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+;;; installed-scm-file
+
+;;;; 	Copyright (C) 1995, 1996 Free Software Foundation, Inc.
+;;;; 
+;;;; This program 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 2, 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 General Public License for more details.
+;;;; 
+;;;; You should have received a copy of the GNU General Public License
+;;;; along with this software; see the file COPYING.  If not, write to
+;;;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
+;;;; 
+
+
+(define-module  #/ice-9/hcons)
+
+
+;;; {Eq? hash-consing}
+;;;
+;;; A hash conser maintains a private universe of pairs s.t. if 
+;;; two cons calls pass eq? arguments, the pairs returned are eq?.
+;;;
+;;; A hash conser does not contribute life to the pairs it returns.
+;;;
+
+(define-public (hashq-cons-hash pair n)
+  (modulo (logxor (hashq (car pair) 4194303)
+		  (hashq (cdr pair) 4194303))
+	  n))
+
+(define-public (hashq-cons-assoc key l)
+  (and l (or (and (pair? l)
+		  (pair? (car l))
+		  (pair? (caar l))
+		  (eq? (car key) (caaar l))
+		  (eq? (cdr key) (cdaar l))
+		  (car l))
+	     (hashq-cons-assoc key (cdr l)))))
+
+(define-public (hashq-cons-get-handle table key)
+  (hashx-get-handle hashq-cons-hash hashq-cons-assoc table key #f))
+
+(define-public (hashq-cons-create-handle! table key init)
+  (hashx-create-handle! hashq-cons-hash hashq-cons-assoc table key init))
+
+(define-public (hashq-cons-ref table key)
+  (hashx-ref hashq-cons-hash hashq-cons-assoc table key #f))
+
+(define-public (hashq-cons-set! table key val)
+  (hashx-set! hashq-cons-hash hashq-cons-assoc table key val))
+
+(define-public (hashq-cons table a d)
+  (car (hashq-cons-create-handle! table (cons a d) #f)))
+
+(define-public (hashq-conser hash-tab-or-size)
+  (let ((table (if (vector? hash-tab-or-size)
+		   hash-tab-or-size
+		   (make-doubly-weak-hash-table hash-tab-or-size))))
+    (lambda (a d) (hashq-cons table a d))))
+
+
+
+
+(define-public (make-gc-buffer n)
+  (let ((ring (make-list n #f)))
+    (append! ring ring)
+    (lambda (next)
+      (set-car! ring next)
+      (set! ring (cdr ring))
+      next)))