLIST
+SCHEME_EXPORT INLINE int hasprop(pointer p)     { return (is_symbol(p)); }
+#define symprop(p)       cdr(p)
+#endif
+
+INTERFACE INLINE int is_syntax(pointer p)   { return (typeflag(p)&T_SYNTAX); }
+INTERFACE INLINE int is_proc(pointer p)     { return (type(p)==T_PROC); }
+INTERFACE INLINE int is_foreign(pointer p)  { return (type(p)==T_FOREIGN); }
+INTERFACE INLINE char *syntaxname(pointer p) { return strvalue(car(p)); }
+#define procnum(p)       ivalue_unchecked(p)
+static const char *procname(pointer x);
+
+INTERFACE INLINE int is_closure(pointer p)  { return (type(p)==T_CLOSURE); }
+INTERFACE INLINE int is_macro(pointer p)    { return (type(p)==T_MACRO); }
+INTERFACE INLINE pointer closure_code(pointer p)   { return car(p); }
+INTERFACE INLINE pointer closure_env(pointer p)    { return cdr(p); }
+
+INTERFACE INLINE int is_continuation(pointer p)    { return (type(p)==T_CONTINUATION); }
+#define cont_dump(p)     cdr(p)
+
+INTERFACE INLINE int is_foreign_object(pointer p) { return (type(p)==T_FOREIGN_OBJECT); }
+INTERFACE const foreign_object_vtable *get_foreign_object_vtable(pointer p) {
+  return p->_object._foreign_object._vtable;
+}
+INTERFACE void *get_foreign_object_data(pointer p) {
+  return p->_object._foreign_object._data;
+}
+
+/* To do: promise should be forced ONCE only */
+INTERFACE INLINE int is_promise(pointer p)  { return (type(p)==T_PROMISE); }
+
+INTERFACE INLINE int is_environment(pointer p) { return (type(p)==T_ENVIRONMENT); }
+#define setenvironment(p)    typeflag(p) = T_ENVIRONMENT
+
+INTERFACE INLINE int is_frame(pointer p) { return (type(p) == T_FRAME); }
+#define setframe(p)    settype(p, T_FRAME)
+
+#define is_atom(p)       (typeflag(p)&T_ATOM)
+#define setatom(p)       typeflag(p) |= T_ATOM
+#define clratom(p)       typeflag(p) &= CLRATOM
+
+#define is_mark(p)       (typeflag(p)&MARK)
+#define setmark(p)       typeflag(p) |= MARK
+#define clrmark(p)       typeflag(p) &= UNMARK
+
+INTERFACE INLINE int is_immutable(pointer p) { return (typeflag(p)&T_IMMUTABLE); }
+/*#define setimmutable(p)  typeflag(p) |= T_IMMUTABLE*/
+INTERFACE INLINE void setimmutable(pointer p) { typeflag(p) |= T_IMMUTABLE; }
+
+#define caar(p)          car(car(p))
+#define cadr(p)          car(cdr(p))
+#define cdar(p)          cdr(car(p))
+#define cddr(p)          cdr(cdr(p))
+#define cadar(p)         car(cdr(car(p)))
+#define caddr(p)         car(cdr(cdr(p)))
+#define cdaar(p)         cdr(car(car(p)))
+#define cadaar(p)        car(cdr(car(car(p))))
+#define cadddr(p)        car(cdr(cdr(cdr(p))))
+#define cddddr(p)        cdr(cdr(cdr(cdr(p))))
+
+#if USE_HISTORY
+static pointer history_flatten(scheme *sc);
+static void history_mark(scheme *sc);
+#else
+# define history_mark(SC)	(void) 0
+# define history_flatten(SC)	(SC)->NIL
+#endif
+
+#if USE_CHAR_CLASSIFIERS
+static INLINE int Cisalpha(int c) { return isascii(c) && isalpha(c); }
+static INLINE int Cisdigit(int c) { return isascii(c) && isdigit(c); }
+static INLINE int Cisspace(int c) { return isascii(c) && isspace(c); }
+static INLINE int Cisupper(int c) { return isascii(c) && isupper(c); }
+static INLINE int Cislower(int c) { return isascii(c) && islower(c); }
+#endif
+
+#if USE_ASCII_NAMES
+static const char charnames[32][3]={
+ "nul",
+ "soh",
+ "stx",
+ "etx",
+ "eot",
+ "enq",
+ "ack",
+ "bel",
+ "bs",
+ "ht",
+ "lf",
+ "vt",
+ "ff",
+ "cr",
+ "so",
+ "si",
+ "dle",
+ "dc1",
+ "dc2",
+ "dc3",
+ "dc4",
+ "nak",
+ "syn",
+ "etb",
+ "can",
+ "em",
+ "sub",
+ "esc",
+ "fs",
+ "gs",
+ "rs",
+ "us"
+};
+
+static int is_ascii_name(const char *name, int *pc) {
+  int i;
+  for(i=0; i<32; i++) {
+     if (strncasecmp(name, charnames[i], 3) == 0) {
+          *pc=i;
+          return 1;
+     }
+  }
+  if (strcasecmp(name, "del") == 0) {
+     *pc=127;
+     return 1;
+  }
+  return 0;
+}
+
+#endif
+
+static int file_push(scheme *sc, pointer fname);
+static void file_pop(scheme *sc);
+static int file_interactive(scheme *sc);
+static INLINE int is_one_of(char *s, int c);
+static int alloc_cellseg(scheme *sc, int n);
+static long binary_decode(const char *s);
+static INLINE pointer get_cell(scheme *sc, pointer a, pointer b);
+static pointer _get_cell(scheme *sc, pointer a, pointer b);
+static pointer reserve_cells(scheme *sc, int n);
+static pointer get_consecutive_cells(scheme *sc, int n);
+static pointer find_consecutive_cells(scheme *sc, int n);
+static int finalize_cell(scheme *sc, pointer a);
+static int count_consecutive_cells(pointer x, int needed);
+static pointer find_slot_in_env(scheme *sc, pointer env, pointer sym, int all);
+static pointer mk_number(scheme *sc, num n);
+static char *store_string(scheme *sc, int len, const char *str, char fill);
+static pointer mk_vector(scheme *sc, int len);
+static pointer mk_atom(scheme *sc, char *q);
+static pointer mk_sharp_const(scheme *sc, char *name);
+static pointer mk_port(scheme *sc, port *p);
+static pointer port_from_filename(scheme *sc, const char *fn, int prop);
+static pointer port_from_file(scheme *sc, FILE *, int prop);
+static pointer port_from_string(scheme *sc, char *start, char *past_the_end, int prop);
+static port *port_rep_from_filename(scheme *sc, const char *fn, int prop);
+static port *port_rep_from_file(scheme *sc, FILE *, int prop);
+static port *port_rep_from_string(scheme *sc, char *start, char *past_the_end, int prop);
+static void port_close(scheme *sc, pointer p, int flag);
+static void mark(pointer a);
+static void gc(scheme *sc, pointer a, pointer b);
+static int basic_inchar(port *pt);
+static int inchar(scheme *sc);
+static void backchar(scheme *sc, int c);
+static char   *readstr_upto(scheme *sc, char *delim);
+static pointer readstrexp(scheme *sc);
+static INLINE int skipspace(scheme *sc);
+static int token(scheme *sc);
+static void printslashstring(scheme *sc, char *s, int len);
+static void atom2str(scheme *sc, pointer l, int f, char **pp, int *plen);
+static void printatom(scheme *sc, pointer l, int f);
+static pointer mk_proc(scheme *sc, enum scheme_opcodes op);
+static pointer mk_closure(scheme *sc, pointer c, pointer e);
+static pointer mk_continuation(scheme *sc, pointer d);
+static pointer reverse(scheme *sc, pointer term, pointer list);
+static pointer reverse_in_place(scheme *sc, pointer term, pointer list);
+static pointer revappend(scheme *sc, pointer a, pointer b);
+static void dump_stack_preallocate_frame(scheme *sc);
+static void dump_stack_mark(scheme *);
+struct op_code_info {
+  char name[31];	/* strlen ("call-with-current-continuation") + 1 */
+  unsigned char min_arity;
+  unsigned char max_arity;
+  char arg_tests_encoding[3];
+};
+static const struct op_code_info dispatch_table[];
+static int check_arguments (scheme *sc, const struct op_code_info *pcd, char *msg, size_t msg_size);
+static void Eval_Cycle(scheme *sc, enum scheme_opcodes op);
+static void assign_syntax(scheme *sc, enum scheme_opcodes op, char *name);
+static int syntaxnum(scheme *sc, pointer p);
+static void assign_proc(scheme *sc, enum scheme_opcodes, const char *name);
+
+#define num_ivalue(n)       (n.is_fixnum?(n).value.ivalue:(long)(n).value.rvalue)
+#define num_rvalue(n)       (!n.is_fixnum?(n).value.rvalue:(double)(n).value.ivalue)
+
+static num num_add(num a, num b) {
+ num ret;
+ ret.is_fixnum=a.is_fixnum && b.is_fixnum;
+ if(ret.is_fixnum) {
+     ret.value.ivalue= a.value.ivalue+b.value.ivalue;
+ } else {
+     ret.value.rvalue=num_rvalue(a)+num_rvalue(b);
+ }
+ return ret;
+}
+
+static num num_mul(num a, num b) {
+ num ret;
+ ret.is_fixnum=a.is_fixnum && b.is_fixnum;
+ if(ret.is_fixnum) {
+     ret.value.ivalue= a.value.ivalue*b.value.ivalue;
+ } else {
+     ret.value.rvalue=num_rvalue(a)*num_rvalue(b);
+ }
+ return ret;
+}
+
+static num num_div(num a, num b) {
+ num ret;
+ ret.is_fixnum=a.is_fixnum && b.is_fixnum && a.value.ivalue%b.value.ivalue==0;
+ if(ret.is_fixnum) {
+     ret.value.ivalue= a.value.ivalue/b.value.ivalue;
+ } else {
+     ret.value.rvalue=num_rvalue(a)/num_rvalue(b);
+ }
+ return ret;
+}
+
+static num num_intdiv(num a, num b) {
+ num ret;
+ ret.is_fixnum=a.is_fixnum && b.is_fixnum;
+ if(ret.is_fixnum) {
+     ret.value.ivalue= a.value.ivalue/b.value.ivalue;
+ } else {
+     ret.value.rvalue=num_rvalue(a)/num_rvalue(b);
+ }
+ return ret;
+}
+
+static num num_sub(num a, num b) {
+ num ret;
+ ret.is_fixnum=a.is_fixnum && b.is_fixnum;
+ if(ret.is_fixnum) {
+     ret.value.ivalue= a.value.ivalue-b.value.ivalue;
+ } else {
+     ret.value.rvalue=num_rvalue(a)-num_rvalue(b);
+ }
+ return ret;
+}
+
+static num num_rem(num a, num b) {
+ num ret;
+ long e1, e2, res;
+ ret.is_fixnum=a.is_fixnum && b.is_fixnum;
+ e1=num_ivalue(a);
+ e2=num_ivalue(b);
+ res=e1%e2;
+ /* remainder should have same sign as second operand */
+ if (res > 0) {
+     if (e1 < 0) {
+        res -= labs(e2);
+     }
+ } else if (res < 0) {
+     if (e1 > 0) {
+         res += labs(e2);
+     }
+ }
+ ret.value.ivalue=res;
+ return ret;
+}
+
+static num num_mod(num a, num b) {
+ num ret;
+ long e1, e2, res;
+ ret.is_fixnum=a.is_fixnum && b.is_fixnum;
+ e1=num_ivalue(a);
+ e2=num_ivalue(b);
+ res=e1%e2;
+ /* modulo should have same sign as second operand */
+ if (res * e2 < 0) {
+    res += e2;
+ }
+ ret.value.ivalue=res;
+ return ret;
+}
+
+static int num_eq(num a, num b) {
+ int ret;
+ int is_fixnum=a.is_fixnum && b.is_fixnum;
+ if(is_fixnum) {
+     ret= a.value.ivalue==b.value.ivalue;
+ } else {
+     ret=num_rvalue(a)==num_rvalue(b);
+ }
+ return ret;
+}
+
+
+static int num_gt(num a, num b) {
+ int ret;
+ int is_fixnum=a.is_fixnum && b.is_fixnum;
+ if(is_fixnum) {
+     ret= a.value.ivalue>b.value.ivalue;
+ } else {
+     ret=num_rvalue(a)>num_rvalue(b);
+ }
+ return ret;
+}
+
+static int num_ge(num a, num b) {
+ return !num_lt(a,b);
+}
+
+static int num_lt(num a, num b) {
+ int ret;
+ int is_fixnum=a.is_fixnum && b.is_fixnum;
+ if(is_fixnum) {
+     ret= a.value.ivalue<b.value.ivalue;
+ } else {
+     ret=num_rvalue(a)<num_rvalue(b);
+ }
+ return ret;
+}
+
+static int num_le(num a, num b) {
+ return !num_gt(a,b);
+}
+
+#if USE_MATH
+/* Round to nearest. Round to even if midway */
+static double round_per_R5RS(double x) {
+ double fl=floor(x);
+ double ce=ceil(x);
+ double dfl=x-fl;
+ double dce=ce-x;
+ if(dfl>dce) {
+     return ce;
+ } else if(dfl<dce) {
+     return fl;
+ } else {
+     if(fmod(fl,2.0)==0.0) {       /* I imagine this holds */
+          return fl;
+     } else {
+          return ce;
+     }
+ }
+}
+#endif
+
+static int is_zero_double(double x) {
+ return x<DBL_MIN && x>-DBL_MIN;
+}
+
+static long binary_decode(const char *s) {
+ long x=0;
+
+ while(*s!=0 && (*s=='1' || *s=='0')) {
+     x<<=1;
+     x+=*s-'0';
+     s++;
+ }
+
+ return x;
+}
+
+
+
+/*
+ * Copying values.
+ *
+ * Occasionally, we need to copy a value from one location in the
+ * storage to another.  Scheme objects are fine.  Some primitive
+ * objects, however, require finalization, usually to free resources.
+ *
+ * For these values, we either make a copy or acquire a reference.
+ */
+
+/*
+ * Copy SRC to DST.
+ *
+ * Copies the representation of SRC to DST.  This makes SRC
+ * indistinguishable from DST from the perspective of a Scheme
+ * expression modulo the fact that they reside at a different location
+ * in the store.
+ *
+ * Conditions:
+ *
+ *     - SRC must not be a vector.
+ *     - Caller must ensure that any resources associated with the
+ *       value currently stored in DST is accounted for.
+ */
+static void
+copy_value(scheme *sc, pointer dst, pointer src)
+{
+  memcpy(dst, src, sizeof *src);
+
+  /* We may need to make a copy or acquire a reference.  */
+  if (typeflag(dst) & T_FINALIZE)
+    switch (type(dst)) {
+    case T_STRING:
+      strvalue(dst) = store_string(sc, strlength(dst), strvalue(dst), 0);
+      break;
+    case T_PORT:
+      /* XXX acquire reference */
+      assert (!"implemented");
+      break;
+    case T_FOREIGN_OBJECT:
+      /* XXX acquire reference */
+      assert (!"implemented");
+      break;
+     case T_VECTOR:
+      assert (!"vectors cannot be copied");
+    }
+}
+
+
+
+/* Tags are like property lists, but can be attached to arbitrary
+ * values.  */
+
+static pointer
+mk_tagged_value(scheme *sc, pointer v, pointer tag_car, pointer tag_cdr)
+{
+  pointer r, t;
+
+  assert(! is_vector(v));
+
+  r = get_consecutive_cells(sc, 2);
+  if (r == sc->sink)
+    return sc->sink;
+
+  copy_value(sc, r, v);
+  typeflag(r) |= T_TAGGED;
+
+  t = r + 1;
+  typeflag(t) = T_PAIR;
+  car(t) = tag_car;
+  cdr(t) = tag_cdr;
+
+  return r;
+}
+
+static INLINE int
+has_tag(pointer v)
+{
+  return !! (typeflag(v) & T_TAGGED);
+}
+
+static INLINE pointer
+get_tag(scheme *sc, pointer v)
+{
+  if (has_tag(v))
+    return v + 1;
+  return sc->NIL;
+}
+
+
+
+/* Low-level allocator.
+ *
+ * Memory is allocated in segments.  Every segment holds a fixed
+ * number of cells.  Segments are linked into a list, sorted in
+ * reverse address order (i.e. those with a higher address first).
+ * This is used in the garbage collector to build the freelist in
+ * address order.
+ */
+
+struct cell_segment
+{
+     struct cell_segment *next;
+     void *alloc;
+     pointer cells;
+     size_t cells_len;
+};
+
+/* Allocate a new cell segment but do not make it available yet.  */
+static int
+_alloc_cellseg(scheme *sc, size_t len, struct cell_segment **segment)
+{
+  int adj = ADJ;
+  void *cp;
+
+  if (adj < sizeof(struct cell))
+    adj = sizeof(struct cell);
+
+  /* The segment header is conveniently allocated with the cells.  */
+  cp = sc->malloc(sizeof **segment + len * sizeof(struct cell) + adj);
+  if (cp == NULL)
+    return 1;
+
+  *segment = cp;
+  (*segment)->next = NULL;
+  (*segment)->alloc = cp;
+  cp = (void *) ((uintptr_t) cp + sizeof **segment);
+
+  /* adjust in TYPE_BITS-bit boundary */
+  if (((uintptr_t) cp) % adj != 0)
+    cp = (void *) (adj * ((uintptr_t) cp / adj + 1));
+
+  (*segment)->cells = cp;
+  (*segment)->cells_len = len;
+  return 0;
+}
+
+/* Deallocate a cell segment.  Returns the next cell segment.
+ * Convenient for deallocation in a loop.  */
+static struct cell_segment *
+_dealloc_cellseg(scheme *sc, struct cell_segment *segment)
+{
+
+  struct cell_segment *next;
+
+  if (segment == NULL)
+    return NULL;
+
+  next = segment->next;
+  sc->free(segment->alloc);
+  return next;
+}
+
+/* allocate new cell segment */
+static int alloc_cellseg(scheme *sc, int n) {
+     pointer last;
+     pointer p;
+     int k;
+
+     for (k = 0; k < n; k++) {
+	 struct cell_segment *new, **s;
+	 if (_alloc_cellseg(sc, CELL_SEGSIZE, &new)) {
+	      return k;
+	 }
+	 /* insert new segment in reverse address order */
+	 for (s = &sc->cell_segments;
+	      *s && (uintptr_t) (*s)->alloc > (uintptr_t) new->alloc;
+	      s = &(*s)->next) {
+	     /* walk */
+	 }
+	 new->next = *s;
+	 *s = new;
+
+         sc->fcells += new->cells_len;
+         last = new->cells + new->cells_len - 1;
+          for (p = new->cells; p <= last; p++) {
+              typeflag(p) = 0;
+              cdr(p) = p + 1;
+              car(p) = sc->NIL;
+         }
+         /* insert new cells in address order on free list */
+         if (sc->free_cell == sc->NIL || p < sc->free_cell) {
+              cdr(last) = sc->free_cell;
+              sc->free_cell = new->cells;
+         } else {
+               p = sc->free_cell;
+               while (cdr(p) != sc->NIL && (uintptr_t) new->cells > (uintptr_t) cdr(p))
+                    p = cdr(p);
+               cdr(last) = cdr(p);
+               cdr(p) = new->cells;
+         }
+     }
+     return n;
+}
+
+
+
+/* Controlling the garbage collector.
+ *
+ * Every time a cell is allocated, the interpreter may run out of free
+ * cells and do a garbage collection.  This is problematic because it
+ * might garbage collect objects that have been allocated, but are not
+ * yet made available to the interpreter.
+ *
+ * Previously, we would plug such newly allocated cells into the list
+ * of newly allocated objects rooted at car(sc->sink), but that
+ * requires allocating yet another cell increasing pressure on the
+ * memory management system.
+ *
+ * A faster alternative is to preallocate the cells needed for an
+ * operation and make sure the garbage collection is not run until all
+ * allocated objects are plugged in.  This can be done with gc_disable
+ * and gc_enable.
+ */
+
+/* The garbage collector is enabled if the inhibit counter is
+ * zero.  */
+#define GC_ENABLED	0
+
+/* For now we provide a way to disable this optimization for
+ * benchmarking and because it produces slightly smaller code.  */
+#ifndef USE_GC_LOCKING
+# define USE_GC_LOCKING 1
+#endif
+
+/* To facilitate nested calls to gc_disable, functions that allocate
+ * more than one cell may define a macro, e.g. foo_allocates.  This
+ * macro can be used to compute the amount of preallocation at the
+ * call site with the help of this macro.  */
+#define gc_reservations(fn) fn ## _allocates
+
+#if USE_GC_LOCKING
+
+/* Report a shortage in reserved cells, and terminate the program.  */
+static void
+gc_reservation_failure(struct scheme *sc)
+{
+#ifdef NDEBUG
+  fprintf(stderr,
+	  "insufficient reservation\n")
+#else
+  fprintf(stderr,
+	  "insufficient %s reservation in line %d\n",
+	  sc->frame_freelist == sc->NIL ? "frame" : "cell",
+	  sc->reserved_lineno);
+#endif
+  abort();
+}
+
+/* Disable the garbage collection and reserve the given number of
+ * cells.  gc_disable may be nested, but the enclosing reservation
+ * must include the reservations of all nested calls.  Note: You must
+ * re-enable the gc before calling Error_X.  */
+static void
+_gc_disable(struct scheme *sc, size_t reserve, int lineno)
+{
+  if (sc->inhibit_gc == 0) {
+    reserve_cells(sc, (reserve));
+    sc->reserved_cells = (reserve);
+#ifdef NDEBUG
+    (void) lineno;
+#else
+    sc->reserved_lineno = lineno;
+#endif
+  } else if (sc->reserved_cells < (reserve))
+    gc_reservation_failure (sc);
+  sc->inhibit_gc += 1;
+}
+#define gc_disable(sc, reserve)			\
+     do {					\
+       if (sc->frame_freelist == sc->NIL) {	\
+	 if (gc_enabled(sc))			\
+	   dump_stack_preallocate_frame(sc);	\
+	 else					\
+	   gc_reservation_failure(sc);		\
+       }					\
+       _gc_disable (sc, reserve, __LINE__);	\
+     } while (0)
+
+/* Enable the garbage collector.  */
+#define gc_enable(sc)				\
+     do {					\
+	  assert(sc->inhibit_gc);		\
+	  sc->inhibit_gc -= 1;			\
+     } while (0)
+
+/* Test whether the garbage collector is enabled.  */
+#define gc_enabled(sc)				\
+     (sc->inhibit_gc == GC_ENABLED)
+
+/* Consume a reserved cell.  */
+#define gc_consume(sc)							\
+     do {								\
+	  assert(! gc_enabled (sc));					\
+	  if (sc->reserved_cells == 0)					\
+	       gc_reservation_failure (sc);				\
+	  sc->reserved_cells -= 1;					\
+     } while (0)
+
+#else /* USE_GC_LOCKING */
+
+#define gc_reservation_failure(sc)	(void) 0
+#define gc_disable(sc, reserve)			\
+     do {					\
+       if (sc->frame_freelist == sc->NIL)	\
+	 dump_stack_preallocate_frame(sc);	\
+     } while (0)
+#define gc_enable(sc)	(void) 0
+#define gc_enabled(sc)	1
+#define gc_consume(sc)	(void) 0
+
+#endif /* USE_GC_LOCKING */
+
+static INLINE pointer get_cell_x(scheme *sc, pointer a, pointer b) {
+  if (! gc_enabled (sc) || sc->free_cell != sc->NIL) {
+    pointer x = sc->free_cell;
+    if (! gc_enabled (sc))
+	 gc_consume (sc);
+    sc->free_cell = cdr(x);
+    --sc->fcells;
+    return (x);
+  }
+  assert (gc_enabled (sc));
+  return _get_cell (sc, a, b);
+}
+
+
+/* get new cell.  parameter a, b is marked by gc. */
+static pointer _get_cell(scheme *sc, pointer a, pointer b) {
+  pointer x;
+
+  if(sc->no_memory) {
+    return sc->sink;
+  }
+
+  assert (gc_enabled (sc));
+  if (sc->free_cell == sc->NIL) {
+    gc(sc,a, b);
+    if (sc->free_cell == sc->NIL) {
+	 sc->no_memory=1;
+	 return sc->sink;
+    }
+  }
+  x = sc->free_cell;
+  sc->free_cell = cdr(x);
+  --sc->fcells;
+  return (x);
+}
+
+/* make sure that there is a given number of cells free */
+static pointer reserve_cells(scheme *sc, int n) {
+    if(sc->no_memory) {
+        return sc->NIL;
+    }
+
+    /* Are there enough cells available? */
+    if (sc->fcells < n) {
+        /* If not, try gc'ing some */
+        gc(sc, sc->NIL, sc->NIL);
+        if (sc->fcells < n) {
+            /* If there still aren't, try getting more heap */
+            if (!alloc_cellseg(sc,1)) {
+                sc->no_memory=1;
+                return sc->NIL;
+            }
+        }
+        if (sc->fcells < n) {
+            /* If all fail, report failure */
+            sc->no_memory=1;
+            return sc->NIL;
+        }
+    }
+    return (sc->T);
+}
+
+static pointer get_consecutive_cells(scheme *sc, int n) {
+  pointer x;
+
+  if(sc->no_memory) { return sc->sink; }
+
+  /* Are there any cells available? */
+  x=find_consecutive_cells(sc,n);
+  if (x != sc->NIL) { return x; }
+
+  /* If not, try gc'ing some */
+  gc(sc, sc->NIL, sc->NIL);
+  x=find_consecutive_cells(sc,n);
+  if (x != sc->NIL) { return x; }
+
+  /* If there still aren't, try getting more heap */
+  if (!alloc_cellseg(sc,1))
+    {
+      sc->no_memory=1;
+      return sc->sink;
+    }
+
+  x=find_consecutive_cells(sc,n);
+  if (x != sc->NIL) { return x; }
+
+  /* If all fail, report failure */
+  sc->no_memory=1;
+  return sc->sink;
+}
+
+static int count_consecutive_cells(pointer x, int needed) {
+ int n=1;
+ while(cdr(x)==x+1) {
+     x=cdr(x);
+     n++;
+     if(n>needed) return n;
+ }
+ return n;
+}
+
+static pointer find_consecutive_cells(scheme *sc, int n) {
+  pointer *pp;
+  int cnt;
+
+  pp=&sc->free_cell;
+  while(*pp!=sc->NIL) {
+    cnt=count_consecutive_cells(*pp,n);
+    if(cnt>=n) {
+      pointer x=*pp;
+      *pp=cdr(*pp+n-1);
+      sc->fcells -= n;
+      return x;
+    }
+    pp=&cdr(*pp+cnt-1);
+  }
+  return sc->NIL;
+}
+
+/* Free a cell.  This is dangerous.  Only free cells that are not
+ * referenced.  */
+static INLINE void
+free_cell(scheme *sc, pointer a)
+{
+  cdr(a) = sc->free_cell;
+  sc->free_cell = a;
+  sc->fcells += 1;
+}
+
+/* Free a cell and retrieve its content.  This is dangerous.  Only
+ * free cells that are not referenced.  */
+static INLINE void
+free_cons(scheme *sc, pointer a, pointer *r_car, pointer *r_cdr)
+{
+  *r_car = car(a);
+  *r_cdr = cdr(a);
+  free_cell(sc, a);
+}
+
+/* To retain recent allocs before interpreter knows about them -
+   Tehom */
+
+static void push_recent_alloc(scheme *sc, pointer recent, pointer extra)
+{
+  pointer holder = get_cell_x(sc, recent, extra);
+  typeflag(holder) = T_PAIR | T_IMMUTABLE;
+  car(holder) = recent;
+  cdr(holder) = car(sc->sink);
+  car(sc->sink) = holder;
+}
+
+static INLINE void ok_to_freely_gc(scheme *sc)
+{
+  pointer a = car(sc->sink), next;
+  car(sc->sink) = sc->NIL;
+  while (a != sc->NIL)
+    {
+      next = cdr(a);
+      free_cell(sc, a);
+      a = next;
+    }
+}
+
+static pointer get_cell(scheme *sc, pointer a, pointer b)
+{
+  pointer cell   = get_cell_x(sc, a, b);
+  /* For right now, include "a" and "b" in "cell" so that gc doesn't
+     think they are garbage. */
+  /* Tentatively record it as a pair so gc understands it. */
+  typeflag(cell) = T_PAIR;
+  car(cell) = a;
+  cdr(cell) = b;
+  if (gc_enabled (sc))
+    push_recent_alloc(sc, cell, sc->NIL);
+  return cell;
+}
+
+static pointer get_vector_object(scheme *sc, int len, pointer init)
+{
+  pointer cells = get_consecutive_cells(sc, vector_size(len));
+  int i;
+  int alloc_len = 1 + 3 * (vector_size(len) - 1);
+  if(sc->no_memory) { return sc->sink; }
+  /* Record it as a vector so that gc understands it. */
+  typeflag(cells) = (T_VECTOR | T_ATOM | T_FINALIZE);
+  vector_length(cells) = len;
+  fill_vector(cells,init);
+
+  /* Initialize the unused slots at the end.  */
+  assert (alloc_len - len < 3);
+  for (i = len; i < alloc_len; i++)
+    cells->_object._vector._elements[i] = sc->NIL;
+
+  if (gc_enabled (sc))
+    push_recent_alloc(sc, cells, sc->NIL);
+  return cells;
+}
+
+/* Medium level cell allocation */
+
+/* get new cons cell */
+pointer _cons(scheme *sc, pointer a, pointer b, int immutable) {
+  pointer x = get_cell(sc,a, b);
+
+  typeflag(x) = T_PAIR;
+  if(immutable) {
+    setimmutable(x);
+  }
+  car(x) = a;
+  cdr(x) = b;
+  return (x);
+}
+
+
+/* ========== oblist implementation  ========== */
+
+#ifndef USE_OBJECT_LIST
+
+static int hash_fn(const char *key, int table_size);
+
+static pointer oblist_initial_value(scheme *sc)
+{
+  /* There are about 768 symbols used after loading the
+   * interpreter.  */
+  return mk_vector(sc, 1009);
+}
+
+/* Lookup the symbol NAME.  Returns the symbol, or NIL if it does not
+ * exist.  In that case, SLOT points to the point where the new symbol
+ * is to be inserted.  */
+static INLINE pointer
+oblist_find_by_name(scheme *sc, const char *name, pointer **slot)
+{
+  int location;
+  pointer x;
+  char *s;
+  int d;
+
+  location = hash_fn(name, vector_length(sc->oblist));
+  for (*slot = vector_elem_slot(sc->oblist, location), x = **slot;
+       x != sc->NIL; *slot = &cdr(x), x = **slot) {
+    s = symname(car(x));
+    /* case-insensitive, per R5RS section 2. */
+    d = stricmp(name, s);
+    if (d == 0)
+      return car(x);		/* Hit.  */
+    else if (d > 0)
+      break;			/* Miss.  */
+  }
+  return sc->NIL;
+}
+
+static pointer oblist_all_symbols(scheme *sc)
+{
+  int i;
+  pointer x;
+  pointer ob_list = sc->NIL;
+
+  for (i = 0; i < vector_length(sc->oblist); i++) {
+    for (x  = vector_elem(sc->oblist, i); x != sc->NIL; x = cdr(x)) {
+      ob_list = cons(sc, x, ob_list);
+    }
+  }
+  return ob_list;
+}
+
+#else
+
+static pointer oblist_initial_value(scheme *sc)
+{
+  return sc->NIL;
+}
+
+/* Lookup the symbol NAME.  Returns the symbol, or NIL if it does not
+ * exist.  In that case, SLOT points to the point where the new symbol
+ * is to be inserted.  */
+static INLINE pointer
+oblist_find_by_name(scheme *sc, const char *name, pointer **slot)
+{
+     pointer x;
+     char    *s;
+     int     d;
+
+     for (*slot = &sc->oblist, x = **slot; x != sc->NIL; *slot = &cdr(x), x = **slot) {
+        s = symname(car(x));
+        /* case-insensitive, per R5RS section 2. */
+	d = stricmp(name, s);
+        if (d == 0)
+          return car(x);	/* Hit.  */
+        else if (d > 0)
+	  break;		/* Miss.  */
+     }
+     return sc->NIL;
+}
+
+static pointer oblist_all_symbols(scheme *sc)
+{
+  return sc->oblist;
+}
+
+#endif
+
+/* Add a new symbol NAME at SLOT.  SLOT must be obtained using
+ * oblist_find_by_name, and no insertion must be done between
+ * obtaining the SLOT and calling this function.  Returns the new
+ * symbol.  */
+static pointer oblist_add_by_name(scheme *sc, const char *name, pointer *slot)
+{
+#define oblist_add_by_name_allocates	3
+  pointer x;
+
+  gc_disable(sc, gc_reservations (oblist_add_by_name));
+  x = immutable_cons(sc, mk_string(sc, name), sc->NIL);
+  typeflag(x) = T_SYMBOL;
+  setimmutable(car(x));
+  *slot = immutable_cons(sc, x, *slot);
+  gc_enable(sc);
+  return x;
+}
+
+
+
+static pointer mk_port(scheme *sc, port *p) {
+  pointer x = get_cell(sc, sc->NIL, sc->NIL);
+
+  typeflag(x) = T_PORT|T_ATOM|T_FINALIZE;
+  x->_object._port=p;
+  return (x);
+}
+
+pointer mk_foreign_func(scheme *sc, foreign_func f) {
+  pointer x = get_cell(sc, sc->NIL, sc->NIL);
+
+  typeflag(x) = (T_FOREIGN | T_ATOM);
+  x->_object._ff=f;
+  return (x);
+}
+
+pointer mk_foreign_object(scheme *sc, const foreign_object_vtable *vtable, void *data) {
+  pointer x = get_cell(sc, sc->NIL, sc->NIL);
+
+  typeflag(x) = (T_FOREIGN_OBJECT | T_ATOM | T_FINALIZE);
+  x->_object._foreign_object._vtable=vtable;
+  x->_object._foreign_object._data = data;
+  return (x);
+}
+
+INTERFACE pointer mk_character(scheme *sc, int c) {
+  pointer x = get_cell(sc,sc->NIL, sc->NIL);
+
+  typeflag(x) = (T_CHARACTER | T_ATOM);
+  ivalue_unchecked(x)= c;
+  set_num_integer(x);
+  return (x);
+}
+
+
+
+#if USE_SMALL_INTEGERS
+
+static const struct cell small_integers[] = {
+#define DEFINE_INTEGER(n) { T_NUMBER | T_ATOM | MARK, {{ 1, {n}}}},
+#include "small-integers.h"
+#undef DEFINE_INTEGER
+     {0}
+};
+
+#define MAX_SMALL_INTEGER	(sizeof small_integers / sizeof *small_integers - 1)
+
+static INLINE pointer
+mk_small_integer(scheme *sc, long n)
+{
+#define mk_small_integer_allocates	0
+  (void) sc;
+  assert(0 <= n && n < MAX_SMALL_INTEGER);
+  return (pointer) &small_integers[n];
+}
+#else
+
+#define mk_small_integer_allocates	1
+#define mk_small_integer	mk_integer
+
+#endif
+
+/* get number atom (integer) */
+INTERFACE pointer mk_integer(scheme *sc, long n) {
+  pointer x;
+
+#if USE_SMALL_INTEGERS
+  if (0 <= n && n < MAX_SMALL_INTEGER)
+    return mk_small_integer(sc, n);
+#endif
+
+  x = get_cell(sc,sc->NIL, sc->NIL);
+  typeflag(x) = (T_NUMBER | T_ATOM);
+  ivalue_unchecked(x)= n;
+  set_num_integer(x);
+  return (x);
+}
+
+
+
+INTERFACE pointer mk_real(scheme *sc, double n) {
+  pointer x = get_cell(sc,sc->NIL, sc->NIL);
+
+  typeflag(x) = (T_NUMBER | T_ATOM);
+  rvalue_unchecked(x)= n;
+  set_num_real(x);
+  return (x);
+}
+
+static pointer mk_number(scheme *sc, num n) {
+ if(n.is_fixnum) {
+     return mk_integer(sc,n.value.ivalue);
+ } else {
+     return mk_real(sc,n.value.rvalue);
+ }
+}
+
+/* allocate name to string area */
+static char *store_string(scheme *sc, int len_str, const char *str, char fill) {
+     char *q;
+
+     q=(char*)sc->malloc(len_str+1);
+     if(q==0) {
+          sc->no_memory=1;
+          return sc->strbuff;
+     }
+     if(str!=0) {
+	  memcpy (q, str, len_str);
+          q[len_str]=0;
+     } else {
+          memset(q, fill, len_str);
+          q[len_str]=0;
+     }
+     return (q);
+}
+
+/* get new string */
+INTERFACE pointer mk_string(scheme *sc, const char *str) {
+     return mk_counted_string(sc,str,strlen(str));
+}
+
+INTERFACE pointer mk_counted_string(scheme *sc, const char *str, int len) {
+     pointer x = get_cell(sc, sc->NIL, sc->NIL);
+     typeflag(x) = (T_STRING | T_ATOM | T_FINALIZE);
+     strvalue(x) = store_string(sc,len,str,0);
+     strlength(x) = len;
+     return (x);
+}
+
+INTERFACE pointer mk_empty_string(scheme *sc, int len, char fill) {
+     pointer x = get_cell(sc, sc->NIL, sc->NIL);
+     typeflag(x) = (T_STRING | T_ATOM | T_FINALIZE);
+     strvalue(x) = store_string(sc,len,0,fill);
+     strlength(x) = len;
+     return (x);
+}
+
+INTERFACE static pointer mk_vector(scheme *sc, int len)
+{ return get_vector_object(sc,len,sc->NIL); }
+
+INTERFACE static void fill_vector(pointer vec, pointer obj) {
+     size_t i;
+     assert (is_vector (vec));
+     for(i = 0; i < vector_length(vec); i++) {
+          vec->_object._vector._elements[i] = obj;
+     }
+}
+
+INTERFACE static pointer *vector_elem_slot(pointer vec, int ielem) {
+     assert (is_vector (vec));
+     assert (ielem < vector_length(vec));
+     return &vec->_object._vector._elements[ielem];
+}
+
+INTERFACE static pointer vector_elem(pointer vec, int ielem) {
+     assert (is_vector (vec));
+     assert (ielem < vector_length(vec));
+     return vec->_object._vector._elements[ielem];
+}
+
+INTERFACE static pointer set_vector_elem(pointer vec, int ielem, pointer a) {
+     assert (is_vector (vec));
+     assert (ielem < vector_length(vec));
+     vec->_object._vector._elements[ielem] = a;
+     return a;
+}
+
+/* get new symbol */
+INTERFACE pointer mk_symbol(scheme *sc, const char *name) {
+#define mk_symbol_allocates	oblist_add_by_name_allocates
+     pointer x;
+     pointer *slot;
+
+     /* first check oblist */
+     x = oblist_find_by_name(sc, name, &slot);
+     if (x != sc->NIL) {
+          return (x);
+     } else {
+          x = oblist_add_by_name(sc, name, slot);
+          return (x);
+     }
+}
+
+INTERFACE pointer gensym(scheme *sc) {
+     pointer x;
+     pointer *slot;
+     char name[40];
+
+     for(; sc->gensym_cnt<LONG_MAX; sc->gensym_cnt++) {
+          snprintf(name,40,"gensym-%ld",sc->gensym_cnt);
+
+          /* first check oblist */
+          x = oblist_find_by_name(sc, name, &slot);
+
+          if (x != sc->NIL) {
+               continue;
+          } else {
+	       x = oblist_add_by_name(sc, name, slot);
+               return (x);
+          }
+     }
+
+     return sc->NIL;
+}
+
+/* double the size of the string buffer */
+static int expand_strbuff(scheme *sc) {
+  size_t new_size = sc->strbuff_size * 2;
+  char *new_buffer = sc->malloc(new_size);
+  if (new_buffer == 0) {
+    sc->no_memory = 1;
+    return 1;
+  }
+  memcpy(new_buffer, sc->strbuff, sc->strbuff_size);
+  sc->free(sc->strbuff);
+  sc->strbuff = new_buffer;
+  sc->strbuff_size = new_size;
+  return 0;
+}
+
+/* make symbol or number atom from string */
+static pointer mk_atom(scheme *sc, char *q) {
+     char    c, *p;
+     int has_dec_point=0;
+     int has_fp_exp = 0;
+
+#if USE_COLON_HOOK
+     char *next;
+     next = p = q;
+     while ((next = strstr(next, "::")) != 0) {
+	  /* Keep looking for the last occurrence.  */
+	  p = next;
+	  next = next + 2;
+     }
+
+     if (p != q) {
+          *p=0;
+          return cons(sc, sc->COLON_HOOK,
+                          cons(sc,
+                              cons(sc,
+                                   sc->QUOTE,
+                                   cons(sc, mk_symbol(sc, strlwr(p + 2)),
+					sc->NIL)),
+                              cons(sc, mk_atom(sc, q), sc->NIL)));
+     }
+#endif
+
+     p = q;
+     c = *p++;
+     if ((c == '+') || (c == '-')) {
+       c = *p++;
+       if (c == '.') {
+         has_dec_point=1;
+         c = *p++;
+       }
+       if (!isdigit(c)) {
+         return (mk_symbol(sc, strlwr(q)));
+       }
+     } else if (c == '.') {
+       has_dec_point=1;
+       c = *p++;
+       if (!isdigit(c)) {
+         return (mk_symbol(sc, strlwr(q)));
+       }
+     } else if (!isdigit(c)) {
+       return (mk_symbol(sc, strlwr(q)));
+     }
+
+     for ( ; (c = *p) != 0; ++p) {
+          if (!isdigit(c)) {
+               if(c=='.') {
+                    if(!has_dec_point) {
+                         has_dec_point=1;
+                         continue;
+                    }
+               }
+               else if ((c == 'e') || (c == 'E')) {
+                       if(!has_fp_exp) {
+                          has_dec_point = 1; /* decimal point illegal
+                                                from now on */
+                          p++;
+                          if ((*p == '-') || (*p == '+') || isdigit(*p)) {
+                             continue;
+                          }
+                       }
+               }
+               return (mk_symbol(sc, strlwr(q)));
+          }
+     }
+     if(has_dec_point) {
+          return mk_real(sc,atof(q));
+     }
+     return (mk_integer(sc, atol(q)));
+}
+
+/* make constant */
+static pointer mk_sharp_const(scheme *sc, char *name) {
+     long    x;
+     char    tmp[STRBUFFSIZE];
+
+     if (!strcmp(name, "t"))
+          return (sc->T);
+     else if (!strcmp(name, "f"))
+          return (sc->F);
+     else if (*name == 'o') {/* #o (octal) */
+          snprintf(tmp, STRBUFFSIZE, "0%s", name+1);
+          sscanf(tmp, "%lo", (long unsigned *)&x);
+          return (mk_integer(sc, x));
+     } else if (*name == 'd') {    /* #d (decimal) */
+          sscanf(name+1, "%ld", (long int *)&x);
+          return (mk_integer(sc, x));
+     } else if (*name == 'x') {    /* #x (hex) */
+          snprintf(tmp, STRBUFFSIZE, "0x%s", name+1);
+          sscanf(tmp, "%lx", (long unsigned *)&x);
+          return (mk_integer(sc, x));
+     } else if (*name == 'b') {    /* #b (binary) */
+          x = binary_decode(name+1);
+          return (mk_integer(sc, x));
+     } else if (*name == '\\') { /* #\w (character) */
+          int c=0;
+          if(stricmp(name+1,"space")==0) {
+               c=' ';
+          } else if(stricmp(name+1,"newline")==0) {
+               c='\n';
+          } else if(stricmp(name+1,"return")==0) {
+               c='\r';
+          } else if(stricmp(name+1,"tab")==0) {
+               c='\t';
+     } else if(name[1]=='x' && name[2]!=0) {
+          int c1=0;
+          if(sscanf(name+2,"%x",(unsigned int *)&c1)==1 && c1 < UCHAR_MAX) {
+               c=c1;
+          } else {
+               return sc->NIL;
+     }
+#if USE_ASCII_NAMES
+          } else if(is_ascii_name(name+1,&c)) {
+               /* nothing */
+#endif
+          } else if(name[2]==0) {
+               c=name[1];
+          } else {
+               return sc->NIL;
+          }
+          return mk_character(sc,c);
+     } else
+          return (sc->NIL);
+}
+
+/* ========== garbage collector ========== */
+
+const int frame_length;
+static void dump_stack_deallocate_frame(scheme *sc, pointer frame);
+
+/*--
+ *  We use algorithm E (Knuth, The Art of Computer Programming Vol.1,
+ *  sec. 2.3.5), the Schorr-Deutsch-Waite link-inversion algorithm,
+ *  for marking.
+ */
+static void mark(pointer a) {
+     pointer t, q, p;
+
+     t = (pointer) 0;
+     p = a;
+E2:  if (! is_mark(p))
+	  setmark(p);
+     if (is_vector(p) || is_frame(p)) {
+          int i;
+	  int len = is_vector(p) ? vector_length(p) : frame_length;
+          for (i = 0; i < len; i++) {
+               mark(p->_object._vector._elements[i]);
+          }
+     }
+#if SHOW_ERROR_LINE
+     else if (is_port(p)) {
+	  port *pt = p->_object._port;
+	  mark(pt->curr_line);
+	  mark(pt->filename);
+     }
+#endif
+     /* Mark tag if p has one.  */
+     if (has_tag(p))
+       mark(p + 1);
+     if (is_atom(p))
+          goto E6;
+     /* E4: down car */
+     q = car(p);
+     if (q && !is_mark(q)) {
+          setatom(p);  /* a note that we have moved car */
+          car(p) = t;
+          t = p;
+          p = q;
+          goto E2;
+     }
+E5:  q = cdr(p); /* down cdr */
+     if (q && !is_mark(q)) {
+          cdr(p) = t;
+          t = p;
+          p = q;
+          goto E2;
+     }
+E6:   /* up.  Undo the link switching from steps E4 and E5. */
+     if (!t)
+          return;
+     q = t;
+     if (is_atom(q)) {
+          clratom(q);
+          t = car(q);
+          car(q) = p;
+          p = q;
+          goto E5;
+     } else {
+          t = cdr(q);
+          cdr(q) = p;
+          p = q;
+          goto E6;
+     }
+}
+
+/* garbage collection. parameter a, b is marked. */
+static void gc(scheme *sc, pointer a, pointer b) {
+  pointer p;
+  struct cell_segment *s;
+  int i;
+
+  assert (gc_enabled (sc));
+
+  if(sc->gc_verbose) {
+    putstr(sc, "gc...");
+  }
+
+  /* mark system globals */
+  mark(sc->oblist);
+  mark(sc->global_env);
+
+  /* mark current registers */
+  mark(sc->args);
+  mark(sc->envir);
+  mark(sc->code);
+  history_mark(sc);
+  dump_stack_mark(sc);
+  mark(sc->value);
+  mark(sc->inport);
+  mark(sc->save_inport);
+  mark(sc->outport);
+  mark(sc->loadport);
+  for (i = 0; i <= sc->file_i; i++) {
+    mark(sc->load_stack[i].filename);
+    mark(sc->load_stack[i].curr_line);
+  }
+
+  /* Mark recent objects the interpreter doesn't know about yet. */
+  mark(car(sc->sink));
+  /* Mark any older stuff above nested C calls */
+  mark(sc->c_nest);
+
+  /* mark variables a, b */
+  mark(a);
+  mark(b);
+
+  /* garbage collect */
+  clrmark(sc->NIL);
+  sc->fcells = 0;
+  sc->free_cell = sc->NIL;
+  /* free-list is kept sorted by address so as to maintain consecutive
+     ranges, if possible, for use with vectors. Here we scan the cells
+     (which are also kept sorted by address) downwards to build the
+     free-list in sorted order.
+  */
+  for (s = sc->cell_segments; s; s = s->next) {
+    p = s->cells + s->cells_len;
+    while (--p >= s->cells) {
+      if ((typeflag(p) & 1) == 0)
+	/* All types have the LSB set.  This is not a typeflag.  */
+	continue;
+      if (is_mark(p)) {
+    clrmark(p);
+      } else {
+	/* reclaim cell */
+        if ((typeflag(p) & T_FINALIZE) == 0
+	    || finalize_cell(sc, p)) {
+	  /* Reclaim cell.  */
+	  ++sc->fcells;
+	  typeflag(p) = 0;
+	  car(p) = sc->NIL;
+	  cdr(p) = sc->free_cell;
+	  sc->free_cell = p;
+	}
+      }
+    }
+  }
+
+  if (sc->gc_verbose) {
+    char msg[80];
+    snprintf(msg,80,"done: %ld cells were recovered.\n", sc->fcells);
+    putstr(sc,msg);
+  }
+
+  /* if only a few recovered, get more to avoid fruitless gc's */
+  if (sc->fcells < CELL_MINRECOVER
+       && alloc_cellseg(sc, 1) == 0)
+       sc->no_memory = 1;
+}
+
+/* Finalize A.  Returns true if a can be added to the list of free
+ * cells.  */
+static int
+finalize_cell(scheme *sc, pointer a)
+{
+  switch (type(a)) {
+  case T_STRING:
+    sc->free(strvalue(a));
+    break;
+
+  case T_PORT:
+    if(a->_object._port->kind&port_file
+       && a->_object._port->rep.stdio.closeit) {
+      port_close(sc,a,port_input|port_output);
+    } else if (a->_object._port->kind & port_srfi6) {
+      sc->free(a->_object._port->rep.string.start);
+    }
+    sc->free(a->_object._port);
+    break;
+
+  case T_FOREIGN_OBJECT:
+    a->_object._foreign_object._vtable->finalize(sc, a->_object._foreign_object._data);
+    break;
+
+  case T_VECTOR:
+    do {
+      int i;
+      for (i = vector_size(vector_length(a)) - 1; i > 0; i--) {
+	pointer p = a + i;
+	typeflag(p) = 0;
+	car(p) = sc->NIL;
+	cdr(p) = sc->free_cell;
+	sc->free_cell = p;
+	sc->fcells += 1;
+      }
+    } while (0);
+    break;
+
+  case T_FRAME:
+    dump_stack_deallocate_frame(sc, a);
+    return 0;	/* Do not free cell.  */
+  }
+
+  return 1;	/* Free cell.  */
+}
+
+#if SHOW_ERROR_LINE
+static void
+port_clear_location (scheme *sc, port *p)
+{
+  p->curr_line = sc->NIL;
+  p->filename = sc->NIL;
+}
+
+static void
+port_increment_current_line (scheme *sc, port *p, long delta)
+{
+  if (delta == 0)
+    return;
+
+  p->curr_line =
+    mk_integer(sc, ivalue_unchecked(p->curr_line) + delta);
+}
+
+static void
+port_init_location (scheme *sc, port *p, pointer name)
+{
+  p->curr_line = mk_integer(sc, 0);
+  p->filename = name ? name : mk_string(sc, "<unknown>");
+}
+
+#else
+
+static void
+port_clear_location (scheme *sc, port *p)
+{
+}
+
+static void
+port_increment_current_line (scheme *sc, port *p, long delta)
+{
+}
+
+static void
+port_init_location (scheme *sc, port *p, pointer name)
+{
+}
+
+#endif
+
+/* ========== Routines for Reading ========== */
+
+static int file_push(scheme *sc, pointer fname) {
+  FILE *fin = NULL;
+
+  if (sc->file_i == MAXFIL-1)
+     return 0;
+  fin = fopen(string_value(fname), "r");
+  if(fin!=0) {
+    sc->file_i++;
+    sc->load_stack[sc->file_i].kind=port_file|port_input;
+    sc->load_stack[sc->file_i].rep.stdio.file=fin;
+    sc->load_stack[sc->file_i].rep.stdio.closeit=1;
+    sc->nesting_stack[sc->file_i]=0;
+    sc->loadport->_object._port=sc->load_stack+sc->file_i;
+    port_init_location(sc, &sc->load_stack[sc->file_i], fname);
+  }
+  return fin!=0;
+}
+
+static void file_pop(scheme *sc) {
+ if(sc->file_i != 0) {
+   sc->nesting=sc->nesting_stack[sc->file_i];
+   port_close(sc,sc->loadport,port_input);
+   port_clear_location(sc, &sc->load_stack[sc->file_i]);
+   sc->file_i--;
+   sc->loadport->_object._port=sc->load_stack+sc->file_i;
+ }
+}
+
+static int file_interactive(scheme *sc) {
+ return sc->file_i==0 && sc->load_stack[0].rep.stdio.file==stdin
+     && sc->inport->_object._port->kind&port_file;
+}
+
+static port *port_rep_from_filename(scheme *sc, const char *fn, int prop) {
+  FILE *f;
+  char *rw;
+  port *pt;
+  if(prop==(port_input|port_output)) {
+    rw="a+";
+  } else if(prop==port_output) {
+    rw="w";
+  } else {
+    rw="r";
+  }
+  f=fopen(fn,rw);
+  if(f==0) {
+    return 0;
+  }
+  pt=port_rep_from_file(sc,f,prop);
+  pt->rep.stdio.closeit=1;
+  port_init_location(sc, pt, mk_string(sc, fn));
+  return pt;
+}
+
+static pointer port_from_filename(scheme *sc, const char *fn, int prop) {
+  port *pt;
+  pt=port_rep_from_filename(sc,fn,prop);
+  if(pt==0) {
+    return sc->NIL;
+  }
+  return mk_port(sc,pt);
+}
+
+static port *port_rep_from_file(scheme *sc, FILE *f, int prop)
+{
+    port *pt;
+
+    pt = (port *)sc->malloc(sizeof *pt);
+    if (pt == NULL) {
+        return NULL;
+    }
+    pt->kind = port_file | prop;
+    pt->rep.stdio.file = f;
+    pt->rep.stdio.closeit = 0;
+    port_init_location(sc, pt, NULL);
+    return pt;
+}
+
+static pointer port_from_file(scheme *sc, FILE *f, int prop) {
+  port *pt;
+  pt=port_rep_from_file(sc,f,prop);
+  if(pt==0) {
+    return sc->NIL;
+  }
+  return mk_port(sc,pt);
+}
+
+static port *port_rep_from_string(scheme *sc, char *start, char *past_the_end, int prop) {
+  port *pt;
+  pt=(port*)sc->malloc(sizeof(port));
+  if(pt==0) {
+    return 0;
+  }
+  pt->kind=port_string|prop;
+  pt->rep.string.start=start;
+  pt->rep.string.curr=start;
+  pt->rep.string.past_the_end=past_the_end;
+  port_init_location(sc, pt, NULL);
+  return pt;
+}
+
+static pointer port_from_string(scheme *sc, char *start, char *past_the_end, int prop) {
+  port *pt;
+  pt=port_rep_from_string(sc,start,past_the_end,prop);
+  if(pt==0) {
+    return sc->NIL;
+  }
+  return mk_port(sc,pt);
+}
+
+#define BLOCK_SIZE 256
+
+static port *port_rep_from_scratch(scheme *sc) {
+  port *pt;
+  char *start;
+  pt=(port*)sc->malloc(sizeof(port));
+  if(pt==0) {
+    return 0;
+  }
+  start=sc->malloc(BLOCK_SIZE);
+  if(start==0) {
+    return 0;
+  }
+  memset(start,' ',BLOCK_SIZE-1);
+  start[BLOCK_SIZE-1]='\0';
+  pt->kind=port_string|port_output|port_srfi6;
+  pt->rep.string.start=start;
+  pt->rep.string.curr=start;
+  pt->rep.string.past_the_end=start+BLOCK_SIZE-1;
+  port_init_location(sc, pt, NULL);
+  return pt;
+}
+
+static pointer port_from_scratch(scheme *sc) {
+  port *pt;
+  pt=port_rep_from_scratch(sc);
+  if(pt==0) {
+    return sc->NIL;
+  }
+  return mk_port(sc,pt);
+}
+
+static void port_close(scheme *sc, pointer p, int flag) {
+  port *pt=p->_object._port;
+  pt->kind&=~flag;
+  if((pt->kind & (port_input|port_output))==0) {
+    /* Cleanup is here so (close-*-port) functions could work too */
+    port_clear_location(sc, pt);
+    if(pt->kind&port_file) {
+      fclose(pt->rep.stdio.file);
+    }
+    pt->kind=port_free;
+  }
+}
+
+/* get new character from input file */
+static int inchar(scheme *sc) {
+  int c;
+  port *pt;
+
+  pt = sc->inport->_object._port;
+  if(pt->kind & port_saw_EOF)
+    { return EOF; }
+  c = basic_inchar(pt);
+  if(c == EOF && sc->inport == sc->loadport) {
+    /* Instead, set port_saw_EOF */
+    pt->kind |= port_saw_EOF;
+
+    /* file_pop(sc); */
+    return EOF;
+    /* NOTREACHED */
+  }
+  return c;
+}
+
+static int basic_inchar(port *pt) {
+  if(pt->kind & port_file) {
+    return fgetc(pt->rep.stdio.file);
+  } else {
+    if(*pt->rep.string.curr == 0 ||
+       pt->rep.string.curr == pt->rep.string.past_the_end) {
+      return EOF;
+    } else {
+      return *pt->rep.string.curr++;
+    }
+  }
+}
+
+/* back character to input buffer */
+static void backchar(scheme *sc, int c) {
+  port *pt;
+  if(c==EOF) return;
+  pt=sc->inport->_object._port;
+  if(pt->kind&port_file) {
+    ungetc(c,pt->rep.stdio.file);
+  } else {
+    if(pt->rep.string.curr!=pt->rep.string.start) {
+      --pt->rep.string.curr;
+    }
+  }
+}
+
+static int realloc_port_string(scheme *sc, port *p)
+{
+  char *start=p->rep.string.start;
+  size_t old_size = p->rep.string.past_the_end - start;
+  size_t new_size=p->rep.string.past_the_end-start+1+BLOCK_SIZE;
+  char *str=sc->malloc(new_size);
+  if(str) {
+    memset(str,' ',new_size-1);
+    str[new_size-1]='\0';
+    memcpy(str, start, old_size);
+    p->rep.string.start=str;
+    p->rep.string.past_the_end=str+new_size-1;
+    p->rep.string.curr-=start-str;
+    sc->free(start);
+    return 1;
+  } else {
+    return 0;
+  }
+}
+
+INTERFACE void putstr(scheme *sc, const char *s) {
+  port *pt=sc->outport->_object._port;
+  if(pt->kind&port_file) {
+    fputs(s,pt->rep.stdio.file);
+  } else {
+    for(;*s;s++) {
+      if(pt->rep.string.curr!=pt->rep.string.past_the_end) {
+        *pt->rep.string.curr++=*s;
+      } else if(pt->kind&port_srfi6&&realloc_port_string(sc,pt)) {
+        *pt->rep.string.curr++=*s;
+      }
+    }
+  }
+}
+
+static void putchars(scheme *sc, const char *s, int len) {
+  port *pt=sc->outport->_object._port;
+  if(pt->kind&port_file) {
+    fwrite(s,1,len,pt->rep.stdio.file);
+  } else {
+    for(;len;len--) {
+      if(pt->rep.string.curr!=pt->rep.string.past_the_end) {
+        *pt->rep.string.curr++=*s++;
+      } else if(pt->kind&port_srfi6&&realloc_port_string(sc,pt)) {
+        *pt->rep.string.curr++=*s++;
+      }
+    }
+  }
+}
+
+INTERFACE void putcharacter(scheme *sc, int c) {
+  port *pt=sc->outport->_object._port;
+  if(pt->kind&port_file) {
+    fputc(c,pt->rep.stdio.file);
+  } else {
+    if(pt->rep.string.curr!=pt->rep.string.past_the_end) {
+      *pt->rep.string.curr++=c;
+    } else if(pt->kind&port_srfi6&&realloc_port_string(sc,pt)) {
+        *pt->rep.string.curr++=c;
+    }
+  }
+}
+
+/* read characters up to delimiter, but cater to character constants */
+static char *readstr_upto(scheme *sc, char *delim) {
+  char *p = sc->strbuff;
+
+  while ((p - sc->strbuff < sc->strbuff_size) &&
+         !is_one_of(delim, (*p++ = inchar(sc))));
+
+  if(p == sc->strbuff+2 && p[-2] == '\\') {
+    *p=0;
+  } else {
+    backchar(sc,p[-1]);
+    *--p = '\0';
+  }
+  return sc->strbuff;
+}
+
+/* read string expression "xxx...xxx" */
+static pointer readstrexp(scheme *sc) {
+  char *p = sc->strbuff;
+  int c;
+  int c1=0;
+  enum { st_ok, st_bsl, st_x1, st_x2, st_oct1, st_oct2 } state=st_ok;
+
+  for (;;) {
+    c=inchar(sc);
+    if(c == EOF) {
+      return sc->F;
+    }
+    if(p-sc->strbuff > (sc->strbuff_size)-1) {
+      ptrdiff_t offset = p - sc->strbuff;
+      if (expand_strbuff(sc) != 0) {
+        return sc->F;
+      }
+      p = sc->strbuff + offset;
+    }
+    switch(state) {
+        case st_ok:
+            switch(c) {
+                case '\\':
+                    state=st_bsl;
+                    break;
+                case '"':
+                    *p=0;
+                    return mk_counted_string(sc,sc->strbuff,p-sc->strbuff);
+                default:
+                    *p++=c;
+                    break;
+            }
+            break;
+        case st_bsl:
+            switch(c) {
+                case '0':
+                case '1':
+                case '2':
+                case '3':
+                case '4':
+                case '5':
+                case '6':
+                case '7':
+                        state=st_oct1;
+                        c1=c-'0';
+                        break;
+                case 'x':
+                case 'X':
+                    state=st_x1;
+                    c1=0;
+                    break;
+                case 'n':
+                    *p++='\n';
+                    state=st_ok;
+                    break;
+                case 't':
+                    *p++='\t';
+                    state=st_ok;
+                    break;
+                case 'r':
+                    *p++='\r';
+                    state=st_ok;
+                    break;
+                case '"':
+                    *p++='"';
+                    state=st_ok;
+                    break;
+                default:
+                    *p++=c;
+                    state=st_ok;
+                    break;
+            }
+            break;
+        case st_x1:
+        case st_x2:
+            c=toupper(c);
+            if(c>='0' && c<='F') {
+                if(c<='9') {
+                    c1=(c1<<4)+c-'0';
+                } else {
+                    c1=(c1<<4)+c-'A'+10;
+                }
+                if(state==st_x1) {
+                    state=st_x2;
+                } else {
+                    *p++=c1;
+                    state=st_ok;
+                }
+            } else {
+                return sc->F;
+            }
+            break;
+        case st_oct1:
+        case st_oct2:
+            if (c < '0' || c > '7')
+            {
+                   *p++=c1;
+                   backchar(sc, c);
+                   state=st_ok;
+            }
+            else
+            {
+                if (state==st_oct2 && c1 >= 32)
+                    return sc->F;
+
+                   c1=(c1<<3)+(c-'0');
+
+                if (state == st_oct1)
+                        state=st_oct2;
+                else
+                {
+                        *p++=c1;
+                        state=st_ok;
+                   }
+            }
+            break;
+
+    }
+  }
+}
+
+/* check c is in chars */
+static INLINE int is_one_of(char *s, int c) {
+     if(c==EOF) return 1;
+     while (*s)
+          if (*s++ == c)
+               return (1);
+     return (0);
+}
+
+/* skip white characters */
+static INLINE int skipspace(scheme *sc) {
+     int c = 0, curr_line = 0;
+
+     do {
+         c=inchar(sc);
+#if SHOW_ERROR_LINE
+         if(c=='\n')
+           curr_line++;
+#endif
+     } while (isspace(c));
+
+     /* record it */
+     port_increment_current_line(sc, &sc->load_stack[sc->file_i], curr_line);
+
+     if(c!=EOF) {
+          backchar(sc,c);
+      return 1;
+     }
+     else
+       { return EOF; }
+}
+
+/* get token */
+static int token(scheme *sc) {
+     int c;
+     c = skipspace(sc);
+     if(c == EOF) { return (TOK_EOF); }
+     switch (c=inchar(sc)) {
+     case EOF:
+          return (TOK_EOF);
+     case '(':
+          return (TOK_LPAREN);
+     case ')':
+          return (TOK_RPAREN);
+     case '.':
+          c=inchar(sc);
+          if(is_one_of(" \n\t",c)) {
+               return (TOK_DOT);
+          } else {
+               backchar(sc,c);
+               backchar(sc,'.');
+               return TOK_ATOM;
+          }
+     case '\'':
+          return (TOK_QUOTE);
+     case ';':
+           while ((c=inchar(sc)) != '\n' && c!=EOF)
+             ;
+
+           if(c == '\n')
+             port_increment_current_line(sc, &sc->load_stack[sc->file_i], 1);
+
+       if(c == EOF)
+         { return (TOK_EOF); }
+       else
+         { return (token(sc));}
+     case '"':
+          return (TOK_DQUOTE);
+     case BACKQUOTE:
+          return (TOK_BQUOTE);
+     case ',':
+         if ((c=inchar(sc)) == '@') {
+               return (TOK_ATMARK);
+         } else {
+               backchar(sc,c);
+               return (TOK_COMMA);
+         }
+     case '#':
+          c=inchar(sc);
+          if (c == '(') {
+               return (TOK_VEC);
+          } else if(c == '!') {
+               while ((c=inchar(sc)) != '\n' && c!=EOF)
+                   ;
+
+           if(c == '\n')
+             port_increment_current_line(sc, &sc->load_stack[sc->file_i], 1);
+
+           if(c == EOF)
+             { return (TOK_EOF); }
+           else
+             { return (token(sc));}
+          } else {
+               backchar(sc,c);
+               if(is_one_of(" tfodxb\\",c)) {
+                    return TOK_SHARP_CONST;
+               } else {
+                    return (TOK_SHARP);
+               }
+          }
+     default:
+          backchar(sc,c);
+          return (TOK_ATOM);
+     }
+}
+
+/* ========== Routines for Printing ========== */
+#define   ok_abbrev(x)   (is_pair(x) && cdr(x) == sc->NIL)
+
+static void printslashstring(scheme *sc, char *p, int len) {
+  int i;
+  unsigned char *s=(unsigned char*)p;
+  putcharacter(sc,'"');
+  for ( i=0; i<len; i++) {
+    if(*s==0xff || *s=='"' || *s<' ' || *s=='\\') {
+      putcharacter(sc,'\\');
+      switch(*s) {
+      case '"':
+        putcharacter(sc,'"');
+        break;
+      case '\n':
+        putcharacter(sc,'n');
+        break;
+      case '\t':
+        putcharacter(sc,'t');
+        break;
+      case '\r':
+        putcharacter(sc,'r');
+        break;
+      case '\\':
+        putcharacter(sc,'\\');
+        break;
+      default: {
+          int d=*s/16;
+          putcharacter(sc,'x');
+          if(d<10) {
+            putcharacter(sc,d+'0');
+          } else {
+            putcharacter(sc,d-10+'A');
+          }
+          d=*s%16;
+          if(d<10) {
+            putcharacter(sc,d+'0');
+          } else {
+            putcharacter(sc,d-10+'A');
+          }
+        }
+      }
+    } else {
+      putcharacter(sc,*s);
+    }
+    s++;
+  }
+  putcharacter(sc,'"');
+}
+
+
+/* print atoms */
+static void printatom(scheme *sc, pointer l, int f) {
+  char *p;
+  int len;
+  atom2str(sc,l,f,&p,&len);
+  putchars(sc,p,len);
+}
+
+
+/* Uses internal buffer unless string pointer is already available */
+static void atom2str(scheme *sc, pointer l, int f, char **pp, int *plen) {
+     char *p;
+
+     if (l == sc->NIL) {
+          p = "()";
+     } else if (l == sc->T) {
+          p = "#t";
+     } else if (l == sc->F) {
+          p = "#f";
+     } else if (l == sc->EOF_OBJ) {
+          p = "#<EOF>";
+     } else if (is_port(l)) {
+          p = "#<PORT>";
+     } else if (is_number(l)) {
+          p = sc->strbuff;
+          if (f <= 1 || f == 10) /* f is the base for numbers if > 1 */ {
+              if(num_is_integer(l)) {
+                   snprintf(p, STRBUFFSIZE, "%ld", ivalue_unchecked(l));
+              } else {
+                   snprintf(p, STRBUFFSIZE, "%.10g", rvalue_unchecked(l));
+                   /* r5rs says there must be a '.' (unless 'e'?) */
+                   f = strcspn(p, ".e");
+                   if (p[f] == 0) {
+                        p[f] = '.'; /* not found, so add '.0' at the end */
+                        p[f+1] = '0';
+                        p[f+2] = 0;
+                   }
+              }
+          } else {
+              long v = ivalue(l);
+              if (f == 16) {
+                  if (v >= 0)
+                    snprintf(p, STRBUFFSIZE, "%lx", v);
+                  else
+                    snprintf(p, STRBUFFSIZE, "-%lx", -v);
+              } else if (f == 8) {
+                  if (v >= 0)
+                    snprintf(p, STRBUFFSIZE, "%lo", v);
+                  else
+                    snprintf(p, STRBUFFSIZE, "-%lo", -v);
+              } else if (f == 2) {
+                  unsigned long b = (v < 0) ? -v : v;
+                  p = &p[STRBUFFSIZE-1];
+                  *p = 0;
+                  do { *--p = (b&1) ? '1' : '0'; b >>= 1; } while (b != 0);
+                  if (v < 0) *--p = '-';
+              }
+          }
+     } else if (is_string(l)) {
+          if (!f) {
+               *pp = strvalue(l);
+	       *plen = strlength(l);
+	       return;
+          } else { /* Hack, uses the fact that printing is needed */
+               *pp=sc->strbuff;
+               *plen=0;
+               printslashstring(sc, strvalue(l), strlength(l));
+               return;
+          }
+     } else if (is_character(l)) {
+          int c=charvalue(l);
+          p = sc->strbuff;
+          if (!f) {
+               p[0]=c;
+               p[1]=0;
+          } else {
+               switch(c) {
+               case ' ':
+                    p = "#\\space";
+                    break;
+               case '\n':
+                    p = "#\\newline";
+                    break;
+               case '\r':
+                    p = "#\\return";
+                    break;
+               case '\t':
+                    p = "#\\tab";
+                    break;
+               default:
+#if USE_ASCII_NAMES
+                    if(c==127) {
+                         p = "#\\del";
+                         break;
+                    } else if(c<32) {
+                         snprintf(p,STRBUFFSIZE, "#\\%s",charnames[c]);
+                         break;
+                    }
+#else
+                    if(c<32) {
+                      snprintf(p,STRBUFFSIZE,"#\\x%x",c);
+                      break;
+                    }
+#endif
+                    snprintf(p,STRBUFFSIZE,"#\\%c",c);
+                    break;
+               }
+          }
+     } else if (is_symbol(l)) {
+          p = symname(l);
+     } else if (is_proc(l)) {
+          p = sc->strbuff;
+          snprintf(p,STRBUFFSIZE,"#<%s PROCEDURE %ld>", procname(l),procnum(l));
+     } else if (is_macro(l)) {
+          p = "#<MACRO>";
+     } else if (is_closure(l)) {
+          p = "#<CLOSURE>";
+     } else if (is_promise(l)) {
+          p = "#<PROMISE>";
+     } else if (is_foreign(l)) {
+          p = sc->strbuff;
+          snprintf(p,STRBUFFSIZE,"#<FOREIGN PROCEDURE %ld>", procnum(l));
+     } else if (is_continuation(l)) {
+          p = "#<CONTINUATION>";
+     } else if (is_foreign_object(l)) {
+          p = sc->strbuff;
+          l->_object._foreign_object._vtable->to_string(sc, p, STRBUFFSIZE, l->_object._foreign_object._data);
+     } else {
+          p = "#<ERROR>";
+     }
+     *pp=p;
+     *plen=strlen(p);
+}
+/* ========== Routines for Evaluation Cycle ========== */
+
+/* make closure. c is code. e is environment */
+static pointer mk_closure(scheme *sc, pointer c, pointer e) {
+     pointer x = get_cell(sc, c, e);
+
+     typeflag(x) = T_CLOSURE;
+     car(x) = c;
+     cdr(x) = e;
+     return (x);
+}
+
+/* make continuation. */
+static pointer mk_continuation(scheme *sc, pointer d) {
+     pointer x = get_cell(sc, sc->NIL, d);
+
+     typeflag(x) = T_CONTINUATION;
+     cont_dump(x) = d;
+     return (x);
+}
+
+static pointer list_star(scheme *sc, pointer d) {
+  pointer p, q;
+  if(cdr(d)==sc->NIL) {
+    return car(d);
+  }
+  p=cons(sc,car(d),cdr(d));
+  q=p;
+  while(cdr(cdr(p))!=sc->NIL) {
+    d=cons(sc,car(p),cdr(p));
+    if(cdr(cdr(p))!=sc->NIL) {
+      p=cdr(d);
+    }
+  }
+  cdr(p)=car(cdr(p));
+  return q;
+}
+
+/* reverse list -- produce new list */
+static pointer reverse(scheme *sc, pointer term, pointer list) {
+/* a must be checked by gc */
+     pointer a = list, p = term;
+
+     for ( ; is_pair(a); a = cdr(a)) {
+          p = cons(sc, car(a), p);
+     }
+     return (p);
+}
+
+/* reverse list --- in-place */
+static pointer reverse_in_place(scheme *sc, pointer term, pointer list) {
+     pointer p = list, result = term, q;
+
+     while (p != sc->NIL) {
+          q = cdr(p);
+          cdr(p) = result;
+          result = p;
+          p = q;
+     }
+     return (result);
+}
+
+/* append list -- produce new list (in reverse order) */
+static pointer revappend(scheme *sc, pointer a, pointer b) {
+    pointer result = a;
+    pointer p = b;
+
+    while (is_pair(p)) {
+        result = cons(sc, car(p), result);
+        p = cdr(p);
+    }
+
+    if (p == sc->NIL) {
+        return result;
+    }
+
+    return sc->F;   /* signal an error */
+}
+
+/* equivalence of atoms */
+int eqv(pointer a, pointer b) {
+     if (is_string(a)) {
+          if (is_string(b))
+               return (strvalue(a) == strvalue(b));
+          else
+               return (0);
+     } else if (is_number(a)) {
+          if (is_number(b)) {
+               if (num_is_integer(a) == num_is_integer(b))
+                    return num_eq(nvalue(a),nvalue(b));
+          }
+          return (0);
+     } else if (is_character(a)) {
+          if (is_character(b))
+               return charvalue(a)==charvalue(b);
+          else
+               return (0);
+     } else if (is_port(a)) {
+          if (is_port(b))
+               return a==b;
+          else
+               return (0);
+     } else if (is_proc(a)) {
+          if (is_proc(b))
+               return procnum(a)==procnum(b);
+          else
+               return (0);
+     } else {
+          return (a == b);
+     }
+}
+
+/* true or false value macro */
+/* () is #t in R5RS */
+#define is_true(p)       ((p) != sc->F)
+#define is_false(p)      ((p) == sc->F)
+
+
+/* ========== Environment implementation  ========== */
+
+#if !defined(USE_ALIST_ENV) || !defined(USE_OBJECT_LIST)
+
+static int hash_fn(const char *key, int table_size)
+{
+  unsigned int hashed = 0;
+  const char *c;
+  int bits_per_int = sizeof(unsigned int)*8;
+
+  for (c = key; *c; c++) {
+    /* letters have about 5 bits in them */
+    hashed = (hashed<<5) | (hashed>>(bits_per_int-5));
+    hashed ^= *c;
+  }
+  return hashed % table_size;
+}
+#endif
+
+/* Compares A and B.  Returns an integer less than, equal to, or
+ * greater than zero if A is stored at a memory location that is
+ * numerical less than, equal to, or greater than that of B.  */
+static int
+pointercmp(pointer a, pointer b)
+{
+  uintptr_t a_n = (uintptr_t) a;
+  uintptr_t b_n = (uintptr_t) b;
+
+  if (a_n < b_n)
+    return -1;
+  if (a_n > b_n)
+    return 1;
+  return 0;
+}
+
+#ifndef USE_ALIST_ENV
+
+/*
+ * In this implementation, each frame of the environment may be
+ * a hash table: a vector of alists hashed by variable name.
+ * In practice, we use a vector only for the initial frame;
+ * subsequent frames are too small and transient for the lookup
+ * speed to out-weigh the cost of making a new vector.
+ */
+
+static void new_frame_in_env(scheme *sc, pointer old_env)
+{
+  pointer new_frame;
+
+  /* The interaction-environment has about 480 variables in it. */
+  if (old_env == sc->NIL) {
+    new_frame = mk_vector(sc, 751);
+  } else {
+    new_frame = sc->NIL;
+  }
+
+  gc_disable(sc, 1);
+  sc->envir = immutable_cons(sc, new_frame, old_env);
+  gc_enable(sc);
+  setenvironment(sc->envir);
+}
+
+/* Find the slot in ENV under the key HDL.  If ALL is given, look in
+ * all environments enclosing ENV.  If the lookup fails, and SSLOT is
+ * given, the position where the new slot has to be inserted is stored
+ * at SSLOT.  */
+static pointer
+find_slot_spec_in_env(scheme *sc, pointer env, pointer hdl, int all, pointer **sslot)
+{
+  pointer x,y;
+  int location;
+  pointer *sl;
+  int d;
+  assert(is_symbol(hdl));
+
+  for (x = env; x != sc->NIL; x = cdr(x)) {
+    if (is_vector(car(x))) {
+      location = hash_fn(symname(hdl), vector_length(car(x)));
+      sl = vector_elem_slot(car(x), location);
+    } else {
+      sl = &car(x);
+    }
+    for (y = *sl ; y != sc->NIL; sl = &cdr(y), y = *sl) {
+      d = pointercmp(caar(y), hdl);
+      if (d == 0)
+	return car(y);		/* Hit.  */
+      else if (d > 0)
+	break;			/* Miss.  */
+    }
+
+    if (x == env && sslot)
+      *sslot = sl;		/* Insert here.  */
+
+    if (!all)
+      return sc->NIL;		/* Miss, and stop looking.  */
+  }
+
+  return sc->NIL;		/* Not found in any environment.  */
+}
+
+#else /* USE_ALIST_ENV */
+
+static INLINE void new_frame_in_env(scheme *sc, pointer old_env)
+{
+  sc->envir = immutable_cons(sc, sc->NIL, old_env);
+  setenvironment(sc->envir);
+}
+
+/* Find the slot in ENV under the key HDL.  If ALL is given, look in
+ * all environments enclosing ENV.  If the lookup fails, and SSLOT is
+ * given, the position where the new slot has to be inserted is stored
+ * at SSLOT.  */
+static pointer
+find_slot_spec_in_env(scheme *sc, pointer env, pointer hdl, int all, pointer **sslot)
+{
+    pointer x,y;
+    pointer *sl;
+    int d;
+    assert(is_symbol(hdl));
+
+    for (x = env; x != sc->NIL; x = cdr(x)) {
+      for (sl = &car(x), y = *sl; y != sc->NIL; sl = &cdr(y), y = *sl) {
+	d = pointercmp(caar(y), hdl);
+	if (d == 0)
+	  return car(y);	/* Hit.  */
+	else if (d > 0)
+	  break;		/* Miss.  */
+      }
+
+      if (x == env && sslot)
+	*sslot = sl;		/* Insert here.  */
+
+      if (!all)
+	return sc->NIL;		/* Miss, and stop looking.  */
+    }
+
+    return sc->NIL;		/* Not found in any environment.  */
+}
+
+#endif /* USE_ALIST_ENV else */
+
+static pointer find_slot_in_env(scheme *sc, pointer env, pointer hdl, int all)
+{
+  return find_slot_spec_in_env(sc, env, hdl, all, NULL);
+}
+
+/* Insert (VARIABLE, VALUE) at SSLOT.  SSLOT must be obtained using
+ * find_slot_spec_in_env, and no insertion must be done between
+ * obtaining SSLOT and the call to this function.  */
+static INLINE void new_slot_spec_in_env(scheme *sc,
+                                        pointer variable, pointer value,
+					pointer *sslot)
+{
+#define new_slot_spec_in_env_allocates	2
+  pointer slot;
+  gc_disable(sc, gc_reservations (new_slot_spec_in_env));
+  slot = immutable_cons(sc, variable, value);
+  *sslot = immutable_cons(sc, slot, *sslot);
+  gc_enable(sc);
+}
+
+static INLINE void new_slot_in_env(scheme *sc, pointer variable, pointer value)
+{
+#define new_slot_in_env_allocates	new_slot_spec_in_env_allocates
+  pointer slot;
+  pointer *sslot;
+  assert(is_symbol(variable));
+  slot = find_slot_spec_in_env(sc, sc->envir, variable, 0, &sslot);
+  assert(slot == sc->NIL);
+  new_slot_spec_in_env(sc, variable, value, sslot);
+}
+
+static INLINE void set_slot_in_env(scheme *sc, pointer slot, pointer value)
+{
+  (void)sc;
+  cdr(slot) = value;
+}
+
+static INLINE pointer slot_value_in_env(pointer slot)
+{
+  return cdr(slot);
+}
+
+
+/* ========== Evaluation Cycle ========== */
+
+
+static enum scheme_opcodes
+_Error_1(scheme *sc, const char *s, pointer a) {
+     const char *str = s;
+     pointer history;
+#if USE_ERROR_HOOK
+     pointer x;
+     pointer hdl=sc->ERROR_HOOK;
+#endif
+
+#if SHOW_ERROR_LINE
+     char sbuf[STRBUFFSIZE];
+#endif
+
+     history = history_flatten(sc);
+
+#if SHOW_ERROR_LINE
+     /* make sure error is not in REPL */
+     if (((sc->load_stack[sc->file_i].kind & port_file) == 0
+	  || sc->load_stack[sc->file_i].rep.stdio.file != stdin)) {
+       pointer tag;
+       const char *fname;
+       int ln;
+
+       if (history != sc->NIL && has_tag(car(history))
+	   && (tag = get_tag(sc, car(history)))
+	   && is_string(car(tag)) && is_integer(cdr(tag))) {
+	 fname = string_value(car(tag));
+	 ln = ivalue_unchecked(cdr(tag));
+       } else {
+	 fname = string_value(sc->load_stack[sc->file_i].filename);
+	 ln = ivalue_unchecked(sc->load_stack[sc->file_i].curr_line);
+       }
+
+       /* should never happen */
+       if(!fname) fname = "<unknown>";
+
+       /* we started from 0 */
+       ln++;
+       snprintf(sbuf, STRBUFFSIZE, "%s:%i: %s", fname, ln, s);
+
+       str = (const char*)sbuf;
+     }
+#endif
+
+#if USE_ERROR_HOOK
+     x=find_slot_in_env(sc,sc->envir,hdl,1);
+    if (x != sc->NIL) {
+	 sc->code = cons(sc, cons(sc, sc->QUOTE,
+				  cons(sc, history, sc->NIL)),
+			 sc->NIL);
+         if(a!=0) {
+	   sc->code = cons(sc, cons(sc, sc->QUOTE, cons(sc, a, sc->NIL)),
+	                   sc->code);
+         } else {
+	   sc->code = cons(sc, sc->F, sc->code);
+	 }
+         sc->code = cons(sc, mk_string(sc, str), sc->code);
+         setimmutable(car(sc->code));
+         sc->code = cons(sc, slot_value_in_env(x), sc->code);
+         return OP_EVAL;
+    }
+#endif
+
+    if(a!=0) {
+          sc->args = cons(sc, (a), sc->NIL);
+    } else {
+          sc->args = sc->NIL;
+    }
+    sc->args = cons(sc, mk_string(sc, str), sc->args);
+    setimmutable(car(sc->args));
+    return OP_ERR0;
+}
+#define Error_1(sc,s, a) { op = _Error_1(sc,s,a); goto dispatch; }
+#define Error_0(sc,s)    { op = _Error_1(sc,s,0); goto dispatch; }
+
+/* Too small to turn into function */
+# define  BEGIN     do {
+# define  END  } while (0)
+
+
+
+/* Flags.  The interpreter has a flags field.  When the interpreter
+ * pushes a frame to the dump stack, it is encoded with the opcode.
+ * Therefore, we do not use the least significant byte.  */
+
+/* Masks used to encode and decode opcode and flags.  */
+#define S_OP_MASK	0x000000ff
+#define S_FLAG_MASK	0xffffff00
+
+/* Set if the interpreter evaluates an expression in a tail context
+ * (see R5RS, section 3.5).  If a function, procedure, or continuation
+ * is invoked while this flag is set, the call is recorded as tail
+ * call in the history buffer.  */
+#define S_FLAG_TAIL_CONTEXT	0x00000100
+
+/* Set flag F.  */
+#define s_set_flag(sc, f)			\
+	   BEGIN				\
+	   (sc)->flags |= S_FLAG_ ## f;		\
+	   END
+
+/* Clear flag F.  */
+#define s_clear_flag(sc, f)			\
+	   BEGIN				\
+	   (sc)->flags &= ~ S_FLAG_ ## f;	\
+	   END
+
+/* Check if flag F is set.  */
+#define s_get_flag(sc, f)			\
+	   !!((sc)->flags & S_FLAG_ ## f)
+
+
+
+/* Bounce back to Eval_Cycle and execute A.  */
+#define s_goto(sc, a) { op = (a); goto dispatch; }
+
+#if USE_THREADED_CODE
+
+/* Do not bounce back to Eval_Cycle but execute A by jumping directly
+ * to it.  */
+#define s_thread_to(sc, a)	\
+     BEGIN			\
+     op = (a);			\
+     goto a;			\
+     END
+
+/* Define a label OP and emit a case statement for OP.  For use in the
+ * dispatch function.  The slightly peculiar goto that is never
+ * executed avoids warnings about unused labels.  */
+#define CASE(OP)	case OP: if (0) goto OP; OP
+
+#else	/* USE_THREADED_CODE */
+#define s_thread_to(sc, a)	s_goto(sc, a)
+#define CASE(OP)		case OP
+#endif	/* USE_THREADED_CODE */
+
+/* Return to the previous frame on the dump stack, setting the current
+ * value to A.  */
+#define s_return(sc, a)	s_goto(sc, _s_return(sc, a, 0))
+
+/* Return to the previous frame on the dump stack, setting the current
+ * value to A, and re-enable the garbage collector.  */
+#define s_return_enable_gc(sc, a) s_goto(sc, _s_return(sc, a, 1))
+
+static INLINE void dump_stack_reset(scheme *sc)
+{
+  sc->dump = sc->NIL;
+}
+
+static INLINE void dump_stack_initialize(scheme *sc)
+{
+  dump_stack_reset(sc);
+  sc->frame_freelist = sc->NIL;
+}
+
+static void dump_stack_free(scheme *sc)
+{
+  dump_stack_initialize(sc);
+}
+
+const int frame_length = 4;
+
+static pointer
+dump_stack_make_frame(scheme *sc)
+{
+  pointer frame;
+
+  frame = mk_vector(sc, frame_length);
+  if (! sc->no_memory)
+    setframe(frame);
+
+  return frame;
+}
+
+static INLINE pointer *
+frame_slots(pointer frame)
+{
+  return &frame->_object._vector._elements[0];
+}
+
+#define frame_payload	vector_length
+
+static pointer
+dump_stack_allocate_frame(scheme *sc)
+{
+  pointer frame = sc->frame_freelist;
+  if (frame == sc->NIL) {
+    if (gc_enabled(sc))
+      frame = dump_stack_make_frame(sc);
+    else
+      gc_reservation_failure(sc);
+  } else
+    sc->frame_freelist = *frame_slots(frame);
+  return frame;
+}
+
+static void
+dump_stack_deallocate_frame(scheme *sc, pointer frame)
+{
+  pointer *p = frame_slots(frame);
+  *p++ = sc->frame_freelist;
+  *p++ = sc->NIL;
+  *p++ = sc->NIL;
+  *p++ = sc->NIL;
+  sc->frame_freelist = frame;
+}
+
+static void
+dump_stack_preallocate_frame(scheme *sc)
+{
+  pointer frame = dump_stack_make_frame(sc);
+  if (! sc->no_memory)
+    dump_stack_deallocate_frame(sc, frame);
+}
+
+static enum scheme_opcodes
+_s_return(scheme *sc, pointer a, int enable_gc) {
+  pointer dump = sc->dump;
+  pointer *p;
+  unsigned long v;
+  enum scheme_opcodes next_op;
+  sc->value = (a);
+  if (enable_gc)
+       gc_enable(sc);
+  if (dump == sc->NIL)
+    return OP_QUIT;
+  v = frame_payload(dump);
+  next_op = (int) (v & S_OP_MASK);
+  sc->flags = v & S_FLAG_MASK;
+  p = frame_slots(dump);
+  sc->args = *p++;
+  sc->envir = *p++;
+  sc->code = *p++;
+  sc->dump = *p++;
+  dump_stack_deallocate_frame(sc, dump);
+  return next_op;
+}
+
+static void s_save(scheme *sc, enum scheme_opcodes op, pointer args, pointer code) {
+#define s_save_allocates	0
+    pointer dump;
+    pointer *p;
+    gc_disable(sc, gc_reservations (s_save));
+    dump = dump_stack_allocate_frame(sc);
+    frame_payload(dump) = (size_t) (sc->flags | (unsigned long) op);
+    p = frame_slots(dump);
+    *p++ = args;
+    *p++ = sc->envir;
+    *p++ = code;
+    *p++ = sc->dump;
+    sc->dump = dump;
+    gc_enable(sc);
+}
+
+static INLINE void dump_stack_mark(scheme *sc)
+{
+  mark(sc->dump);
+  mark(sc->frame_freelist);
+}
+
+
+
+#if USE_HISTORY
+
+static void
+history_free(scheme *sc)
+{
+  sc->free(sc->history.m);
+  sc->history.tailstacks = sc->NIL;
+  sc->history.callstack = sc->NIL;
+}
+
+static pointer
+history_init(scheme *sc, size_t N, size_t M)
+{
+  size_t i;
+  struct history *h = &sc->history;
+
+  h->N = N;
+  h->mask_N = N - 1;
+  h->n = N - 1;
+  assert ((N & h->mask_N) == 0);
+
+  h->M = M;
+  h->mask_M = M - 1;
+  assert ((M & h->mask_M) == 0);
+
+  h->callstack = mk_vector(sc, N);
+  if (h->callstack == sc->sink)
+    goto fail;
+
+  h->tailstacks = mk_vector(sc, N);
+  for (i = 0; i < N; i++) {
+    pointer tailstack = mk_vector(sc, M);
+    if (tailstack == sc->sink)
+      goto fail;
+    set_vector_elem(h->tailstacks, i, tailstack);
+  }
+
+  h->m = sc->malloc(N * sizeof *h->m);
+  if (h->m == NULL)
+    goto fail;
+
+  for (i = 0; i < N; i++)
+    h->m[i] = 0;
+
+  return sc->T;
+
+fail:
+  history_free(sc);
+  return sc->F;
+}
+
+static void
+history_mark(scheme *sc)
+{
+  struct history *h = &sc->history;
+  mark(h->callstack);
+  mark(h->tailstacks);
+}
+
+#define add_mod(a, b, mask)	(((a) + (b)) & (mask))
+#define sub_mod(a, b, mask)	add_mod(a, (mask) + 1 - (b), mask)
+
+static INLINE void
+tailstack_clear(scheme *sc, pointer v)
+{
+  assert(is_vector(v));
+  /* XXX optimize */
+  fill_vector(v, sc->NIL);
+}
+
+static pointer
+callstack_pop(scheme *sc)
+{
+  struct history *h = &sc->history;
+  size_t n = h->n;
+  pointer item;
+
+  if (h->callstack == sc->NIL)
+    return sc->NIL;
+
+  item = vector_elem(h->callstack, n);
+  /* Clear our frame so that it can be gc'ed and we don't run into it
+   * when walking the history.  */
+  set_vector_elem(h->callstack, n, sc->NIL);
+  tailstack_clear(sc, vector_elem(h->tailstacks, n));
+
+  /* Exit from the frame.  */
+  h->n = sub_mod(h->n, 1, h->mask_N);
+
+  return item;
+}
+
+static void
+callstack_push(scheme *sc, pointer item)
+{
+  struct history *h = &sc->history;
+  size_t n = h->n;
+
+  if (h->callstack == sc->NIL)
+    return;
+
+  /* Enter a new frame.  */
+  n = h->n = add_mod(n, 1, h->mask_N);
+
+  /* Initialize tail stack.  */
+  tailstack_clear(sc, vector_elem(h->tailstacks, n));
+  h->m[n] = h->mask_M;
+
+  set_vector_elem(h->callstack, n, item);
+}
+
+static void
+tailstack_push(scheme *sc, pointer item)
+{
+  struct history *h = &sc->history;
+  size_t n = h->n;
+  size_t m = h->m[n];
+
+  if (h->callstack == sc->NIL)
+    return;
+
+  /* Enter a new tail frame.  */
+  m = h->m[n] = add_mod(m, 1, h->mask_M);
+  set_vector_elem(vector_elem(h->tailstacks, n), m, item);
+}
+
+static pointer
+tailstack_flatten(scheme *sc, pointer tailstack, size_t i, size_t n,
+		  pointer acc)
+{
+  struct history *h = &sc->history;
+  pointer frame;
+
+  assert(i <= h->M);
+  assert(n < h->M);
+
+  if (acc == sc->sink)
+    return sc->sink;
+
+  if (i == 0) {
+    /* We reached the end, but we did not see a unused frame.  Signal
+       this using '... .  */
+    return cons(sc, mk_symbol(sc, "..."), acc);
+  }
+
+  frame = vector_elem(tailstack, n);
+  if (frame == sc->NIL) {
+    /* A unused frame.  We reached the end of the history.  */
+    return acc;
+  }
+
+  /* Add us.  */
+  acc = cons(sc, frame, acc);
+
+  return tailstack_flatten(sc, tailstack, i - 1, sub_mod(n, 1, h->mask_M),
+			   acc);
+}
+
+static pointer
+callstack_flatten(scheme *sc, size_t i, size_t n, pointer acc)
+{
+  struct history *h = &sc->history;
+  pointer frame;
+
+  assert(i <= h->N);
+  assert(n < h->N);
+
+  if (acc == sc->sink)
+    return sc->sink;
+
+  if (i == 0) {
+    /* We reached the end, but we did not see a unused frame.  Signal
+       this using '... .  */
+    return cons(sc, mk_symbol(sc, "..."), acc);
+  }
+
+  frame = vector_elem(h->callstack, n);
+  if (frame == sc->NIL) {
+    /* A unused frame.  We reached the end of the history.  */
+    return acc;
+  }
+
+  /* First, emit the tail calls.  */
+  acc = tailstack_flatten(sc, vector_elem(h->tailstacks, n), h->M, h->m[n],
+			  acc);
+
+  /* Then us.  */
+  acc = cons(sc, frame, acc);
+
+  return callstack_flatten(sc, i - 1, sub_mod(n, 1, h->mask_N), acc);
+}
+
+static pointer
+history_flatten(scheme *sc)
+{
+  struct history *h = &sc->history;
+  pointer history;
+
+  if (h->callstack == sc->NIL)
+    return sc->NIL;
+
+  history = callstack_flatten(sc, h->N, h->n, sc->NIL);
+  if (history == sc->sink)
+    return sc->sink;
+
+  return reverse_in_place(sc, sc->NIL, history);
+}
+
+#undef add_mod
+#undef sub_mod
+
+#else	/* USE_HISTORY */
+
+#define history_init(SC, A, B)	(void) 0
+#define history_free(SC)	(void) 0
+#define callstack_pop(SC)	(void) 0
+#define callstack_push(SC, X)	(void) 0
+#define tailstack_push(SC, X)	(void) 0
+
+#endif	/* USE_HISTORY */
+
+
+
+#if USE_PLIST
+static pointer
+get_property(scheme *sc, pointer obj, pointer key)
+{
+  pointer x;
+
+  assert (is_symbol(obj));
+  assert (is_symbol(key));
+
+  for (x = symprop(obj); x != sc->NIL; x = cdr(x)) {
+    if (caar(x) == key)
+      break;
+  }
+
+  if (x != sc->NIL)
+    return cdar(x);
+
+  return sc->NIL;
+}
+
+static pointer
+set_property(scheme *sc, pointer obj, pointer key, pointer value)
+{
+#define set_property_allocates	2
+  pointer x;
+
+  assert (is_symbol(obj));
+  assert (is_symbol(key));
+
+  for (x = symprop(obj); x != sc->NIL; x = cdr(x)) {
+    if (caar(x) == key)
+      break;
+  }
+
+  if (x != sc->NIL)
+    cdar(x) = value;
+  else {
+    gc_disable(sc, gc_reservations(set_property));
+    symprop(obj) = cons(sc, cons(sc, key, value), symprop(obj));
+    gc_enable(sc);
+  }
+
+  return sc->T;
+}
+#endif
+
+
+
+static int is_list(scheme *sc, pointer a)
+{ return list_length(sc,a) >= 0; }
+
+/* Result is:
+   proper list: length
+   circular list: -1
+   not even a pair: -2
+   dotted list: -2 minus length before dot
+*/
+int list_length(scheme *sc, pointer a) {
+    int i=0;
+    pointer slow, fast;
+
+    slow = fast = a;
+    while (1)
+    {
+        if (fast == sc->NIL)
+                return i;
+        if (!is_pair(fast))
+                return -2 - i;
+        fast = cdr(fast);
+        ++i;
+        if (fast == sc->NIL)
+                return i;
+        if (!is_pair(fast))
+                return -2 - i;
+        ++i;
+        fast = cdr(fast);
+
+        /* Safe because we would have already returned if `fast'
+           encountered a non-pair. */
+        slow = cdr(slow);
+        if (fast == slow)
+        {
+            /* the fast pointer has looped back around and caught up
+               with the slow pointer, hence the structure is circular,
+               not of finite length, and therefore not a list */
+            return -1;
+        }
+    }
+}
+
+
+
+#define s_retbool(tf)    s_return(sc,(tf) ? sc->T : sc->F)
+
+/* kernel of this interpreter */
+static void
+Eval_Cycle(scheme *sc, enum scheme_opcodes op) {
+  for (;;) {
+     pointer x, y;
+     pointer callsite;
+     num v;
+#if USE_MATH
+     double dd;
+#endif
+     int (*comp_func)(num, num) = NULL;
+     const struct op_code_info *pcd;
+
+  dispatch:
+     pcd = &dispatch_table[op];
+     if (pcd->name[0] != 0) { /* if built-in function, check arguments */
+       char msg[STRBUFFSIZE];
+       if (! check_arguments (sc, pcd, msg, sizeof msg)) {
+	 s_goto(sc, _Error_1(sc, msg, 0));
+       }
+     }
+
+     if(sc->no_memory) {
+       fprintf(stderr,"No memory!\n");
+       exit(1);
+     }
+     ok_to_freely_gc(sc);
+
+     switch (op) {
+     CASE(OP_LOAD):       /* load */
+          if(file_interactive(sc)) {
+               fprintf(sc->outport->_object._port->rep.stdio.file,
+               "Loading %s\n", strvalue(car(sc->args)));
+          }
+          if (!file_push(sc, car(sc->args))) {
+               Error_1(sc,"unable to open", car(sc->args));
+          }
+      else
+        {
+          sc->args = mk_integer(sc,sc->file_i);
+          s_thread_to(sc,OP_T0LVL);
+        }
+
+     CASE(OP_T0LVL): /* top level */
+       /* If we reached the end of file, this loop is done. */
+       if(sc->loadport->_object._port->kind & port_saw_EOF)
+     {
+       if(sc->file_i == 0)
+         {
+           sc->args=sc->NIL;
+           sc->nesting = sc->nesting_stack[0];
+           s_thread_to(sc,OP_QUIT);
+         }
+       else
+         {
+           file_pop(sc);
+           s_return(sc,sc->value);
+         }
+       /* NOTREACHED */
+     }
+
+       /* If interactive, be nice to user. */
+       if(file_interactive(sc))
+     {
+       sc->envir = sc->global_env;
+       dump_stack_reset(sc);
+       putstr(sc,"\n");
+       putstr(sc,prompt);
+     }
+
+       /* Set up another iteration of REPL */
+       sc->nesting=0;
+       sc->save_inport=sc->inport;
+       sc->inport = sc->loadport;
+       s_save(sc,OP_T0LVL, sc->NIL, sc->NIL);
+       s_save(sc,OP_VALUEPRINT, sc->NIL, sc->NIL);
+       s_save(sc,OP_T1LVL, sc->NIL, sc->NIL);
+       s_thread_to(sc,OP_READ_INTERNAL);
+
+     CASE(OP_T1LVL): /* top level */
+          sc->code = sc->value;
+          sc->inport=sc->save_inport;
+          s_thread_to(sc,OP_EVAL);
+
+     CASE(OP_READ_INTERNAL):       /* internal read */
+          sc->tok = token(sc);
+          if(sc->tok==TOK_EOF)
+        { s_return(sc,sc->EOF_OBJ); }
+          s_thread_to(sc,OP_RDSEXPR);
+
+     CASE(OP_GENSYM):
+          s_return(sc, gensym(sc));
+
+     CASE(OP_VALUEPRINT): /* print evaluation result */
+          /* OP_VALUEPRINT is always pushed, because when changing from
+             non-interactive to interactive mode, it needs to be
+             already on the stack */
+       if(sc->tracing) {
+         putstr(sc,"\nGives: ");
+       }
+       if(file_interactive(sc)) {
+         sc->print_flag = 1;
+         sc->args = sc->value;
+         s_thread_to(sc,OP_P0LIST);
+       } else {
+         s_return(sc,sc->value);
+       }
+
+     CASE(OP_EVAL):       /* main part of evaluation */
+#if USE_TRACING
+       if(sc->tracing) {
+         /*s_save(sc,OP_VALUEPRINT,sc->NIL,sc->NIL);*/
+         s_save(sc,OP_REAL_EVAL,sc->args,sc->code);
+         sc->args=sc->code;
+         putstr(sc,"\nEval: ");
+         s_thread_to(sc,OP_P0LIST);
+       }
+       /* fall through */
+     CASE(OP_REAL_EVAL):
+#endif
+          if (is_symbol(sc->code)) {    /* symbol */
+               x=find_slot_in_env(sc,sc->envir,sc->code,1);
+               if (x != sc->NIL) {
+                    s_return(sc,slot_value_in_env(x));
+               } else {
+                    Error_1(sc, "eval: unbound variable", sc->code);
+               }
+          } else if (is_pair(sc->code)) {
+               if (is_syntax(x = car(sc->code))) {     /* SYNTAX */
+                    sc->code = cdr(sc->code);
+                    s_goto(sc, syntaxnum(sc, x));
+               } else {/* first, eval top element and eval arguments */
+                    s_save(sc,OP_E0ARGS, sc->NIL, sc->code);
+                    /* If no macros => s_save(sc,OP_E1ARGS, sc->NIL, cdr(sc->code));*/
+                    sc->code = car(sc->code);
+		    s_clear_flag(sc, TAIL_CONTEXT);
+                    s_thread_to(sc,OP_EVAL);
+               }
+          } else {
+               s_return(sc,sc->code);
+          }
+
+     CASE(OP_E0ARGS):     /* eval arguments */
+          if (is_macro(sc->value)) {    /* macro expansion */
+	       gc_disable(sc, 1 + gc_reservations (s_save));
+               s_save(sc,OP_DOMACRO, sc->NIL, sc->NIL);
+               sc->args = cons(sc,sc->code, sc->NIL);
+	       gc_enable(sc);
+               sc->code = sc->value;
+	       s_clear_flag(sc, TAIL_CONTEXT);
+               s_thread_to(sc,OP_APPLY);
+          } else {
+	       gc_disable(sc, 1);
+	       sc->args = cons(sc, sc->code, sc->NIL);
+	       gc_enable(sc);
+	       sc->code = cdr(sc->code);
+               s_thread_to(sc,OP_E1ARGS);
+          }
+
+     CASE(OP_E1ARGS):     /* eval arguments */
+	  gc_disable(sc, 1);
+	  sc->args = cons(sc, sc->value, sc->args);
+	  gc_enable(sc);
+          if (is_pair(sc->code)) { /* continue */
+               s_save(sc,OP_E1ARGS, sc->args, cdr(sc->code));
+               sc->code = car(sc->code);
+               sc->args = sc->NIL;
+	       s_clear_flag(sc, TAIL_CONTEXT);
+               s_thread_to(sc,OP_EVAL);
+          } else {  /* end */
+               sc->args = reverse_in_place(sc, sc->NIL, sc->args);
+               s_thread_to(sc,OP_APPLY_CODE);
+          }
+
+#if USE_TRACING
+     CASE(OP_TRACING): {
+       int tr=sc->tracing;
+       sc->tracing=ivalue(car(sc->args));
+       gc_disable(sc, 1);
+       s_return_enable_gc(sc, mk_integer(sc, tr));
+     }
+#endif
+
+#if USE_HISTORY
+     CASE(OP_CALLSTACK_POP):      /* pop the call stack */
+	  callstack_pop(sc);
+	  s_return(sc, sc->value);
+#endif
+
+     CASE(OP_APPLY_CODE): /* apply 'cadr(args)' to 'cddr(args)',
+			   * record in the history as invoked from
+			   * 'car(args)' */
+	  free_cons(sc, sc->args, &callsite, &sc->args);
+	  sc->code = car(sc->args);
+	  sc->args = cdr(sc->args);
+	  /* Fallthrough.  */
+
+     CASE(OP_APPLY):      /* apply 'code' to 'args' */
+#if USE_TRACING
+       if(sc->tracing) {
+         s_save(sc,OP_REAL_APPLY,sc->args,sc->code);
+         sc->print_flag = 1;
+         /*  sc->args=cons(sc,sc->code,sc->args);*/
+         putstr(sc,"\nApply to: ");
+         s_thread_to(sc,OP_P0LIST);
+       }
+       /* fall through */
+     CASE(OP_REAL_APPLY):
+#endif
+#if USE_HISTORY
+          if (op != OP_APPLY_CODE)
+            callsite = sc->code;
+          if (s_get_flag(sc, TAIL_CONTEXT)) {
+            /* We are evaluating a tail call.  */
+            tailstack_push(sc, callsite);
+          } else {
+            callstack_push(sc, callsite);
+            s_save(sc, OP_CALLSTACK_POP, sc->NIL, sc->NIL);
+          }
+#endif
+
+          if (is_proc(sc->code)) {
+               s_goto(sc,procnum(sc->code));   /* PROCEDURE */
+          } else if (is_foreign(sc->code))
+            {
+              /* Keep nested calls from GC'ing the arglist */
+              push_recent_alloc(sc,sc->args,sc->NIL);
+               x=sc->code->_object._ff(sc,sc->args);
+               s_return(sc,x);
+          } else if (is_closure(sc->code) || is_macro(sc->code)
+             || is_promise(sc->code)) { /* CLOSURE */
+        /* Should not accept promise */
+               /* make environment */
+               new_frame_in_env(sc, closure_env(sc->code));
+               for (x = car(closure_code(sc->code)), y = sc->args;
+                    is_pair(x); x = cdr(x), y = cdr(y)) {
+                    if (y == sc->NIL) {
+                         Error_1(sc, "not enough arguments, missing", x);
+                    } else if (is_symbol(car(x))) {
+                         new_slot_in_env(sc, car(x), car(y));
+                    } else {
+			 Error_1(sc, "syntax error in closure: not a symbol", car(x));
+		    }
+               }
+
+               if (x == sc->NIL) {
+                    if (y != sc->NIL) {
+                      Error_0(sc, "too many arguments");
+                    }
+               } else if (is_symbol(x))
+                    new_slot_in_env(sc, x, y);
+               else {
+                    Error_1(sc, "syntax error in closure: not a symbol", x);
+               }
+               sc->code = cdr(closure_code(sc->code));
+               sc->args = sc->NIL;
+	       s_set_flag(sc, TAIL_CONTEXT);
+               s_thread_to(sc,OP_BEGIN);
+          } else if (is_continuation(sc->code)) { /* CONTINUATION */
+               sc->dump = cont_dump(sc->code);
+               s_return(sc,sc->args != sc->NIL ? car(sc->args) : sc->NIL);
+          } else {
+               Error_1(sc,"illegal function",sc->code);
+          }
+
+     CASE(OP_DOMACRO):    /* do macro */
+          sc->code = sc->value;
+          s_thread_to(sc,OP_EVAL);
+
+#if USE_COMPILE_HOOK
+     CASE(OP_LAMBDA):     /* lambda */
+          /* If the hook is defined, apply it to sc->code, otherwise
+             set sc->value fall through */
+          {
+               pointer f=find_slot_in_env(sc,sc->envir,sc->COMPILE_HOOK,1);
+               if(f==sc->NIL) {
+                    sc->value = sc->code;
+                    /* Fallthru */
+               } else {
+		    gc_disable(sc, 1 + gc_reservations (s_save));
+                    s_save(sc,OP_LAMBDA1,sc->args,sc->code);
+                    sc->args=cons(sc,sc->code,sc->NIL);
+		    gc_enable(sc);
+                    sc->code=slot_value_in_env(f);
+                    s_thread_to(sc,OP_APPLY);
+               }
+          }
+	  /* Fallthrough. */
+#else
+     CASE(OP_LAMBDA):     /* lambda */
+	  sc->value = sc->code;
+	  /* Fallthrough. */
+#endif
+
+     CASE(OP_LAMBDA1):
+	  gc_disable(sc, 1);
+          s_return_enable_gc(sc, mk_closure(sc, sc->value, sc->envir));
+
+
+     CASE(OP_MKCLOSURE): /* make-closure */
+       x=car(sc->args);
+       if(car(x)==sc->LAMBDA) {
+         x=cdr(x);
+       }
+       if(cdr(sc->args)==sc->NIL) {
+         y=sc->envir;
+       } else {
+         y=cadr(sc->args);
+       }
+       gc_disable(sc, 1);
+       s_return_enable_gc(sc, mk_closure(sc, x, y));
+
+     CASE(OP_QUOTE):      /* quote */
+          s_return(sc,car(sc->code));
+
+     CASE(OP_DEF0):  /* define */
+          if(is_immutable(car(sc->code)))
+            Error_1(sc,"define: unable to alter immutable", car(sc->code));
+
+          if (is_pair(car(sc->code))) {
+               x = caar(sc->code);
+	       gc_disable(sc, 2);
+               sc->code = cons(sc, sc->LAMBDA, cons(sc, cdar(sc->code), cdr(sc->code)));
+	       gc_enable(sc);
+          } else {
+               x = car(sc->code);
+               sc->code = cadr(sc->code);
+          }
+          if (!is_symbol(x)) {
+               Error_0(sc,"variable is not a symbol");
+          }
+          s_save(sc,OP_DEF1, sc->NIL, x);
+          s_thread_to(sc,OP_EVAL);
+
+     CASE(OP_DEF1): { /* define */
+	  pointer *sslot;
+          x = find_slot_spec_in_env(sc, sc->envir, sc->code, 0, &sslot);
+          if (x != sc->NIL) {
+               set_slot_in_env(sc, x, sc->value);
+          } else {
+	       new_slot_spec_in_env(sc, sc->code, sc->value, sslot);
+          }
+          s_return(sc,sc->code);
+     }
+
+     CASE(OP_DEFP):  /* defined? */
+          x=sc->envir;
+          if(cdr(sc->args)!=sc->NIL) {
+               x=cadr(sc->args);
+          }
+          s_retbool(find_slot_in_env(sc,x,car(sc->args),1)!=sc->NIL);
+
+     CASE(OP_SET0):       /* set! */
+          if(is_immutable(car(sc->code)))
+                Error_1(sc,"set!: unable to alter immutable variable",car(sc->code));
+          s_save(sc,OP_SET1, sc->NIL, car(sc->code));
+          sc->code = cadr(sc->code);
+          s_thread_to(sc,OP_EVAL);
+
+     CASE(OP_SET1):       /* set! */
+          y=find_slot_in_env(sc,sc->envir,sc->code,1);
+          if (y != sc->NIL) {
+               set_slot_in_env(sc, y, sc->value);
+               s_return(sc,sc->value);
+          } else {
+               Error_1(sc, "set!: unbound variable", sc->code);
+          }
+
+
+     CASE(OP_BEGIN):      /* begin */
+	  {
+	    int last;
+
+	    if (!is_pair(sc->code)) {
+	      s_return(sc,sc->code);
+	    }
+
+	    last = cdr(sc->code) == sc->NIL;
+	    if (!last) {
+	      s_save(sc,OP_BEGIN, sc->NIL, cdr(sc->code));
+	    }
+	    sc->code = car(sc->code);
+	    if (! last)
+	      /* This is not the end of the list.  This is not a tail
+	       * position.  */
+	      s_clear_flag(sc, TAIL_CONTEXT);
+	    s_thread_to(sc,OP_EVAL);
+	  }
+
+     CASE(OP_IF0):        /* if */
+          s_save(sc,OP_IF1, sc->NIL, cdr(sc->code));
+          sc->code = car(sc->code);
+	  s_clear_flag(sc, TAIL_CONTEXT);
+          s_thread_to(sc,OP_EVAL);
+
+     CASE(OP_IF1):        /* if */
+          if (is_true(sc->value))
+               sc->code = car(sc->code);
+          else
+               sc->code = cadr(sc->code);  /* (if #f 1) ==> () because
+                                            * car(sc->NIL) = sc->NIL */
+          s_thread_to(sc,OP_EVAL);
+
+     CASE(OP_LET0):       /* let */
+          sc->args = sc->NIL;
+          sc->value = sc->code;
+          sc->code = is_symbol(car(sc->code)) ? cadr(sc->code) : car(sc->code);
+          s_thread_to(sc,OP_LET1);
+
+     CASE(OP_LET1):       /* let (calculate parameters) */
+	  gc_disable(sc, 1 + (is_pair(sc->code) ? gc_reservations (s_save) : 0));
+          sc->args = cons(sc, sc->value, sc->args);
+          if (is_pair(sc->code)) { /* continue */
+               if (!is_pair(car(sc->code)) || !is_pair(cdar(sc->code))) {
+		    gc_enable(sc);
+                    Error_1(sc, "Bad syntax of binding spec in let",
+                            car(sc->code));
+               }
+               s_save(sc,OP_LET1, sc->args, cdr(sc->code));
+	       gc_enable(sc);
+               sc->code = cadar(sc->code);
+               sc->args = sc->NIL;
+	       s_clear_flag(sc, TAIL_CONTEXT);
+               s_thread_to(sc,OP_EVAL);
+          } else {  /* end */
+	       gc_enable(sc);
+               sc->args = reverse_in_place(sc, sc->NIL, sc->args);
+               sc->code = car(sc->args);
+               sc->args = cdr(sc->args);
+               s_thread_to(sc,OP_LET2);
+          }
+
+     CASE(OP_LET2):       /* let */
+          new_frame_in_env(sc, sc->envir);
+          for (x = is_symbol(car(sc->code)) ? cadr(sc->code) : car(sc->code), y = sc->args;
+               y != sc->NIL; x = cdr(x), y = cdr(y)) {
+               new_slot_in_env(sc, caar(x), car(y));
+          }
+          if (is_symbol(car(sc->code))) {    /* named let */
+               for (x = cadr(sc->code), sc->args = sc->NIL; x != sc->NIL; x = cdr(x)) {
+                    if (!is_pair(x))
+                        Error_1(sc, "Bad syntax of binding in let", x);
+                    if (!is_list(sc, car(x)))
+                        Error_1(sc, "Bad syntax of binding in let", car(x));
+		    gc_disable(sc, 1);
+                    sc->args = cons(sc, caar(x), sc->args);
+		    gc_enable(sc);
+               }
+	       gc_disable(sc, 2 + gc_reservations (new_slot_in_env));
+               x = mk_closure(sc, cons(sc, reverse_in_place(sc, sc->NIL, sc->args), cddr(sc->code)), sc->envir);
+               new_slot_in_env(sc, car(sc->code), x);
+	       gc_enable(sc);
+               sc->code = cddr(sc->code);
+               sc->args = sc->NIL;
+          } else {
+               sc->code = cdr(sc->code);
+               sc->args = sc->NIL;
+          }
+          s_thread_to(sc,OP_BEGIN);
+
+     CASE(OP_LET0AST):    /* let* */
+          if (car(sc->code) == sc->NIL) {
+               new_frame_in_env(sc, sc->envir);
+               sc->code = cdr(sc->code);
+               s_thread_to(sc,OP_BEGIN);
+          }
+          if(!is_pair(car(sc->code)) || !is_pair(caar(sc->code)) || !is_pair(cdaar(sc->code))) {
+               Error_1(sc, "Bad syntax of binding spec in let*", car(sc->code));
+          }
+          s_save(sc,OP_LET1AST, cdr(sc->code), car(sc->code));
+          sc->code = cadaar(sc->code);
+	  s_clear_flag(sc, TAIL_CONTEXT);
+          s_thread_to(sc,OP_EVAL);
+
+     CASE(OP_LET1AST):    /* let* (make new frame) */
+          new_frame_in_env(sc, sc->envir);
+          s_thread_to(sc,OP_LET2AST);
+
+     CASE(OP_LET2AST):    /* let* (calculate parameters) */
+          new_slot_in_env(sc, caar(sc->code), sc->value);
+          sc->code = cdr(sc->code);
+          if (is_pair(sc->code)) { /* continue */
+               s_save(sc,OP_LET2AST, sc->args, sc->code);
+               sc->code = cadar(sc->code);
+               sc->args = sc->NIL;
+	       s_clear_flag(sc, TAIL_CONTEXT);
+               s_thread_to(sc,OP_EVAL);
+          } else {  /* end */
+               sc->code = sc->args;
+               sc->args = sc->NIL;
+               s_thread_to(sc,OP_BEGIN);
+          }
+
+     CASE(OP_LET0REC):    /* letrec */
+          new_frame_in_env(sc, sc->envir);
+          sc->args = sc->NIL;
+          sc->value = sc->code;
+          sc->code = car(sc->code);
+          s_thread_to(sc,OP_LET1REC);
+
+     CASE(OP_LET1REC):    /* letrec (calculate parameters) */
+	  gc_disable(sc, 1);
+          sc->args = cons(sc, sc->value, sc->args);
+	  gc_enable(sc);
+          if (is_pair(sc->code)) { /* continue */
+               if (!is_pair(car(sc->code)) || !is_pair(cdar(sc->code))) {
+                    Error_1(sc, "Bad syntax of binding spec in letrec",
+                            car(sc->code));
+               }
+               s_save(sc,OP_LET1REC, sc->args, cdr(sc->code));
+               sc->code = cadar(sc->code);
+               sc->args = sc->NIL;
+	       s_clear_flag(sc, TAIL_CONTEXT);
+               s_thread_to(sc,OP_EVAL);
+          } else {  /* end */
+               sc->args = reverse_in_place(sc, sc->NIL, sc->args);
+               sc->code = car(sc->args);
+               sc->args = cdr(sc->args);
+               s_thread_to(sc,OP_LET2REC);
+          }
+
+     CASE(OP_LET2REC):    /* letrec */
+          for (x = car(sc->code), y = sc->args; y != sc->NIL; x = cdr(x), y = cdr(y)) {
+               new_slot_in_env(sc, caar(x), car(y));
+          }
+          sc->code = cdr(sc->code);
+          sc->args = sc->NIL;
+          s_thread_to(sc,OP_BEGIN);
+
+     CASE(OP_COND0):      /* cond */
+          if (!is_pair(sc->code)) {
+               Error_0(sc,"syntax error in cond");
+          }
+          s_save(sc,OP_COND1, sc->NIL, sc->code);
+          sc->code = caar(sc->code);
+	  s_clear_flag(sc, TAIL_CONTEXT);
+          s_thread_to(sc,OP_EVAL);
+
+     CASE(OP_COND1):      /* cond */
+          if (is_true(sc->value)) {
+               if ((sc->code = cdar(sc->code)) == sc->NIL) {
+                    s_return(sc,sc->value);
+               }
+               if(!sc->code || car(sc->code)==sc->FEED_TO) {
+                    if(!is_pair(cdr(sc->code))) {
+                         Error_0(sc,"syntax error in cond");
+                    }
+		    gc_disable(sc, 4);
+                    x=cons(sc, sc->QUOTE, cons(sc, sc->value, sc->NIL));
+                    sc->code=cons(sc,cadr(sc->code),cons(sc,x,sc->NIL));
+		    gc_enable(sc);
+                    s_thread_to(sc,OP_EVAL);
+               }
+               s_thread_to(sc,OP_BEGIN);
+          } else {
+               if ((sc->code = cdr(sc->code)) == sc->NIL) {
+                    s_return(sc,sc->NIL);
+               } else {
+                    s_save(sc,OP_COND1, sc->NIL, sc->code);
+                    sc->code = caar(sc->code);
+		    s_clear_flag(sc, TAIL_CONTEXT);
+                    s_thread_to(sc,OP_EVAL);
+               }
+          }
+
+     CASE(OP_DELAY):      /* delay */
+	  gc_disable(sc, 2);
+          x = mk_closure(sc, cons(sc, sc->NIL, sc->code), sc->envir);
+          typeflag(x)=T_PROMISE;
+          s_return_enable_gc(sc,x);
+
+     CASE(OP_AND0):       /* and */
+          if (sc->code == sc->NIL) {
+               s_return(sc,sc->T);
+          }
+          s_save(sc,OP_AND1, sc->NIL, cdr(sc->code));
+	  if (cdr(sc->code) != sc->NIL)
+	       s_clear_flag(sc, TAIL_CONTEXT);
+          sc->code = car(sc->code);
+          s_thread_to(sc,OP_EVAL);
+
+     CASE(OP_AND1):       /* and */
+          if (is_false(sc->value)) {
+               s_return(sc,sc->value);
+          } else if (sc->code == sc->NIL) {
+               s_return(sc,sc->value);
+          } else {
+               s_save(sc,OP_AND1, sc->NIL, cdr(sc->code));
+	       if (cdr(sc->code) != sc->NIL)
+		    s_clear_flag(sc, TAIL_CONTEXT);
+               sc->code = car(sc->code);
+               s_thread_to(sc,OP_EVAL);
+          }
+
+     CASE(OP_OR0):        /* or */
+          if (sc->code == sc->NIL) {
+               s_return(sc,sc->F);
+          }
+          s_save(sc,OP_OR1, sc->NIL, cdr(sc->code));
+	  if (cdr(sc->code) != sc->NIL)
+	       s_clear_flag(sc, TAIL_CONTEXT);
+          sc->code = car(sc->code);
+          s_thread_to(sc,OP_EVAL);
+
+     CASE(OP_OR1):        /* or */
+          if (is_true(sc->value)) {
+               s_return(sc,sc->value);
+          } else if (sc->code == sc->NIL) {
+               s_return(sc,sc->value);
+          } else {
+               s_save(sc,OP_OR1, sc->NIL, cdr(sc->code));
+	       if (cdr(sc->code) != sc->NIL)
+		    s_clear_flag(sc, TAIL_CONTEXT);
+               sc->code = car(sc->code);
+               s_thread_to(sc,OP_EVAL);
+          }
+
+     CASE(OP_C0STREAM):   /* cons-stream */
+          s_save(sc,OP_C1STREAM, sc->NIL, cdr(sc->code));
+          sc->code = car(sc->code);
+          s_thread_to(sc,OP_EVAL);
+
+     CASE(OP_C1STREAM):   /* cons-stream */
+          sc->args = sc->value;  /* save sc->value to register sc->args for gc */
+	  gc_disable(sc, 3);
+          x = mk_closure(sc, cons(sc, sc->NIL, sc->code), sc->envir);
+          typeflag(x)=T_PROMISE;
+          s_return_enable_gc(sc, cons(sc, sc->args, x));
+
+     CASE(OP_MACRO0):     /* macro */
+          if (is_pair(car(sc->code))) {
+               x = caar(sc->code);
+	       gc_disable(sc, 2);
+               sc->code = cons(sc, sc->LAMBDA, cons(sc, cdar(sc->code), cdr(sc->code)));
+	       gc_enable(sc);
+          } else {
+               x = car(sc->code);
+               sc->code = cadr(sc->code);
+          }
+          if (!is_symbol(x)) {
+               Error_0(sc,"variable is not a symbol");
+          }
+          s_save(sc,OP_MACRO1, sc->NIL, x);
+          s_thread_to(sc,OP_EVAL);
+
+     CASE(OP_MACRO1): {   /* macro */
+	  pointer *sslot;
+          typeflag(sc->value) = T_MACRO;
+          x = find_slot_spec_in_env(sc, sc->envir, sc->code, 0, &sslot);
+          if (x != sc->NIL) {
+               set_slot_in_env(sc, x, sc->value);
+          } else {
+	       new_slot_spec_in_env(sc, sc->code, sc->value, sslot);
+          }
+          s_return(sc,sc->code);
+     }
+
+     CASE(OP_CASE0):      /* case */
+          s_save(sc,OP_CASE1, sc->NIL, cdr(sc->code));
+          sc->code = car(sc->code);
+	  s_clear_flag(sc, TAIL_CONTEXT);
+          s_thread_to(sc,OP_EVAL);
+
+     CASE(OP_CASE1):      /* case */
+          for (x = sc->code; x != sc->NIL; x = cdr(x)) {
+               if (!is_pair(y = caar(x))) {
+                    break;
+               }
+               for ( ; y != sc->NIL; y = cdr(y)) {
+                    if (eqv(car(y), sc->value)) {
+                         break;
+                    }
+               }
+               if (y != sc->NIL) {
+                    break;
+               }
+          }
+          if (x != sc->NIL) {
+               if (is_pair(caar(x))) {
+                    sc->code = cdar(x);
+                    s_thread_to(sc,OP_BEGIN);
+               } else {/* else */
+                    s_save(sc,OP_CASE2, sc->NIL, cdar(x));
+                    sc->code = caar(x);
+                    s_thread_to(sc,OP_EVAL);
+               }
+          } else {
+               s_return(sc,sc->NIL);
+          }
+
+     CASE(OP_CASE2):      /* case */
+          if (is_true(sc->value)) {
+               s_thread_to(sc,OP_BEGIN);
+          } else {
+               s_return(sc,sc->NIL);
+          }
+
+     CASE(OP_PAPPLY):     /* apply */
+          sc->code = car(sc->args);
+          sc->args = list_star(sc,cdr(sc->args));
+          /*sc->args = cadr(sc->args);*/
+          s_thread_to(sc,OP_APPLY);
+
+     CASE(OP_PEVAL): /* eval */
+          if(cdr(sc->args)!=sc->NIL) {
+               sc->envir=cadr(sc->args);
+          }
+          sc->code = car(sc->args);
+          s_thread_to(sc,OP_EVAL);
+
+     CASE(OP_CONTINUATION):    /* call-with-current-continuation */
+          sc->code = car(sc->args);
+	  gc_disable(sc, 2);
+          sc->args = cons(sc, mk_continuation(sc, sc->dump), sc->NIL);
+	  gc_enable(sc);
+          s_thread_to(sc,OP_APPLY);
+
+#if USE_MATH
+     CASE(OP_INEX2EX):    /* inexact->exact */
+          x=car(sc->args);
+          if(num_is_integer(x)) {
+               s_return(sc,x);
+          } else if(modf(rvalue_unchecked(x),&dd)==0.0) {
+               s_return(sc,mk_integer(sc,ivalue(x)));
+          } else {
+               Error_1(sc, "inexact->exact: not integral", x);
+          }
+
+     CASE(OP_EXP):
+          x=car(sc->args);
+          s_return(sc, mk_real(sc, exp(rvalue(x))));
+
+     CASE(OP_LOG):
+          x=car(sc->args);
+          s_return(sc, mk_real(sc, log(rvalue(x))));
+
+     CASE(OP_SIN):
+          x=car(sc->args);
+          s_return(sc, mk_real(sc, sin(rvalue(x))));
+
+     CASE(OP_COS):
+          x=car(sc->args);
+          s_return(sc, mk_real(sc, cos(rvalue(x))));
+
+     CASE(OP_TAN):
+          x=car(sc->args);
+          s_return(sc, mk_real(sc, tan(rvalue(x))));
+
+     CASE(OP_ASIN):
+          x=car(sc->args);
+          s_return(sc, mk_real(sc, asin(rvalue(x))));
+
+     CASE(OP_ACOS):
+          x=car(sc->args);
+          s_return(sc, mk_real(sc, acos(rvalue(x))));
+
+     CASE(OP_ATAN):
+          x=car(sc->args);
+          if(cdr(sc->args)==sc->NIL) {
+               s_return(sc, mk_real(sc, atan(rvalue(x))));
+          } else {
+               pointer y=cadr(sc->args);
+               s_return(sc, mk_real(sc, atan2(rvalue(x),rvalue(y))));
+          }
+
+     CASE(OP_SQRT):
+          x=car(sc->args);
+          s_return(sc, mk_real(sc, sqrt(rvalue(x))));
+
+     CASE(OP_EXPT): {
+          double result;
+          int real_result=1;
+          pointer y=cadr(sc->args);
+          x=car(sc->args);
+          if (num_is_integer(x) && num_is_integer(y))
+             real_result=0;
+          /* This 'if' is an R5RS compatibility fix. */
+          /* NOTE: Remove this 'if' fix for R6RS.    */
+          if (rvalue(x) == 0 && rvalue(y) < 0) {
+             result = 0.0;
+          } else {
+             result = pow(rvalue(x),rvalue(y));
+          }
+          /* Before returning integer result make sure we can. */
+          /* If the test fails, result is too big for integer. */
+          if (!real_result)
+          {
+            long result_as_long = (long)result;
+            if (result != (double)result_as_long)
+              real_result = 1;
+          }
+          if (real_result) {
+             s_return(sc, mk_real(sc, result));
+          } else {
+             s_return(sc, mk_integer(sc, result));
+          }
+     }
+
+     CASE(OP_FLOOR):
+          x=car(sc->args);
+          s_return(sc, mk_real(sc, floor(rvalue(x))));
+
+     CASE(OP_CEILING):
+          x=car(sc->args);
+          s_return(sc, mk_real(sc, ceil(rvalue(x))));
+
+     CASE(OP_TRUNCATE ): {
+          double rvalue_of_x ;
+          x=car(sc->args);
+          rvalue_of_x = rvalue(x) ;
+          if (rvalue_of_x > 0) {
+            s_return(sc, mk_real(sc, floor(rvalue_of_x)));
+          } else {
+            s_return(sc, mk_real(sc, ceil(rvalue_of_x)));
+          }
+     }
+
+     CASE(OP_ROUND):
+        x=car(sc->args);
+        if (num_is_integer(x))
+            s_return(sc, x);
+        s_return(sc, mk_real(sc, round_per_R5RS(rvalue(x))));
+#endif
+
+     CASE(OP_ADD):        /* + */
+       v=num_zero;
+       for (x = sc->args; x != sc->NIL; x = cdr(x)) {
+         v=num_add(v,nvalue(car(x)));
+       }
+       gc_disable(sc, 1);
+       s_return_enable_gc(sc, mk_number(sc, v));
+
+     CASE(OP_MUL):        /* * */
+       v=num_one;
+       for (x = sc->args; x != sc->NIL; x = cdr(x)) {
+         v=num_mul(v,nvalue(car(x)));
+       }
+       gc_disable(sc, 1);
+       s_return_enable_gc(sc, mk_number(sc, v));
+
+     CASE(OP_SUB):        /* - */
+       if(cdr(sc->args)==sc->NIL) {
+         x=sc->args;
+         v=num_zero;
+       } else {
+         x = cdr(sc->args);
+         v = nvalue(car(sc->args));
+       }
+       for (; x != sc->NIL; x = cdr(x)) {
+         v=num_sub(v,nvalue(car(x)));
+       }
+       gc_disable(sc, 1);
+       s_return_enable_gc(sc, mk_number(sc, v));
+
+     CASE(OP_DIV):        /* / */
+       if(cdr(sc->args)==sc->NIL) {
+         x=sc->args;
+         v=num_one;
+       } else {
+         x = cdr(sc->args);
+         v = nvalue(car(sc->args));
+       }
+       for (; x != sc->NIL; x = cdr(x)) {
+         if (!is_zero_double(rvalue(car(x))))
+           v=num_div(v,nvalue(car(x)));
+         else {
+           Error_0(sc,"/: division by zero");
+         }
+       }
+       gc_disable(sc, 1);
+       s_return_enable_gc(sc, mk_number(sc, v));
+
+     CASE(OP_INTDIV):        /* quotient */
+          if(cdr(sc->args)==sc->NIL) {
+               x=sc->args;
+               v=num_one;
+          } else {
+               x = cdr(sc->args);
+               v = nvalue(car(sc->args));
+          }
+          for (; x != sc->NIL; x = cdr(x)) {
+               if (ivalue(car(x)) != 0)
+                    v=num_intdiv(v,nvalue(car(x)));
+               else {
+                    Error_0(sc,"quotient: division by zero");
+               }
+          }
+	  gc_disable(sc, 1);
+          s_return_enable_gc(sc, mk_number(sc, v));
+
+     CASE(OP_REM):        /* remainder */
+          v = nvalue(car(sc->args));
+          if (ivalue(cadr(sc->args)) != 0)
+               v=num_rem(v,nvalue(cadr(sc->args)));
+          else {
+               Error_0(sc,"remainder: division by zero");
+          }
+	  gc_disable(sc, 1);
+          s_return_enable_gc(sc, mk_number(sc, v));
+
+     CASE(OP_MOD):        /* modulo */
+          v = nvalue(car(sc->args));
+          if (ivalue(cadr(sc->args)) != 0)
+               v=num_mod(v,nvalue(cadr(sc->args)));
+          else {
+               Error_0(sc,"modulo: division by zero");
+          }
+	  gc_disable(sc, 1);
+          s_return_enable_gc(sc, mk_number(sc, v));
+
+     CASE(OP_CAR):        /* car */
+          s_return(sc,caar(sc->args));
+
+     CASE(OP_CDR):        /* cdr */
+          s_return(sc,cdar(sc->args));
+
+     CASE(OP_CONS):       /* cons */
+          cdr(sc->args) = cadr(sc->args);
+          s_return(sc,sc->args);
+
+     CASE(OP_SETCAR):     /* set-car! */
+       if(!is_immutable(car(sc->args))) {
+         caar(sc->args) = cadr(sc->args);
+         s_return(sc,car(sc->args));
+       } else {
+         Error_0(sc,"set-car!: unable to alter immutable pair");
+       }
+
+     CASE(OP_SETCDR):     /* set-cdr! */
+       if(!is_immutable(car(sc->args))) {
+         cdar(sc->args) = cadr(sc->args);
+         s_return(sc,car(sc->args));
+       } else {
+         Error_0(sc,"set-cdr!: unable to alter immutable pair");
+       }
+
+     CASE(OP_CHAR2INT): { /* char->integer */
+          char c;
+          c=(char)ivalue(car(sc->args));
+	  gc_disable(sc, 1);
+          s_return_enable_gc(sc, mk_integer(sc, (unsigned char) c));
+     }
+
+     CASE(OP_INT2CHAR): { /* integer->char */
+          unsigned char c;
+          c=(unsigned char)ivalue(car(sc->args));
+	  gc_disable(sc, 1);
+          s_return_enable_gc(sc, mk_character(sc, (char) c));
+     }
+
+     CASE(OP_CHARUPCASE): {
+          unsigned char c;
+          c=(unsigned char)ivalue(car(sc->args));
+          c=toupper(c);
+	  gc_disable(sc, 1);
+          s_return_enable_gc(sc, mk_character(sc, (char) c));
+     }
+
+     CASE(OP_CHARDNCASE): {
+          unsigned char c;
+          c=(unsigned char)ivalue(car(sc->args));
+          c=tolower(c);
+	  gc_disable(sc, 1);
+          s_return_enable_gc(sc, mk_character(sc, (char) c));
+     }
+
+     CASE(OP_STR2SYM):  /* string->symbol */
+          gc_disable(sc, gc_reservations (mk_symbol));
+          s_return_enable_gc(sc, mk_symbol(sc, strvalue(car(sc->args))));
+
+     CASE(OP_STR2ATOM): /* string->atom */ {
+          char *s=strvalue(car(sc->args));
+          long pf = 0;
+          if(cdr(sc->args)!=sc->NIL) {
+            /* we know cadr(sc->args) is a natural number */
+            /* see if it is 2, 8, 10, or 16, or error */
+            pf = ivalue_unchecked(cadr(sc->args));
+            if(pf == 16 || pf == 10 || pf == 8 || pf == 2) {
+               /* base is OK */
+            }
+            else {
+              pf = -1;
+            }
+          }
+          if (pf < 0) {
+            Error_1(sc, "string->atom: bad base", cadr(sc->args));
+          } else if(*s=='#') /* no use of base! */ {
+            s_return(sc, mk_sharp_const(sc, s+1));
+          } else {
+            if (pf == 0 || pf == 10) {
+              s_return(sc, mk_atom(sc, s));
+            }
+            else {
+              char *ep;
+              long iv = strtol(s,&ep,(int )pf);
+              if (*ep == 0) {
+                s_return(sc, mk_integer(sc, iv));
+              }
+              else {
+                s_return(sc, sc->F);
+              }
+            }
+          }
+        }
+
+     CASE(OP_SYM2STR): /* symbol->string */
+	  gc_disable(sc, 1);
+          x=mk_string(sc,symname(car(sc->args)));
+          setimmutable(x);
+          s_return_enable_gc(sc, x);
+
+     CASE(OP_ATOM2STR): /* atom->string */ {
+          long pf = 0;
+          x=car(sc->args);
+          if(cdr(sc->args)!=sc->NIL) {
+            /* we know cadr(sc->args) is a natural number */
+            /* see if it is 2, 8, 10, or 16, or error */
+            pf = ivalue_unchecked(cadr(sc->args));
+            if(is_number(x) && (pf == 16 || pf == 10 || pf == 8 || pf == 2)) {
+              /* base is OK */
+            }
+            else {
+              pf = -1;
+            }
+          }
+          if (pf < 0) {
+            Error_1(sc, "atom->string: bad base", cadr(sc->args));
+          } else if(is_number(x) || is_character(x) || is_string(x) || is_symbol(x)) {
+            char *p;
+            int len;
+            atom2str(sc,x,(int )pf,&p,&len);
+	    gc_disable(sc, 1);
+            s_return_enable_gc(sc, mk_counted_string(sc, p, len));
+          } else {
+            Error_1(sc, "atom->string: not an atom", x);
+          }
+        }
+
+     CASE(OP_MKSTRING): { /* make-string */
+          int fill=' ';
+          int len;
+
+          len=ivalue(car(sc->args));
+
+          if(cdr(sc->args)!=sc->NIL) {
+               fill=charvalue(cadr(sc->args));
+          }
+	  gc_disable(sc, 1);
+          s_return_enable_gc(sc, mk_empty_string(sc, len, (char) fill));
+     }
+
+     CASE(OP_STRLEN):  /* string-length */
+	  gc_disable(sc, 1);
+          s_return_enable_gc(sc, mk_integer(sc, strlength(car(sc->args))));
+
+     CASE(OP_STRREF): { /* string-ref */
+          char *str;
+          int index;
+
+          str=strvalue(car(sc->args));
+
+          index=ivalue(cadr(sc->args));
+
+          if(index>=strlength(car(sc->args))) {
+               Error_1(sc, "string-ref: out of bounds", cadr(sc->args));
+          }
+
+	  gc_disable(sc, 1);
+          s_return_enable_gc(sc,
+			     mk_character(sc, ((unsigned char*) str)[index]));
+     }
+
+     CASE(OP_STRSET): { /* string-set! */
+          char *str;
+          int index;
+          int c;
+
+          if(is_immutable(car(sc->args))) {
+               Error_1(sc, "string-set!: unable to alter immutable string",
+		       car(sc->args));
+          }
+          str=strvalue(car(sc->args));
+
+          index=ivalue(cadr(sc->args));
+          if(index>=strlength(car(sc->args))) {
+               Error_1(sc, "string-set!: out of bounds", cadr(sc->args));
+          }
+
+          c=charvalue(caddr(sc->args));
+
+          str[index]=(char)c;
+          s_return(sc,car(sc->args));
+     }
+
+     CASE(OP_STRAPPEND): { /* string-append */
+       /* in 1.29 string-append was in Scheme in init.scm but was too slow */
+       int len = 0;
+       pointer newstr;
+       char *pos;
+
+       /* compute needed length for new string */
+       for (x = sc->args; x != sc->NIL; x = cdr(x)) {
+          len += strlength(car(x));
+       }
+       gc_disable(sc, 1);
+       newstr = mk_empty_string(sc, len, ' ');
+       /* store the contents of the argument strings into the new string */
+       for (pos = strvalue(newstr), x = sc->args; x != sc->NIL;
+           pos += strlength(car(x)), x = cdr(x)) {
+           memcpy(pos, strvalue(car(x)), strlength(car(x)));
+       }
+       s_return_enable_gc(sc, newstr);
+     }
+
+     CASE(OP_SUBSTR): { /* substring */
+          char *str;
+          int index0;
+          int index1;
+
+          str=strvalue(car(sc->args));
+
+          index0=ivalue(cadr(sc->args));
+
+          if(index0>strlength(car(sc->args))) {
+               Error_1(sc, "substring: start out of bounds", cadr(sc->args));
+          }
+
+          if(cddr(sc->args)!=sc->NIL) {
+               index1=ivalue(caddr(sc->args));
+               if(index1>strlength(car(sc->args)) || index1<index0) {
+                    Error_1(sc, "substring: end out of bounds", caddr(sc->args));
+               }
+          } else {
+               index1=strlength(car(sc->args));
+          }
+
+	  gc_disable(sc, 1);
+          s_return_enable_gc(sc, mk_counted_string(sc, str + index0, index1 - index0));
+     }
+
+     CASE(OP_VECTOR): {   /* vector */
+          int i;
+          pointer vec;
+          int len=list_length(sc,sc->args);
+          if(len<0) {
+               Error_1(sc, "vector: not a proper list", sc->args);
+          }
+          vec=mk_vector(sc,len);
+          if(sc->no_memory) { s_return(sc, sc->sink); }
+          for (x = sc->args, i = 0; is_pair(x); x = cdr(x), i++) {
+               set_vector_elem(vec,i,car(x));
+          }
+          s_return(sc,vec);
+     }
+
+     CASE(OP_MKVECTOR): { /* make-vector */
+          pointer fill=sc->NIL;
+          int len;
+          pointer vec;
+
+          len=ivalue(car(sc->args));
+
+          if(cdr(sc->args)!=sc->NIL) {
+               fill=cadr(sc->args);
+          }
+          vec=mk_vector(sc,len);
+          if(sc->no_memory) { s_return(sc, sc->sink); }
+          if(fill!=sc->NIL) {
+               fill_vector(vec,fill);
+          }
+          s_return(sc,vec);
+     }
+
+     CASE(OP_VECLEN):  /* vector-length */
+	  gc_disable(sc, 1);
+          s_return_enable_gc(sc, mk_integer(sc, vector_length(car(sc->args))));
+
+     CASE(OP_VECREF): { /* vector-ref */
+          int index;
+
+          index=ivalue(cadr(sc->args));
+
+          if(index >= vector_length(car(sc->args))) {
+               Error_1(sc, "vector-ref: out of bounds", cadr(sc->args));
+          }
+
+          s_return(sc,vector_elem(car(sc->args),index));
+     }
+
+     CASE(OP_VECSET): {   /* vector-set! */
+          int index;
+
+          if(is_immutable(car(sc->args))) {
+               Error_1(sc, "vector-set!: unable to alter immutable vector",
+		       car(sc->args));
+          }
+
+          index=ivalue(cadr(sc->args));
+          if(index >= vector_length(car(sc->args))) {
+               Error_1(sc, "vector-set!: out of bounds", cadr(sc->args));
+          }
+
+          set_vector_elem(car(sc->args),index,caddr(sc->args));
+          s_return(sc,car(sc->args));
+     }
+
+     CASE(OP_NOT):        /* not */
+          s_retbool(is_false(car(sc->args)));
+     CASE(OP_BOOLP):       /* boolean? */
+          s_retbool(car(sc->args) == sc->F || car(sc->args) == sc->T);
+     CASE(OP_EOFOBJP):       /* boolean? */
+          s_retbool(car(sc->args) == sc->EOF_OBJ);
+     CASE(OP_NULLP):       /* null? */
+          s_retbool(car(sc->args) == sc->NIL);
+     CASE(OP_NUMEQ):      /* = */
+	  /* Fallthrough.  */
+     CASE(OP_LESS):       /* < */
+	  /* Fallthrough.  */
+     CASE(OP_GRE):        /* > */
+	  /* Fallthrough.  */
+     CASE(OP_LEQ):        /* <= */
+	  /* Fallthrough.  */
+     CASE(OP_GEQ):        /* >= */
+          switch(op) {
+               case OP_NUMEQ: comp_func=num_eq; break;
+               case OP_LESS:  comp_func=num_lt; break;
+               case OP_GRE:   comp_func=num_gt; break;
+               case OP_LEQ:   comp_func=num_le; break;
+               case OP_GEQ:   comp_func=num_ge; break;
+               default: assert (! "reached");
+          }
+          x=sc->args;
+          v=nvalue(car(x));
+          x=cdr(x);
+
+          for (; x != sc->NIL; x = cdr(x)) {
+               if(!comp_func(v,nvalue(car(x)))) {
+                    s_retbool(0);
+               }
+           v=nvalue(car(x));
+          }
+          s_retbool(1);
+     CASE(OP_SYMBOLP):     /* symbol? */
+          s_retbool(is_symbol(car(sc->args)));
+     CASE(OP_NUMBERP):     /* number? */
+          s_retbool(is_number(car(sc->args)));
+     CASE(OP_STRINGP):     /* string? */
+          s_retbool(is_string(car(sc->args)));
+     CASE(OP_INTEGERP):     /* integer? */
+          s_retbool(is_integer(car(sc->args)));
+     CASE(OP_REALP):     /* real? */
+          s_retbool(is_number(car(sc->args))); /* All numbers are real */
+     CASE(OP_CHARP):     /* char? */
+          s_retbool(is_character(car(sc->args)));
+#if USE_CHAR_CLASSIFIERS
+     CASE(OP_CHARAP):     /* char-alphabetic? */
+          s_retbool(Cisalpha(ivalue(car(sc->args))));
+     CASE(OP_CHARNP):     /* char-numeric? */
+          s_retbool(Cisdigit(ivalue(car(sc->args))));
+     CASE(OP_CHARWP):     /* char-whitespace? */
+          s_retbool(Cisspace(ivalue(car(sc->args))));
+     CASE(OP_CHARUP):     /* char-upper-case? */
+          s_retbool(Cisupper(ivalue(car(sc->args))));
+     CASE(OP_CHARLP):     /* char-lower-case? */
+          s_retbool(Cislower(ivalue(car(sc->args))));
+#endif
+     CASE(OP_PORTP):     /* port? */
+          s_retbool(is_port(car(sc->args)));
+     CASE(OP_INPORTP):     /* input-port? */
+          s_retbool(is_inport(car(sc->args)));
+     CASE(OP_OUTPORTP):     /* output-port? */
+          s_retbool(is_outport(car(sc->args)));
+     CASE(OP_PROCP):       /* procedure? */
+          /*--
+              * continuation should be procedure by the example
+              * (call-with-current-continuation procedure?) ==> #t
+                 * in R^3 report sec. 6.9
+              */
+          s_retbool(is_proc(car(sc->args)) || is_closure(car(sc->args))
+                 || is_continuation(car(sc->args)) || is_foreign(car(sc->args)));
+     CASE(OP_PAIRP):       /* pair? */
+          s_retbool(is_pair(car(sc->args)));
+     CASE(OP_LISTP):       /* list? */
+       s_retbool(list_length(sc,car(sc->args)) >= 0);
+
+     CASE(OP_ENVP):        /* environment? */
+          s_retbool(is_environment(car(sc->args)));
+     CASE(OP_VECTORP):     /* vector? */
+          s_retbool(is_vector(car(sc->args)));
+     CASE(OP_EQ):         /* eq? */
+          s_retbool(car(sc->args) == cadr(sc->args));
+     CASE(OP_EQV):        /* eqv? */
+          s_retbool(eqv(car(sc->args), cadr(sc->args)));
+
+     CASE(OP_FORCE):      /* force */
+          sc->code = car(sc->args);
+          if (is_promise(sc->code)) {
+               /* Should change type to closure here */
+               s_save(sc, OP_SAVE_FORCED, sc->NIL, sc->code);
+               sc->args = sc->NIL;
+               s_thread_to(sc,OP_APPLY);
+          } else {
+               s_return(sc,sc->code);
+          }
+
+     CASE(OP_SAVE_FORCED):     /* Save forced value replacing promise */
+	  copy_value(sc, sc->code, sc->value);
+          s_return(sc,sc->value);
+
+     CASE(OP_WRITE):      /* write */
+	  /* Fallthrough.  */
+     CASE(OP_DISPLAY):    /* display */
+	  /* Fallthrough.  */
+     CASE(OP_WRITE_CHAR): /* write-char */
+          if(is_pair(cdr(sc->args))) {
+               if(cadr(sc->args)!=sc->outport) {
+                    x=cons(sc,sc->outport,sc->NIL);
+                    s_save(sc,OP_SET_OUTPORT, x, sc->NIL);
+                    sc->outport=cadr(sc->args);
+               }
+          }
+          sc->args = car(sc->args);
+          if(op==OP_WRITE) {
+               sc->print_flag = 1;
+          } else {
+               sc->print_flag = 0;
+          }
+          s_thread_to(sc,OP_P0LIST);
+
+     CASE(OP_NEWLINE):    /* newline */
+          if(is_pair(sc->args)) {
+               if(car(sc->args)!=sc->outport) {
+                    x=cons(sc,sc->outport,sc->NIL);
+                    s_save(sc,OP_SET_OUTPORT, x, sc->NIL);
+                    sc->outport=car(sc->args);
+               }
+          }
+          putstr(sc, "\n");
+          s_return(sc,sc->T);
+
+     CASE(OP_ERR0):  /* error */
+          sc->retcode=-1;
+          if (!is_string(car(sc->args))) {
+               sc->args=cons(sc,mk_string(sc," -- "),sc->args);
+               setimmutable(car(sc->args));
+          }
+          putstr(sc, "Error: ");
+          putstr(sc, strvalue(car(sc->args)));
+          sc->args = cdr(sc->args);
+          s_thread_to(sc,OP_ERR1);
+
+     CASE(OP_ERR1):  /* error */
+          putstr(sc, " ");
+          if (sc->args != sc->NIL) {
+               s_save(sc,OP_ERR1, cdr(sc->args), sc->NIL);
+               sc->args = car(sc->args);
+               sc->print_flag = 1;
+               s_thread_to(sc,OP_P0LIST);
+          } else {
+               putstr(sc, "\n");
+               if(sc->interactive_repl) {
+                    s_thread_to(sc,OP_T0LVL);
+               } else {
+                    return;
+               }
+          }
+
+     CASE(OP_REVERSE):   /* reverse */
+          s_return(sc,reverse(sc, sc->NIL, car(sc->args)));
+
+     CASE(OP_REVERSE_IN_PLACE):   /* reverse! */
+          s_return(sc, reverse_in_place(sc, sc->NIL, car(sc->args)));
+
+     CASE(OP_LIST_STAR): /* list* */
+          s_return(sc,list_star(sc,sc->args));
+
+     CASE(OP_APPEND):    /* append */
+          x = sc->NIL;
+          y = sc->args;
+          if (y == x) {
+              s_return(sc, x);
+          }
+
+          /* cdr() in the while condition is not a typo. If car() */
+          /* is used (append '() 'a) will return the wrong result.*/
+          while (cdr(y) != sc->NIL) {
+              x = revappend(sc, x, car(y));
+              y = cdr(y);
+              if (x == sc->F) {
+                  Error_0(sc, "non-list argument to append");
+              }
+          }
+
+          s_return(sc, reverse_in_place(sc, car(y), x));
+
+#if USE_PLIST
+     CASE(OP_SET_SYMBOL_PROPERTY): /* set-symbol-property! */
+	  gc_disable(sc, gc_reservations(set_property));
+          s_return_enable_gc(sc,
+			     set_property(sc, car(sc->args),
+					  cadr(sc->args), caddr(sc->args)));
+
+     CASE(OP_SYMBOL_PROPERTY):  /* symbol-property */
+	  s_return(sc, get_property(sc, car(sc->args), cadr(sc->args)));
+#endif /* USE_PLIST */
+
+     CASE(OP_TAG_VALUE): {      /* not exposed */
+	  /* This tags sc->value with car(sc->args).  Useful to tag
+	   * results of opcode evaluations.  */
+	  pointer a, b, c;
+	  free_cons(sc, sc->args, &a, &b);
+	  free_cons(sc, b, &b, &c);
+	  assert(c == sc->NIL);
+          s_return(sc, mk_tagged_value(sc, sc->value, a, b));
+	}
+
+     CASE(OP_MK_TAGGED):        /* make-tagged-value */
+	  if (is_vector(car(sc->args)))
+	       Error_0(sc, "cannot tag vector");
+          s_return(sc, mk_tagged_value(sc, car(sc->args),
+				       car(cadr(sc->args)),
+				       cdr(cadr(sc->args))));
+
+     CASE(OP_GET_TAG):        /* get-tag */
+	  s_return(sc, get_tag(sc, car(sc->args)));
+
+     CASE(OP_QUIT):       /* quit */
+          if(is_pair(sc->args)) {
+               sc->retcode=ivalue(car(sc->args));
+          }
+          return;
+
+     CASE(OP_GC):         /* gc */
+          gc(sc, sc->NIL, sc->NIL);
+          s_return(sc,sc->T);
+
+     CASE(OP_GCVERB):          /* gc-verbose */
+     {    int  was = sc->gc_verbose;
+
+          sc->gc_verbose = (car(sc->args) != sc->F);
+          s_retbool(was);
+     }
+
+     CASE(OP_NEWSEGMENT): /* new-segment */
+          if (!is_pair(sc->args) || !is_number(car(sc->args))) {
+               Error_0(sc,"new-segment: argument must be a number");
+          }
+          alloc_cellseg(sc, (int) ivalue(car(sc->args)));
+          s_return(sc,sc->T);
+
+     CASE(OP_OBLIST): /* oblist */
+          s_return(sc, oblist_all_symbols(sc));
+
+     CASE(OP_CURR_INPORT): /* current-input-port */
+          s_return(sc,sc->inport);
+
+     CASE(OP_CURR_OUTPORT): /* current-output-port */
+          s_return(sc,sc->outport);
+
+     CASE(OP_OPEN_INFILE): /* open-input-file */
+	  /* Fallthrough.  */
+     CASE(OP_OPEN_OUTFILE): /* open-output-file */
+	  /* Fallthrough.  */
+     CASE(OP_OPEN_INOUTFILE): /* open-input-output-file */ {
+          int prop=0;
+          pointer p;
+          switch(op) {
+               case OP_OPEN_INFILE:     prop=port_input; break;
+               case OP_OPEN_OUTFILE:    prop=port_output; break;
+               case OP_OPEN_INOUTFILE: prop=port_input|port_output; break;
+               default: assert (! "reached");
+          }
+          p=port_from_filename(sc,strvalue(car(sc->args)),prop);
+          if(p==sc->NIL) {
+               s_return(sc,sc->F);
+          }
+          s_return(sc,p);
+	  break;
+     }
+
+#if USE_STRING_PORTS
+     CASE(OP_OPEN_INSTRING): /* open-input-string */
+	  /* Fallthrough.  */
+     CASE(OP_OPEN_INOUTSTRING): /* open-input-output-string */ {
+          int prop=0;
+          pointer p;
+          switch(op) {
+               case OP_OPEN_INSTRING:     prop=port_input; break;
+               case OP_OPEN_INOUTSTRING:  prop=port_input|port_output; break;
+               default: assert (! "reached");
+          }
+          p=port_from_string(sc, strvalue(car(sc->args)),
+                 strvalue(car(sc->args))+strlength(car(sc->args)), prop);
+          if(p==sc->NIL) {
+               s_return(sc,sc->F);
+          }
+          s_return(sc,p);
+     }
+     CASE(OP_OPEN_OUTSTRING): /* open-output-string */ {
+          pointer p;
+          if(car(sc->args)==sc->NIL) {
+               p=port_from_scratch(sc);
+               if(p==sc->NIL) {
+                    s_return(sc,sc->F);
+               }
+          } else {
+               p=port_from_string(sc, strvalue(car(sc->args)),
+                      strvalue(car(sc->args))+strlength(car(sc->args)),
+                          port_output);
+               if(p==sc->NIL) {
+                    s_return(sc,sc->F);
+               }
+          }
+          s_return(sc,p);
+     }
+     CASE(OP_GET_OUTSTRING): /* get-output-string */ {
+          port *p;
+
+          if ((p=car(sc->args)->_object._port)->kind&port_string) {
+	       gc_disable(sc, 1);
+	       s_return_enable_gc(
+		    sc,
+		    mk_counted_string(sc,
+				      p->rep.string.start,
+				      p->rep.string.curr - p->rep.string.start));
+          }
+          s_return(sc,sc->F);
+     }
+#endif
+
+     CASE(OP_CLOSE_INPORT): /* close-input-port */
+          port_close(sc,car(sc->args),port_input);
+          s_return(sc,sc->T);
+
+     CASE(OP_CLOSE_OUTPORT): /* close-output-port */
+          port_close(sc,car(sc->args),port_output);
+          s_return(sc,sc->T);
+
+     CASE(OP_INT_ENV): /* interaction-environment */
+          s_return(sc,sc->global_env);
+
+     CASE(OP_CURR_ENV): /* current-environment */
+          s_return(sc,sc->envir);
+
+
+     /* ========== reading part ========== */
+     CASE(OP_READ):
+          if(!is_pair(sc->args)) {
+               s_thread_to(sc,OP_READ_INTERNAL);
+          }
+          if(!is_inport(car(sc->args))) {
+               Error_1(sc, "read: not an input port", car(sc->args));
+          }
+          if(car(sc->args)==sc->inport) {
+               s_thread_to(sc,OP_READ_INTERNAL);
+          }
+          x=sc->inport;
+          sc->inport=car(sc->args);
+          x=cons(sc,x,sc->NIL);
+          s_save(sc,OP_SET_INPORT, x, sc->NIL);
+          s_thread_to(sc,OP_READ_INTERNAL);
+
+     CASE(OP_READ_CHAR): /* read-char */
+	  /* Fallthrough.  */
+     CASE(OP_PEEK_CHAR): /* peek-char */ {
+          int c;
+          if(is_pair(sc->args)) {
+               if(car(sc->args)!=sc->inport) {
+                    x=sc->inport;
+                    x=cons(sc,x,sc->NIL);
+                    s_save(sc,OP_SET_INPORT, x, sc->NIL);
+                    sc->inport=car(sc->args);
+               }
+          }
+          c=inchar(sc);
+          if(c==EOF) {
+               s_return(sc,sc->EOF_OBJ);
+          }
+          if(op==OP_PEEK_CHAR) {
+               backchar(sc,c);
+          }
+          s_return(sc,mk_character(sc,c));
+     }
+
+     CASE(OP_CHAR_READY): /* char-ready? */ {
+          pointer p=sc->inport;
+          int res;
+          if(is_pair(sc->args)) {
+               p=car(sc->args);
+          }
+          res=p->_object._port->kind&port_string;
+          s_retbool(res);
+     }
+
+     CASE(OP_SET_INPORT): /* set-input-port */
+          sc->inport=car(sc->args);
+          s_return(sc,sc->value);
+
+     CASE(OP_SET_OUTPORT): /* set-output-port */
+          sc->outport=car(sc->args);
+          s_return(sc,sc->value);
+
+     CASE(OP_RDSEXPR):
+          switch (sc->tok) {
+          case TOK_EOF:
+               s_return(sc,sc->EOF_OBJ);
+          /* NOTREACHED */
+          case TOK_VEC:
+               s_save(sc,OP_RDVEC,sc->NIL,sc->NIL);
+               /* fall through */
+          case TOK_LPAREN:
+               sc->tok = token(sc);
+               if (sc->tok == TOK_RPAREN) {
+                    s_return(sc,sc->NIL);
+               } else if (sc->tok == TOK_DOT) {
+                    Error_0(sc,"syntax error: illegal dot expression");
+               } else {
+#if SHOW_ERROR_LINE
+		    pointer filename;
+		    pointer lineno;
+#endif
+                    sc->nesting_stack[sc->file_i]++;
+#if SHOW_ERROR_LINE
+		    filename = sc->load_stack[sc->file_i].filename;
+		    lineno = sc->load_stack[sc->file_i].curr_line;
+
+		    s_save(sc, OP_TAG_VALUE,
+			   cons(sc, filename, cons(sc, lineno, sc->NIL)),
+			   sc->NIL);
+#endif
+                    s_save(sc,OP_RDLIST, sc->NIL, sc->NIL);
+                    s_thread_to(sc,OP_RDSEXPR);
+               }
+          case TOK_QUOTE:
+               s_save(sc,OP_RDQUOTE, sc->NIL, sc->NIL);
+               sc->tok = token(sc);
+               s_thread_to(sc,OP_RDSEXPR);
+          case TOK_BQUOTE:
+               sc->tok = token(sc);
+               if(sc->tok==TOK_VEC) {
+                 s_save(sc,OP_RDQQUOTEVEC, sc->NIL, sc->NIL);
+                 sc->tok=TOK_LPAREN;
+                 s_thread_to(sc,OP_RDSEXPR);
+               } else {
+                 s_save(sc,OP_RDQQUOTE, sc->NIL, sc->NIL);
+               }
+               s_thread_to(sc,OP_RDSEXPR);
+          case TOK_COMMA:
+               s_save(sc,OP_RDUNQUOTE, sc->NIL, sc->NIL);
+               sc->tok = token(sc);
+               s_thread_to(sc,OP_RDSEXPR);
+          case TOK_ATMARK:
+               s_save(sc,OP_RDUQTSP, sc->NIL, sc->NIL);
+               sc->tok = token(sc);
+               s_thread_to(sc,OP_RDSEXPR);
+          case TOK_ATOM:
+               s_return(sc,mk_atom(sc, readstr_upto(sc, DELIMITERS)));
+          case TOK_DQUOTE:
+               x=readstrexp(sc);
+               if(x==sc->F) {
+                 Error_0(sc,"Error reading string");
+               }
+               setimmutable(x);
+               s_return(sc,x);
+          case TOK_SHARP: {
+               pointer f=find_slot_in_env(sc,sc->envir,sc->SHARP_HOOK,1);
+               if(f==sc->NIL) {
+                    Error_0(sc,"undefined sharp expression");
+               } else {
+                    sc->code=cons(sc,slot_value_in_env(f),sc->NIL);
+                    s_thread_to(sc,OP_EVAL);
+               }
+          }
+          case TOK_SHARP_CONST:
+               if ((x = mk_sharp_const(sc, readstr_upto(sc, DELIMITERS))) == sc->NIL) {
+                    Error_0(sc,"undefined sharp expression");
+               } else {
+                    s_return(sc,x);
+               }
+          default:
+               Error_0(sc,"syntax error: illegal token");
+          }
+          break;
+
+     CASE(OP_RDLIST): {
+	  gc_disable(sc, 1);
+          sc->args = cons(sc, sc->value, sc->args);
+	  gc_enable(sc);
+          sc->tok = token(sc);
+          if (sc->tok == TOK_EOF)
+               { s_return(sc,sc->EOF_OBJ); }
+          else if (sc->tok == TOK_RPAREN) {
+               int c = inchar(sc);
+               if (c != '\n')
+                 backchar(sc,c);
+	       else
+		 port_increment_current_line(sc, &sc->load_stack[sc->file_i], 1);
+               sc->nesting_stack[sc->file_i]--;
+               s_return(sc,reverse_in_place(sc, sc->NIL, sc->args));
+          } else if (sc->tok == TOK_DOT) {
+               s_save(sc,OP_RDDOT, sc->args, sc->NIL);
+               sc->tok = token(sc);
+               s_thread_to(sc,OP_RDSEXPR);
+          } else {
+               s_save(sc,OP_RDLIST, sc->args, sc->NIL);;
+               s_thread_to(sc,OP_RDSEXPR);
+          }
+     }
+
+     CASE(OP_RDDOT):
+          if (token(sc) != TOK_RPAREN) {
+               Error_0(sc,"syntax error: illegal dot expression");
+          } else {
+               sc->nesting_stack[sc->file_i]--;
+               s_return(sc,reverse_in_place(sc, sc->value, sc->args));
+          }
+
+     CASE(OP_RDQUOTE):
+	  gc_disable(sc, 2);
+          s_return_enable_gc(sc, cons(sc, sc->QUOTE,
+				      cons(sc, sc->value, sc->NIL)));
+
+     CASE(OP_RDQQUOTE):
+	  gc_disable(sc, 2);
+          s_return_enable_gc(sc, cons(sc, sc->QQUOTE,
+				      cons(sc, sc->value, sc->NIL)));
+
+     CASE(OP_RDQQUOTEVEC):
+	  gc_disable(sc, 5 + 2 * gc_reservations (mk_symbol));
+	  s_return_enable_gc(sc,cons(sc, mk_symbol(sc,"apply"),
+           cons(sc, mk_symbol(sc,"vector"),
+                 cons(sc,cons(sc, sc->QQUOTE,
+                  cons(sc,sc->value,sc->NIL)),
+                  sc->NIL))));
+
+     CASE(OP_RDUNQUOTE):
+	  gc_disable(sc, 2);
+          s_return_enable_gc(sc, cons(sc, sc->UNQUOTE,
+				      cons(sc, sc->value, sc->NIL)));
+
+     CASE(OP_RDUQTSP):
+	  gc_disable(sc, 2);
+          s_return_enable_gc(sc, cons(sc, sc->UNQUOTESP,
+				      cons(sc, sc->value, sc->NIL)));
+
+     CASE(OP_RDVEC):
+          /*sc->code=cons(sc,mk_proc(sc,OP_VECTOR),sc->value);
+          s_thread_to(sc,OP_EVAL); Cannot be quoted*/
+          /*x=cons(sc,mk_proc(sc,OP_VECTOR),sc->value);
+          s_return(sc,x); Cannot be part of pairs*/
+          /*sc->code=mk_proc(sc,OP_VECTOR);
+          sc->args=sc->value;
+          s_thread_to(sc,OP_APPLY);*/
+          sc->args=sc->value;
+          s_thread_to(sc,OP_VECTOR);
+
+     /* ========== printing part ========== */
+     CASE(OP_P0LIST):
+          if(is_vector(sc->args)) {
+               putstr(sc,"#(");
+               sc->args=cons(sc,sc->args,mk_integer(sc,0));
+               s_thread_to(sc,OP_PVECFROM);
+          } else if(is_environment(sc->args)) {
+               putstr(sc,"#<ENVIRONMENT>");
+               s_return(sc,sc->T);
+          } else if (!is_pair(sc->args)) {
+               printatom(sc, sc->args, sc->print_flag);
+               s_return(sc,sc->T);
+          } else if (car(sc->args) == sc->QUOTE && ok_abbrev(cdr(sc->args))) {
+               putstr(sc, "'");
+               sc->args = cadr(sc->args);
+               s_thread_to(sc,OP_P0LIST);
+          } else if (car(sc->args) == sc->QQUOTE && ok_abbrev(cdr(sc->args))) {
+               putstr(sc, "`");
+               sc->args = cadr(sc->args);
+               s_thread_to(sc,OP_P0LIST);
+          } else if (car(sc->args) == sc->UNQUOTE && ok_abbrev(cdr(sc->args))) {
+               putstr(sc, ",");
+               sc->args = cadr(sc->args);
+               s_thread_to(sc,OP_P0LIST);
+          } else if (car(sc->args) == sc->UNQUOTESP && ok_abbrev(cdr(sc->args))) {
+               putstr(sc, ",@");
+               sc->args = cadr(sc->args);
+               s_thread_to(sc,OP_P0LIST);
+          } else {
+               putstr(sc, "(");
+               s_save(sc,OP_P1LIST, cdr(sc->args), sc->NIL);
+               sc->args = car(sc->args);
+               s_thread_to(sc,OP_P0LIST);
+          }
+
+     CASE(OP_P1LIST):
+          if (is_pair(sc->args)) {
+            s_save(sc,OP_P1LIST, cdr(sc->args), sc->NIL);
+            putstr(sc, " ");
+            sc->args = car(sc->args);
+            s_thread_to(sc,OP_P0LIST);
+          } else if(is_vector(sc->args)) {
+            s_save(sc,OP_P1LIST,sc->NIL,sc->NIL);
+            putstr(sc, " . ");
+            s_thread_to(sc,OP_P0LIST);
+          } else {
+            if (sc->args != sc->NIL) {
+              putstr(sc, " . ");
+              printatom(sc, sc->args, sc->print_flag);
+            }
+            putstr(sc, ")");
+            s_return(sc,sc->T);
+          }
+     CASE(OP_PVECFROM): {
+          int i=ivalue_unchecked(cdr(sc->args));
+          pointer vec=car(sc->args);
+          int len = vector_length(vec);
+          if(i==len) {
+               putstr(sc,")");
+               s_return(sc,sc->T);
+          } else {
+               pointer elem=vector_elem(vec,i);
+               cdr(sc->args) = mk_integer(sc, i + 1);
+               s_save(sc,OP_PVECFROM, sc->args, sc->NIL);
+               sc->args=elem;
+               if (i > 0)
+                   putstr(sc," ");
+               s_thread_to(sc,OP_P0LIST);
+          }
+     }
+
+     CASE(OP_LIST_LENGTH): {   /* length */   /* a.k */
+	  long l = list_length(sc, car(sc->args));
+          if(l<0) {
+               Error_1(sc, "length: not a list", car(sc->args));
+          }
+	  gc_disable(sc, 1);
+          s_return_enable_gc(sc, mk_integer(sc, l));
+     }
+     CASE(OP_ASSQ):       /* assq */     /* a.k */
+          x = car(sc->args);
+          for (y = cadr(sc->args); is_pair(y); y = cdr(y)) {
+               if (!is_pair(car(y))) {
+                    Error_0(sc,"unable to handle non pair element");
+               }
+               if (x == caar(y))
+                    break;
+          }
+          if (is_pair(y)) {
+               s_return(sc,car(y));
+          } else {
+               s_return(sc,sc->F);
+          }
+
+
+     CASE(OP_GET_CLOSURE):     /* get-closure-code */   /* a.k */
+          sc->args = car(sc->args);
+          if (sc->args == sc->NIL) {
+               s_return(sc,sc->F);
+          } else if (is_closure(sc->args)) {
+	       gc_disable(sc, 1);
+               s_return_enable_gc(sc, cons(sc, sc->LAMBDA,
+					   closure_code(sc->value)));
+          } else if (is_macro(sc->args)) {
+	       gc_disable(sc, 1);
+               s_return_enable_gc(sc, cons(sc, sc->LAMBDA,
+					   closure_code(sc->value)));
+          } else {
+               s_return(sc,sc->F);
+          }
+     CASE(OP_CLOSUREP):        /* closure? */
+          /*
+           * Note, macro object is also a closure.
+           * Therefore, (closure? <#MACRO>) ==> #t
+           */
+          s_retbool(is_closure(car(sc->args)));
+     CASE(OP_MACROP):          /* macro? */
+          s_retbool(is_macro(car(sc->args)));
+     CASE(OP_VM_HISTORY):          /* *vm-history* */
+          s_return(sc, history_flatten(sc));
+     default:
+          snprintf(sc->strbuff,STRBUFFSIZE,"%d: illegal operator", op);
+          Error_0(sc,sc->strbuff);
+     }
+  }
+}
+
+typedef int (*test_predicate)(pointer);
+
+static int is_any(pointer p) {
+   (void)p;
+   return 1;
+}
+
+static int is_nonneg(pointer p) {
+  return ivalue(p)>=0 && is_integer(p);
+}
+
+/* Correspond carefully with following defines! */
+static const struct {
+  test_predicate fct;
+  const char *kind;
+} tests[]={
+  {0,0}, /* unused */
+  {is_any, 0},
+  {is_string, "string"},
+  {is_symbol, "symbol"},
+  {is_port, "port"},
+  {is_inport,"input port"},
+  {is_outport,"output port"},
+  {is_environment, "environment"},
+  {is_pair, "pair"},
+  {0, "pair or '()"},
+  {is_character, "character"},
+  {is_vector, "vector"},
+  {is_number, "number"},
+  {is_integer, "integer"},
+  {is_nonneg, "non-negative integer"}
+};
+
+#define TST_NONE 0
+#define TST_ANY "\001"
+#define TST_STRING "\002"
+#define TST_SYMBOL "\003"
+#define TST_PORT "\004"
+#define TST_INPORT "\005"
+#define TST_OUTPORT "\006"
+#define TST_ENVIRONMENT "\007"
+#define TST_PAIR "\010"
+#define TST_LIST "\011"
+#define TST_CHAR "\012"
+#define TST_VECTOR "\013"
+#define TST_NUMBER "\014"
+#define TST_INTEGER "\015"
+#define TST_NATURAL "\016"
+
+#define INF_ARG 0xff
+
+static const struct op_code_info dispatch_table[]= {
+#define _OP_DEF(A,B,C,D,OP) {{A},B,C,{D}},
+#include "opdefines.h"
+#undef _OP_DEF
+  {{0},0,0,{0}},
+};
+
+static const char *procname(pointer x) {
+ int n=procnum(x);
+ const char *name=dispatch_table[n].name;
+ if (name[0] == 0) {
+     name="ILLEGAL!";
+ }
+ return name;
+}
+
+static int
+check_arguments (scheme *sc, const struct op_code_info *pcd, char *msg, size_t msg_size)
+{
+  int ok = 1;
+  int n = list_length(sc, sc->args);
+
+  /* Check number of arguments */
+  if (n < pcd->min_arity) {
+    ok = 0;
+    snprintf(msg, msg_size, "%s: needs%s %d argument(s)",
+	     pcd->name,
+	     pcd->min_arity == pcd->max_arity ? "" : " at least",
+	     pcd->min_arity);
+  }
+  if (ok && n>pcd->max_arity) {
+    ok = 0;
+    snprintf(msg, msg_size, "%s: needs%s %d argument(s)",
+	     pcd->name,
+	     pcd->min_arity == pcd->max_arity ? "" : " at most",
+	     pcd->max_arity);
+  }
+  if (ok) {
+    if (pcd->arg_tests_encoding[0] != 0) {
+      int i = 0;
+      int j;
+      const char *t = pcd->arg_tests_encoding;
+      pointer arglist = sc->args;
+
+      do {
+	pointer arg = car(arglist);
+	j = (int)t[0];
+	if (j == TST_LIST[0]) {
+	  if (arg != sc->NIL && !is_pair(arg)) break;
+	} else {
+	  if (!tests[j].fct(arg)) break;
+	}
+
+	if (t[1] != 0 && i < sizeof pcd->arg_tests_encoding) {
+	  /* last test is replicated as necessary */
+	  t++;
+	}
+	arglist = cdr(arglist);
+	i++;
+      } while (i < n);
+
+      if (i < n) {
+	ok = 0;
+	snprintf(msg, msg_size, "%s: argument %d must be: %s, got: %s",
+		 pcd->name,
+		 i + 1,
+		 tests[j].kind,
+		 type_to_string(type(car(arglist))));
+      }
+    }
+  }
+
+  return ok;
+}
+
+/* ========== Initialization of internal keywords ========== */
+
+/* Symbols representing syntax are tagged with (OP . '()).  */
+static void assign_syntax(scheme *sc, enum scheme_opcodes op, char *name) {
+     pointer x, y;
+     pointer *slot;
+
+     x = oblist_find_by_name(sc, name, &slot);
+     assert (x == sc->NIL);
+
+     x = immutable_cons(sc, mk_string(sc, name), sc->NIL);
+     typeflag(x) = T_SYMBOL | T_SYNTAX;
+     setimmutable(car(x));
+     y = mk_tagged_value(sc, x, mk_integer(sc, op), sc->NIL);
+     free_cell(sc, x);
+     setimmutable(get_tag(sc, y));
+     *slot = immutable_cons(sc, y, *slot);
+}
+
+/* Returns the opcode for the syntax represented by P.  */
+static int syntaxnum(scheme *sc, pointer p) {
+  int op = ivalue_unchecked(car(get_tag(sc, p)));
+  assert (op < OP_MAXDEFINED);
+  return op;
+}
+
+static void assign_proc(scheme *sc, enum scheme_opcodes op, const char *name) {
+     pointer x, y;
+
+     x = mk_symbol(sc, name);
+     y = mk_proc(sc,op);
+     new_slot_in_env(sc, x, y);
+}
+
+static pointer mk_proc(scheme *sc, enum scheme_opcodes op) {
+     pointer y;
+
+     y = get_cell(sc, sc->NIL, sc->NIL);
+     typeflag(y) = (T_PROC | T_ATOM);
+     ivalue_unchecked(y) = (long) op;
+     set_num_integer(y);
+     return y;
+}
+
+/* initialization of TinyScheme */
+#if USE_INTERFACE
+INTERFACE static pointer s_cons(scheme *sc, pointer a, pointer b) {
+ return cons(sc,a,b);
+}
+INTERFACE static pointer s_immutable_cons(scheme *sc, pointer a, pointer b) {
+ return immutable_cons(sc,a,b);
+}
+
+static const struct scheme_interface vtbl = {
+  scheme_define,
+  s_cons,
+  s_immutable_cons,
+  reserve_cells,
+  mk_integer,
+  mk_real,
+  mk_symbol,
+  gensym,
+  mk_string,
+  mk_counted_string,
+  mk_character,
+  mk_vector,
+  mk_foreign_func,
+  mk_foreign_object,
+  get_foreign_object_vtable,
+  get_foreign_object_data,
+  putstr,
+  putcharacter,
+
+  is_string,
+  string_value,
+  is_number,
+  nvalue,
+  ivalue,
+  rvalue,
+  is_integer,
+  is_real,
+  is_character,
+  charvalue,
+  is_list,
+  is_vector,
+  list_length,
+  ivalue,
+  fill_vector,
+  vector_elem,
+  set_vector_elem,
+  is_port,
+  is_pair,
+  pair_car,
+  pair_cdr,
+  set_car,
+  set_cdr,
+
+  is_symbol,
+  symname,
+
+  is_syntax,
+  is_proc,
+  is_foreign,
+  syntaxname,
+  is_closure,
+  is_macro,
+  closure_code,
+  closure_env,
+
+  is_continuation,
+  is_promise,
+  is_environment,
+  is_immutable,
+  setimmutable,
+
+  scheme_load_file,
+  scheme_load_string,
+  port_from_file
+};
+#endif
+
+scheme *scheme_init_new() {
+  scheme *sc=(scheme*)malloc(sizeof(scheme));
+  if(!scheme_init(sc)) {
+    free(sc);
+    return 0;
+  } else {
+    return sc;
+  }
+}
+
+scheme *scheme_init_new_custom_alloc(func_alloc malloc, func_dealloc free) {
+  scheme *sc=(scheme*)malloc(sizeof(scheme));
+  if(!scheme_init_custom_alloc(sc,malloc,free)) {
+    free(sc);
+    return 0;
+  } else {
+    return sc;
+  }
+}
+
+
+int scheme_init(scheme *sc) {
+ return scheme_init_custom_alloc(sc,malloc,free);
+}
+
+int scheme_init_custom_alloc(scheme *sc, func_alloc malloc, func_dealloc free) {
+  int i, n=sizeof(dispatch_table)/sizeof(dispatch_table[0]);
+  pointer x;
+
+#if USE_INTERFACE
+  sc->vptr=&vtbl;
+#endif
+  sc->gensym_cnt=0;
+  sc->malloc=malloc;
+  sc->free=free;
+  sc->sink = &sc->_sink;
+  sc->NIL = &sc->_NIL;
+  sc->T = &sc->_HASHT;
+  sc->F = &sc->_HASHF;
+  sc->EOF_OBJ=&sc->_EOF_OBJ;
+
+  sc->free_cell = &sc->_NIL;
+  sc->fcells = 0;
+  sc->inhibit_gc = GC_ENABLED;
+  sc->reserved_cells = 0;
+  sc->reserved_lineno = 0;
+  sc->no_memory=0;
+  sc->inport=sc->NIL;
+  sc->outport=sc->NIL;
+  sc->save_inport=sc->NIL;
+  sc->loadport=sc->NIL;
+  sc->nesting=0;
+  memset (sc->nesting_stack, 0, sizeof sc->nesting_stack);
+  sc->interactive_repl=0;
+  sc->strbuff = sc->malloc(STRBUFFSIZE);
+  if (sc->strbuff == 0) {
+     sc->no_memory=1;
+     return 0;
+  }
+  sc->strbuff_size = STRBUFFSIZE;
+
+  sc->cell_segments = NULL;
+  if (alloc_cellseg(sc,FIRST_CELLSEGS) != FIRST_CELLSEGS) {
+    sc->no_memory=1;
+    return 0;
+  }
+  sc->gc_verbose = 0;
+  dump_stack_initialize(sc);
+  sc->code = sc->NIL;
+  sc->tracing=0;
+  sc->flags = 0;
+
+  /* init sc->NIL */
+  typeflag(sc->NIL) = (T_NIL | T_ATOM | MARK);
+  car(sc->NIL) = cdr(sc->NIL) = sc->NIL;
+  /* init T */
+  typeflag(sc->T) = (T_BOOLEAN | T_ATOM | MARK);
+  car(sc->T) = cdr(sc->T) = sc->T;
+  /* init F */
+  typeflag(sc->F) = (T_BOOLEAN | T_ATOM | MARK);
+  car(sc->F) = cdr(sc->F) = sc->F;
+  /* init EOF_OBJ */
+  typeflag(sc->EOF_OBJ) = (T_EOF_OBJ | T_ATOM | MARK);
+  car(sc->EOF_OBJ) = cdr(sc->EOF_OBJ) = sc->EOF_OBJ;
+  /* init sink */
+  typeflag(sc->sink) = (T_SINK | T_PAIR | MARK);
+  car(sc->sink) = cdr(sc->sink) = sc->NIL;
+  /* init c_nest */
+  sc->c_nest = sc->NIL;
+
+  sc->oblist = oblist_initial_value(sc);
+  /* init global_env */
+  new_frame_in_env(sc, sc->NIL);
+  sc->global_env = sc->envir;
+  /* init else */
+  x = mk_symbol(sc,"else");
+  new_slot_in_env(sc, x, sc->T);
+
+  assign_syntax(sc, OP_LAMBDA, "lambda");
+  assign_syntax(sc, OP_QUOTE, "quote");
+  assign_syntax(sc, OP_DEF0, "define");
+  assign_syntax(sc, OP_IF0, "if");
+  assign_syntax(sc, OP_BEGIN, "begin");
+  assign_syntax(sc, OP_SET0, "set!");
+  assign_syntax(sc, OP_LET0, "let");
+  assign_syntax(sc, OP_LET0AST, "let*");
+  assign_syntax(sc, OP_LET0REC, "letrec");
+  assign_syntax(sc, OP_COND0, "cond");
+  assign_syntax(sc, OP_DELAY, "delay");
+  assign_syntax(sc, OP_AND0, "and");
+  assign_syntax(sc, OP_OR0, "or");
+  assign_syntax(sc, OP_C0STREAM, "cons-stream");
+  assign_syntax(sc, OP_MACRO0, "macro");
+  assign_syntax(sc, OP_CASE0, "case");
+
+  for(i=0; i<n; i++) {
+    if (dispatch_table[i].name[0] != 0) {
+      assign_proc(sc, (enum scheme_opcodes)i, dispatch_table[i].name);
+    }
+  }
+
+  history_init(sc, 8, 8);
+
+  /* initialization of global pointers to special symbols */
+  sc->LAMBDA = mk_symbol(sc, "lambda");
+  sc->QUOTE = mk_symbol(sc, "quote");
+  sc->QQUOTE = mk_symbol(sc, "quasiquote");
+  sc->UNQUOTE = mk_symbol(sc, "unquote");
+  sc->UNQUOTESP = mk_symbol(sc, "unquote-splicing");
+  sc->FEED_TO = mk_symbol(sc, "=>");
+  sc->COLON_HOOK = mk_symbol(sc,"*colon-hook*");
+  sc->ERROR_HOOK = mk_symbol(sc, "*error-hook*");
+  sc->SHARP_HOOK = mk_symbol(sc, "*sharp-hook*");
+#if USE_COMPILE_HOOK
+  sc->COMPILE_HOOK = mk_symbol(sc, "*compile-hook*");
+#endif
+
+  return !sc->no_memory;
+}
+
+void scheme_set_input_port_file(scheme *sc, FILE *fin) {
+  sc->inport=port_from_file(sc,fin,port_input);
+}
+
+void scheme_set_input_port_string(scheme *sc, char *start, char *past_the_end) {
+  sc->inport=port_from_string(sc,start,past_the_end,port_input);
+}
+
+void scheme_set_output_port_file(scheme *sc, FILE *fout) {
+  sc->outport=port_from_file(sc,fout,port_output);
+}
+
+void scheme_set_output_port_string(scheme *sc, char *start, char *past_the_end) {
+  sc->outport=port_from_string(sc,start,past_the_end,port_output);
+}
+
+void scheme_set_external_data(scheme *sc, void *p) {
+ sc->ext_data=p;
+}
+
+void scheme_deinit(scheme *sc) {
+  struct cell_segment *s;
+  int i;
+
+  sc->oblist=sc->NIL;
+  sc->global_env=sc->NIL;
+  dump_stack_free(sc);
+  sc->envir=sc->NIL;
+  sc->code=sc->NIL;
+  history_free(sc);
+  sc->args=sc->NIL;
+  sc->value=sc->NIL;
+  if(is_port(sc->inport)) {
+    typeflag(sc->inport) = T_ATOM;
+  }
+  sc->inport=sc->NIL;
+  sc->outport=sc->NIL;
+  if(is_port(sc->save_inport)) {
+    typeflag(sc->save_inport) = T_ATOM;
+  }
+  sc->save_inport=sc->NIL;
+  if(is_port(sc->loadport)) {
+    typeflag(sc->loadport) = T_ATOM;
+  }
+  sc->loadport=sc->NIL;
+
+  for(i=0; i<=sc->file_i; i++) {
+    port_clear_location(sc, &sc->load_stack[i]);
+  }
+
+  sc->gc_verbose=0;
+  gc(sc,sc->NIL,sc->NIL);
+
+  for (s = sc->cell_segments; s; s = _dealloc_cellseg(sc, s)) {
+    /* nop */
+  }
+  sc->free(sc->strbuff);
+}
+
+void scheme_load_file(scheme *sc, FILE *fin)
+{ scheme_load_named_file(sc,fin,0); }
+
+void scheme_load_named_file(scheme *sc, FILE *fin, const char *filename) {
+  dump_stack_reset(sc);
+  sc->envir = sc->global_env;
+  sc->file_i=0;
+  sc->load_stack[0].kind=port_input|port_file;
+  sc->load_stack[0].rep.stdio.file=fin;
+  sc->loadport=mk_port(sc,sc->load_stack);
+  sc->retcode=0;
+  if(fin==stdin) {
+    sc->interactive_repl=1;
+  }
+
+  port_init_location(sc, &sc->load_stack[0],
+		     (fin != stdin && filename)
+		     ? mk_string(sc, filename)
+		     : NULL);
+
+  sc->inport=sc->loadport;
+  sc->args = mk_integer(sc,sc->file_i);
+  Eval_Cycle(sc, OP_T0LVL);
+  typeflag(sc->loadport)=T_ATOM;
+  if(sc->retcode==0) {
+    sc->retcode=sc->nesting!=0;
+  }
+
+  port_clear_location(sc, &sc->load_stack[0]);
+}
+
+void scheme_load_string(scheme *sc, const char *cmd) {
+  scheme_load_memory(sc, cmd, strlen(cmd), NULL);
+}
+
+void scheme_load_memory(scheme *sc, const char *buf, size_t len, const char *filename) {
+  dump_stack_reset(sc);
+  sc->envir = sc->global_env;
+  sc->file_i=0;
+  sc->load_stack[0].kind=port_input|port_string;
+  sc->load_stack[0].rep.string.start = (char *) buf; /* This func respects const */
+  sc->load_stack[0].rep.string.past_the_end = (char *) buf + len;
+  sc->load_stack[0].rep.string.curr = (char *) buf;
+  port_init_location(sc, &sc->load_stack[0], filename ? mk_string(sc, filename) : NULL);
+  sc->loadport=mk_port(sc,sc->load_stack);
+  sc->retcode=0;
+  sc->interactive_repl=0;
+  sc->inport=sc->loadport;
+  sc->args = mk_integer(sc,sc->file_i);
+  Eval_Cycle(sc, OP_T0LVL);
+  typeflag(sc->loadport)=T_ATOM;
+  if(sc->retcode==0) {
+    sc->retcode=sc->nesting!=0;
+  }
+
+  port_clear_location(sc, &sc->load_stack[0]);
+}
+
+void scheme_define(scheme *sc, pointer envir, pointer symbol, pointer value) {
+     pointer x;
+     pointer *sslot;
+     x = find_slot_spec_in_env(sc, envir, symbol, 0, &sslot);
+     if (x != sc->NIL) {
+          set_slot_in_env(sc, x, value);
+     } else {
+          new_slot_spec_in_env(sc, symbol, value, sslot);
+     }
+}
+
+#if !STANDALONE
+void scheme_register_foreign_func(scheme * sc, scheme_registerable * sr)
+{
+  scheme_define(sc,
+                sc->global_env,
+                mk_symbol(sc,sr->name),
+                mk_foreign_func(sc, sr->f));
+}
+
+void scheme_register_foreign_func_list(scheme * sc,
+                                       scheme_registerable * list,
+                                       int count)
+{
+  int i;
+  for(i = 0; i < count; i++)
+    {
+      scheme_register_foreign_func(sc, list + i);
+    }
+}
+
+pointer scheme_apply0(scheme *sc, const char *procname)
+{ return scheme_eval(sc, cons(sc,mk_symbol(sc,procname),sc->NIL)); }
+
+void save_from_C_call(scheme *sc)
+{
+  pointer saved_data =
+    cons(sc,
+         car(sc->sink),
+         cons(sc,
+              sc->envir,
+              sc->dump));
+  /* Push */
+  sc->c_nest = cons(sc, saved_data, sc->c_nest);
+  /* Truncate the dump stack so TS will return here when done, not
+     directly resume pre-C-call operations. */
+  dump_stack_reset(sc);
+}
+void restore_from_C_call(scheme *sc)
+{
+  car(sc->sink) = caar(sc->c_nest);
+  sc->envir = cadar(sc->c_nest);
+  sc->dump = cdr(cdar(sc->c_nest));
+  /* Pop */
+  sc->c_nest = cdr(sc->c_nest);
+}
+
+/* "func" and "args" are assumed to be already eval'ed. */
+pointer scheme_call(scheme *sc, pointer func, pointer args)
+{
+  int old_repl = sc->interactive_repl;
+  sc->interactive_repl = 0;
+  save_from_C_call(sc);
+  sc->envir = sc->global_env;
+  sc->args = args;
+  sc->code = func;
+  sc->retcode = 0;
+  Eval_Cycle(sc, OP_APPLY);
+  sc->interactive_repl = old_repl;
+  restore_from_C_call(sc);
+  return sc->value;
+}
+
+pointer scheme_eval(scheme *sc, pointer obj)
+{
+  int old_repl = sc->interactive_repl;
+  sc->interactive_repl = 0;
+  save_from_C_call(sc);
+  sc->args = sc->NIL;
+  sc->code = obj;
+  sc->retcode = 0;
+  Eval_Cycle(sc, OP_EVAL);
+  sc->interactive_repl = old_repl;
+  restore_from_C_call(sc);
+  return sc->value;
+}
+
+
+#endif
+
+/* ========== Main ========== */
+
+#if STANDALONE
+
+#if defined(__APPLE__) && !defined (OSX)
+int main()
+{
+     extern MacTS_main(int argc, char **argv);
+     char**    argv;
+     int argc = ccommand(&argv);
+     MacTS_main(argc,argv);
+     return 0;
+}
+int MacTS_main(int argc, char **argv) {
+#else
+int main(int argc, char **argv) {
+#endif
+  scheme sc;
+  FILE *fin;
+  char *file_name=InitFile;
+  int retcode;
+  int isfile=1;
+
+  if(argc==1) {
+    printf(banner);
+  }
+  if(argc==2 && strcmp(argv[1],"-?")==0) {
+    printf("Usage: tinyscheme -?\n");
+    printf("or:    tinyscheme [<file1> <file2> ...]\n");
+    printf("followed by\n");
+    printf("          -1 <file> [<arg1> <arg2> ...]\n");
+    printf("          -c <Scheme commands> [<arg1> <arg2> ...]\n");
+    printf("assuming that the executable is named tinyscheme.\n");
+    printf("Use - as filename for stdin.\n");
+    return 1;
+  }
+  if(!scheme_init(&sc)) {
+    fprintf(stderr,"Could not initialize!\n");
+    return 2;
+  }
+  scheme_set_input_port_file(&sc, stdin);
+  scheme_set_output_port_file(&sc, stdout);
+#if USE_DL
+  scheme_define(&sc,sc.global_env,mk_symbol(&sc,"load-extension"),mk_foreign_func(&sc, scm_load_ext));
+#endif
+  argv++;
+  if(access(file_name,0)!=0) {
+    char *p=getenv("TINYSCHEMEINIT");
+    if(p!=0) {
+      file_name=p;
+    }
+  }
+  do {
+    if(strcmp(file_name,"-")==0) {
+      fin=stdin;
+    } else if(strcmp(file_name,"-1")==0 || strcmp(file_name,"-c")==0) {
+      pointer args=sc.NIL;
+      isfile=file_name[1]=='1';
+      file_name=*argv++;
+      if(strcmp(file_name,"-")==0) {
+        fin=stdin;
+      } else if(isfile) {
+        fin=fopen(file_name,"r");
+      }
+      for(;*argv;argv++) {
+        pointer value=mk_string(&sc,*argv);
+        args=cons(&sc,value,args);
+      }
+      args=reverse_in_place(&sc,sc.NIL,args);
+      scheme_define(&sc,sc.global_env,mk_symbol(&sc,"*args*"),args);
+
+    } else {
+      fin=fopen(file_name,"r");
+    }
+    if(isfile && fin==0) {
+      fprintf(stderr,"Could not open file %s\n",file_name);
+    } else {
+      if(isfile) {
+        scheme_load_named_file(&sc,fin,file_name);
+      } else {
+        scheme_load_string(&sc,file_name);
+      }
+      if(!isfile || fin!=stdin) {
+        if(sc.retcode!=0) {
+          fprintf(stderr,"Errors encountered reading %s\n",file_name);
+        }
+        if(isfile) {
+          fclose(fin);
+        }
+      }
+    }
+    file_name=*argv++;
+  } while(file_name!=0);
+  if(argc==1) {
+    scheme_load_named_file(&sc,stdin,0);
+  }
+  retcode=sc.retcode;
+  scheme_deinit(&sc);
+
+  return retcode;
+}
+
+#endif
+
+/*
+Local variables:
+c-file-style: "k&r"
+End:
+*/
diff --git a/gpgscm/scheme.h b/gpgscm/scheme.h
new file mode 100644
index 0000000..6f917da
--- /dev/null
+++ b/gpgscm/scheme.h
@@ -0,0 +1,290 @@
+/* SCHEME.H */
+
+#ifndef _SCHEME_H
+#define _SCHEME_H
+
+#include <stdio.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+ * Default values for #define'd symbols
+ */
+#ifndef STANDALONE       /* If used as standalone interpreter */
+# define STANDALONE 1
+#endif
+
+#ifndef _MSC_VER
+# define USE_STRCASECMP 1
+# ifndef USE_STRLWR
+#   define USE_STRLWR 1
+# endif
+# define SCHEME_EXPORT
+#else
+# define USE_STRCASECMP 0
+# define USE_STRLWR 0
+# ifdef _SCHEME_SOURCE
+#  define SCHEME_EXPORT __declspec(dllexport)
+# else
+#  define SCHEME_EXPORT __declspec(dllimport)
+# endif
+#endif
+
+#if USE_NO_FEATURES
+# define USE_MATH 0
+# define USE_CHAR_CLASSIFIERS 0
+# define USE_ASCII_NAMES 0
+# define USE_STRING_PORTS 0
+# define USE_ERROR_HOOK 0
+# define USE_TRACING 0
+# define USE_COLON_HOOK 0
+# define USE_COMPILE_HOOK 0
+# define USE_DL 0
+# define USE_PLIST 0
+# define USE_SMALL_INTEGERS 0
+# define USE_HISTORY 0
+#endif
+
+
+#if USE_DL
+# define USE_INTERFACE 1
+#endif
+
+
+#ifndef USE_MATH         /* If math support is needed */
+# define USE_MATH 1
+#endif
+
+#ifndef USE_CHAR_CLASSIFIERS  /* If char classifiers are needed */
+# define USE_CHAR_CLASSIFIERS 1
+#endif
+
+#ifndef USE_ASCII_NAMES  /* If extended escaped characters are needed */
+# define USE_ASCII_NAMES 1
+#endif
+
+#ifndef USE_STRING_PORTS      /* Enable string ports */
+# define USE_STRING_PORTS 1
+#endif
+
+#ifndef USE_TRACING
+# define USE_TRACING 1
+#endif
+
+#ifndef USE_PLIST
+# define USE_PLIST 0
+#endif
+
+/* Keep a history of function calls.  This enables a feature similar
+ * to stack traces.  */
+#ifndef USE_HISTORY
+# define USE_HISTORY 1
+#endif
+
+/* To force system errors through user-defined error handling (see *error-hook*) */
+#ifndef USE_ERROR_HOOK
+# define USE_ERROR_HOOK 1
+#endif
+
+#ifndef USE_COLON_HOOK   /* Enable qualified qualifier */
+# define USE_COLON_HOOK 1
+#endif
+
+/* Compile functions using *compile-hook*.  The default hook expands
+ * macros.  */
+#ifndef USE_COMPILE_HOOK
+# define USE_COMPILE_HOOK 1
+#endif
+
+/* Enable faster opcode dispatch.  */
+#ifndef USE_THREADED_CODE
+# define USE_THREADED_CODE 1
+#endif
+
+/* Use a static set of cells to represent small numbers.  This set
+ * notably includes all opcodes, and hence saves a cell reservation
+ * during 's_save'.  */
+#ifndef USE_SMALL_INTEGERS
+# define USE_SMALL_INTEGERS 1
+#endif
+
+#ifndef USE_STRCASECMP   /* stricmp for Unix */
+# define USE_STRCASECMP 0
+#endif
+
+#ifndef USE_STRLWR
+# define USE_STRLWR 1
+#endif
+
+#ifndef STDIO_ADDS_CR    /* Define if DOS/Windows */
+# define STDIO_ADDS_CR 0
+#endif
+
+#ifndef INLINE
+# define INLINE
+#endif
+
+#ifndef USE_INTERFACE
+# define USE_INTERFACE 0
+#endif
+
+#ifndef SHOW_ERROR_LINE   /* Show error line in file */
+# define SHOW_ERROR_LINE 1
+#endif
+
+typedef struct scheme scheme;
+typedef struct cell *pointer;
+
+typedef void * (*func_alloc)(size_t);
+typedef void (*func_dealloc)(void *);
+
+/* table of functions required for foreign objects */
+typedef struct foreign_object_vtable {
+     void (*finalize)(scheme *sc, void *data);
+     void (*to_string)(scheme *sc, char *out, size_t size, void *data);
+} foreign_object_vtable;
+
+/* num, for generic arithmetic */
+typedef struct num {
+     char is_fixnum;
+     union {
+          long ivalue;
+          double rvalue;
+     } value;
+} num;
+
+SCHEME_EXPORT scheme *scheme_init_new(void);
+SCHEME_EXPORT scheme *scheme_init_new_custom_alloc(func_alloc malloc, func_dealloc free);
+SCHEME_EXPORT int scheme_init(scheme *sc);
+SCHEME_EXPORT int scheme_init_custom_alloc(scheme *sc, func_alloc, func_dealloc);
+SCHEME_EXPORT void scheme_deinit(scheme *sc);
+void scheme_set_input_port_file(scheme *sc, FILE *fin);
+void scheme_set_input_port_string(scheme *sc, char *start, char *past_the_end);
+SCHEME_EXPORT void scheme_set_output_port_file(scheme *sc, FILE *fin);
+void scheme_set_output_port_string(scheme *sc, char *start, char *past_the_end);
+SCHEME_EXPORT void scheme_load_file(scheme *sc, FILE *fin);
+SCHEME_EXPORT void scheme_load_named_file(scheme *sc, FILE *fin, const char *filename);
+SCHEME_EXPORT void scheme_load_string(scheme *sc, const char *cmd);
+SCHEME_EXPORT void scheme_load_memory(scheme *sc, const char *buf, size_t len,
+                                      const char *filename);
+SCHEME_EXPORT pointer scheme_apply0(scheme *sc, const char *procname);
+SCHEME_EXPORT pointer scheme_call(scheme *sc, pointer func, pointer args);
+SCHEME_EXPORT pointer scheme_eval(scheme *sc, pointer obj);
+void scheme_set_external_data(scheme *sc, void *p);
+SCHEME_EXPORT void scheme_define(scheme *sc, pointer env, pointer symbol, pointer value);
+
+typedef pointer (*foreign_func)(scheme *, pointer);
+
+pointer _cons(scheme *sc, pointer a, pointer b, int immutable);
+pointer mk_integer(scheme *sc, long num);
+pointer mk_real(scheme *sc, double num);
+pointer mk_symbol(scheme *sc, const char *name);
+pointer gensym(scheme *sc);
+pointer mk_string(scheme *sc, const char *str);
+pointer mk_counted_string(scheme *sc, const char *str, int len);
+pointer mk_empty_string(scheme *sc, int len, char fill);
+pointer mk_character(scheme *sc, int c);
+pointer mk_foreign_func(scheme *sc, foreign_func f);
+pointer mk_foreign_object(scheme *sc, const foreign_object_vtable *vtable, void *data);
+void putstr(scheme *sc, const char *s);
+int list_length(scheme *sc, pointer a);
+int eqv(pointer a, pointer b);
+
+
+#if USE_INTERFACE
+struct scheme_interface {
+  void (*scheme_define)(scheme *sc, pointer env, pointer symbol, pointer value);
+  pointer (*cons)(scheme *sc, pointer a, pointer b);
+  pointer (*immutable_cons)(scheme *sc, pointer a, pointer b);
+  pointer (*reserve_cells)(scheme *sc, int n);
+  pointer (*mk_integer)(scheme *sc, long num);
+  pointer (*mk_real)(scheme *sc, double num);
+  pointer (*mk_symbol)(scheme *sc, const char *name);
+  pointer (*gensym)(scheme *sc);
+  pointer (*mk_string)(scheme *sc, const char *str);
+  pointer (*mk_counted_string)(scheme *sc, const char *str, int len);
+  pointer (*mk_character)(scheme *sc, int c);
+  pointer (*mk_vector)(scheme *sc, int len);
+  pointer (*mk_foreign_func)(scheme *sc, foreign_func f);
+  pointer (*mk_foreign_object)(scheme *sc, const foreign_object_vtable *vtable, void *data);
+  const foreign_object_vtable *(*get_foreign_object_vtable)(pointer p);
+  void *(*get_foreign_object_data)(pointer p);
+  void (*putstr)(scheme *sc, const char *s);
+  void (*putcharacter)(scheme *sc, int c);
+
+  int (*is_string)(pointer p);
+  char *(*string_value)(pointer p);
+  int (*is_number)(pointer p);
+  num (*nvalue)(pointer p);
+  long (*ivalue)(pointer p);
+  double (*rvalue)(pointer p);
+  int (*is_integer)(pointer p);
+  int (*is_real)(pointer p);
+  int (*is_character)(pointer p);
+  long (*charvalue)(pointer p);
+  int (*is_list)(scheme *sc, pointer p);
+  int (*is_vector)(pointer p);
+  int (*list_length)(scheme *sc, pointer vec);
+  long (*vector_length)(pointer vec);
+  void (*fill_vector)(pointer vec, pointer elem);
+  pointer (*vector_elem)(pointer vec, int ielem);
+  pointer (*set_vector_elem)(pointer vec, int ielem, pointer newel);
+  int (*is_port)(pointer p);
+
+  int (*is_pair)(pointer p);
+  pointer (*pair_car)(pointer p);
+  pointer (*pair_cdr)(pointer p);
+  pointer (*set_car)(pointer p, pointer q);
+  pointer (*set_cdr)(pointer p, pointer q);
+
+  int (*is_symbol)(pointer p);
+  char *(*symname)(pointer p);
+
+  int (*is_syntax)(pointer p);
+  int (*is_proc)(pointer p);
+  int (*is_foreign)(pointer p);
+  char *(*syntaxname)(pointer p);
+  int (*is_closure)(pointer p);
+  int (*is_macro)(pointer p);
+  pointer (*closure_code)(pointer p);
+  pointer (*closure_env)(pointer p);
+
+  int (*is_continuation)(pointer p);
+  int (*is_promise)(pointer p);
+  int (*is_environment)(pointer p);
+  int (*is_immutable)(pointer p);
+  void (*setimmutable)(pointer p);
+  void (*load_file)(scheme *sc, FILE *fin);
+  void (*load_string)(scheme *sc, const char *input);
+  pointer (*mk_port_from_file)(scheme *sc, FILE *f, int kind);
+};
+#endif
+
+#if !STANDALONE
+typedef struct scheme_registerable
+{
+  foreign_func  f;
+  const char *  name;
+}
+scheme_registerable;
+
+void scheme_register_foreign_func_list(scheme * sc,
+                                       scheme_registerable * list,
+                                       int n);
+
+#endif /* !STANDALONE */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+
+
+/*
+Local variables:
+c-file-style: "k&r"
+End:
+*/
diff --git a/gpgscm/small-integers.h b/gpgscm/small-integers.h
new file mode 100644
index 0000000..46eda34
--- /dev/null
+++ b/gpgscm/small-integers.h
@@ -0,0 +1,847 @@
+/* Constant integer objects for TinySCHEME.
+ *
+ * Copyright (C) 2017 g10 code GmbH
+ *
+ * This file is part of GnuPG.
+ *
+ * GnuPG is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * GnuPG is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses/>.
+ */
+
+/*
+ * Ohne Worte.  Generated using:
+ *
+ *    $ n=0; while read line ; do           \
+ *              echo "DEFINE_INTEGER($n)" ; \
+ *              n="$(expr $n + 1)" ;        \
+ *      done <./init.scm >> small-integers.h
+ */
+
+DEFINE_INTEGER(0)
+DEFINE_INTEGER(1)
+DEFINE_INTEGER(2)
+DEFINE_INTEGER(3)
+DEFINE_INTEGER(4)
+DEFINE_INTEGER(5)
+DEFINE_INTEGER(6)
+DEFINE_INTEGER(7)
+DEFINE_INTEGER(8)
+DEFINE_INTEGER(9)
+DEFINE_INTEGER(10)
+DEFINE_INTEGER(11)
+DEFINE_INTEGER(12)
+DEFINE_INTEGER(13)
+DEFINE_INTEGER(14)
+DEFINE_INTEGER(15)
+DEFINE_INTEGER(16)
+DEFINE_INTEGER(17)
+DEFINE_INTEGER(18)
+DEFINE_INTEGER(19)
+DEFINE_INTEGER(20)
+DEFINE_INTEGER(21)
+DEFINE_INTEGER(22)
+DEFINE_INTEGER(23)
+DEFINE_INTEGER(24)
+DEFINE_INTEGER(25)
+DEFINE_INTEGER(26)
+DEFINE_INTEGER(27)
+DEFINE_INTEGER(28)
+DEFINE_INTEGER(29)
+DEFINE_INTEGER(30)
+DEFINE_INTEGER(31)
+DEFINE_INTEGER(32)
+DEFINE_INTEGER(33)
+DEFINE_INTEGER(34)
+DEFINE_INTEGER(35)
+DEFINE_INTEGER(36)
+DEFINE_INTEGER(37)
+DEFINE_INTEGER(38)
+DEFINE_INTEGER(39)
+DEFINE_INTEGER(40)
+DEFINE_INTEGER(41)
+DEFINE_INTEGER(42)
+DEFINE_INTEGER(43)
+DEFINE_INTEGER(44)
+DEFINE_INTEGER(45)
+DEFINE_INTEGER(46)
+DEFINE_INTEGER(47)
+DEFINE_INTEGER(48)
+DEFINE_INTEGER(49)
+DEFINE_INTEGER(50)
+DEFINE_INTEGER(51)
+DEFINE_INTEGER(52)
+DEFINE_INTEGER(53)
+DEFINE_INTEGER(54)
+DEFINE_INTEGER(55)
+DEFINE_INTEGER(56)
+DEFINE_INTEGER(57)
+DEFINE_INTEGER(58)
+DEFINE_INTEGER(59)
+DEFINE_INTEGER(60)
+DEFINE_INTEGER(61)
+DEFINE_INTEGER(62)
+DEFINE_INTEGER(63)
+DEFINE_INTEGER(64)
+DEFINE_INTEGER(65)
+DEFINE_INTEGER(66)
+DEFINE_INTEGER(67)
+DEFINE_INTEGER(68)
+DEFINE_INTEGER(69)
+DEFINE_INTEGER(70)
+DEFINE_INTEGER(71)
+DEFINE_INTEGER(72)
+DEFINE_INTEGER(73)
+DEFINE_INTEGER(74)
+DEFINE_INTEGER(75)
+DEFINE_INTEGER(76)
+DEFINE_INTEGER(77)
+DEFINE_INTEGER(78)
+DEFINE_INTEGER(79)
+DEFINE_INTEGER(80)
+DEFINE_INTEGER(81)
+DEFINE_INTEGER(82)
+DEFINE_INTEGER(83)
+DEFINE_INTEGER(84)
+DEFINE_INTEGER(85)
+DEFINE_INTEGER(86)
+DEFINE_INTEGER(87)
+DEFINE_INTEGER(88)
+DEFINE_INTEGER(89)
+DEFINE_INTEGER(90)
+DEFINE_INTEGER(91)
+DEFINE_INTEGER(92)
+DEFINE_INTEGER(93)
+DEFINE_INTEGER(94)
+DEFINE_INTEGER(95)
+DEFINE_INTEGER(96)
+DEFINE_INTEGER(97)
+DEFINE_INTEGER(98)
+DEFINE_INTEGER(99)
+DEFINE_INTEGER(100)
+DEFINE_INTEGER(101)
+DEFINE_INTEGER(102)
+DEFINE_INTEGER(103)
+DEFINE_INTEGER(104)
+DEFINE_INTEGER(105)
+DEFINE_INTEGER(106)
+DEFINE_INTEGER(107)
+DEFINE_INTEGER(108)
+DEFINE_INTEGER(109)
+DEFINE_INTEGER(110)
+DEFINE_INTEGER(111)
+DEFINE_INTEGER(112)
+DEFINE_INTEGER(113)
+DEFINE_INTEGER(114)
+DEFINE_INTEGER(115)
+DEFINE_INTEGER(116)
+DEFINE_INTEGER(117)
+DEFINE_INTEGER(118)
+DEFINE_INTEGER(119)
+DEFINE_INTEGER(120)
+DEFINE_INTEGER(121)
+DEFINE_INTEGER(122)
+DEFINE_INTEGER(123)
+DEFINE_INTEGER(124)
+DEFINE_INTEGER(125)
+DEFINE_INTEGER(126)
+DEFINE_INTEGER(127)
+DEFINE_INTEGER(128)
+DEFINE_INTEGER(129)
+DEFINE_INTEGER(130)
+DEFINE_INTEGER(131)
+DEFINE_INTEGER(132)
+DEFINE_INTEGER(133)
+DEFINE_INTEGER(134)
+DEFINE_INTEGER(135)
+DEFINE_INTEGER(136)
+DEFINE_INTEGER(137)
+DEFINE_INTEGER(138)
+DEFINE_INTEGER(139)
+DEFINE_INTEGER(140)
+DEFINE_INTEGER(141)
+DEFINE_INTEGER(142)
+DEFINE_INTEGER(143)
+DEFINE_INTEGER(144)
+DEFINE_INTEGER(145)
+DEFINE_INTEGER(146)
+DEFINE_INTEGER(147)
+DEFINE_INTEGER(148)
+DEFINE_INTEGER(149)
+DEFINE_INTEGER(150)
+DEFINE_INTEGER(151)
+DEFINE_INTEGER(152)
+DEFINE_INTEGER(153)
+DEFINE_INTEGER(154)
+DEFINE_INTEGER(155)
+DEFINE_INTEGER(156)
+DEFINE_INTEGER(157)
+DEFINE_INTEGER(158)
+DEFINE_INTEGER(159)
+DEFINE_INTEGER(160)
+DEFINE_INTEGER(161)
+DEFINE_INTEGER(162)
+DEFINE_INTEGER(163)
+DEFINE_INTEGER(164)
+DEFINE_INTEGER(165)
+DEFINE_INTEGER(166)
+DEFINE_INTEGER(167)
+DEFINE_INTEGER(168)
+DEFINE_INTEGER(169)
+DEFINE_INTEGER(170)
+DEFINE_INTEGER(171)
+DEFINE_INTEGER(172)
+DEFINE_INTEGER(173)
+DEFINE_INTEGER(174)
+DEFINE_INTEGER(175)
+DEFINE_INTEGER(176)
+DEFINE_INTEGER(177)
+DEFINE_INTEGER(178)
+DEFINE_INTEGER(179)
+DEFINE_INTEGER(180)
+DEFINE_INTEGER(181)
+DEFINE_INTEGER(182)
+DEFINE_INTEGER(183)
+DEFINE_INTEGER(184)
+DEFINE_INTEGER(185)
+DEFINE_INTEGER(186)
+DEFINE_INTEGER(187)
+DEFINE_INTEGER(188)
+DEFINE_INTEGER(189)
+DEFINE_INTEGER(190)
+DEFINE_INTEGER(191)
+DEFINE_INTEGER(192)
+DEFINE_INTEGER(193)
+DEFINE_INTEGER(194)
+DEFINE_INTEGER(195)
+DEFINE_INTEGER(196)
+DEFINE_INTEGER(197)
+DEFINE_INTEGER(198)
+DEFINE_INTEGER(199)
+DEFINE_INTEGER(200)
+DEFINE_INTEGER(201)
+DEFINE_INTEGER(202)
+DEFINE_INTEGER(203)
+DEFINE_INTEGER(204)
+DEFINE_INTEGER(205)
+DEFINE_INTEGER(206)
+DEFINE_INTEGER(207)
+DEFINE_INTEGER(208)
+DEFINE_INTEGER(209)
+DEFINE_INTEGER(210)
+DEFINE_INTEGER(211)
+DEFINE_INTEGER(212)
+DEFINE_INTEGER(213)
+DEFINE_INTEGER(214)
+DEFINE_INTEGER(215)
+DEFINE_INTEGER(216)
+DEFINE_INTEGER(217)
+DEFINE_INTEGER(218)
+DEFINE_INTEGER(219)
+DEFINE_INTEGER(220)
+DEFINE_INTEGER(221)
+DEFINE_INTEGER(222)
+DEFINE_INTEGER(223)
+DEFINE_INTEGER(224)
+DEFINE_INTEGER(225)
+DEFINE_INTEGER(226)
+DEFINE_INTEGER(227)
+DEFINE_INTEGER(228)
+DEFINE_INTEGER(229)
+DEFINE_INTEGER(230)
+DEFINE_INTEGER(231)
+DEFINE_INTEGER(232)
+DEFINE_INTEGER(233)
+DEFINE_INTEGER(234)
+DEFINE_INTEGER(235)
+DEFINE_INTEGER(236)
+DEFINE_INTEGER(237)
+DEFINE_INTEGER(238)
+DEFINE_INTEGER(239)
+DEFINE_INTEGER(240)
+DEFINE_INTEGER(241)
+DEFINE_INTEGER(242)
+DEFINE_INTEGER(243)
+DEFINE_INTEGER(244)
+DEFINE_INTEGER(245)
+DEFINE_INTEGER(246)
+DEFINE_INTEGER(247)
+DEFINE_INTEGER(248)
+DEFINE_INTEGER(249)
+DEFINE_INTEGER(250)
+DEFINE_INTEGER(251)
+DEFINE_INTEGER(252)
+DEFINE_INTEGER(253)
+DEFINE_INTEGER(254)
+DEFINE_INTEGER(255)
+DEFINE_INTEGER(256)
+DEFINE_INTEGER(257)
+DEFINE_INTEGER(258)
+DEFINE_INTEGER(259)
+DEFINE_INTEGER(260)
+DEFINE_INTEGER(261)
+DEFINE_INTEGER(262)
+DEFINE_INTEGER(263)
+DEFINE_INTEGER(264)
+DEFINE_INTEGER(265)
+DEFINE_INTEGER(266)
+DEFINE_INTEGER(267)
+DEFINE_INTEGER(268)
+DEFINE_INTEGER(269)
+DEFINE_INTEGER(270)
+DEFINE_INTEGER(271)
+DEFINE_INTEGER(272)
+DEFINE_INTEGER(273)
+DEFINE_INTEGER(274)
+DEFINE_INTEGER(275)
+DEFINE_INTEGER(276)
+DEFINE_INTEGER(277)
+DEFINE_INTEGER(278)
+DEFINE_INTEGER(279)
+DEFINE_INTEGER(280)
+DEFINE_INTEGER(281)
+DEFINE_INTEGER(282)
+DEFINE_INTEGER(283)
+DEFINE_INTEGER(284)
+DEFINE_INTEGER(285)
+DEFINE_INTEGER(286)
+DEFINE_INTEGER(287)
+DEFINE_INTEGER(288)
+DEFINE_INTEGER(289)
+DEFINE_INTEGER(290)
+DEFINE_INTEGER(291)
+DEFINE_INTEGER(292)
+DEFINE_INTEGER(293)
+DEFINE_INTEGER(294)
+DEFINE_INTEGER(295)
+DEFINE_INTEGER(296)
+DEFINE_INTEGER(297)
+DEFINE_INTEGER(298)
+DEFINE_INTEGER(299)
+DEFINE_INTEGER(300)
+DEFINE_INTEGER(301)
+DEFINE_INTEGER(302)
+DEFINE_INTEGER(303)
+DEFINE_INTEGER(304)
+DEFINE_INTEGER(305)
+DEFINE_INTEGER(306)
+DEFINE_INTEGER(307)
+DEFINE_INTEGER(308)
+DEFINE_INTEGER(309)
+DEFINE_INTEGER(310)
+DEFINE_INTEGER(311)
+DEFINE_INTEGER(312)
+DEFINE_INTEGER(313)
+DEFINE_INTEGER(314)
+DEFINE_INTEGER(315)
+DEFINE_INTEGER(316)
+DEFINE_INTEGER(317)
+DEFINE_INTEGER(318)
+DEFINE_INTEGER(319)
+DEFINE_INTEGER(320)
+DEFINE_INTEGER(321)
+DEFINE_INTEGER(322)
+DEFINE_INTEGER(323)
+DEFINE_INTEGER(324)
+DEFINE_INTEGER(325)
+DEFINE_INTEGER(326)
+DEFINE_INTEGER(327)
+DEFINE_INTEGER(328)
+DEFINE_INTEGER(329)
+DEFINE_INTEGER(330)
+DEFINE_INTEGER(331)
+DEFINE_INTEGER(332)
+DEFINE_INTEGER(333)
+DEFINE_INTEGER(334)
+DEFINE_INTEGER(335)
+DEFINE_INTEGER(336)
+DEFINE_INTEGER(337)
+DEFINE_INTEGER(338)
+DEFINE_INTEGER(339)
+DEFINE_INTEGER(340)
+DEFINE_INTEGER(341)
+DEFINE_INTEGER(342)
+DEFINE_INTEGER(343)
+DEFINE_INTEGER(344)
+DEFINE_INTEGER(345)
+DEFINE_INTEGER(346)
+DEFINE_INTEGER(347)
+DEFINE_INTEGER(348)
+DEFINE_INTEGER(349)
+DEFINE_INTEGER(350)
+DEFINE_INTEGER(351)
+DEFINE_INTEGER(352)
+DEFINE_INTEGER(353)
+DEFINE_INTEGER(354)
+DEFINE_INTEGER(355)
+DEFINE_INTEGER(356)
+DEFINE_INTEGER(357)
+DEFINE_INTEGER(358)
+DEFINE_INTEGER(359)
+DEFINE_INTEGER(360)
+DEFINE_INTEGER(361)
+DEFINE_INTEGER(362)
+DEFINE_INTEGER(363)
+DEFINE_INTEGER(364)
+DEFINE_INTEGER(365)
+DEFINE_INTEGER(366)
+DEFINE_INTEGER(367)
+DEFINE_INTEGER(368)
+DEFINE_INTEGER(369)
+DEFINE_INTEGER(370)
+DEFINE_INTEGER(371)
+DEFINE_INTEGER(372)
+DEFINE_INTEGER(373)
+DEFINE_INTEGER(374)
+DEFINE_INTEGER(375)
+DEFINE_INTEGER(376)
+DEFINE_INTEGER(377)
+DEFINE_INTEGER(378)
+DEFINE_INTEGER(379)
+DEFINE_INTEGER(380)
+DEFINE_INTEGER(381)
+DEFINE_INTEGER(382)
+DEFINE_INTEGER(383)
+DEFINE_INTEGER(384)
+DEFINE_INTEGER(385)
+DEFINE_INTEGER(386)
+DEFINE_INTEGER(387)
+DEFINE_INTEGER(388)
+DEFINE_INTEGER(389)
+DEFINE_INTEGER(390)
+DEFINE_INTEGER(391)
+DEFINE_INTEGER(392)
+DEFINE_INTEGER(393)
+DEFINE_INTEGER(394)
+DEFINE_INTEGER(395)
+DEFINE_INTEGER(396)
+DEFINE_INTEGER(397)
+DEFINE_INTEGER(398)
+DEFINE_INTEGER(399)
+DEFINE_INTEGER(400)
+DEFINE_INTEGER(401)
+DEFINE_INTEGER(402)
+DEFINE_INTEGER(403)
+DEFINE_INTEGER(404)
+DEFINE_INTEGER(405)
+DEFINE_INTEGER(406)
+DEFINE_INTEGER(407)
+DEFINE_INTEGER(408)
+DEFINE_INTEGER(409)
+DEFINE_INTEGER(410)
+DEFINE_INTEGER(411)
+DEFINE_INTEGER(412)
+DEFINE_INTEGER(413)
+DEFINE_INTEGER(414)
+DEFINE_INTEGER(415)
+DEFINE_INTEGER(416)
+DEFINE_INTEGER(417)
+DEFINE_INTEGER(418)
+DEFINE_INTEGER(419)
+DEFINE_INTEGER(420)
+DEFINE_INTEGER(421)
+DEFINE_INTEGER(422)
+DEFINE_INTEGER(423)
+DEFINE_INTEGER(424)
+DEFINE_INTEGER(425)
+DEFINE_INTEGER(426)
+DEFINE_INTEGER(427)
+DEFINE_INTEGER(428)
+DEFINE_INTEGER(429)
+DEFINE_INTEGER(430)
+DEFINE_INTEGER(431)
+DEFINE_INTEGER(432)
+DEFINE_INTEGER(433)
+DEFINE_INTEGER(434)
+DEFINE_INTEGER(435)
+DEFINE_INTEGER(436)
+DEFINE_INTEGER(437)
+DEFINE_INTEGER(438)
+DEFINE_INTEGER(439)
+DEFINE_INTEGER(440)
+DEFINE_INTEGER(441)
+DEFINE_INTEGER(442)
+DEFINE_INTEGER(443)
+DEFINE_INTEGER(444)
+DEFINE_INTEGER(445)
+DEFINE_INTEGER(446)
+DEFINE_INTEGER(447)
+DEFINE_INTEGER(448)
+DEFINE_INTEGER(449)
+DEFINE_INTEGER(450)
+DEFINE_INTEGER(451)
+DEFINE_INTEGER(452)
+DEFINE_INTEGER(453)
+DEFINE_INTEGER(454)
+DEFINE_INTEGER(455)
+DEFINE_INTEGER(456)
+DEFINE_INTEGER(457)
+DEFINE_INTEGER(458)
+DEFINE_INTEGER(459)
+DEFINE_INTEGER(460)
+DEFINE_INTEGER(461)
+DEFINE_INTEGER(462)
+DEFINE_INTEGER(463)
+DEFINE_INTEGER(464)
+DEFINE_INTEGER(465)
+DEFINE_INTEGER(466)
+DEFINE_INTEGER(467)
+DEFINE_INTEGER(468)
+DEFINE_INTEGER(469)
+DEFINE_INTEGER(470)
+DEFINE_INTEGER(471)
+DEFINE_INTEGER(472)
+DEFINE_INTEGER(473)
+DEFINE_INTEGER(474)
+DEFINE_INTEGER(475)
+DEFINE_INTEGER(476)
+DEFINE_INTEGER(477)
+DEFINE_INTEGER(478)
+DEFINE_INTEGER(479)
+DEFINE_INTEGER(480)
+DEFINE_INTEGER(481)
+DEFINE_INTEGER(482)
+DEFINE_INTEGER(483)
+DEFINE_INTEGER(484)
+DEFINE_INTEGER(485)
+DEFINE_INTEGER(486)
+DEFINE_INTEGER(487)
+DEFINE_INTEGER(488)
+DEFINE_INTEGER(489)
+DEFINE_INTEGER(490)
+DEFINE_INTEGER(491)
+DEFINE_INTEGER(492)
+DEFINE_INTEGER(493)
+DEFINE_INTEGER(494)
+DEFINE_INTEGER(495)
+DEFINE_INTEGER(496)
+DEFINE_INTEGER(497)
+DEFINE_INTEGER(498)
+DEFINE_INTEGER(499)
+DEFINE_INTEGER(500)
+DEFINE_INTEGER(501)
+DEFINE_INTEGER(502)
+DEFINE_INTEGER(503)
+DEFINE_INTEGER(504)
+DEFINE_INTEGER(505)
+DEFINE_INTEGER(506)
+DEFINE_INTEGER(507)
+DEFINE_INTEGER(508)
+DEFINE_INTEGER(509)
+DEFINE_INTEGER(510)
+DEFINE_INTEGER(511)
+DEFINE_INTEGER(512)
+DEFINE_INTEGER(513)
+DEFINE_INTEGER(514)
+DEFINE_INTEGER(515)
+DEFINE_INTEGER(516)
+DEFINE_INTEGER(517)
+DEFINE_INTEGER(518)
+DEFINE_INTEGER(519)
+DEFINE_INTEGER(520)
+DEFINE_INTEGER(521)
+DEFINE_INTEGER(522)
+DEFINE_INTEGER(523)
+DEFINE_INTEGER(524)
+DEFINE_INTEGER(525)
+DEFINE_INTEGER(526)
+DEFINE_INTEGER(527)
+DEFINE_INTEGER(528)
+DEFINE_INTEGER(529)
+DEFINE_INTEGER(530)
+DEFINE_INTEGER(531)
+DEFINE_INTEGER(532)
+DEFINE_INTEGER(533)
+DEFINE_INTEGER(534)
+DEFINE_INTEGER(535)
+DEFINE_INTEGER(536)
+DEFINE_INTEGER(537)
+DEFINE_INTEGER(538)
+DEFINE_INTEGER(539)
+DEFINE_INTEGER(540)
+DEFINE_INTEGER(541)
+DEFINE_INTEGER(542)
+DEFINE_INTEGER(543)
+DEFINE_INTEGER(544)
+DEFINE_INTEGER(545)
+DEFINE_INTEGER(546)
+DEFINE_INTEGER(547)
+DEFINE_INTEGER(548)
+DEFINE_INTEGER(549)
+DEFINE_INTEGER(550)
+DEFINE_INTEGER(551)
+DEFINE_INTEGER(552)
+DEFINE_INTEGER(553)
+DEFINE_INTEGER(554)
+DEFINE_INTEGER(555)
+DEFINE_INTEGER(556)
+DEFINE_INTEGER(557)
+DEFINE_INTEGER(558)
+DEFINE_INTEGER(559)
+DEFINE_INTEGER(560)
+DEFINE_INTEGER(561)
+DEFINE_INTEGER(562)
+DEFINE_INTEGER(563)
+DEFINE_INTEGER(564)
+DEFINE_INTEGER(565)
+DEFINE_INTEGER(566)
+DEFINE_INTEGER(567)
+DEFINE_INTEGER(568)
+DEFINE_INTEGER(569)
+DEFINE_INTEGER(570)
+DEFINE_INTEGER(571)
+DEFINE_INTEGER(572)
+DEFINE_INTEGER(573)
+DEFINE_INTEGER(574)
+DEFINE_INTEGER(575)
+DEFINE_INTEGER(576)
+DEFINE_INTEGER(577)
+DEFINE_INTEGER(578)
+DEFINE_INTEGER(579)
+DEFINE_INTEGER(580)
+DEFINE_INTEGER(581)
+DEFINE_INTEGER(582)
+DEFINE_INTEGER(583)
+DEFINE_INTEGER(584)
+DEFINE_INTEGER(585)
+DEFINE_INTEGER(586)
+DEFINE_INTEGER(587)
+DEFINE_INTEGER(588)
+DEFINE_INTEGER(589)
+DEFINE_INTEGER(590)
+DEFINE_INTEGER(591)
+DEFINE_INTEGER(592)
+DEFINE_INTEGER(593)
+DEFINE_INTEGER(594)
+DEFINE_INTEGER(595)
+DEFINE_INTEGER(596)
+DEFINE_INTEGER(597)
+DEFINE_INTEGER(598)
+DEFINE_INTEGER(599)
+DEFINE_INTEGER(600)
+DEFINE_INTEGER(601)
+DEFINE_INTEGER(602)
+DEFINE_INTEGER(603)
+DEFINE_INTEGER(604)
+DEFINE_INTEGER(605)
+DEFINE_INTEGER(606)
+DEFINE_INTEGER(607)
+DEFINE_INTEGER(608)
+DEFINE_INTEGER(609)
+DEFINE_INTEGER(610)
+DEFINE_INTEGER(611)
+DEFINE_INTEGER(612)
+DEFINE_INTEGER(613)
+DEFINE_INTEGER(614)
+DEFINE_INTEGER(615)
+DEFINE_INTEGER(616)
+DEFINE_INTEGER(617)
+DEFINE_INTEGER(618)
+DEFINE_INTEGER(619)
+DEFINE_INTEGER(620)
+DEFINE_INTEGER(621)
+DEFINE_INTEGER(622)
+DEFINE_INTEGER(623)
+DEFINE_INTEGER(624)
+DEFINE_INTEGER(625)
+DEFINE_INTEGER(626)
+DEFINE_INTEGER(627)
+DEFINE_INTEGER(628)
+DEFINE_INTEGER(629)
+DEFINE_INTEGER(630)
+DEFINE_INTEGER(631)
+DEFINE_INTEGER(632)
+DEFINE_INTEGER(633)
+DEFINE_INTEGER(634)
+DEFINE_INTEGER(635)
+DEFINE_INTEGER(636)
+DEFINE_INTEGER(637)
+DEFINE_INTEGER(638)
+DEFINE_INTEGER(639)
+DEFINE_INTEGER(640)
+DEFINE_INTEGER(641)
+DEFINE_INTEGER(642)
+DEFINE_INTEGER(643)
+DEFINE_INTEGER(644)
+DEFINE_INTEGER(645)
+DEFINE_INTEGER(646)
+DEFINE_INTEGER(647)
+DEFINE_INTEGER(648)
+DEFINE_INTEGER(649)
+DEFINE_INTEGER(650)
+DEFINE_INTEGER(651)
+DEFINE_INTEGER(652)
+DEFINE_INTEGER(653)
+DEFINE_INTEGER(654)
+DEFINE_INTEGER(655)
+DEFINE_INTEGER(656)
+DEFINE_INTEGER(657)
+DEFINE_INTEGER(658)
+DEFINE_INTEGER(659)
+DEFINE_INTEGER(660)
+DEFINE_INTEGER(661)
+DEFINE_INTEGER(662)
+DEFINE_INTEGER(663)
+DEFINE_INTEGER(664)
+DEFINE_INTEGER(665)
+DEFINE_INTEGER(666)
+DEFINE_INTEGER(667)
+DEFINE_INTEGER(668)
+DEFINE_INTEGER(669)
+DEFINE_INTEGER(670)
+DEFINE_INTEGER(671)
+DEFINE_INTEGER(672)
+DEFINE_INTEGER(673)
+DEFINE_INTEGER(674)
+DEFINE_INTEGER(675)
+DEFINE_INTEGER(676)
+DEFINE_INTEGER(677)
+DEFINE_INTEGER(678)
+DEFINE_INTEGER(679)
+DEFINE_INTEGER(680)
+DEFINE_INTEGER(681)
+DEFINE_INTEGER(682)
+DEFINE_INTEGER(683)
+DEFINE_INTEGER(684)
+DEFINE_INTEGER(685)
+DEFINE_INTEGER(686)
+DEFINE_INTEGER(687)
+DEFINE_INTEGER(688)
+DEFINE_INTEGER(689)
+DEFINE_INTEGER(690)
+DEFINE_INTEGER(691)
+DEFINE_INTEGER(692)
+DEFINE_INTEGER(693)
+DEFINE_INTEGER(694)
+DEFINE_INTEGER(695)
+DEFINE_INTEGER(696)
+DEFINE_INTEGER(697)
+DEFINE_INTEGER(698)
+DEFINE_INTEGER(699)
+DEFINE_INTEGER(700)
+DEFINE_INTEGER(701)
+DEFINE_INTEGER(702)
+DEFINE_INTEGER(703)
+DEFINE_INTEGER(704)
+DEFINE_INTEGER(705)
+DEFINE_INTEGER(706)
+DEFINE_INTEGER(707)
+DEFINE_INTEGER(708)
+DEFINE_INTEGER(709)
+DEFINE_INTEGER(710)
+DEFINE_INTEGER(711)
+DEFINE_INTEGER(712)
+DEFINE_INTEGER(713)
+DEFINE_INTEGER(714)
+DEFINE_INTEGER(715)
+DEFINE_INTEGER(716)
+DEFINE_INTEGER(717)
+DEFINE_INTEGER(718)
+DEFINE_INTEGER(719)
+DEFINE_INTEGER(720)
+DEFINE_INTEGER(721)
+DEFINE_INTEGER(722)
+DEFINE_INTEGER(723)
+DEFINE_INTEGER(724)
+DEFINE_INTEGER(725)
+DEFINE_INTEGER(726)
+DEFINE_INTEGER(727)
+DEFINE_INTEGER(728)
+DEFINE_INTEGER(729)
+DEFINE_INTEGER(730)
+DEFINE_INTEGER(731)
+DEFINE_INTEGER(732)
+DEFINE_INTEGER(733)
+DEFINE_INTEGER(734)
+DEFINE_INTEGER(735)
+DEFINE_INTEGER(736)
+DEFINE_INTEGER(737)
+DEFINE_INTEGER(738)
+DEFINE_INTEGER(739)
+DEFINE_INTEGER(740)
+DEFINE_INTEGER(741)
+DEFINE_INTEGER(742)
+DEFINE_INTEGER(743)
+DEFINE_INTEGER(744)
+DEFINE_INTEGER(745)
+DEFINE_INTEGER(746)
+DEFINE_INTEGER(747)
+DEFINE_INTEGER(748)
+DEFINE_INTEGER(749)
+DEFINE_INTEGER(750)
+DEFINE_INTEGER(751)
+DEFINE_INTEGER(752)
+DEFINE_INTEGER(753)
+DEFINE_INTEGER(754)
+DEFINE_INTEGER(755)
+DEFINE_INTEGER(756)
+DEFINE_INTEGER(757)
+DEFINE_INTEGER(758)
+DEFINE_INTEGER(759)
+DEFINE_INTEGER(760)
+DEFINE_INTEGER(761)
+DEFINE_INTEGER(762)
+DEFINE_INTEGER(763)
+DEFINE_INTEGER(764)
+DEFINE_INTEGER(765)
+DEFINE_INTEGER(766)
+DEFINE_INTEGER(767)
+DEFINE_INTEGER(768)
+DEFINE_INTEGER(769)
+DEFINE_INTEGER(770)
+DEFINE_INTEGER(771)
+DEFINE_INTEGER(772)
+DEFINE_INTEGER(773)
+DEFINE_INTEGER(774)
+DEFINE_INTEGER(775)
+DEFINE_INTEGER(776)
+DEFINE_INTEGER(777)
+DEFINE_INTEGER(778)
+DEFINE_INTEGER(779)
+DEFINE_INTEGER(780)
+DEFINE_INTEGER(781)
+DEFINE_INTEGER(782)
+DEFINE_INTEGER(783)
+DEFINE_INTEGER(784)
+DEFINE_INTEGER(785)
+DEFINE_INTEGER(786)
+DEFINE_INTEGER(787)
+DEFINE_INTEGER(788)
+DEFINE_INTEGER(789)
+DEFINE_INTEGER(790)
+DEFINE_INTEGER(791)
+DEFINE_INTEGER(792)
+DEFINE_INTEGER(793)
+DEFINE_INTEGER(794)
+DEFINE_INTEGER(795)
+DEFINE_INTEGER(796)
+DEFINE_INTEGER(797)
+DEFINE_INTEGER(798)
+DEFINE_INTEGER(799)
+DEFINE_INTEGER(800)
+DEFINE_INTEGER(801)
+DEFINE_INTEGER(802)
+DEFINE_INTEGER(803)
+DEFINE_INTEGER(804)
+DEFINE_INTEGER(805)
+DEFINE_INTEGER(806)
+DEFINE_INTEGER(807)
+DEFINE_INTEGER(808)
+DEFINE_INTEGER(809)
+DEFINE_INTEGER(810)
+DEFINE_INTEGER(811)
+DEFINE_INTEGER(812)
+DEFINE_INTEGER(813)
+DEFINE_INTEGER(814)
+DEFINE_INTEGER(815)
+DEFINE_INTEGER(816)
+DEFINE_INTEGER(817)
diff --git a/gpgscm/t-child.c b/gpgscm/t-child.c
new file mode 100644
index 0000000..f4e3a04
--- /dev/null
+++ b/gpgscm/t-child.c
@@ -0,0 +1,74 @@
+/* Sanity check for the process and IPC primitives.
+ *
+ * Copyright (C) 2016 g10 code GmbH
+ *
+ * This file is part of GnuPG.
+ *
+ * GnuPG is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * GnuPG is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+
+#ifdef _WIN32
+# include <fcntl.h>
+# include <io.h>
+#endif
+
+int
+main (int argc, char **argv)
+{
+  char buffer[4096];
+  memset (buffer, 'A', sizeof buffer);
+#if _WIN32
+  if (! setmode (fileno (stdin), O_BINARY))
+    return 23;
+  if (! setmode (fileno (stdout), O_BINARY))
+    return 23;
+#endif
+
+  if (argc == 1)
+    return 2;
+  else if (strcmp (argv[1], "return0") == 0)
+    return 0;
+  else if (strcmp (argv[1], "return1") == 0)
+    return 1;
+  else if (strcmp (argv[1], "return77") == 0)
+    return 77;
+  else if (strcmp (argv[1], "hello_stdout") == 0)
+    fprintf (stdout, "hello");
+  else if (strcmp (argv[1], "hello_stderr") == 0)
+    fprintf (stderr, "hello");
+  else if (strcmp (argv[1], "stdout4096") == 0)
+    fwrite (buffer, 1, sizeof buffer, stdout);
+  else if (strcmp (argv[1], "stdout8192") == 0)
+    {
+      fwrite (buffer, 1, sizeof buffer, stdout);
+      fwrite (buffer, 1, sizeof buffer, stdout);
+    }
+  else if (strcmp (argv[1], "cat") == 0)
+    while (! feof (stdin))
+      {
+        size_t bytes_read;
+        bytes_read = fread (buffer, 1, sizeof buffer, stdin);
+        fwrite (buffer, 1, bytes_read, stdout);
+      }
+  else
+    {
+      fprintf (stderr, "unknown command %s\n", argv[1]);
+      return 2;
+    }
+  return 0;
+}
diff --git a/gpgscm/t-child.scm b/gpgscm/t-child.scm
new file mode 100644
index 0000000..fd1dcc3
--- /dev/null
+++ b/gpgscm/t-child.scm
@@ -0,0 +1,118 @@
+;; Tests for the low-level process and IPC primitives.
+;;
+;; Copyright (C) 2016 g10 Code GmbH
+;;
+;; This file is part of GnuPG.
+;;
+;; GnuPG is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation; either version 3 of the License, or
+;; (at your option) any later version.
+;;
+;; GnuPG is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+;;
+;; You should have received a copy of the GNU General Public License
+;; along with this program; if not, see <http://www.gnu.org/licenses/>.
+
+(echo "Testing process and IPC primitives...")
+
+(define (qualify executable)
+  (string-append executable (getenv "EXEEXT")))
+
+(define child (qualify "t-child"))
+
+(assert (= 0 (call `(,(qualify "t-child") "return0"))))
+(assert (= 1 (call `(,(qualify "t-child") "return1"))))
+(assert (= 77 (call `(,(qualify "t-child") "return77"))))
+
+(let ((r (call-with-io `(,(qualify "t-child") "return0") "")))
+  (assert (= 0 (:retcode r)))
+  (assert (string=? "" (:stdout r)))
+  (assert (string=? "" (:stderr r))))
+
+(let ((r (call-with-io `(,(qualify "t-child") "return1") "")))
+  (assert (= 1 (:retcode r)))
+  (assert (string=? "" (:stdout r)))
+  (assert (string=? "" (:stderr r))))
+
+(let ((r (call-with-io `(,(qualify "t-child") "return77") "")))
+  (assert (= 77 (:retcode r)))
+  (assert (string=? "" (:stdout r)))
+  (assert (string=? "" (:stderr r))))
+
+(let ((r (call-with-io `(,(qualify "t-child") "hello_stdout") "")))
+  (assert (= 0 (:retcode r)))
+  (assert (string=? "hello" (:stdout r)))
+  (assert (string=? "" (:stderr r))))
+
+(let ((r (call-with-io `(,(qualify "t-child") "hello_stderr") "")))
+  (assert (= 0 (:retcode r)))
+  (assert (string=? "" (:stdout r)))
+  (assert (string=? "hello" (:stderr r))))
+
+(let ((r (call-with-io `(,(qualify "t-child") "stdout4096") "")))
+  (assert (= 0 (:retcode r)))
+  (assert (= 4096 (string-length (:stdout r))))
+  (assert (string=? "" (:stderr r))))
+
+(let ((r (call-with-io `(,(qualify "t-child") "stdout8192") "")))
+  (assert (= 0 (:retcode r)))
+  (assert (= 8192 (string-length (:stdout r))))
+  (assert (string=? "" (:stderr r))))
+
+(let ((r (call-with-io `(,(qualify "t-child") "cat") "hellohello")))
+  (assert (= 0 (:retcode r)))
+  (assert (string=? "hellohello" (:stdout r)))
+  (assert (string=? "" (:stderr r))))
+
+(define (spawn what)
+  (spawn-process-fd what CLOSED_FD STDOUT_FILENO STDERR_FILENO))
+
+(let ((pid0 (spawn `(,(qualify "t-child") "return0")))
+      (pid1 (spawn `(,(qualify "t-child") "return0"))))
+  (assert (equal? '(0 0)
+		  (wait-processes '("child0" "child1") (list pid0 pid1) #t))))
+
+(let ((pid0 (spawn `(,(qualify "t-child") "return1")))
+      (pid1 (spawn `(,(qualify "t-child") "return0"))))
+  (assert (equal? '(1 0)
+		  (wait-processes '("child0" "child1") (list pid0 pid1) #t))))
+
+(let ((pid0 (spawn `(,(qualify "t-child") "return0")))
+      (pid1 (spawn `(,(qualify "t-child") "return77")))
+      (pid2 (spawn `(,(qualify "t-child") "return1"))))
+  (assert (equal? '(0 77 1)
+		  (wait-processes '("child0" "child1" "child2")
+				  (list pid0 pid1 pid2) #t))))
+
+(let* ((p (pipe))
+       (pid0 (spawn-process-fd
+	       `(,(qualify "t-child") "hello_stdout")
+	       CLOSED_FD (:write-end p) STDERR_FILENO))
+       (_ (close (:write-end p)))
+       (pid1 (spawn-process-fd
+	       `(,(qualify "t-child") "cat")
+	       (:read-end p) STDOUT_FILENO STDERR_FILENO)))
+  (close (:read-end p))
+  (assert
+   (equal? '(0 0)
+	   (wait-processes '("child0" "child1") (list pid0 pid1) #t))))
+(echo " world.")
+
+(tr:do
+ (tr:pipe-do
+  (pipe:spawn `(,child stdout4096))
+  (pipe:spawn `(,child cat)))
+ (tr:call-with-content (lambda (c)
+			 (assert (= 4096 (string-length c))))))
+(tr:do
+ (tr:pipe-do
+  (pipe:spawn `(,child stdout8192))
+  (pipe:spawn `(,child cat)))
+ (tr:call-with-content (lambda (c)
+			 (assert (= 8192 (string-length c))))))
+
+(echo "All good.")
diff --git a/gpgscm/tests.scm b/gpgscm/tests.scm
new file mode 100644
index 0000000..5141002
--- /dev/null
+++ b/gpgscm/tests.scm
@@ -0,0 +1,886 @@
+;; Common definitions for writing tests.
+;;
+;; Copyright (C) 2016 g10 Code GmbH
+;;
+;; This file is part of GnuPG.
+;;
+;; GnuPG is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation; either version 3 of the License, or
+;; (at your option) any later version.
+;;
+;; GnuPG is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+;;
+;; You should have received a copy of the GNU General Public License
+;; along with this program; if not, see <http://www.gnu.org/licenses/>.
+
+;; Reporting.
+(define (echo . msg)
+  (for-each (lambda (x) (display x) (display " ")) msg)
+  (newline))
+
+(define (info . msg)
+  (apply echo msg)
+  (flush-stdio))
+
+(define (log . msg)
+  (if (> (*verbose*) 0)
+      (apply info msg)))
+
+(define (fail . msg)
+  (apply info msg)
+  (exit 1))
+
+(define (skip . msg)
+  (apply info msg)
+  (exit 77))
+
+(define (make-counter)
+  (let ((c 0))
+    (lambda ()
+      (let ((r c))
+	(set! c (+ 1 c))
+	r))))
+
+(define *progress-nesting* 0)
+
+(define (call-with-progress msg what)
+  (set! *progress-nesting* (+ 1 *progress-nesting*))
+  (if (= 1 *progress-nesting*)
+      (begin
+	(info msg)
+	(display "    > ")
+	(flush-stdio)
+	(what (lambda (item)
+	      (display item)
+	      (display " ")
+	      (flush-stdio)))
+	(info "< "))
+      (begin
+	(what (lambda (item) (display ".") (flush-stdio)))
+	(display " ")
+	(flush-stdio)))
+  (set! *progress-nesting* (- *progress-nesting* 1)))
+
+(define (for-each-p msg proc lst . lsts)
+  (apply for-each-p' `(,msg ,proc ,(lambda (x . xs) x) ,lst ,@lsts)))
+
+(define (for-each-p' msg proc fmt lst . lsts)
+  (call-with-progress
+   msg
+   (lambda (progress)
+     (apply for-each
+	    `(,(lambda args
+		 (progress (apply fmt args))
+		 (apply proc args))
+	      ,lst ,@lsts)))))
+
+;; Process management.
+(define CLOSED_FD -1)
+(define (call-with-fds what infd outfd errfd)
+  (wait-process (stringify what) (spawn-process-fd what infd outfd errfd) #t))
+(define (call what)
+  (call-with-fds what
+		 CLOSED_FD
+		 (if (< (*verbose*) 0) STDOUT_FILENO CLOSED_FD)
+		 (if (< (*verbose*) 0) STDERR_FILENO CLOSED_FD)))
+
+;; Accessor functions for the results of 'spawn-process'.
+(define :stdin car)
+(define :stdout cadr)
+(define :stderr caddr)
+(define :pid cadddr)
+
+(define (call-with-io what in)
+  (let ((h (spawn-process what 0)))
+    (es-write (:stdin h) in)
+    (es-fclose (:stdin h))
+    (let* ((out (es-read-all (:stdout h)))
+	   (err (es-read-all (:stderr h)))
+	   (result (wait-process (car what) (:pid h) #t)))
+      (es-fclose (:stdout h))
+      (es-fclose (:stderr h))
+      (if (> (*verbose*) 2)
+	  (info "Child" (:pid h) "returned:"
+		`((command ,(stringify what))
+		  (status ,result)
+		  (stdout ,out)
+		  (stderr ,err))))
+      (list result out err))))
+
+;; Accessor function for the results of 'call-with-io'.  ':stdout' and
+;; ':stderr' can also be used.
+(define :retcode car)
+
+(define (call-check what)
+  (let ((result (call-with-io what "")))
+    (if (= 0 (:retcode result))
+	(:stdout result)
+	(throw (string-append (stringify what) " failed")
+	       (:stderr result)))))
+
+(define (call-popen command input-string)
+  (let ((result (call-with-io command input-string)))
+    (if (= 0 (:retcode result))
+	(:stdout result)
+	(throw (:stderr result)))))
+
+;;
+;; estream helpers.
+;;
+
+(define (es-read-all stream)
+  (let loop
+      ((acc ""))
+    (if (es-feof stream)
+	acc
+	(loop (string-append acc (es-read stream 4096))))))
+
+;;
+;; File management.
+;;
+(define (file-exists? name)
+  (call-with-input-file name (lambda (port) #t)))
+
+(define (file=? a b)
+  (file-equal a b #t))
+
+(define (text-file=? a b)
+  (file-equal a b #f))
+
+(define (file-copy from to)
+  (catch '() (unlink to))
+  (letfd ((source (open from (logior O_RDONLY O_BINARY)))
+	  (sink (open to (logior O_WRONLY O_CREAT O_BINARY) #o600)))
+    (splice source sink)))
+
+(define (text-file-copy from to)
+  (catch '() (unlink to))
+  (letfd ((source (open from O_RDONLY))
+	  (sink (open to (logior O_WRONLY O_CREAT) #o600)))
+    (splice source sink)))
+
+(define (path-join . components)
+  (let loop ((acc #f) (rest (filter (lambda (s)
+				      (not (string=? "" s))) components)))
+    (if (null? rest)
+	acc
+	(loop (if (string? acc)
+		  (string-append acc "/" (car rest))
+		  (car rest))
+	      (cdr rest)))))
+(assert (string=? (path-join "foo" "bar" "baz") "foo/bar/baz"))
+(assert (string=? (path-join "" "bar" "baz") "bar/baz"))
+
+;; Is PATH an absolute path?
+(define (absolute-path? path)
+  (or (char=? #\/ (string-ref path 0))
+      (and *win32* (char=? #\\ (string-ref path 0)))
+      (and *win32*
+	   (char-alphabetic? (string-ref path 0))
+	   (char=? #\: (string-ref path 1))
+	   (or (char=? #\/ (string-ref path 2))
+	       (char=? #\\ (string-ref path 2))))))
+
+;; Make PATH absolute.
+(define (canonical-path path)
+  (if (absolute-path? path) path (path-join (getcwd) path)))
+
+(define (in-srcdir . names)
+  (canonical-path (apply path-join (cons (getenv "abs_top_srcdir") names))))
+
+;; Split a list of paths.
+(define (pathsep-split s)
+  (string-split s *pathsep*))
+
+;; Join a list of paths.
+(define (pathsep-join paths)
+  (foldr (lambda (a b) (string-append a (string *pathsep*) b))
+	 (car paths)
+	 (cdr paths)))
+
+;; Try to find NAME in PATHS.  Returns the full path name on success,
+;; or raises an error.
+(define (path-expand name paths)
+  (let loop ((path paths))
+    (if (null? path)
+	(throw "Could not find" name "in" paths)
+	(let* ((qualified-name (path-join (car path) name))
+	       (file-exists (call-with-input-file qualified-name
+			      (lambda (x) #t))))
+	  (if file-exists
+	      qualified-name
+	      (loop (cdr path)))))))
+
+;; Expand NAME using the gpgscm load path.  Use like this:
+;;   (load (with-path "library.scm"))
+(define (with-path name)
+  (catch name
+	 (path-expand name (pathsep-split (getenv "GPGSCM_PATH")))))
+
+(define (basename path)
+  (let ((i (string-index path #\/)))
+    (if (equal? i #f)
+	path
+	(basename (substring path (+ 1 i) (string-length path))))))
+
+(define (basename-suffix path suffix)
+  (basename
+   (if (string-suffix? path suffix)
+       (substring path 0 (- (string-length path) (string-length suffix)))
+       path)))
+
+(define (dirname path)
+  (let ((i (string-rindex path #\/)))
+    (if i (substring path 0 i) ".")))
+(assert (string=? "foo/bar" (dirname "foo/bar/baz")))
+
+;; Helper for (pipe).
+(define :read-end car)
+(define :write-end cadr)
+
+;; let-like macro that manages file descriptors.
+;;
+;; (letfd <bindings> <body>)
+;;
+;; Bind all variables given in <bindings> and initialize each of them
+;; to the given initial value, and close them after evaluating <body>.
+(define-macro (letfd bindings . body)
+  (let bind ((bindings' bindings))
+    (if (null? bindings')
+	`(begin ,@body)
+	(let* ((binding (car bindings'))
+	       (name (car binding))
+	       (initializer (cadr binding)))
+	  `(let ((,name ,initializer))
+	     (finally (close ,name)
+		      ,(bind (cdr bindings'))))))))
+
+(define-macro (with-working-directory new-directory . expressions)
+  (let ((new-dir (gensym))
+	(old-dir (gensym)))
+    `(let* ((,new-dir ,new-directory)
+	    (,old-dir (getcwd)))
+       (dynamic-wind
+	   (lambda () (if ,new-dir (chdir ,new-dir)))
+	   (lambda () ,@expressions)
+	   (lambda () (chdir ,old-dir))))))
+
+;; Make a temporary directory.  If arguments are given, they are
+;; joined using path-join, and must end in a component ending in
+;; "XXXXXX".  If no arguments are given, a suitable location and
+;; generic name is used.  Returns an absolute path.
+(define (mkdtemp . components)
+  (canonical-path (_mkdtemp (if (null? components)
+				(path-join
+				 (get-temp-path)
+				 (string-append "gpgscm-" (get-isotime) "-"
+						(basename-suffix *scriptname* ".scm")
+						"-XXXXXX"))
+				(apply path-join components)))))
+
+;; Make a temporary directory and remove it at interpreter shutdown.
+;; Note that there are macros that limit the lifetime of temporary
+;; directories and files to a lexical scope.  Use those if possible.
+;; Otherwise this works like mkdtemp.
+(define (mkdtemp-autoremove . components)
+  (let ((dir (apply mkdtemp components)))
+    (atexit (lambda () (unlink-recursively dir)))
+    dir))
+
+(define-macro (with-temporary-working-directory . expressions)
+  (let ((tmp-sym (gensym)))
+    `(let* ((,tmp-sym (mkdtemp)))
+       (finally (unlink-recursively ,tmp-sym)
+		(with-working-directory ,tmp-sym
+					,@expressions)))))
+
+(define (make-temporary-file . args)
+  (canonical-path (path-join
+		   (mkdtemp)
+		   (if (null? args) "a" (car args)))))
+
+(define (remove-temporary-file filename)
+  (catch '()
+    (unlink filename))
+  (let ((dirname (substring filename 0 (string-rindex filename #\/))))
+    (catch (echo "removing temporary directory" dirname "failed")
+      (rmdir dirname))))
+
+;; let-like macro that manages temporary files.
+;;
+;; (lettmp <bindings> <body>)
+;;
+;; Bind all variables given in <bindings>, initialize each of them to
+;; a string representing an unique path in the filesystem, and delete
+;; them after evaluating <body>.
+(define-macro (lettmp bindings . body)
+  (let bind ((bindings' bindings))
+    (if (null? bindings')
+	`(begin ,@body)
+	(let ((name (car bindings'))
+	      (rest (cdr bindings')))
+	  `(let ((,name (make-temporary-file ,(symbol->string name))))
+	     (finally (remove-temporary-file ,name)
+		      ,(bind rest)))))))
+
+(define (check-execution source transformer)
+  (lettmp (sink)
+	  (transformer source sink)))
+
+(define (check-identity source transformer)
+  (lettmp (sink)
+	  (transformer source sink)
+	  (if (not (file=? source sink))
+	      (fail "mismatch"))))
+
+;;
+;; Monadic pipe support.
+;;
+
+(define pipeM
+  (package
+   (define (new procs source sink producer)
+     (package
+      (define (dump)
+	(write (list procs source sink producer))
+	(newline))
+      (define (add-proc command pid)
+	(new (cons (list command pid) procs) source sink producer))
+      (define (commands)
+	(map car procs))
+      (define (pids)
+	(map cadr procs))
+      (define (set-source source')
+	(new procs source' sink producer))
+      (define (set-sink sink')
+	(new procs source sink' producer))
+      (define (set-producer producer')
+	(if producer
+	    (throw "producer already set"))
+	(new procs source sink producer'))))))
+
+
+(define (pipe:do . commands)
+  (let loop ((M (pipeM::new '() CLOSED_FD CLOSED_FD #f)) (cmds commands))
+    (if (null? cmds)
+	(begin
+	  (if M::producer (M::producer))
+	  (if (not (null? M::procs))
+	      (let* ((retcodes (wait-processes (map stringify (M::commands))
+					       (M::pids) #t))
+		     (results (map (lambda (p r) (append p (list r)))
+				   M::procs retcodes))
+		     (failed (filter (lambda (x) (not (= 0 (caddr x))))
+				     results)))
+		(if (not (null? failed))
+		    (throw failed))))) ; xxx nicer reporting
+	(if (and (= 2 (length cmds)) (number? (cadr cmds)))
+	    ;; hack: if it's an fd, use it as sink
+	    (let ((M' ((car cmds) (M::set-sink (cadr cmds)))))
+	      (if (> M::source 2) (close M::source))
+	      (if (> (cadr cmds) 2) (close (cadr cmds)))
+	      (loop M' '()))
+	    (let ((M' ((car cmds) M)))
+	      (if (> M::source 2) (close M::source))
+	      (loop M' (cdr cmds)))))))
+
+(define (pipe:open pathname flags)
+  (lambda (M)
+    (M::set-source (open pathname flags))))
+
+(define (pipe:defer producer)
+  (lambda (M)
+    (let* ((p (outbound-pipe))
+	   (M' (M::set-source (:read-end p))))
+      (M'::set-producer (lambda ()
+			  (producer (:write-end p))
+			  (close (:write-end p)))))))
+(define (pipe:echo data)
+ (pipe:defer (lambda (sink) (display data (fdopen sink "wb")))))
+
+(define (pipe:spawn command)
+  (lambda (M)
+    (define (do-spawn M new-source)
+      (let ((pid (spawn-process-fd command M::source M::sink
+				   (if (> (*verbose*) 0)
+				       STDERR_FILENO CLOSED_FD)))
+	    (M' (M::set-source new-source)))
+	(M'::add-proc command pid)))
+    (if (= CLOSED_FD M::sink)
+	(let* ((p (pipe))
+	       (M' (do-spawn (M::set-sink (:write-end p)) (:read-end p))))
+	  (close (:write-end p))
+	  (M'::set-sink CLOSED_FD))
+	(do-spawn M CLOSED_FD))))
+
+(define (pipe:splice sink)
+  (lambda (M)
+    (splice M::source sink)
+    (M::set-source CLOSED_FD)))
+
+(define (pipe:write-to pathname flags mode)
+  (open pathname flags mode))
+
+;;
+;; Monadic transformer support.
+;;
+
+(define (tr:do . commands)
+  (let loop ((tmpfiles '()) (source  #f) (cmds commands))
+    (if (null? cmds)
+	(for-each remove-temporary-file tmpfiles)
+	(let* ((v ((car cmds) tmpfiles source))
+	       (tmpfiles' (car v))
+	       (sink (cadr v))
+	       (error (caddr v)))
+	  (if error
+	      (begin
+		(for-each remove-temporary-file tmpfiles')
+		(apply throw error)))
+	  (loop tmpfiles' sink (cdr cmds))))))
+
+(define (tr:open pathname)
+  (lambda (tmpfiles source)
+    (list tmpfiles pathname #f)))
+
+(define (tr:spawn input command)
+  (lambda (tmpfiles source)
+    (if (and (member '**in** command) (not source))
+	(fail (string-append (stringify cmd) " needs an input")))
+    (let* ((t (make-temporary-file))
+	   (cmd (map (lambda (x)
+		       (cond
+			((equal? '**in** x) source)
+			((equal? '**out** x) t)
+			(else x))) command)))
+      (catch (list (cons t tmpfiles) t *error*)
+	     (call-popen cmd input)
+	     (if (and (member '**out** command) (not (file-exists? t)))
+		 (fail (string-append (stringify cmd)
+				       " did not produce '" t "'.")))
+	     (list (cons t tmpfiles) t #f)))))
+
+(define (tr:write-to pathname)
+  (lambda (tmpfiles source)
+    (rename source pathname)
+    (list tmpfiles pathname #f)))
+
+(define (tr:pipe-do . commands)
+  (lambda (tmpfiles source)
+    (let ((t (make-temporary-file)))
+      (apply pipe:do
+        `(,@(if source `(,(pipe:open source (logior O_RDONLY O_BINARY))) '())
+	  ,@commands
+	  ,(pipe:write-to t (logior O_WRONLY O_BINARY O_CREAT) #o600)))
+      (list (cons t tmpfiles) t #f))))
+
+(define (tr:assert-identity reference)
+  (lambda (tmpfiles source)
+    (if (not (file=? source reference))
+	(fail "mismatch"))
+    (list tmpfiles source #f)))
+
+(define (tr:assert-weak-identity reference)
+  (lambda (tmpfiles source)
+    (if (not (text-file=? source reference))
+	(fail "mismatch"))
+    (list tmpfiles source #f)))
+
+(define (tr:call-with-content function . args)
+  (lambda (tmpfiles source)
+    (catch (list tmpfiles source *error*)
+	   (apply function `(,(call-with-input-file source read-all) ,@args)))
+    (list tmpfiles source #f)))
+
+;;
+;; Developing and debugging tests.
+;;
+
+;; Spawn an os shell.
+(define (interactive-shell)
+  (call-with-fds `(,(getenv "SHELL") -i) 0 1 2))
+
+;;
+;; The main test framework.
+;;
+
+(define semaphore
+  (package
+   (define (new n)
+     (package
+      (define (acquire!?)
+	(if (> n 0)
+	    (begin
+	      (set! n (- n 1))
+	      #t)
+	    #f))
+      (define (release!)
+	(set! n (+ n 1)))))))
+
+;; A pool of tests.
+(define test-pool
+  (package
+   (define (new n)
+     (package
+      ;; A semaphore to restrict the number of spawned processes.
+      (define sem (semaphore::new n))
+
+      ;; A list of enqueued, but not yet run tests.
+      (define enqueued '())
+
+      ;; A list of running or finished processes.
+      (define procs '())
+
+      (define (add test)
+	(if (test::started?)
+	    (set! procs (cons test procs))
+	    (if (sem::acquire!?)
+		(add (test::run-async))
+		(set! enqueued (cons test enqueued))))
+	(current-environment))
+
+      ;; Pop the last of the enqueued tests off the fifo queue.
+      (define (pop-test!)
+	(let ((i (length enqueued)))
+	  (assert (> i 0))
+	  (cond
+	   ((= i 1)
+	    (let ((test (car enqueued)))
+	      (set! enqueued '())
+	      test))
+	   (else
+	    (let* ((tail (list-tail enqueued (- i 2)))
+		   (test (cadr tail)))
+	      (set-cdr! tail '())
+	      (assert (= (length enqueued) (- i 1)))
+	      test)))))
+
+      (define (pid->test pid)
+	(let ((t (filter (lambda (x) (= pid x::pid)) procs)))
+	  (if (null? t) #f (car t))))
+      (define (wait)
+	(if (null? enqueued)
+	    ;; If no tests are enqueued, we can just block until all
+	    ;; of them finished.
+	    (wait' #t)
+	    ;; Otherwise, we must not block, but give some tests the
+	    ;; chance to finish so that we can start new ones.
+	    (begin
+	      (wait' #f)
+	      (usleep (/ 1000000 10))
+	      (wait))))
+      (define (wait' hang)
+	(let ((unfinished (filter (lambda (t) (not t::retcode)) procs)))
+	  (if (null? unfinished)
+	      (current-environment)
+	      (let ((names (map (lambda (t) t::name) unfinished))
+		    (pids (map (lambda (t) t::pid) unfinished))
+		    (any #f))
+		(for-each
+		 (lambda (test retcode)
+		   (unless (< retcode 0)
+			   (test::set-end-time!)
+			   (test:::set! 'retcode retcode)
+			   (test::report)
+			   (sem::release!)
+			   (set! any #t)))
+		 (map pid->test pids)
+		 (wait-processes (map stringify names) pids hang))
+
+		;; If some processes finished, try to start new ones.
+		(let loop ()
+		  (cond
+		   ((not any) #f)
+		   ((pair? enqueued)
+		    (if (sem::acquire!?)
+			(let ((test (pop-test!)))
+			  (add (test::run-async))
+			  (loop)))))))))
+	(current-environment))
+      (define (filter-tests status)
+	(filter (lambda (p) (eq? status (p::status))) procs))
+      (define (report)
+	(define (print-tests tests message)
+	  (unless (null? tests)
+		  (apply echo (cons message
+				    (map (lambda (t) t::name) tests)))))
+
+	(let ((failed (filter-tests 'FAIL))
+	      (xfailed (filter-tests 'XFAIL))
+	      (xpassed (filter-tests 'XPASS))
+	      (skipped (filter-tests 'SKIP)))
+          (echo "===================")
+	  (echo (length procs) "tests run,"
+		(length (filter-tests 'PASS)) "succeeded,"
+		(length failed) "failed,"
+		(length xfailed) "failed expectedly,"
+		(length xpassed) "succeeded unexpectedly,"
+		(length skipped) "skipped.")
+	  (print-tests failed "Failed tests:")
+	  (print-tests xfailed "Expectedly failed tests:")
+	  (print-tests xpassed "Unexpectedly passed tests:")
+	  (print-tests skipped "Skipped tests:")
+          (echo "===================")
+	  (+ (length failed) (length xpassed))))
+
+      (define (xml)
+	(xx::document
+	 (xx::tag 'testsuites
+		  `((xmlns:xsi "http://www.w3.org/2001/XMLSchema-instance")
+		    ("xsi:noNamespaceSchemaLocation"
+		     "https://windyroad.com.au/dl/Open%20Source/JUnit.xsd"))
+		  (map (lambda (t) (t::xml)) procs))))))))
+
+(define (verbosity n)
+  (if (= 0 n) '() (cons '--verbose (verbosity (- n 1)))))
+
+(define (locate-test path)
+  (if (absolute-path? path) path (in-srcdir path)))
+
+;; A single test.
+(define test
+ (begin
+
+  ;; Private definitions.
+
+  (define (isotime->junit t)
+    "[0-9]{4}-[0-9]{2}-[0-9]{2}T[0-9]{2}:[0-9]{2}:[0-9]{2}"
+    "20170418T145809"
+    (string-append (substring t 0 4)
+		   "-"
+		   (substring t 4 6)
+		   "-"
+		   (substring t 6 11)
+		   ":"
+		   (substring t 11 13)
+		   ":"
+		   (substring t 13 15)))
+
+  ;; If a tests name ends with a bang (!), it is expected to fail.
+  (define (expect-failure? name)
+    (string-suffix? name "!"))
+  ;; Strips the bang (if any).
+  (define (test-name name)
+    (if (expect-failure? name)
+	(substring name 0 (- (string-length name) 1))
+	name))
+
+  (package
+   (define (scm setup name path . args)
+     ;; Start the process.
+     (define (spawn-scm args' in out err)
+       (spawn-process-fd `(,*argv0* ,@(verbosity (*verbose*))
+				    ,(locate-test (test-name path))
+				    ,@(if setup (force setup) '())
+				    ,@args' ,@args) in out err))
+     (new name #f spawn-scm #f #f CLOSED_FD (expect-failure? name)))
+
+   (define (binary setup name path . args)
+     ;; Start the process.
+     (define (spawn-binary args' in out err)
+       (spawn-process-fd `(,(test-name path)
+			   ,@(if setup (force setup) '()) ,@args' ,@args)
+			 in out err))
+     (new name #f spawn-binary #f #f CLOSED_FD (expect-failure? name)))
+
+   (define (new name directory spawn pid retcode logfd expect-failure)
+     (package
+
+      ;; XXX: OO glue.
+      (define self (current-environment))
+      (define (:set! key value)
+	(eval `(set! ,key ,value) (current-environment))
+	(current-environment))
+
+      ;; The log is written here.
+      (define log-file-name #f)
+
+      ;; Record time stamps.
+      (define timestamp #f)
+      (define start-time 0)
+      (define end-time 0)
+
+      (define (set-start-time!)
+	(set! timestamp (isotime->junit (get-isotime)))
+	(set! start-time (get-time)))
+      (define (set-end-time!)
+	(set! end-time (get-time)))
+
+      ;; Has the test been started yet?
+      (define (started?)
+	(number? pid))
+
+      (define (open-log-file)
+	(unless log-file-name
+		(set! log-file-name (string-append (basename name) ".log")))
+	(catch '() (unlink log-file-name))
+	(open log-file-name (logior O_RDWR O_BINARY O_CREAT) #o600))
+
+      (define (run-sync . args)
+	(set-start-time!)
+	(letfd ((log (open-log-file)))
+	  (with-working-directory directory
+	    (let* ((p (inbound-pipe))
+		   (pid' (spawn args 0 (:write-end p) (:write-end p))))
+	      (close (:write-end p))
+	      (splice (:read-end p) STDERR_FILENO log)
+	      (close (:read-end p))
+	      (set! pid pid')
+	      (set! retcode (wait-process name pid' #t)))))
+	(report)
+	(current-environment))
+      (define (run-sync-quiet . args)
+	(set-start-time!)
+	(with-working-directory directory
+	  (set! pid (spawn args CLOSED_FD CLOSED_FD CLOSED_FD)))
+	(set! retcode (wait-process name pid #t))
+	(set-end-time!)
+	(current-environment))
+      (define (run-async . args)
+	(set-start-time!)
+	(let ((log (open-log-file)))
+	  (with-working-directory directory
+	    (set! pid (spawn args CLOSED_FD log log)))
+	  (set! logfd log))
+	(current-environment))
+      (define (status)
+	(let* ((t' (assoc retcode '((0 PASS) (77 SKIP) (99 ERROR))))
+	       (t (if (not t') 'FAIL (cadr t'))))
+	  (if expect-failure
+	      (case t ((PASS) 'XPASS) ((FAIL) 'XFAIL) (else t))
+	      t)))
+      (define (status-string)
+	(cadr (assoc (status) '((PASS "PASS")
+			       (SKIP "SKIP")
+			       (ERROR "ERROR")
+			       (FAIL "FAIL")
+			       (XPASS "XPASS")
+			       (XFAIL "XFAIL")))))
+      (define (report)
+	(unless (= logfd CLOSED_FD)
+		(seek logfd 0 SEEK_SET)
+		(splice logfd STDERR_FILENO)
+		(close logfd))
+	(echo (string-append (status-string) ":") name))
+
+      (define (xml)
+	(xx::tag
+	 'testsuite
+	 `((name ,name)
+	   (time ,(- end-time start-time))
+	   (package ,(dirname name))
+	   (id 0)
+	   (timestamp ,timestamp)
+	   (hostname "unknown")
+	   (tests 1)
+	   (failures ,(if (eq? FAIL (status)) 1 0))
+	   (errors ,(if (eq? ERROR (status)) 1 0)))
+	 (list
+	  (xx::tag 'properties)
+	  (xx::tag 'testcase
+		   `((name ,(basename name))
+		     (classname ,(string-translate (dirname name) "/" "."))
+		     (time ,(- end-time start-time)))
+		   `(,@(case (status)
+			 ((PASS XFAIL) '())
+			 ((SKIP) (list (xx::tag 'skipped)))
+			 ((ERROR) (list
+				   (xx::tag 'error '((message "Unknown error.")))))
+			 (else
+			  (list (xx::tag 'failure '((message "Unknown error."))))))))
+	  (xx::tag 'system-out '()
+		   (list (xx::textnode (read-all (open-input-file log-file-name)))))
+	  (xx::tag 'system-err '() (list (xx::textnode "")))))))))))
+
+;; Run the setup target to create an environment, then run all given
+;; tests in parallel.
+(define (run-tests-parallel tests n)
+  (let loop ((pool (test-pool::new n)) (tests' tests))
+    (if (null? tests')
+	(let ((results (pool::wait)))
+	  ((results::xml) (open-output-file "report.xml"))
+	  (exit (results::report)))
+	(let ((wd (mkdtemp-autoremove))
+	      (test (car tests')))
+	  (test:::set! 'directory wd)
+	  (loop (pool::add test)
+		(cdr tests'))))))
+
+;; Run the setup target to create an environment, then run all given
+;; tests in sequence.
+(define (run-tests-sequential tests)
+  (let loop ((pool (test-pool::new 1)) (tests' tests))
+    (if (null? tests')
+	(let ((results (pool::wait)))
+	  ((results::xml) (open-output-file "report.xml"))
+	  (exit (results::report)))
+	(let ((wd (mkdtemp-autoremove))
+	      (test (car tests')))
+	  (test:::set! 'directory wd)
+	  (loop (pool::add (test::run-sync))
+		(cdr tests'))))))
+
+;; Run tests either in sequence or in parallel, depending on the
+;; number of tests and the command line flags.
+(define (run-tests tests)
+  (let ((parallel (flag "--parallel" *args*))
+	(default-parallel-jobs 32))
+    (if (and parallel (> (length tests) 1))
+	(run-tests-parallel tests (if (and (pair? parallel)
+					   (string->number (car parallel)))
+				      (string->number (car parallel))
+				      default-parallel-jobs))
+	(run-tests-sequential tests))))
+
+;; Load all tests from the given path.
+(define (load-tests . path)
+  (load (apply in-srcdir `(,@path "all-tests.scm")))
+  all-tests)
+
+;; Helper to create environment caches from test functions.  SETUP
+;; must be a test implementing the producer side cache protocol.
+;; Returns a promise containing the arguments that must be passed to a
+;; test implementing the consumer side of the cache protocol.
+(define (make-environment-cache setup)
+  (delay (with-temporary-working-directory
+	  (let ((tarball (make-temporary-file "environment-cache")))
+	    (atexit (lambda () (remove-temporary-file tarball)))
+	    (setup::run-sync '--create-tarball tarball)
+	    (if (not (equal? 'PASS (setup::status)))
+		(fail "Setup failed."))
+	    `(--unpack-tarball ,tarball)))))
+
+;; Command line flag handling.  Returns the elements following KEY in
+;; ARGUMENTS up to the next argument, or #f if KEY is not in
+;; ARGUMENTS.  If 'KEY=XYZ' is encountered, then the singleton list
+;; containing 'XYZ' is returned.
+(define (flag key arguments)
+  (cond
+   ((null? arguments)
+    #f)
+   ((string=? key (car arguments))
+    (let loop ((acc '())
+	       (args (cdr arguments)))
+      (if (or (null? args) (string-prefix? (car args) "--"))
+	  (reverse acc)
+	  (loop (cons (car args) acc) (cdr args)))))
+   ((string-prefix? (car arguments) (string-append key "="))
+    (list (substring (car arguments)
+		     (+ (string-length key) 1)
+		     (string-length (car arguments)))))
+   ((string=? "--" (car arguments))
+    #f)
+   (else
+    (flag key (cdr arguments)))))
+(assert (equal? (flag "--xxx" '("--yyy")) #f))
+(assert (equal? (flag "--xxx" '("--xxx")) '()))
+(assert (equal? (flag "--xxx" '("--xxx" "yyy")) '("yyy")))
+(assert (equal? (flag "--xxx" '("--xxx=foo" "yyy")) '("foo")))
+(assert (equal? (flag "--xxx" '("--xxx" "yyy" "zzz")) '("yyy" "zzz")))
+(assert (equal? (flag "--xxx" '("--xxx" "yyy" "zzz" "--")) '("yyy" "zzz")))
+(assert (equal? (flag "--xxx" '("--xxx" "yyy" "--" "zzz")) '("yyy")))
+(assert (equal? (flag "--" '("--" "xxx" "yyy" "--" "zzz")) '("xxx" "yyy")))
diff --git a/gpgscm/time.scm b/gpgscm/time.scm
new file mode 100644
index 0000000..a9b06d0
--- /dev/null
+++ b/gpgscm/time.scm
@@ -0,0 +1,42 @@
+;; Simple time manipulation library.
+;;
+;; Copyright (C) 2017 g10 Code GmbH
+;;
+;; This file is part of GnuPG.
+;;
+;; GnuPG is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation; either version 3 of the License, or
+;; (at your option) any later version.
+;;
+;; GnuPG is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+;;
+;; You should have received a copy of the GNU General Public License
+;; along with this program; if not, see <http://www.gnu.org/licenses/>.
+
+;; This library mimics what GnuPG thinks about expiration times.
+;; Granularity is one second.  Its focus is not on correctness.
+
+;; Conversion functions.
+(define (minutes->seconds minutes)
+  (* minutes 60))
+(define (hours->seconds hours)
+  (* hours 60 60))
+(define (days->seconds days)
+  (* days 24 60 60))
+(define (weeks->seconds weeks)
+  (days->seconds (* weeks 7)))
+(define (months->seconds months)
+  (days->seconds (* months 30)))
+(define (years->seconds years)
+  (days->seconds (* years 365)))
+
+(define (time-matches? a b slack)
+  (< (abs (- a b)) slack))
+(assert (time-matches? (hours->seconds 1) (hours->seconds 2) (hours->seconds 2)))
+(assert (time-matches? (hours->seconds 2) (hours->seconds 1) (hours->seconds 2)))
+(assert (not (time-matches? (hours->seconds 4) (hours->seconds 1) (hours->seconds 2))))
+(assert (not (time-matches? (hours->seconds 1) (hours->seconds 4) (hours->seconds 2))))
diff --git a/gpgscm/xml.scm b/gpgscm/xml.scm
new file mode 100644
index 0000000..771ec36
--- /dev/null
+++ b/gpgscm/xml.scm
@@ -0,0 +1,142 @@
+;; A tiny XML library.
+;;
+;; Copyright (C) 2017 g10 Code GmbH
+;;
+;; This file is part of GnuPG.
+;;
+;; GnuPG is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation; either version 3 of the License, or
+;; (at your option) any later version.
+;;
+;; GnuPG is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+;;
+;; You should have received a copy of the GNU General Public License
+;; along with this program; if not, see <http://www.gnu.org/licenses/>.
+
+(define xx
+  (begin
+
+    ;; Private declarations.
+    (define quote-text
+      '((#\< "&lt;")
+	(#\> "&gt;")
+	(#\& "&amp;")))
+
+    (define quote-attribute-'
+      '((#\< "&lt;")
+	(#\> "&gt;")
+	(#\& "&amp;")
+	(#\' "&apos;")))
+
+    (define quote-attribute-''
+      '((#\< "&lt;")
+	(#\> "&gt;")
+	(#\& "&amp;")
+	(#\" "&quot;")))
+
+    (define (escape-string quotation string sink)
+      ;; This implementation is a bit awkward because iteration is so
+      ;; slow in TinySCHEME.  We rely on string-index to skip to the
+      ;; next character we need to escape.  We also avoid allocations
+      ;; wherever possible.
+
+      ;; Given a list of integers or #f, return the sublist that
+      ;; starts with the lowest integer.
+      (define (min* x)
+	(let loop ((lowest x) (rest x))
+	  (if (null? rest)
+	      lowest
+	      (loop (if (or (null? lowest) (not (car lowest))
+			    (and (car rest) (> (car lowest) (car rest)))) rest lowest)
+		    (cdr rest)))))
+
+      (let ((i 0) (start 0) (len (string-length string))
+	    (indices (map (lambda (x) (string-index string (car x))) quotation))
+	    (next #f) (c #f))
+
+	;; Set 'i' to the index of the next character that needs
+	;; escaping, 'c' to the character that needs to be escaped,
+	;; and update 'indices'.
+	(define (skip!)
+	  (set! next (min* indices))
+	  (set! i (if (null? next) #f (car next)))
+	  (if i
+	      (begin
+		(set! c (string-ref string i))
+		(set-car! next (string-index string c (+ 1 i))))
+	      (set! i (string-length string))))
+
+	(let loop ()
+	  (skip!)
+	  (if (< i len)
+	      (begin
+		(display (substring string start i) sink)
+		(display (cadr (assv c quotation)) sink)
+		(set! i (+ 1 i))
+		(set! start i)
+		(loop))
+	      (display (substring string start len) sink)))))
+
+    (let ((escape-string-s (lambda (quotation string)
+			     (let ((sink (open-output-string)))
+			       (escape-string quotation string sink)
+			       (get-output-string sink)))))
+      (assert (equal? (escape-string-s quote-text "foo") "foo"))
+      (assert (equal? (escape-string-s quote-text "foo&") "foo&amp;"))
+      (assert (equal? (escape-string-s quote-text "&foo") "&amp;foo"))
+      (assert (equal? (escape-string-s quote-text "foo&bar") "foo&amp;bar"))
+      (assert (equal? (escape-string-s quote-text "foo<bar") "foo&lt;bar"))
+      (assert (equal? (escape-string-s quote-text "foo>bar") "foo&gt;bar")))
+
+    (define (escape quotation datum sink)
+      (cond
+       ((string? datum) (escape-string quotation datum sink))
+       ((symbol? datum) (escape-string quotation (symbol->string datum) sink))
+       ((number? datum) (display (number->string datum) sink))
+       (else
+	(throw "Do not know how to encode" datum))))
+
+    (define (name->string name)
+      (cond
+       ((symbol? name) (symbol->string name))
+       (else name)))
+
+    (package
+
+     (define (textnode string)
+       (lambda (sink)
+	 (escape quote-text string sink)))
+
+     (define (tag name . rest)
+       (let ((attributes (if (null? rest) '() (car rest)))
+	     (children (if (> (length rest) 1) (cadr rest) '())))
+	 (lambda (sink)
+	   (display "<" sink)
+	   (display (name->string name) sink)
+	   (unless (null? attributes)
+		   (display " " sink)
+		   (for-each (lambda (a)
+			       (display (car a) sink)
+			       (display "=\"" sink)
+			       (escape quote-attribute-'' (cadr a) sink)
+			       (display "\" " sink)) attributes))
+	   (if (null? children)
+	       (display "/>\n" sink)
+	       (begin
+		 (display ">\n" sink)
+		 (for-each (lambda (c) (c sink)) children)
+		 (display "</" sink)
+		 (display (name->string name) sink)
+		 (display ">\n" sink))))))
+
+     (define (document root . rest)
+       (let ((attributes (if (null? rest) '() (car rest))))
+	 (lambda (sink)
+	   ;; xxx ignores attributes
+	   (display "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n" sink)
+	   (root sink)
+	   (newline sink)))))))