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-rw-r--r--locale/programs/simple-hash.c401
1 files changed, 401 insertions, 0 deletions
diff --git a/locale/programs/simple-hash.c b/locale/programs/simple-hash.c
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+/* hash - implement simple hashing table with string based keys.
+   Copyright (C) 1994, 1995, 1996 Free Software Foundation, Inc.
+   Written by Ulrich Drepper <drepper@gnu.ai.mit.edu>, October 1994.
+
+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 program; if not, write to the Free Software
+Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+
+#if HAVE_OBSTACK
+# include <obstack.h>
+#else
+# include "obstack.h"
+#endif
+
+#ifdef HAVE_VALUES_H
+# include <values.h>
+#endif
+
+#include "simple-hash.h"
+
+#define obstack_chunk_alloc xmalloc
+#define obstack_chunk_free free
+
+#ifndef BITSPERBYTE
+# define BITSPERBYTE 8
+#endif
+
+#ifndef	LONGBITS
+# define LONGBITS (sizeof (long) * BITSPERBYTE)
+#endif
+
+#ifndef bcopy
+# define bcopy(s, d, n)	memcpy ((d), (s), (n))
+#endif
+
+void *xmalloc __P ((size_t __n));
+
+typedef struct hash_entry
+{
+  unsigned long used;
+  const void *key;
+  size_t keylen;
+  void *data;
+  struct hash_entry *next;
+}
+hash_entry;
+
+/* Prototypes for local functions.  */
+static void insert_entry_2 __P ((hash_table *htab, const void *key,
+				 size_t keylen, unsigned long hval,
+				 size_t idx, void *data));
+static size_t lookup __P ((hash_table *htab, const void *key, size_t keylen,
+			   unsigned long int hval));
+static size_t lookup_2 __P ((hash_table *htab, const void *key,
+			     size_t keylen, unsigned long int hval));
+static unsigned long compute_hashval __P ((const void *key, size_t keylen));
+static int is_prime __P ((unsigned long int candidate));
+
+
+int
+init_hash (htab, init_size)
+     hash_table *htab;
+     unsigned long int init_size;
+{
+  /* We need the size to be a prime.  */
+  init_size = next_prime (init_size);
+
+  /* Initialize the data structure.  */
+  htab->size = init_size;
+  htab->filled = 0;
+  htab->first = NULL;
+  htab->table = (void *) xmalloc ((init_size + 1) * sizeof (hash_entry));
+  if (htab->table == NULL)
+    return -1;
+
+  memset (htab->table, '\0', (init_size + 1) * sizeof (hash_entry));
+  obstack_init (&htab->mem_pool);
+
+  return 0;
+}
+
+
+int
+delete_hash (htab)
+     hash_table *htab;
+{
+  free (htab->table);
+  obstack_free (&htab->mem_pool, NULL);
+  return 0;
+}
+
+
+int
+insert_entry (htab, key, keylen, data)
+     hash_table *htab;
+     const void *key;
+     size_t keylen;
+     void *data;
+{
+  unsigned long int hval = compute_hashval (key, keylen);
+  hash_entry *table = (hash_entry *) htab->table;
+  size_t idx = lookup (htab, key, keylen, hval);
+
+  if (table[idx].used)
+    /* We don't want to overwrite the old value.  */
+    return -1;
+  else
+    {
+      /* An empty bucket has been found.  */
+      insert_entry_2 (htab, obstack_copy (&htab->mem_pool, key, keylen),
+		      keylen, hval, idx, data);
+      return 0;
+    }
+}
+
+static void
+insert_entry_2 (htab, key, keylen, hval, idx, data)
+     hash_table *htab;
+     const void *key;
+     size_t keylen;
+     unsigned long int hval;
+     size_t idx;
+     void *data;
+{
+  hash_entry *table = (hash_entry *) htab->table;
+
+  table[idx].used = hval;
+  table[idx].key = key;
+  table[idx].keylen = keylen;
+  table[idx].data = data;
+
+      /* List the new value in the list.  */
+  if ((hash_entry *) htab->first == NULL)
+    {
+      table[idx].next = &table[idx];
+      *(hash_entry **) &htab->first = &table[idx];
+    }
+  else
+    {
+      table[idx].next = ((hash_entry *) htab->first)->next;
+      ((hash_entry *) htab->first)->next = &table[idx];
+      *(hash_entry **) &htab->first = &table[idx];
+    }
+
+  ++htab->filled;
+  if (100 * htab->filled > 90 * htab->size)
+    {
+      /* Table is filled more than 90%.  Resize the table.  */
+      unsigned long int old_size = htab->size;
+
+      htab->size = next_prime (htab->size * 2);
+      htab->filled = 0;
+      htab->first = NULL;
+      htab->table = (void *) xmalloc ((1 + htab->size)
+				      * sizeof (hash_entry));
+      memset (htab->table, '\0', (1 + htab->size) * sizeof (hash_entry));
+
+      for (idx = 1; idx <= old_size; ++idx)
+	if (table[idx].used)
+	  insert_entry_2 (htab, table[idx].key, table[idx].keylen,
+			  table[idx].used,
+			  lookup_2 (htab, table[idx].key, table[idx].keylen,
+				    table[idx].used),
+			  table[idx].data);
+
+      free (table);
+    }
+}
+
+
+int
+find_entry (htab, key, keylen, result)
+     hash_table *htab;
+     const void *key;
+     size_t keylen;
+     void **result;
+{
+  hash_entry *table = (hash_entry *) htab->table;
+  size_t idx = lookup (htab, key, keylen, compute_hashval (key, keylen));
+
+  if (table[idx].used == 0)
+    return -1;
+
+  *result = table[idx].data;
+  return 0;
+}
+
+
+int
+set_entry (htab, key, keylen, newval)
+     hash_table *htab;
+     const void *key;
+     size_t keylen;
+     void *newval;
+{
+  hash_entry *table = (hash_entry *) htab->table;
+  size_t idx = lookup (htab, key, keylen, compute_hashval (key, keylen));
+
+  if (table[idx].used == 0)
+    return -1;
+
+  table[idx].data = newval;
+  return 0;
+}
+
+
+int
+iterate_table (htab, ptr, key, keylen, data)
+     hash_table *htab;
+     void **ptr;
+     const void **key;
+     size_t *keylen;
+     void **data;
+{
+  if (*ptr == NULL)
+    {
+      if (htab->first == NULL)
+	return -1;
+      *ptr = (void *) ((hash_entry *) htab->first)->next;
+    }
+  else
+    {
+      if (*ptr == htab->first)
+	return -1;
+      *ptr = (void *) (((hash_entry *) *ptr)->next);
+    }
+
+  *key = ((hash_entry *) *ptr)->key;
+  *keylen = ((hash_entry *) *ptr)->keylen;
+  *data = ((hash_entry *) *ptr)->data;
+  return 0;
+}
+
+
+static size_t
+lookup (htab, key, keylen, hval)
+     hash_table *htab;
+     const void *key;
+     size_t keylen;
+     unsigned long hval;
+{
+  unsigned long hash;
+  size_t idx;
+  hash_entry *table = (hash_entry *) htab->table;
+
+  /* First hash function: simply take the modul but prevent zero.  */
+  hash = 1 + hval % htab->size;
+
+  idx = hash;
+
+  if (table[idx].used)
+    {
+      if (table[idx].used == hval && table[idx].keylen == keylen
+	  && memcmp (key, table[idx].key, keylen) == 0)
+	return idx;
+
+      /* Second hash function as suggested in [Knuth].  */
+      hash = 1 + hval % (htab->size - 2);
+
+      do
+	{
+	  if (idx <= hash)
+	    idx = htab->size + idx - hash;
+	  else
+	    idx -= hash;
+
+	  /* If entry is found use it.  */
+	  if (table[idx].used == hval && table[idx].keylen == keylen
+	      && memcmp (key, table[idx].key, keylen) == 0)
+	    return idx;
+	}
+      while (table[idx].used);
+    }
+  return idx;
+}
+
+
+/* References:
+   [Aho,Sethi,Ullman] Compilers: Principles, Techniques and Tools, 1986
+   [Knuth]	      The Art of Computer Programming, part3 (6.4) */
+
+static size_t
+lookup_2 (htab, key, keylen, hval)
+     hash_table *htab;
+     const void *key;
+     size_t keylen;
+     unsigned long int hval;
+{
+  unsigned long int hash;
+  size_t idx;
+  hash_entry *table = (hash_entry *) htab->table;
+
+  /* First hash function: simply take the modul but prevent zero.  */
+  hash = 1 + hval % htab->size;
+
+  idx = hash;
+
+  if (table[idx].used)
+    {
+      if (table[idx].used == hval && table[idx].keylen == keylen
+	  && memcmp (table[idx].key, key, keylen) == 0)
+	return idx;
+
+      /* Second hash function as suggested in [Knuth].  */
+      hash = 1 + hval % (htab->size - 2);
+
+      do
+	{
+	  if (idx <= hash)
+	    idx = htab->size + idx - hash;
+	  else
+	    idx -= hash;
+
+	  /* If entry is found use it.  */
+	  if (table[idx].used == hval && table[idx].keylen == keylen
+	      && memcmp (table[idx].key, key, keylen) == 0)
+	    return idx;
+	}
+      while (table[idx].used);
+    }
+  return idx;
+}
+
+
+static unsigned long
+compute_hashval (key, keylen)
+     const void *key;
+     size_t keylen;
+{
+  size_t cnt;
+  unsigned long int hval, g;
+
+  /* Compute the hash value for the given string.  The algorithm
+     is taken from [Aho,Sethi,Ullman].  */
+  cnt = 0;
+  hval = keylen;
+  while (cnt < keylen)
+    {
+      hval <<= 4;
+      hval += (unsigned long int) *(((char *) key) + cnt++);
+      g = hval & ((unsigned long) 0xf << (LONGBITS - 4));
+      if (g != 0)
+	{
+	  hval ^= g >> (LONGBITS - 8);
+	  hval ^= g;
+	}
+    }
+  return hval != 0 ? hval : ~((unsigned long) 0);
+}
+
+
+unsigned long
+next_prime (seed)
+     unsigned long int seed;
+{
+  /* Make it definitely odd.  */
+  seed |= 1;
+
+  while (!is_prime (seed))
+    seed += 2;
+
+  return seed;
+}
+
+
+static int
+is_prime (candidate)
+     unsigned long int candidate;
+{
+  /* No even number and none less than 10 will be passed here.  */
+  unsigned long int divn = 3;
+  unsigned long int sq = divn * divn;
+
+  while (sq < candidate && candidate % divn != 0)
+    {
+      ++divn;
+      sq += 4 * divn;
+      ++divn;
+    }
+
+  return candidate % divn != 0;
+}
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