--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hash.c	Mon Aug 13 11:28:15 2007 +0200
@@ -0,0 +1,354 @@
+/* Hash tables.
+   Copyright (C) 1992, 1993, 1994 Free Software Foundation, Inc.
+
+This file is part of XEmacs.
+
+XEmacs 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.
+
+XEmacs 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 XEmacs; see the file COPYING.  If not, write to
+the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+Boston, MA 02111-1307, USA.  */
+
+/* Synched up with: Not in FSF. */
+
+#include <config.h>
+#include "lisp.h"
+#include "hash.h"
+
+#define NULL_ENTRY ((void *) 0xdeadbeef)
+
+#define COMFORTABLE_SIZE(size) (21 * (size) / 16)
+
+#define KEYS_DIFFER_P(old, new, testfun) \
+  (((old) != (new)) && (!(testfun) || !(testfun) ((old),(new))))
+
+static void rehash (hentry *harray, struct hash_table *ht, hash_size_t size);
+
+unsigned long
+memory_hash (CONST void *xv, size_t size)
+{
+  unsigned int h = 0;
+  unsigned CONST char *x = (unsigned CONST char *) xv;
+
+  if (!x) return 0;
+
+  while (size--)
+    {
+      unsigned int g;
+      h = (h << 4) + *x++;
+      if ((g = h & 0xf0000000) != 0)
+	h = (h ^ (g >> 24)) ^ g;
+    }
+
+  return h;
+}
+
+/* Return a suitable size for a hash table, with at least SIZE slots. */
+static size_t
+hash_table_size (size_t requested_size)
+{
+  /* Return some prime near, but greater than or equal to, SIZE.
+     Decades from the time of writing, someone will have a system large
+     enough that the list below will be too short... */
+  static CONST size_t primes [] =
+  {
+    19, 29, 41, 59, 79, 107, 149, 197, 263, 347, 457, 599, 787, 1031,
+    1361, 1777, 2333, 3037, 3967, 5167, 6719, 8737, 11369, 14783,
+    19219, 24989, 32491, 42257, 54941, 71429, 92861, 120721, 156941,
+    204047, 265271, 344857, 448321, 582821, 757693, 985003, 1280519,
+    1664681, 2164111, 2813353, 3657361, 4754591, 6180989, 8035301,
+    10445899, 13579681, 17653589, 22949669, 29834603, 38784989,
+    50420551, 65546729, 85210757, 110774011, 144006217, 187208107,
+    243370577, 316381771, 411296309, 534685237, 695090819, 903618083,
+    1174703521, 1527114613, 1985248999, 2580823717UL, 3355070839UL
+  };
+  /* We've heard of binary search. */
+  int low, high;
+  for (low = 0, high = countof (primes) - 1; high - low > 1;)
+    {
+      /* Loop Invariant: size < primes [high] */
+      int mid = (low + high) / 2;
+      if (primes [mid] < requested_size)
+	low = mid;
+      else
+	high = mid;
+    }
+  return primes [high];
+}
+
+CONST void *
+gethash (CONST void *key, struct hash_table *hash_table, CONST void **ret_value)
+{
+  if (!key)
+    {
+      *ret_value = hash_table->zero_entry;
+      return (void *) hash_table->zero_set;
+    }
+  else
+    {
+      hentry *harray = hash_table->harray;
+      hash_table_test_function test_function = hash_table->test_function;
+      hash_size_t size = hash_table->size;
+      unsigned int hcode_initial =
+	hash_table->hash_function ?
+	hash_table->hash_function (key) :
+	(unsigned long) key;
+      unsigned int hcode = hcode_initial % size;
+      hentry *e = &harray [hcode];
+      CONST void *e_key = e->key;
+
+      if (e_key ?
+	  KEYS_DIFFER_P (e_key, key, test_function) :
+	  e->contents == NULL_ENTRY)
+	{
+	  size_t h2 = size - 2;
+	  unsigned int incr = 1 + (hcode_initial % h2);
+	  do
+	    {
+	      hcode += incr; if (hcode >= size) hcode -= size;
+	      e = &harray [hcode];
+	      e_key = e->key;
+	    }
+	  while (e_key ?
+		 KEYS_DIFFER_P (e_key, key, test_function) :
+		 e->contents == NULL_ENTRY);
+	}
+
+      *ret_value = e->contents;
+      return e->key;
+    }
+}
+
+void
+clrhash (struct hash_table *hash_table)
+{
+  memset (hash_table->harray, 0, sizeof (hentry) * hash_table->size);
+  hash_table->zero_entry = 0;
+  hash_table->zero_set   = 0;
+  hash_table->fullness   = 0;
+}
+
+void
+free_hash_table (struct hash_table *hash_table)
+{
+  xfree (hash_table->harray);
+  xfree (hash_table);
+}
+
+struct hash_table*
+make_hash_table (hash_size_t size)
+{
+  struct hash_table *hash_table = xnew_and_zero (struct hash_table);
+  hash_table->size = hash_table_size (COMFORTABLE_SIZE (size));
+  hash_table->harray = xnew_array (hentry, hash_table->size);
+  clrhash (hash_table);
+  return hash_table;
+}
+
+struct hash_table *
+make_general_hash_table (hash_size_t size,
+			hash_table_hash_function hash_function,
+			hash_table_test_function test_function)
+{
+  struct hash_table* hash_table = make_hash_table (size);
+  hash_table->hash_function = hash_function;
+  hash_table->test_function = test_function;
+  return hash_table;
+}
+
+static void
+grow_hash_table (struct hash_table *hash_table, hash_size_t new_size)
+{
+  hash_size_t old_size   = hash_table->size;
+  hentry     *old_harray = hash_table->harray;
+
+  hash_table->size   = hash_table_size (new_size);
+  hash_table->harray = xnew_array (hentry, hash_table->size);
+
+  /* do the rehash on the "grown" table */
+  {
+    long old_zero_set    = hash_table->zero_set;
+    void *old_zero_entry = hash_table->zero_entry;
+    clrhash (hash_table);
+    hash_table->zero_set   = old_zero_set;
+    hash_table->zero_entry = old_zero_entry;
+    rehash (old_harray, hash_table, old_size);
+  }
+
+  xfree (old_harray);
+}
+
+void
+puthash (CONST void *key, void *contents, struct hash_table *hash_table)
+{
+  if (!key)
+    {
+      hash_table->zero_entry = contents;
+      hash_table->zero_set = 1;
+    }
+  else
+    {
+      hash_table_test_function test_function = hash_table->test_function;
+      hash_size_t size = hash_table->size;
+      hentry *harray   = hash_table->harray;
+      unsigned int hcode_initial =
+	hash_table->hash_function ?
+	hash_table->hash_function (key) :
+	(unsigned long) key;
+      unsigned int hcode = hcode_initial % size;
+      size_t h2 = size - 2;
+      unsigned int incr = 1 + (hcode_initial % h2);
+      CONST void *e_key = harray [hcode].key;
+      CONST void *oldcontents;
+
+      if (e_key && KEYS_DIFFER_P (e_key, key, test_function))
+	{
+	  do
+	    {
+	      hcode += incr; if (hcode >= size) hcode -= size;
+	      e_key = harray [hcode].key;
+	    }
+	  while (e_key && KEYS_DIFFER_P (e_key, key, test_function));
+	}
+      oldcontents = harray [hcode].contents;
+      harray [hcode].key = key;
+      harray [hcode].contents = contents;
+      /* If the entry that we used was a deleted entry,
+	 check for a non deleted entry of the same key,
+	 then delete it. */
+      if (!e_key && oldcontents == NULL_ENTRY)
+	{
+	  hentry *e;
+
+	  do
+	    {
+	      hcode += incr; if (hcode >= size) hcode -= size;
+	      e = &harray [hcode];
+	      e_key = e->key;
+	    }
+	  while (e_key ?
+		 KEYS_DIFFER_P (e_key, key, test_function):
+		 e->contents == NULL_ENTRY);
+
+	  if (e_key)
+	    {
+	      e->key = 0;
+	      e->contents = NULL_ENTRY;
+	    }
+	}
+
+      /* only increment the fullness when we used up a new hentry */
+      if (!e_key || KEYS_DIFFER_P (e_key, key, test_function))
+	{
+	  hash_size_t comfortable_size = COMFORTABLE_SIZE (++(hash_table->fullness));
+	  if (hash_table->size < comfortable_size)
+	    grow_hash_table (hash_table, comfortable_size + 1);
+	}
+    }
+}
+
+static void
+rehash (hentry *harray, struct hash_table *hash_table, hash_size_t size)
+{
+  hentry *limit = harray + size;
+  hentry *e;
+  for (e = harray; e < limit; e++)
+    {
+      if (e->key)
+	puthash (e->key, e->contents, hash_table);
+    }
+}
+
+void
+remhash (CONST void *key, struct hash_table *hash_table)
+{
+  if (!key)
+    {
+      hash_table->zero_entry = 0;
+      hash_table->zero_set = 0;
+    }
+  else
+    {
+      hentry *harray = hash_table->harray;
+      hash_table_test_function test_function = hash_table->test_function;
+      hash_size_t size = hash_table->size;
+      unsigned int hcode_initial =
+	(hash_table->hash_function) ?
+	(hash_table->hash_function (key)) :
+	((unsigned long) key);
+      unsigned int hcode = hcode_initial % size;
+      hentry *e = &harray [hcode];
+      CONST void *e_key = e->key;
+
+      if (e_key ?
+	  KEYS_DIFFER_P (e_key, key, test_function) :
+	  e->contents == NULL_ENTRY)
+	{
+	  size_t h2 = size - 2;
+	  unsigned int incr = 1 + (hcode_initial % h2);
+	  do
+	    {
+	      hcode += incr; if (hcode >= size) hcode -= size;
+	      e = &harray [hcode];
+	      e_key = e->key;
+	    }
+	  while (e_key?
+		 KEYS_DIFFER_P (e_key, key, test_function):
+		 e->contents == NULL_ENTRY);
+	}
+      if (e_key)
+	{
+	  e->key = 0;
+	  e->contents = NULL_ENTRY;
+	  /* Note: you can't do fullness-- here, it breaks the world. */
+	}
+    }
+}
+
+void
+maphash (maphash_function mf, struct hash_table *hash_table, void *arg)
+{
+  hentry *e;
+  hentry *limit;
+
+  if (hash_table->zero_set)
+    {
+      if (mf (0, hash_table->zero_entry, arg))
+	return;
+    }
+
+  for (e = hash_table->harray, limit = e + hash_table->size; e < limit; e++)
+    {
+      if (e->key && mf (e->key, e->contents, arg))
+	return;
+    }
+}
+
+void
+map_remhash (remhash_predicate predicate, struct hash_table *hash_table, void *arg)
+{
+  hentry *e;
+  hentry *limit;
+
+  if (hash_table->zero_set && predicate (0, hash_table->zero_entry, arg))
+    {
+      hash_table->zero_set = 0;
+      hash_table->zero_entry = 0;
+    }
+
+  for (e = hash_table->harray, limit = e + hash_table->size; e < limit; e++)
+    if (predicate (e->key, e->contents, arg))
+      {
+        e->key = 0;
+        e->contents = NULL_ENTRY;
+      }
+}