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/* --------------------------------------------------------------------------
*
* License
*
* The contents of this file are subject to the Jabber Open Source License
* Version 1.0 (the "JOSL"). You may not copy or use this file, in either
* source code or executable form, except in compliance with the JOSL. You
* may obtain a copy of the JOSL at http://www.jabber.org/ or at
* http://www.opensource.org/.
*
* Software distributed under the JOSL is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the JOSL
* for the specific language governing rights and limitations under the
* JOSL.
*
* Copyrights
*
* Portions created by or assigned to Jabber.com, Inc. are
* Copyright (c) 1999-2002 Jabber.com, Inc. All Rights Reserved. Contact
* information for Jabber.com, Inc. is available at http://www.jabber.com/.
*
* Portions Copyright (c) 1998-1999 Jeremie Miller.
*
* Acknowledgements
*
* Special thanks to the Jabber Open Source Contributors for their
* suggestions and support of Jabber.
*
* Alternatively, the contents of this file may be used under the terms of the
* GNU General Public License Version 2 or later (the "GPL"), in which case
* the provisions of the GPL are applicable instead of those above. If you
* wish to allow use of your version of this file only under the terms of the
* GPL and not to allow others to use your version of this file under the JOSL,
* indicate your decision by deleting the provisions above and replace them
* with the notice and other provisions required by the GPL. If you do not
* delete the provisions above, a recipient may use your version of this file
* under either the JOSL or the GPL.
*
*
* --------------------------------------------------------------------------*/
#include "lib.h"
/* Generates a hash code for a string.
* This function uses the ELF hashing algorithm as reprinted in
* Andrew Binstock, "Hashing Rehashed," Dr. Dobb's Journal, April 1996.
*/
int _xhasher(const char *s)
{
/* ELF hash uses unsigned chars and unsigned arithmetic for portability */
const unsigned char *name = (const unsigned char *)s;
unsigned long h = 0, g;
while (*name) { /* do some fancy bitwanking on the string */
h = (h << 4) + (unsigned long)(*name++);
if ((g = (h & 0xF0000000UL)) != 0)
h ^= (g >> 24);
h &= ~g;
}
return (int)h;
}
xhn _xhash_node_new(xht h, int index)
{
xhn n;
int i = index % h->prime;
/* get existing empty one */
for (n = &h->zen[i]; n != NULL; n = n->next)
if (n->key == NULL)
return n;
/* overflowing, new one! */
n = pmalloco(h->p, sizeof(_xhn));
n->next = h->zen[i].next;
h->zen[i].next = n;
return n;
}
xhn _xhash_node_get(xht h, const char *key, int index)
{
xhn n;
int i = index % h->prime;
for (n = &h->zen[i]; n != NULL; n = n->next)
if (j_strcmp(key, n->key) == 0)
return n;
return NULL;
}
xht xhash_new(int prime)
{
xht xnew;
pool p;
/* log_debug(ZONE,"creating new hash table of size %d",prime); */
p = pool_heap(sizeof(_xhn) * prime + sizeof(_xht));
xnew = pmalloco(p, sizeof(_xht));
xnew->prime = prime;
xnew->p = p;
xnew->zen = pmalloco(p, sizeof(_xhn) * prime); /* array of xhn size of prime */
return xnew;
}
void xhash_put(xht h, const char *key, void *val)
{
int index;
xhn n;
if (h == NULL || key == NULL)
return;
index = _xhasher(key);
/* if existing key, replace it */
if ((n = _xhash_node_get(h, key, index)) != NULL) {
/* log_debug(ZONE,"replacing %s with new val %X",key,val); */
n->key = key;
n->val = val;
return;
}
/* log_debug(ZONE,"saving %s val %X",key,val); */
/* new node */
n = _xhash_node_new(h, index);
n->key = key;
n->val = val;
}
void *xhash_get(xht h, const char *key)
{
xhn n;
if (h == NULL || key == NULL
|| (n = _xhash_node_get(h, key, _xhasher(key))) == NULL) {
/* log_debug(ZONE,"failed lookup of %s",key); */
return NULL;
}
/* log_debug(ZONE,"found %s returning %X",key,n->val); */
return n->val;
}
void xhash_zap(xht h, const char *key)
{
xhn n;
if (h == NULL || key == NULL
|| (n = _xhash_node_get(h, key, _xhasher(key))) == NULL)
return;
/* log_debug(ZONE,"zapping %s",key); */
/* kill an entry by zeroing out the key */
n->key = NULL;
}
void xhash_free(xht h)
{
/* log_debug(ZONE,"hash free %X",h); */
if (h != NULL)
pool_free(h->p);
}
void xhash_walk(xht h, xhash_walker w, void *arg)
{
int i;
xhn n;
if (h == NULL || w == NULL)
return;
/* log_debug(ZONE,"walking %X",h); */
for (i = 0; i < h->prime; i++)
for (n = &h->zen[i]; n != NULL; n = n->next)
if (n->key != NULL && n->val != NULL)
(*w) (h, n->key, n->val, arg);
}
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