Squashed commit of the following:

commit 61f2a5e0e48e050b8f73b127202af068b8cb574b
Author: Arnold D. Robbins <arnold@skeeve.com>
Date:   Fri Jun 24 11:08:22 2022 +0300

    Update awkcard.in.

commit 2b84c068b0568b4efaf93f9f6ffeaf2105295de7
Author: Arnold D. Robbins <arnold@skeeve.com>
Date:   Wed Jun 22 22:02:59 2022 +0300

    A few more small doc updates.

commit ce3bb88b7e71e1185c243bcc22cdcc7dbb250988
Author: Arnold D. Robbins <arnold@skeeve.com>
Date:   Wed Jun 22 10:33:08 2022 +0300

    Doc updates.

commit 0c101d168279d1400d3954a84a231ee70862ab61
Merge: 78fd9d6f d43b469f
Author: Arnold D. Robbins <arnold@skeeve.com>
Date:   Wed Jun 22 10:19:58 2022 +0300

    Merge branch 'master' into feature/pma2

commit 78fd9d6f1f45688d32e77ed7eb8cb18f9a140ec8
Author: Arnold D. Robbins <arnold@skeeve.com>
Date:   Mon Jun 20 08:48:35 2022 +0300

    Add --persist option.

commit a6253b1b2f3eba98a42c8b39d4af8916187d7249
Merge: bedd2e70 03f79dcb
Author: Arnold D. Robbins <arnold@skeeve.com>
Date:   Mon Jun 20 08:43:28 2022 +0300

    Merge branch 'master' into feature/pma2

commit bedd2e706af48057805b5221886912545c16f193
Author: Arnold D. Robbins <arnold@skeeve.com>
Date:   Fri Jun 17 14:40:33 2022 +0300

    Fix support/ChangeLog.

commit 8da00d7e8666808ffa50ae654b5498c4ca4b7d8c
Merge: 882a6b67 f2e71851
Author: Arnold D. Robbins <arnold@skeeve.com>
Date:   Fri Jun 17 14:39:48 2022 +0300

    Merge branch 'master' into feature/pma2

commit 882a6b67547204800ca865b530e3f8ef51ebd20c
Merge: 5c689dd7 ae879ed7
Author: Arnold D. Robbins <arnold@skeeve.com>
Date:   Fri Jun 17 14:16:36 2022 +0300

    Merge branch 'master' into feature/pma2

commit 5c689dd7da7f60228a78de3710e7d4f27c3a8eb5
Author: Arnold D. Robbins <arnold@skeeve.com>
Date:   Fri Jun 17 14:10:34 2022 +0300

    Doc fixes and small code fixes.

commit e3e5bc101641ceda429d8d98b1558dcc8aad5b0b
Author: Arnold D. Robbins <arnold@skeeve.com>
Date:   Fri Jun 17 12:33:08 2022 +0300

    Updates to pma for portability.

commit c187096f20b78631fc991898e4db62c5d6a6a441
Merge: de7bb7ee 6b97a4f7
Author: Arnold D. Robbins <arnold@skeeve.com>
Date:   Wed Jun 15 18:11:00 2022 +0300

    Merge branch 'master' into feature/pma2

commit de7bb7ee3e6d69c6c7985f43a0f06527f438e43d
Author: Arnold D. Robbins <arnold@skeeve.com>
Date:   Wed Jun 15 14:16:07 2022 +0300

    Add cygwin case to m4/pma.m4.

commit d78e8b44f8b470d894b46a0ff4cafc88ce8eed29
Author: Arnold D. Robbins <arnold@skeeve.com>
Date:   Tue Jun 14 22:43:52 2022 +0300

    Doc updates.

commit edc9ae773547c911d38b4a6fcb71946762df1e3d
Author: Arnold D. Robbins <arnold@skeeve.com>
Date:   Tue Jun 14 22:40:58 2022 +0300

    Add Mac OS support to configuration machinery.

commit 37dbf039eee81652d647aa2783f4ea4cb0266f52
Author: Arnold D. Robbins <arnold@skeeve.com>
Date:   Tue Jun 14 22:01:23 2022 +0300

    Add --disable-pma configure option and doc for it.

commit b0774ab145fe4828e54da22e6deb850fcceafcf4
Author: Arnold D. Robbins <arnold@skeeve.com>
Date:   Tue Jun 14 15:13:38 2022 +0300

    Use -no-pie only for gcc and clang.

commit fdab60d8bd6d78159571d2c4e1c4d08e0684a0ab
Author: Arnold D. Robbins <arnold@skeeve.com>
Date:   Mon Jun 13 22:59:00 2022 +0300

    Finish doc on persistent memory.

commit 17887261a7537f2e25f6cca63e1d67a93f3a3e36
Author: Arnold D. Robbins <arnold@skeeve.com>
Date:   Mon Jun 13 13:41:19 2022 +0300

    Doc and code improvements.

commit 24184e361b734aff4c7c9e96b0090cfaaf351e2d
Author: Arnold D. Robbins <arnold@skeeve.com>
Date:   Fri Jun 10 14:58:26 2022 +0300

    Fix for non-pma build.

commit f10f4af373c7ace425f2af9a68f5d6f4daa52bb3
Author: Arnold D. Robbins <arnold@skeeve.com>
Date:   Fri Jun 10 14:54:54 2022 +0300

    Get persistent stuff working!

commit 920119080d877186165506ba819a548a5ea4ae85
Author: Arnold D. Robbins <arnold@skeeve.com>
Date:   Fri Jun 10 10:29:53 2022 +0300

    Attempt pma symbol table integration. Works in pass through mode.

commit 36ba3cb86acd0cf8b70d78391ef0b77279b57b7c
Author: Arnold D. Robbins <arnold@skeeve.com>
Date:   Thu Jun 9 22:00:21 2022 +0300

    Add pma support, based on env var.

6 files changed, 1446 insertions, 34 deletions

diff --git a/support/ChangeLog b/support/ChangeLog
index 408137b1..2815c594 100644
--- a/support/ChangeLog
+++ b/support/ChangeLog
@@ -2,6 +2,21 @@
 
 	* dfa.c, dfa.h: Sync with GNULIB.
 
+2022-06-17         Arnold D. Robbins     <arnold@skeeve.com>
+
+	* pma.h (PMA_H_VERSION): Add "+ gawk" to the version string.
+	* pma.c (pma_version): Ditto.
+	(PGSZ): Now a variable, assigned equal to sysconf(_SC_PAGESIZE).
+	Allows portability to Cygwin.
+	(pma_init): Remove no-longer-used `ps' variable. Remove check
+	of PGSZ against sysconf(_SC_PAGESIZE).
+
+2022-06-09         Arnold D. Robbins     <arnold@skeeve.com>
+
+	* Makefile.am (libsupport_a_SOURCES): Add pma.c if we
+	have USE_PERSISTENT_MALLOC defined.
+	* pma.h, pma.c, agpl-3.0.txt: New files.
+
 2022-06-03         Arnold D. Robbins     <arnold@skeeve.com>
 
 	* dfa.c, dfa.h: Sync with GNULIB.
diff --git a/support/Makefile.am b/support/Makefile.am
index f209092a..9afadbd2 100644
--- a/support/Makefile.am
+++ b/support/Makefile.am
@@ -34,6 +34,8 @@ EXTRA_DIST = \
         ChangeLog.0 \
 	Makefile.am \
 	Makefile.in \
+	pma.h \
+	pma.c \
 	regcomp.c \
 	regex_internal.c \
 	regex_internal.h \
@@ -71,6 +73,10 @@ libsupport_a_SOURCES = \
 	malloc/dynarray_resize.c \
 	malloc/dynarray_resize_clear.c
 
+if USE_PERSISTENT_MALLOC
+libsupport_a_SOURCES += pma.c pma.h
+endif
+
 # For some make's, e.g. OpenBSD, that don't define this
 RM = rm -f
 
diff --git a/support/Makefile.in b/support/Makefile.in
index 476e7edf..5cbf33e7 100644
--- a/support/Makefile.in
+++ b/support/Makefile.in
@@ -111,6 +111,7 @@ PRE_UNINSTALL = :
 POST_UNINSTALL = :
 build_triplet = @build@
 host_triplet = @host@
+@USE_PERSISTENT_MALLOC_TRUE@am__append_1 = pma.c pma.h
 subdir = support
 ACLOCAL_M4 = $(top_srcdir)/aclocal.m4
 am__aclocal_m4_deps = $(top_srcdir)/m4/arch.m4 \
@@ -121,8 +122,9 @@ am__aclocal_m4_deps = $(top_srcdir)/m4/arch.m4 \
 	$(top_srcdir)/m4/lib-prefix.m4 $(top_srcdir)/m4/libsigsegv.m4 \
 	$(top_srcdir)/m4/longlong.m4 $(top_srcdir)/m4/mpfr.m4 \
 	$(top_srcdir)/m4/nls.m4 $(top_srcdir)/m4/noreturn.m4 \
-	$(top_srcdir)/m4/po.m4 $(top_srcdir)/m4/progtest.m4 \
-	$(top_srcdir)/m4/readline.m4 $(top_srcdir)/m4/socket.m4 \
+	$(top_srcdir)/m4/pma.m4 $(top_srcdir)/m4/po.m4 \
+	$(top_srcdir)/m4/progtest.m4 $(top_srcdir)/m4/readline.m4 \
+	$(top_srcdir)/m4/socket.m4 \
 	$(top_srcdir)/m4/triplet-transformation.m4 \
 	$(top_srcdir)/m4/ulonglong.m4 $(top_srcdir)/configure.ac
 am__configure_deps = $(am__aclocal_m4_deps) $(CONFIGURE_DEPENDENCIES) \
@@ -140,14 +142,23 @@ am__v_AR_0 = @echo "  AR      " $@;
 am__v_AR_1 = 
 libsupport_a_AR = $(AR) $(ARFLAGS)
 libsupport_a_LIBADD =
+am__libsupport_a_SOURCES_DIST = attribute.h cdefs.h dfa.c dfa.h \
+	dynarray.h flexmember.h getopt.c getopt.h getopt1.c \
+	getopt_int.h idx.h intprops.h libc-config.h localeinfo.c \
+	localeinfo.h random.c random.h regex.c regex.h verify.h \
+	xalloc.h malloc/dynarray.h malloc/dynarray_at_failure.c \
+	malloc/dynarray_emplace_enlarge.c malloc/dynarray_finalize.c \
+	malloc/dynarray_resize.c malloc/dynarray_resize_clear.c pma.c \
+	pma.h
 am__dirstamp = $(am__leading_dot)dirstamp
+@USE_PERSISTENT_MALLOC_TRUE@am__objects_1 = pma.$(OBJEXT)
 am_libsupport_a_OBJECTS = dfa.$(OBJEXT) getopt.$(OBJEXT) \
 	getopt1.$(OBJEXT) localeinfo.$(OBJEXT) random.$(OBJEXT) \
 	regex.$(OBJEXT) malloc/dynarray_at_failure.$(OBJEXT) \
 	malloc/dynarray_emplace_enlarge.$(OBJEXT) \
 	malloc/dynarray_finalize.$(OBJEXT) \
 	malloc/dynarray_resize.$(OBJEXT) \
-	malloc/dynarray_resize_clear.$(OBJEXT)
+	malloc/dynarray_resize_clear.$(OBJEXT) $(am__objects_1)
 libsupport_a_OBJECTS = $(am_libsupport_a_OBJECTS)
 AM_V_P = $(am__v_P_@AM_V@)
 am__v_P_ = $(am__v_P_@AM_DEFAULT_V@)
@@ -166,7 +177,7 @@ depcomp = $(SHELL) $(top_srcdir)/build-aux/depcomp
 am__maybe_remake_depfiles = depfiles
 am__depfiles_remade = ./$(DEPDIR)/dfa.Po ./$(DEPDIR)/getopt.Po \
 	./$(DEPDIR)/getopt1.Po ./$(DEPDIR)/localeinfo.Po \
-	./$(DEPDIR)/random.Po ./$(DEPDIR)/regex.Po \
+	./$(DEPDIR)/pma.Po ./$(DEPDIR)/random.Po ./$(DEPDIR)/regex.Po \
 	malloc/$(DEPDIR)/dynarray_at_failure.Po \
 	malloc/$(DEPDIR)/dynarray_emplace_enlarge.Po \
 	malloc/$(DEPDIR)/dynarray_finalize.Po \
@@ -186,7 +197,7 @@ am__v_CCLD_ = $(am__v_CCLD_@AM_DEFAULT_V@)
 am__v_CCLD_0 = @echo "  CCLD    " $@;
 am__v_CCLD_1 = 
 SOURCES = $(libsupport_a_SOURCES)
-DIST_SOURCES = $(libsupport_a_SOURCES)
+DIST_SOURCES = $(am__libsupport_a_SOURCES_DIST)
 am__can_run_installinfo = \
   case $$AM_UPDATE_INFO_DIR in \
     n|no|NO) false;; \
@@ -356,6 +367,8 @@ EXTRA_DIST = \
         ChangeLog.0 \
 	Makefile.am \
 	Makefile.in \
+	pma.h \
+	pma.c \
 	regcomp.c \
 	regex_internal.c \
 	regex_internal.h \
@@ -365,35 +378,13 @@ EXTRA_DIST = \
 
 # what to make and install
 noinst_LIBRARIES = libsupport.a
-libsupport_a_SOURCES = \
-	attribute.h \
-	cdefs.h \
-	dfa.c \
-	dfa.h \
-	dynarray.h \
-	flexmember.h \
-	getopt.c \
-	getopt.h \
-	getopt1.c \
-	getopt_int.h \
-	idx.h \
-	intprops.h \
-	libc-config.h \
-	localeinfo.c \
-	localeinfo.h \
-	random.c \
-	random.h \
-	regex.c \
-	regex.h \
-	verify.h \
-	xalloc.h \
-	malloc/dynarray.h \
-	malloc/dynarray_at_failure.c \
-	malloc/dynarray_emplace_enlarge.c  \
-	malloc/dynarray_finalize.c \
-	malloc/dynarray_resize.c \
-	malloc/dynarray_resize_clear.c
-
+libsupport_a_SOURCES = attribute.h cdefs.h dfa.c dfa.h dynarray.h \
+	flexmember.h getopt.c getopt.h getopt1.c getopt_int.h idx.h \
+	intprops.h libc-config.h localeinfo.c localeinfo.h random.c \
+	random.h regex.c regex.h verify.h xalloc.h malloc/dynarray.h \
+	malloc/dynarray_at_failure.c malloc/dynarray_emplace_enlarge.c \
+	malloc/dynarray_finalize.c malloc/dynarray_resize.c \
+	malloc/dynarray_resize_clear.c $(am__append_1)
 
 # For some make's, e.g. OpenBSD, that don't define this
 RM = rm -f
@@ -466,6 +457,7 @@ distclean-compile:
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/getopt.Po@am__quote@ # am--include-marker
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/getopt1.Po@am__quote@ # am--include-marker
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/localeinfo.Po@am__quote@ # am--include-marker
+@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/pma.Po@am__quote@ # am--include-marker
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/random.Po@am__quote@ # am--include-marker
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/regex.Po@am__quote@ # am--include-marker
 @AMDEP_TRUE@@am__include@ @am__quote@malloc/$(DEPDIR)/dynarray_at_failure.Po@am__quote@ # am--include-marker
@@ -625,6 +617,7 @@ distclean: distclean-am
 	-rm -f ./$(DEPDIR)/getopt.Po
 	-rm -f ./$(DEPDIR)/getopt1.Po
 	-rm -f ./$(DEPDIR)/localeinfo.Po
+	-rm -f ./$(DEPDIR)/pma.Po
 	-rm -f ./$(DEPDIR)/random.Po
 	-rm -f ./$(DEPDIR)/regex.Po
 	-rm -f malloc/$(DEPDIR)/dynarray_at_failure.Po
@@ -681,6 +674,7 @@ maintainer-clean: maintainer-clean-am
 	-rm -f ./$(DEPDIR)/getopt.Po
 	-rm -f ./$(DEPDIR)/getopt1.Po
 	-rm -f ./$(DEPDIR)/localeinfo.Po
+	-rm -f ./$(DEPDIR)/pma.Po
 	-rm -f ./$(DEPDIR)/random.Po
 	-rm -f ./$(DEPDIR)/regex.Po
 	-rm -f malloc/$(DEPDIR)/dynarray_at_failure.Po
diff --git a/support/agpl-3.0.txt b/support/agpl-3.0.txt
new file mode 100644
index 00000000..be3f7b28
--- /dev/null
+++ b/support/agpl-3.0.txt
@@ -0,0 +1,661 @@
+                    GNU AFFERO GENERAL PUBLIC LICENSE
+                       Version 3, 19 November 2007
+
+ Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+                            Preamble
+
+  The GNU Affero General Public License is a free, copyleft license for
+software and other kinds of works, specifically designed to ensure
+cooperation with the community in the case of network server software.
+
+  The licenses for most software and other practical works are designed
+to take away your freedom to share and change the works.  By contrast,
+our General Public Licenses are intended to guarantee your freedom to
+share and change all versions of a program--to make sure it remains free
+software for all its users.
+
+  When we speak of free software, we are referring to freedom, not
+price.  Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+them if you wish), that you receive source code or can get it if you
+want it, that you can change the software or use pieces of it in new
+free programs, and that you know you can do these things.
+
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+with two steps: (1) assert copyright on the software, and (2) offer
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+and/or modify the software.
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diff --git a/support/pma.c b/support/pma.c
new file mode 100644
index 00000000..da4d0b9a
--- /dev/null
+++ b/support/pma.c
@@ -0,0 +1,663 @@
+/* "pma", a persistent memory allocator (implementation)
+   Copyright (C) 2019, 2022  Terence Kelly
+   Contact:  tpkelly @ { acm.org, cs.princeton.edu, eecs.umich.edu }
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Affero General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 Affero General Public License for more details.
+
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+   Code is intended to be (mostly) C99 / POSIX 2017.
+
+   Compile and link with your programs in the obvious way.  If
+   assertions are enabled (the default) extensive integrity checks
+   are frequently performed; these checks may be slow, depending on
+   the size and state of the persistent heap.
+*/
+
+#define _DEFAULT_SOURCE  // for MAP_ANONYMOUS
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <inttypes.h>
+#include <limits.h>
+#include <math.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#include "pma.h"
+
+// Software version; not the same as backing file format version.
+const char pma_version[] = "2022.05May.01 (Avon 5) + gawk";
+
+#define S(s) #s
+#define S2(s) S(s)
+#define COORDS __FILE__ ":" S2(__LINE__) ": "
+#define FP(...) (void)fprintf(stderr, COORDS __VA_ARGS__)
+#define ERN " errno => '%s'\n", strerror(errno)
+#define ERR(...) do { if (0 < state.vrb) FP("ERROR: "   __VA_ARGS__); } while (0)
+#define WRN(...) do { if (1 < state.vrb) FP("Warning: " __VA_ARGS__); } while (0)
+#define FYI(...) do { if (2 < state.vrb) FP("FYI: "     __VA_ARGS__); } while (0)
+
+int        pma_errno;
+#define SE pma_errno = __LINE__
+#define RL return      __LINE__
+#define RN return NULL
+#define SERL do { SE; RL; } while (0)
+#define SERN do { SE; RN; } while (0)
+
+enum {
+  VERS = 2,     // backing file format version number
+  WDSZ = 8,     // word size (bytes)
+  NFL  = 422    // number of free lists / size classes
+};
+
+static int PGSZ;	// can vary per system and even dynamically
+
+typedef struct ao {  // alloc object
+  struct ao *anext,          // header; singly linked list of all aos in addr order
+            *fprev, *fnext;  // for doubly linked free list
+} ao_t;
+
+// We stash three flags in the least significant bits of a header:
+// bit 0:  is this ao in use (i.e., live, as opposed to free)?
+// bit 1:  is the previous ao on the state.anext list in use?
+// bit 2:  has this ao ever grown via realloc?
+
+// Some older compilers gratuitously reject the himask definition on
+// the first line below despite it being perfectly legal C99.  The
+// workaround on the second line below appears correct by inspection
+// but it has not yet been subjected to the same extensive tests as
+// the original.
+// static const uintptr_t lomask = 0x7, himask = ~lomask;  // requires recent compiler
+static const uintptr_t lomask = 0x7, himask = ~ ( (uintptr_t) 0x7 );  // not extensively tested as of Fri 27 May 2022
+
+// extract bits from header
+#define HIBH(ao_t_ptr) ((ao_t *)((uintptr_t)(ao_t_ptr) & himask))
+#define LOBH(ao_t_ptr) ((ao_t *)((uintptr_t)(ao_t_ptr) & lomask))
+
+// size of an ao is its memory footprint; capacity of ao is number of bytes
+// available to caller; difference is header overhead of live (in-use) ao
+#define AOSZ(ao_t_ptr) ((size_t)((uintptr_t)HIBH((ao_t_ptr)->anext) - (uintptr_t)HIBH(ao_t_ptr)))
+#define AOCAP(ao_t_ptr) (AOSZ(ao_t_ptr) - WDSZ)
+
+#define Z1(i) assert(0 == (i) || 1 == (i))
+static void slobh(ao_t *p, int iu, int piu, int grown) {  // set low bits of header to which p points
+  uintptr_t h;
+  assert(p);  Z1(iu);  Z1(piu);  Z1(grown);
+  h = (uintptr_t)p->anext;
+  h &= himask;  // clear low bits
+  h |= (uintptr_t)(iu | piu << 1 | grown << 2);
+  p->anext = (ao_t *)h;
+}
+
+// getters below could be re-written as simpler macros
+
+static void globh(const ao_t *p, int *iu, int *piu, int *grown) {  // get low bits of header to which p points
+  uintptr_t h;
+  assert(p && iu && piu && grown);
+  h = (uintptr_t)p->anext;
+  *iu    = !!(h & 0x1);  Z1(*iu);
+  *piu   = !!(h & 0x2);  Z1(*piu);
+  *grown = !!(h & 0x4);  Z1(*grown);
+}
+
+typedef struct {     // header of backing file; contains allocator metadata
+  void * mapaddr;    // virtual address where backing file must be mapped
+  uint64_t bf_vers,  // version number of backing file format
+           nallocs,  // number of allocations
+           nfrees,   // number of de-allocations
+           res_0;    // reserved for possible future use
+  void * root;       // live persistent data must be reachable from root
+  ao_t * afirst,     // list of all alloc objects, both live & free, in addr order
+       * abound;     // one beyond end of allocatable area
+  ao_t free[NFL];    // free lists; each has dummy header
+} pma_hdr_t;
+
+static struct {
+  int init,           // has persistent heap been initialized?
+      vrb;            // verbsity level
+  const char * file;  // name of backing file
+  pma_hdr_t * hdr;    // addr where backing file is mapped
+} state;
+
+#define ASI assert(1 == state.init || 2 == state.init)
+
+enum { IU = 0, PIU = 1, GROWN = 2 };
+
+static int getbit(ao_t *p, int bit) {
+  int iu, piu, grown;
+  globh(p, &iu, &piu, &grown);
+  switch (bit) {
+    case     IU:  return      iu;
+    case    PIU:  return     piu;
+    case  GROWN:  return   grown;
+    default:
+      ERR("bad bit: %d\n", bit);
+      assert(0);
+      return INT_MIN;
+  }
+}
+
+#define DP(...) (void)fprintf(stderr, __VA_ARGS__)
+#define VS      (void *)
+
+#ifndef NDEBUG
+static int valid_footer(ao_t *p) {
+  if (!getbit(p, IU)) {
+    ao_t **ftr = (ao_t **)HIBH(p->anext) - 1;
+    return *ftr == p;   // footer should point to header
+  }
+  else
+    return 1;
+}
+// valid ao ptr:
+#define VAO(p)  (VS state.hdr->afirst <= VS (p) && VS state.hdr->abound > VS (p))
+#define VAF(p)  (VAO(p) && valid_footer(p))
+#endif // NDEBUG
+
+static void pao(ao_t *p) {  // print ao
+  int iu, piu, grown;
+  ao_t **footer = (ao_t **) ((char *)p + AOSZ(p)) - 1;  // TODO:  squelch alignment warning?
+  assert(VAO(p));
+  assert(0 == AOSZ(p) % WDSZ);
+  assert(0 == LOBH(p));
+  globh(p, &iu, &piu, &grown);
+  DP("    AO at %p:  size %lu B / %lu w\n"
+     "      hdr %p (H 0%lo L 0%lo) iu %d piu %d grown %d\n"
+     "      fp  %p%s\n"
+     "      fn  %p%s\n"
+     "      ft  %p%s\n",
+     VS p, AOSZ(p), AOSZ(p) / WDSZ,
+     VS p->anext, (uintptr_t)HIBH(p->anext), (uintptr_t)LOBH(p->anext), iu, piu, grown,
+     VS p->fprev, iu ? " (ignore)" : "",
+     VS p->fnext, iu ? " (ignore)" : "",
+     VS *footer,  iu ? " (ignore)" : "");
+}
+
+static size_t UB[NFL];  // UB[c] is upper bound of size class c in machine words
+
+#define IC integrity_check(__LINE__)
+static int integrity_check(int line) {  // can be slow; intended for debugging small heaps
+  pma_hdr_t *h = state.hdr;
+  int nadd = 0, naddfree = 0, tiu = 0, tpiu = 0, tf = 0;  // beware overflow if lists are long
+  FYI("integrity_check called from line %d\n", line);
+#ifdef NDEBUG
+  WRN("integrity check relies on assertions, which are disabled (call at line %d)\n", line);
+#endif
+  assert(h && h == h->mapaddr);
+  // check addr-ordered list
+  for (ao_t *next, *a = h->afirst; a < h->abound; a = next) {
+    next = HIBH(a->anext);
+    assert(VAF(a));
+    assert(32 <= AOSZ(a));
+    assert(next > a && next <= h->abound);
+    if (1000000 < ++nadd) {
+      WRN("integrity check discontinued; anext list too long (call at line %d)\n", line);
+      SE;        // if persistent heap contains too many aos/blocks,
+      return 0;  // integrity check will be too slow; therefore discontinue
+    }
+    if (0 == getbit(a, IU))
+      ++naddfree;
+    tiu  += getbit(a,  IU);  // total number of aos with in-use bit set
+    tpiu += getbit(a, PIU);  // total number of aos with previous-ao-is-in-use bit set
+  }
+  assert(tpiu == tiu || 1 + tpiu == tiu);
+  FYI("anext list length: %d  tiu %d  tpiu %d  nallocs %lu  nfrees %lu\n",
+                          nadd,   tiu,     tpiu,       h->nallocs, h->nfrees);
+  assert(h->nallocs >= h->nfrees);
+  assert(h->nallocs - h->nfrees == (uint64_t)tiu);
+  // check free lists
+  for (int i = 0; i < NFL; i++) {
+    ao_t *p, *f = &(h->free[i]);
+    if (f->fprev == f)   // empty list
+      assert(f->fnext == f);
+    else {
+      int nfwd = 0, nrev = 0;  // count how many we find going forward and reverse
+      for (p = f->fnext; p != f; p = p->fnext) { nfwd++; assert(VAF(p)); assert(0 == getbit(p, IU)); }
+      for (p = f->fprev; p != f; p = p->fprev) { nrev++; assert(VAF(p)); assert(0 == getbit(p, IU)); }
+      assert(nfwd == nrev);    // count should be the same in both directions
+      tf += nfwd;
+      // check ao sizes against UB
+      for (p = f->fnext; p != f; p = p->fnext) {
+        #ifndef NDEBUG
+        size_t capwords = AOCAP(p) / WDSZ;
+        #endif
+        assert(capwords <= UB[i]);
+        if (0 < i)
+          assert(capwords > UB[i-1]);
+      }
+    }
+  }
+  FYI("total free aos: %d  naddfree %d  integrity check line %d\n", tf, naddfree, line);
+  assert(tf == naddfree);
+  return 0;
+}
+
+#define NM " not meaningful in fallback mode\n"
+
+void pma_check_and_dump(void) {
+  pma_hdr_t *h = state.hdr;
+  ASI;
+  if (2 == state.init) { ERR("check_and_dump" NM); assert(0); SE; return; }
+  if (IC) ERR("integrity check failed\n");
+  DP(COORDS "check data structures and dump\n");
+  DP("header version:    %s\n", PMA_H_VERSION);
+  DP("software version:  %s\n", pma_version);
+  DP("sizeof state:  %lu\n", sizeof state);
+  DP("sizeof header: %lu\n", sizeof(pma_hdr_t));
+  DP("state:\n");
+  DP("  init: %d\n", state.init);  assert(0 == state.init || 1 == state.init || 2 == state.init);
+  DP("  vrb:  %d\n", state.vrb);   assert(0 <= state.vrb && 3 >= state.vrb);
+  DP("  file: %p \"%s\"\n", (const void *)state.file, state.file);
+  DP("  hdr:  %p\n", VS h);
+  if (NULL != h) {
+    DP("header:\n");   // nallocs & nfrees not printed; they'd add noise to initial/final state diff
+    DP("  mapaddr: %p\n", h->mapaddr);
+    DP("  bf_vers: %" PRIu64 "\n", h->bf_vers);
+    DP("  root:   %p\n", h->root);    assert(NULL == h->root || (h->root >= VS h->afirst && h->root < VS h->abound));
+    DP("  afirst: %p\n", VS h->afirst);  assert(VS h->afirst > h->mapaddr);
+    DP("  abound: %p\n", VS h->abound);  assert(h->abound > h->afirst);
+    DP("  all allocated objects in addr order:\n");
+    for (ao_t *a = h->afirst; a < h->abound; a = HIBH(a->anext)) {
+      assert(HIBH(a->anext) > a);
+      pao(a);
+    }
+    for (int i = 0; i < NFL; i++) {
+      ao_t *f = &(h->free[i]);
+      if (f->fprev == f)   // empty list
+        assert(f->fnext == f);
+      else {
+        DP("  free list of size class %d UB %lu (prev %lu) list head %p:\n", i, UB[i], i > 0 ? UB[i-1] : 0, VS f);
+        for (ao_t *p = f->fnext; p != f; p = p->fnext)
+          pao(p);
+      }
+    }
+  }
+}
+#undef DP
+
+static int sc(size_t nbytes) {  // compute size class; nbytes is malloc() arg
+  static int init;
+  const size_t maxwords = (size_t)0x1 << 61;  // 2^61 words == 2^64 bytes
+  size_t nwords;
+  int c;
+  if (! init) {
+    FYI("initializing UB[]\n");
+    UB[0] = 3;  // smallest allocation has size (AOSZ) 4 words and capacity (AOCAP) 3 words
+    for (c = 1; ; c++) {
+      long double hi = floorl((long double)(1 + UB[c-1]) * 1.1L);
+      assert(NFL > c);
+      if (hi >= (long double)maxwords) { UB[c] = maxwords; break; }
+      else                               UB[c] = (size_t)hi;
+    }
+    assert(NFL - 1 == c);
+    init = 1;
+  }
+  nwords = (nbytes / WDSZ) + !!(nbytes % WDSZ);
+  assert(nwords <= maxwords);
+  for (c = 0; NFL > c; c++)
+    if (nwords <= UB[c])
+      break;
+  assert(NFL > c);
+  return c;
+}
+
+static void fli(ao_t *p) {  // insert given ao at head of appropriate free list
+  ao_t *h;
+  int fl;
+  assert(NULL != p);
+  assert(VAO(p));
+  fl = sc(AOCAP(p));
+  assert(0 <= fl && NFL > fl);
+  h = &(state.hdr->free[fl]);  // head of free list
+  FYI("fli(%p) h == %p h->fn %p h->fp %p\n", VS p, VS h, VS h->fnext, VS h->fprev);
+  p->fprev = h;
+  p->fnext = h->fnext;
+  h->fnext->fprev = p;
+  h->fnext = p;
+}
+
+static void flr(ao_t *p) {  // remove ao from free list
+  p->fnext->fprev = p->fprev;
+  p->fprev->fnext = p->fnext;
+  p->fprev = p->fnext = NULL;
+}
+
+#define MMAP(N) mmap(NULL, (N), PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE, -1, 0)
+#define MUNMAP(A, N) do { if (0 != munmap((A), (N))) ERR("mmap()" ERN); } while (0)
+static void * addrgap(off_t n) {  // find big gap in address space to map n bytes
+  void *A, *Amax = NULL;  size_t L = 0, U, Max = 0, N = (size_t)n;  char *r;
+  FYI("addrgap(%ld)\n", n);
+  if (N % (size_t)PGSZ) { ERR("file size %lu not multiple of PGSZ\n", N); SERN; }
+  if (N < sizeof(pma_hdr_t) + 10 * PGSZ) { ERR("file size %lu too small\n", N); SERN; }
+  for (U = 1; ; U *= 2)  // double upper bound until failure
+    if (MAP_FAILED == (A = MMAP(U))) break;
+    else                   MUNMAP(A, U);
+  while (1 + L < U) {  // binary search between bounds
+    size_t M = L + (U - L) / 2;  // avoid overflow
+    if (MAP_FAILED == (A = MMAP(M))) {      U = M; }
+    else { Amax = A; Max = M; MUNMAP(A, M); L = M; }
+  }
+  FYI("max gap: %lu bytes at %p\n", Max, Amax);
+  if (Max < N + (size_t)PGSZ * 2) {  // safety margin
+    ERR("max gap %lu too small for required %lu\n", Max, N);
+    SERN;
+  }
+  r = (char *)Amax + (Max - N)/2;
+  while ((uintptr_t)r % PGSZ)  // page align
+    r++;
+  FYI("addrgap returns %p == %lu\n", VS r, (uintptr_t)r);
+  return r;
+}
+#undef MMAP
+#undef MUNMAP
+
+#define MM(a,s,f) mmap((a), (size_t)(s), PROT_READ | PROT_WRITE, MAP_SHARED, (f), 0)
+int pma_init(int verbose, const char *file) {
+  int fd;  void *a1, *a2;  size_t as = sizeof(a1);  struct stat s;
+  pma_hdr_t *h;
+  assert(0 <= verbose && 3 >= verbose);
+  state.vrb = verbose;
+  if (state.init) { ERR("already initialized\n"); assert(0); SERL; }
+  FYI("pma software version \"%s\" header version \"%s\", expects backing file format version %d\n",
+      pma_version, PMA_H_VERSION, VERS);
+  assert(0 == strcmp(pma_version, PMA_H_VERSION));
+  FYI("pma_init(%d,\"%s\")\n", verbose, file);
+  // check assumptions
+  assert(WDSZ == sizeof(void *));  // in C11 we'd static_assert()
+  assert(WDSZ == sizeof(size_t));
+  assert(WDSZ == sizeof(unsigned long));
+  assert(0 == sizeof(pma_hdr_t) % WDSZ);
+
+  PGSZ = sysconf(_SC_PAGESIZE);
+  if (NULL == file) {
+    WRN("no backing file provided; falling back on standard malloc\n");
+    state.init = 2;
+    state.file = NULL;
+    state.hdr  = NULL;
+    return 0;
+  }
+  // map backing file containing persistent heap
+  if (0 > (fd = open(file, O_RDWR)))      { ERR("open()"    ERN); SERL; }
+  if (0 != fstat(fd, &s))                 { ERR("fstat()"   ERN); SERL; }
+  if (!S_ISREG(s.st_mode))                { ERR("not reg\n"    ); SERL; }
+  if ((ssize_t)as != read(fd, &a1, as))   { ERR("read()"    ERN); SERL; }
+  if (NULL == a1) a1 = addrgap(s.st_size);
+  if (NULL == a1)                         { ERR("addrgap()" ERN);   RL; }
+  FYI("map at %p\n", a1);
+  if (a1 != (a2 = MM(a1, s.st_size, fd))) { ERR("mmap()"    ERN); SERL; }
+  if (0 != close(fd))                     { ERR("close()"   ERN); SE;   }  // carry on
+  state.init = 1;
+  state.file = file;
+  state.hdr  = h = (pma_hdr_t *)a2;
+  if (NULL == h->mapaddr) {
+    int i;
+    ao_t *w, **ftr;  // initial "wilderness", footer
+    FYI("initializing persistent heap\n");
+    assert(      0 == h->bf_vers
+           &&    0 == h->nallocs
+           &&    0 == h->nfrees
+           &&    0 == h->res_0
+           && NULL == h->root
+           && NULL == h->afirst
+           && NULL == h->abound);
+    for (i = 0; i < NFL; i++) {
+      assert(   NULL == h->free[i].anext
+             && NULL == h->free[i].fprev
+             && NULL == h->free[i].fnext);
+      // free[i] is dummy node in doubly-linked free list; this simplifies code to splice aos into & out of free list
+      h->free[i].fprev = h->free[i].fnext = &(h->free[i]);
+    }
+    h->mapaddr = h;
+    h->bf_vers = VERS;
+    h->nallocs = 0;
+    h->nfrees  = 0;
+    h->res_0   = 0;
+    h->afirst = (ao_t *)(1 + h);
+    h->abound = (ao_t *)((char *)h + s.st_size);  // TODO: squelch alignment warning?
+    // install "wilderness" free ao on all-object list; every free ao has a
+    // footer pointing to its header, to facilitate coalescing adjacent frees;
+    // header on final ao points beyond allocatable area
+    w = h->afirst;
+    w->anext = h->abound;
+    assert(0 == AOSZ(w) % WDSZ && WDSZ < AOSZ(w));
+    ftr = (ao_t **)h->abound - 1;
+    *ftr = w;
+    fli(w);
+  }
+  else {
+    FYI("persistent heap already initialized\n");
+    if (VERS != h->bf_vers) {
+      ERR("backing file version mismatch: %d vs. %" PRIu64 "\n", VERS, h->bf_vers);
+      SERL;
+    }
+    (void)sc(1);  // to populate UB[]
+  }
+  if (IC) { ERR("integrity check failed\n"); SERL; }
+  return 0;
+}
+#undef MM
+
+// bite off adequate prefix if ao is too large, return remainder to appropriate
+// free list; must handle two cases:  given ao is free, versus given ao is live
+// and is being shrunk by realloc
+static ao_t * split_ao(ao_t *p, size_t s) {
+  size_t c = AOCAP(p), Cw = c / WDSZ, Sw;  int iu, piu, grown;  ao_t *n;
+  if (s < 24) s = 24;  // increase request size to minimum allocation size if necessary; TODO: magic number here
+  Sw = s / WDSZ + !!(s % WDSZ);
+  assert(NULL == LOBH(p));  // lo bits of header (p->anext) might be set, but not lo bits of p
+  assert(NULL == p->fprev && NULL == p->fnext);  // *p should already be spliced out of free lists
+  assert(c >= s && 0 == c % WDSZ);
+  FYI("split_ao(%p,%lu) AOCAP %lu words req %lu words cap %lu\n", VS p, s, c, Sw, Cw);
+  globh(p, &iu, &piu, &grown);
+  if (4 <= Cw - Sw) {  // split ao if remainder is large enough to be allocatable
+    ao_t  *rem = (ao_t *)(&(p->fprev) + Sw),   // remainder
+         **rft = (ao_t **)HIBH(p->anext) - 1;  // footer of remainder
+    FYI("splitting at %p\n", VS rem);
+    rem->anext = HIBH(p->anext);  // set header of remainder
+    *rft = rem;                   // set footer of remainder
+    fli(rem);
+    p->anext = rem;   // set header of *p
+  }
+  assert(AOCAP(p) >= s);
+  slobh(p, 1, piu, grown);  // in-use bit is set; values of prev-in-use and grown bits are preserved
+  // set prev-in-use bit of next ao on anext list (if such exists), preserving iu and grown bits
+  n = HIBH(p->anext);
+  assert(n <= state.hdr->abound);
+  if (n < state.hdr->abound) {
+    globh(n, &iu, &piu, &grown);
+    slobh(n,  iu,    1,  grown);
+  }
+  return p;
+}
+
+void * pma_malloc(size_t size) {
+  ao_t *r = NULL;
+  FYI("malloc(%lu)\n", size);
+  ASI;
+  if (2 == state.init) return malloc(size);
+  assert(!IC);
+  if (0 >= size) {
+    WRN("malloc(%lu) argument <= zero\n", size);  SERN;  }
+  for (int c = sc(size); c < NFL; c++) {
+    ao_t *h = &(state.hdr->free[c]);
+    // FYI("check size class %d UB %lu\n", c, UB[c]);
+    for (ao_t *f = h->fnext; f != h; f = f->fnext) {
+      // FYI("free list contains ao with capacity %lu\n", AOCAP(f));
+      if (AOCAP(f) >= size) {
+        r = f;
+        goto end;
+      }
+    }
+  }
+  end:
+  if (NULL != r) {
+    flr(r);
+    r = split_ao(r, size);
+    FYI("malloc returning %p\n", VS &(r->fprev));
+    ++(state.hdr->nallocs);
+    assert(!IC);
+    return &(r->fprev);
+  }
+  else {
+    WRN("malloc(%lu) cannot satisfy request at this time\n", size);
+    SERN;  // conflates ENOMEM / EAGAIN (request might succeed after frees)
+  }
+}
+
+void * pma_calloc(size_t nmemb, size_t size) {
+  void *p;
+  FYI("calloc(%lu,%lu)\n", nmemb, size);
+  ASI;
+  if (2 == state.init) return calloc(nmemb, size);
+  if (0 >= nmemb || 0 >= size) {
+    WRN("calloc(%lu,%lu) argument <= zero\n", nmemb, size);  SERN;  }
+  // SSIZE_MAX exists but SIZE_MAX apparently doesn't; sheesh
+  if (nmemb > UINT64_MAX / size) {
+    WRN("calloc(%lu,%lu) arguments overflow\n", nmemb, size);  SERN;  }
+  if (NULL != (p = pma_malloc(nmemb * size)))
+    (void)memset(p, 0, nmemb * size);
+  return p;
+}
+
+void * pma_realloc(void *ptr, size_t size) {
+  ao_t *p;  void *nu;  // "new" is a C++ keyword
+  FYI("realloc(%p,%lu)\n", ptr, size);
+  ASI;
+  if (2 == state.init) return realloc(ptr, size);
+  if (NULL == ptr) return pma_malloc(size);
+  if (0 >= size) { pma_free(ptr); RN; }
+  p = (ao_t *)((ao_t **)ptr - 1);
+  if (AOCAP(p) >= size)  // no growth needed
+    return ptr;
+  nu = pma_malloc(size);
+  if (NULL == nu)
+    SERN;
+  (void)memcpy(nu, ptr, AOCAP(p));
+  pma_free(ptr);
+  return nu;
+}
+
+// Merge *p with next ao on anext list; returns 1 if coalesces, 0 otherwise.
+// Flag indicates which of the two aos is on the free list and must be removed.
+static int coalesce(ao_t *p, int flr_lo_hi) {
+  ao_t *n = HIBH(p->anext), **ftr;  int piu;
+  assert(n > p && n <= state.hdr->abound);
+  FYI("coalesce(%p)\n", VS p);
+  if (n >= state.hdr->abound)  // *p is final ao on anext list
+    return 0;
+  if (0 == getbit(n, IU)) {  // next ao is not in use, therefore coalesce
+    flr(flr_lo_hi ? n : p);  // remove appropriate ao from free list
+    piu = getbit(p, PIU);
+    p->anext = HIBH(n->anext);
+    ftr = (ao_t **)p->anext - 1;
+    *ftr = p;
+    slobh(p, 0, piu, 0);  // preserve prev-in-use bit of header of *p
+    return 1;
+  }
+  else  // next ao is in use, therefore do not coalesce
+    return 0;
+}
+
+void pma_free(void *ptr) {
+  ao_t *p, *n, **ftr;  int r;
+  FYI("free(%p)\n", ptr);
+  ASI;
+  if (2 == state.init) { free(ptr); return; }
+  assert(!IC);
+  if (NULL == ptr) return;  // allowed by C & POSIX
+  if (! (VS state.hdr->afirst <= ptr && VS state.hdr->abound > ptr)) {  // e.g., p=strdup("foo") ... pma_free(p);
+    ERR("freed ptr %p outside allocatable area bounds %p %p\n",
+        ptr, VS state.hdr->afirst, VS state.hdr->abound);
+    assert(0);
+    SE;
+    return;
+  }
+  assert(0 == (uintptr_t)ptr % WDSZ);
+  p = (ao_t *)((ao_t **)ptr - 1);
+  assert(VAO(p));
+  n = HIBH(p->anext);
+  assert(p < n && n <= state.hdr->abound);
+  assert(1 == getbit(p, IU));
+  slobh(p, 0, getbit(p, PIU), 0);  // clear iu and grown bits of *p header
+  if (n < state.hdr->abound)
+    assert(1 == getbit(n, PIU));
+  FYI("merge with right/higher ao\n");
+  r = coalesce(p, 1);
+  FYI("%s\n", r ? "yes" : "no");
+  if (0 == getbit(p, PIU) && p > state.hdr->afirst) {  // if ao is not leftmost/lowest and previous/lower ao is not in use, merge
+    ao_t *prev = *((ao_t **)p - 1);
+    assert(prev < p);
+    FYI("merge with left/lower ao\n");
+    r = coalesce(prev, 0);
+    assert(r);
+    p = prev;
+  }
+#ifndef NDEBUG
+  (void)memset(&(p->fprev), 0, AOCAP(p));  // for near-complete "reversibility"
+#endif
+  n = HIBH(p->anext);
+  assert(p < n && n <= state.hdr->abound);
+  ftr = (ao_t **)n - 1;
+  *ftr = p;
+  if (n < state.hdr->abound)
+    slobh(n, getbit(n, IU), 0, getbit(n, GROWN));  // clear prev-in-use bit of next
+  fli(p);
+  ++(state.hdr->nfrees);
+  assert(!IC);
+ }
+
+void pma_set_root(void *p) {
+  FYI("set_root(%p)\n", p);
+  ASI;
+  if (2 == state.init) { ERR("set_root" NM); assert(0); SE; return; }
+  assert(NULL == p || VAO(p));  // could also check that p "looks like" pointer returned by malloc,
+  state.hdr->root = p;          // e.g., header's in-use bit should be set and HIBH should be reasonable
+}
+
+void * pma_get_root(void) {
+  void *p;
+  FYI("get_root()\n");
+  ASI;
+  if (2 == state.init) { ERR("get_root" NM); assert(0); SERN; }
+  p = state.hdr->root;
+  assert(NULL == p || VAO(p));
+  return p;
+}
+
+typedef unsigned long ul_t;
+void pma_set_avail_mem(const ul_t v) {
+  FYI("set_avail_mem(0x%lx)\n", v);
+  ASI;
+  if (2 == state.init) { ERR("set_avail_mem" NM); assert(0); SE; return; }
+  assert(!IC);
+  for (int i = 0; i < NFL; i++) {
+    ao_t *p, *f = &(state.hdr->free[i]);
+    if (f->fprev != f)
+      for (p = f->fnext; p != f; p = p->fnext) {
+        ul_t *q = (ul_t *)(1 + p),
+             *e = (ul_t *)(HIBH(p->anext)) - 1;
+        for ( ; q != e; q++)
+          if (*q != v)  // avoid over-writing same value; gratuitous modification is a Bad Thing for persistent memory
+            *q = v;
+        for ( ; q != e; q++)
+          assert(*q == v);
+      }
+  }
+  assert(!IC);
+}
+
diff --git a/support/pma.h b/support/pma.h
new file mode 100644
index 00000000..f5851d96
--- /dev/null
+++ b/support/pma.h
@@ -0,0 +1,73 @@
+/* "pma", a persistent memory allocator (interface)
+   Copyright (C) 2022  Terence Kelly
+   Contact:  tpkelly @ { acm.org, cs.princeton.edu, eecs.umich.edu }
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Affero General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 Affero General Public License for more details.
+
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+#ifndef PMA_H_INCLUDED
+#define PMA_H_INCLUDED
+
+// version strings of interface and implementation should match
+#define PMA_H_VERSION "2022.05May.01 (Avon 5) + gawk"
+extern const char pma_version[];
+
+/* May contain line number in pma.c where something went wrong if one
+   of the other interfaces fails.  "Use the Source, Luke." */
+extern int pma_errno;
+
+/* Must be called exactly once before any other pma_* function is
+   called, otherwise behavior is undefined.  Available verbosity
+   levels are: 0 => no diagnostic printouts, 1 => errors only printed
+   to stderr, 2 => also warnings, 3 => also very verbose "FYI"
+   messages.  Use verbosity level 2 by default.  File argument
+   specifies backing file containing persistent heap, initially an
+   empty sparse file whose size is a multiple of the system page
+   size.  If file argument is NULL, fall back on standard memory
+   allocator: pma_malloc passes the buck to ordinary malloc, pma_free
+   calls ordinary free, etc.  In fallback-to-standard-malloc mode,
+   only pma_malloc/calloc/realloc/free may be used; other functions
+   such as pma_get/set_root must not be used.  The implementation may
+   store a copy of the file argument, i.e., the pointer, so both this
+   pointer and the memory to which it points (*file) must not
+   change. */
+extern int pma_init(int verbose, const char *file);
+
+/* The following four functions may be used like their standard
+   counterparts.  See notes on pma_init for fallback to standard
+   allocator.  See notes on fork in README. */
+extern void * pma_malloc(size_t size);
+extern void * pma_calloc(size_t nmemb, size_t size);
+extern void * pma_realloc(void *ptr, size_t size);
+extern void   pma_free(void *ptr);
+
+/* The following two functions access the persistent heap's root
+   pointer, which must either be NULL or must point within a block of
+   persistent memory.  If the pointer passed to pma_set_root is not a
+   pointer returned by pma_malloc/calloc/realloc, that is likely a
+   bug, though the implementation is not obliged to check for such
+   bugs. */
+extern void   pma_set_root(void *ptr);
+extern void * pma_get_root(void);
+
+/* Prints to stderr details of internal data structures, e.g., free
+   lists, and performs integrity checks, which may be very slow. */
+extern void pma_check_and_dump(void);
+
+/* Set non-metadata words of free blocks to given value.  Useful for
+   debugging (v == 0xdeadDEADbeefBEEF) and for preparing backing file
+   to be re-sparsified with fallocate (v == 0x0). */
+extern void pma_set_avail_mem(const unsigned long v);
+
+#endif // PMA_H_INCLUDED