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dynamicsizehash.c

/* Copyright (C) 2000, 2001, 2002, 2005 Red Hat, Inc.
   This file is part of Red Hat elfutils.
   Written by Ulrich Drepper <drepper@redhat.com>, 2000.

   Red Hat elfutils 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; version 2 of the License.

   Red Hat elfutils 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 Red Hat elfutils; if not, write to the Free Software Foundation,
   Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.

   In addition, as a special exception, Red Hat, Inc. gives You the
   additional right to link the code of Red Hat elfutils with code licensed
   under any Open Source Initiative certified open source license
   (http://www.opensource.org/licenses/index.php) which requires the
   distribution of source code with any binary distribution and to
   distribute linked combinations of the two.  Non-GPL Code permitted under
   this exception must only link to the code of Red Hat elfutils through
   those well defined interfaces identified in the file named EXCEPTION
   found in the source code files (the "Approved Interfaces").  The files
   of Non-GPL Code may instantiate templates or use macros or inline
   functions from the Approved Interfaces without causing the resulting
   work to be covered by the GNU General Public License.  Only Red Hat,
   Inc. may make changes or additions to the list of Approved Interfaces.
   Red Hat's grant of this exception is conditioned upon your not adding
   any new exceptions.  If you wish to add a new Approved Interface or
   exception, please contact Red Hat.  You must obey the GNU General Public
   License in all respects for all of the Red Hat elfutils code and other
   code used in conjunction with Red Hat elfutils except the Non-GPL Code
   covered by this exception.  If you modify this file, you may extend this
   exception to your version of the file, but you are not obligated to do
   so.  If you do not wish to provide this exception without modification,
   you must delete this exception statement from your version and license
   this file solely under the GPL without exception.

   Red Hat elfutils is an included package of the Open Invention Network.
   An included package of the Open Invention Network is a package for which
   Open Invention Network licensees cross-license their patents.  No patent
   license is granted, either expressly or impliedly, by designation as an
   included package.  Should you wish to participate in the Open Invention
   Network licensing program, please visit www.openinventionnetwork.com
   <http://www.openinventionnetwork.com>.  */

#include <assert.h>
#include <stdlib.h>
#include <system.h>

/* Before including this file the following macros must be defined:

   NAME      name of the hash table structure.
   TYPE      data type of the hash table entries
   COMPARE   comparison function taking two pointers to TYPE objects

   The following macros if present select features:

   ITERATE   iterating over the table entries is possible
   REVERSE   iterate in reverse order of insert
 */


static size_t
lookup (htab, hval, val)
     NAME *htab;
     unsigned long int hval;
     TYPE val __attribute__ ((unused));
{
  /* First hash function: simply take the modul but prevent zero.  */
  size_t idx = 1 + hval % htab->size;

  if (htab->table[idx].hashval != 0)
    {
      unsigned long int hash;

      if (htab->table[idx].hashval == hval
        && COMPARE (htab->table[idx].data, val) == 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 (htab->table[idx].hashval == hval
            && COMPARE (htab->table[idx].data, val) == 0)
          return idx;
      }
      while (htab->table[idx].hashval);
    }
  return idx;
}


static void
insert_entry_2 (NAME *htab, unsigned long int hval, size_t idx, TYPE data)
{
#ifdef ITERATE
  if (htab->table[idx].hashval == 0)
    {
# ifdef REVERSE
      htab->table[idx].next = htab->first;
      htab->first = &htab->table[idx];
# else
      /* Add the new value to the list.  */
      if (htab->first == NULL)
      htab->first = htab->table[idx].next = &htab->table[idx];
      else
      {
        htab->table[idx].next = htab->first->next;
        htab->first = htab->first->next = &htab->table[idx];
      }
# endif
    }
#endif

  htab->table[idx].hashval = hval;
  htab->table[idx].data = data;

  ++htab->filled;
  if (100 * htab->filled > 90 * htab->size)
    {
      /* Table is filled more than 90%.  Resize the table.  */
#ifdef ITERATE
      __typeof__ (htab->first) first;
# ifndef REVERSE
      __typeof__ (htab->first) runp;
# endif
#else
      unsigned long int old_size = htab->size;
#endif
#define _TABLE(name) \
      name##_ent *table = htab->table
#define TABLE(name) _TABLE (name)
      TABLE(NAME);

      htab->size = next_prime (htab->size * 2);
      htab->filled = 0;
#ifdef ITERATE
      first = htab->first;
      htab->first = NULL;
#endif
      htab->table = calloc ((1 + htab->size), sizeof (htab->table[0]));
      if (htab->table == NULL)
      {
        /* We cannot enlarge the table.  Live with what we got.  This
           might lead to an infinite loop at some point, though.  */
        htab->table = table;
        return;
      }

      /* Add the old entries to the new table.  When iteration is
       supported we maintain the order.  */
#ifdef ITERATE
# ifdef REVERSE
      while (first != NULL)
      {
        insert_entry_2 (htab, first->hashval,
                    lookup (htab, first->hashval, first->data),
                    first->data);

        first = first->next;
      }
# else
      assert (first != NULL);
      runp = first = first->next;
      do
      insert_entry_2 (htab, runp->hashval,
                  lookup (htab, runp->hashval, runp->data), runp->data);
      while ((runp = runp->next) != first);
# endif
#else
      for (idx = 1; idx <= old_size; ++idx)
      if (table[idx].hashval != 0)
        insert_entry_2 (htab, table[idx].hashval,
                    lookup (htab, table[idx].hashval, table[idx].data),
                    table[idx].data);
#endif

      free (table);
    }
}


int
#define INIT(name) _INIT (name)
#define _INIT(name) \
  name##_init
INIT(NAME) (htab, init_size)
     NAME *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;
#ifdef ITERATE
  htab->first = NULL;
#endif
  htab->table = (void *) calloc ((init_size + 1), sizeof (htab->table[0]));
  if (htab->table == NULL)
    return -1;

  return 0;
}


int
#define FREE(name) _FREE (name)
#define _FREE(name) \
  name##_free
FREE(NAME) (htab)
     NAME *htab;
{
  free (htab->table);
  return 0;
}


int
#define INSERT(name) _INSERT (name)
#define _INSERT(name) \
  name##_insert
INSERT(NAME) (htab, hval, data)
     NAME *htab;
     unsigned long int hval;
     TYPE data;
{
  size_t idx;

  /* Make the hash value nonzero.  */
  hval = hval ?: 1;

  idx = lookup (htab, hval, data);

  if (htab->table[idx].hashval != 0)
    /* We don't want to overwrite the old value.  */
    return -1;

  /* An empty bucket has been found.  */
  insert_entry_2 (htab, hval, idx, data);
  return 0;
}


#ifdef OVERWRITE
int
#define INSERT(name) _INSERT (name)
#define _INSERT(name) \
  name##_overwrite
INSERT(NAME) (htab, hval, data)
     NAME *htab;
     unsigned long int hval;
     TYPE data;
{
  size_t idx;

  /* Make the hash value nonzero.  */
  hval = hval ?: 1;

  idx = lookup (htab, hval, data);

  /* The correct bucket has been found.  */
  insert_entry_2 (htab, hval, idx, data);
  return 0;
}
#endif


TYPE
#define FIND(name) _FIND (name)
#define _FIND(name) \
  name##_find
FIND(NAME) (htab, hval, val)
     NAME *htab;
     unsigned long int hval;
     TYPE val;
{
  size_t idx;

  /* Make the hash value nonzero.  */
  hval = hval ?: 1;

  idx = lookup (htab, hval, val);

  if (htab->table[idx].hashval == 0)
    return NULL;

  return htab->table[idx].data;
}


#ifdef ITERATE
# define ITERATEFCT(name) _ITERATEFCT (name)
# define _ITERATEFCT(name) \
  name##_iterate
TYPE
ITERATEFCT(NAME) (htab, ptr)
     NAME *htab;
     void **ptr;
{
  void *p = *ptr;

# define TYPENAME(name) _TYPENAME (name)
# define _TYPENAME(name) name##_ent

# ifdef REVERSE
  if (p == NULL)
    p = htab->first;
  else
    p = ((TYPENAME(NAME) *) p)->next;

  if (p == NULL)
    {
      *ptr = NULL;
      return NULL;
    }
# else
  if (p == NULL)
    {
      if (htab->first == NULL)
      return NULL;
      p = htab->first->next;
    }
  else
    {
      if (p == htab->first)
      return NULL;

      p = ((TYPENAME(NAME) *) p)->next;
    }
# endif

  /* Prepare the next element.  If possible this will pull the data
     into the cache, for reading.  */
  __builtin_prefetch (((TYPENAME(NAME) *) p)->next, 0, 2);

  return ((TYPENAME(NAME) *) (*ptr = p))->data;
}
#endif

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