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/* Hash routine.
* Copyright (C) 1998 Kunihiro Ishiguro
*
* This file is part of GNU Zebra.
*
* GNU Zebra 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.
*
* GNU Zebra 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 GNU Zebra; see the file COPYING. If not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#include <zebra.h>
#include "hash.h"
#include "memory.h"
/* Allocate a new hash. */
struct hash *
hash_create_size (unsigned int size, unsigned int (*hash_key) (void *),
int (*hash_cmp) (const void *, const void *))
{
struct hash *hash;
hash = XMALLOC (MTYPE_HASH, sizeof (struct hash));
hash->index = XCALLOC (MTYPE_HASH_INDEX,
sizeof (struct hash_backet *) * size);
hash->size = size;
hash->hash_key = hash_key;
hash->hash_cmp = hash_cmp;
hash->count = 0;
return hash;
}
/* Allocate a new hash with default hash size. */
struct hash *
hash_create (unsigned int (*hash_key) (void *),
int (*hash_cmp) (const void *, const void *))
{
return hash_create_size (HASHTABSIZE, hash_key, hash_cmp);
}
/* Utility function for hash_get(). When this function is specified
as alloc_func, return arugment as it is. This function is used for
intern already allocated value. */
void *
hash_alloc_intern (void *arg)
{
return arg;
}
/* Lookup and return hash backet in hash. If there is no
corresponding hash backet and alloc_func is specified, create new
hash backet. */
void *
hash_get (struct hash *hash, void *data, void * (*alloc_func) (void *))
{
unsigned int key;
unsigned int index;
void *newdata;
struct hash_backet *backet;
key = (*hash->hash_key) (data);
index = key % hash->size;
for (backet = hash->index[index]; backet != NULL; backet = backet->next)
if (backet->key == key && (*hash->hash_cmp) (backet->data, data))
return backet->data;
if (alloc_func)
{
newdata = (*alloc_func) (data);
if (newdata == NULL)
return NULL;
backet = XMALLOC (MTYPE_HASH_BACKET, sizeof (struct hash_backet));
backet->data = newdata;
backet->key = key;
backet->next = hash->index[index];
hash->index[index] = backet;
hash->count++;
return backet->data;
}
return NULL;
}
/* Hash lookup. */
void *
hash_lookup (struct hash *hash, void *data)
{
return hash_get (hash, data, NULL);
}
/* Simple Bernstein hash which is simple and fast for common case */
unsigned int string_hash_make (const char *str)
{
unsigned int hash = 0;
while (*str)
hash = (hash * 33) ^ (unsigned int) *str++;
return hash;
}
/* This function release registered value from specified hash. When
release is successfully finished, return the data pointer in the
hash backet. */
void *
hash_release (struct hash *hash, void *data)
{
void *ret;
unsigned int key;
unsigned int index;
struct hash_backet *backet;
struct hash_backet *pp;
key = (*hash->hash_key) (data);
index = key % hash->size;
for (backet = pp = hash->index[index]; backet; backet = backet->next)
{
if (backet->key == key && (*hash->hash_cmp) (backet->data, data))
{
if (backet == pp)
hash->index[index] = backet->next;
else
pp->next = backet->next;
ret = backet->data;
XFREE (MTYPE_HASH_BACKET, backet);
hash->count--;
return ret;
}
pp = backet;
}
return NULL;
}
/* Iterator function for hash. */
void
hash_iterate (struct hash *hash,
void (*func) (struct hash_backet *, void *), void *arg)
{
unsigned int i;
struct hash_backet *hb;
struct hash_backet *hbnext;
for (i = 0; i < hash->size; i++)
for (hb = hash->index[i]; hb; hb = hbnext)
{
/* get pointer to next hash backet here, in case (*func)
* decides to delete hb by calling hash_release
*/
hbnext = hb->next;
(*func) (hb, arg);
}
}
/* Clean up hash. */
void
hash_clean (struct hash *hash, void (*free_func) (void *))
{
unsigned int i;
struct hash_backet *hb;
struct hash_backet *next;
for (i = 0; i < hash->size; i++)
{
for (hb = hash->index[i]; hb; hb = next)
{
next = hb->next;
if (free_func)
(*free_func) (hb->data);
XFREE (MTYPE_HASH_BACKET, hb);
hash->count--;
}
hash->index[i] = NULL;
}
}
/* Free hash memory. You may call hash_clean before call this
function. */
void
hash_free (struct hash *hash)
{
XFREE (MTYPE_HASH_INDEX, hash->index);
XFREE (MTYPE_HASH, hash);
}
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