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/* hashtable.c 0.1 1999/1/16 Tom Wheeley <tomw@tsys.demon.co.uk> */
/* This code is placed under the GNU Public Licence */
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <errno.h>
#include "chunk.h"
#include "hashtable.h"
static size_t ht_hash_code(char *key, unsigned max)
{
register unsigned long g;
register unsigned long h;
if (!key) return 0;
h = 0;
while (*key) {
h = (h << 4) + *key++;
if ((g = h & 0xf0000000))
h ^= g >> 24;
h &= ~g;
}
return h % max;
}
ht_t *ht_new(size_t size)
{
ht_t *ht;
if (size <= 0)
return NULL;
ht = malloc(sizeof (ht_t));
if (!ht)
return NULL;
ht->size = size;
ht->table = calloc(size, sizeof (ht_entry_t *));
if (!ht->table) {
free(ht);
return NULL;
}
ht->chunk = ch_new(size * sizeof (ht_entry_t));
if (!ht->chunk) {
free(ht->table);
free(ht);
return NULL;
}
return ht;
}
int ht_add(char *key, void *data, ht_t *ht)
{
size_t hashval;
ht_entry_t *node;
if (!ht || !ht->table || ht->size <= 0) {
errno = ENOMEM;
return -1;
}
hashval = ht_hash_code(key, ht->size);
/* check to see if this already exists. Waste of time? If we remove this
* check then a sort of `stack' would be created. Hmm, sounds good
*/
#if 0
for (node=ht->table[hashval]; node; node=node->next) {
if (!strcmp(key, node->key)) {
errno = EBUSY; /* key in use */
return -1;
}
}
#endif
node = ch_malloc(sizeof (ht_entry_t), ht->chunk);
if (!node) {
return -1;
}
/* add to the beginning of the chain - easiest way and gives us this
* nifty stack type mode
*/
node->key = key;
node->data = data;
node->next = ht->table[hashval];
ht->table[hashval] = node;
return 0;
}
void *ht_match(char *key, ht_t *ht)
{
ht_entry_t *node;
unsigned hashval;
if (!ht || !ht->table) {
return NULL;
}
hashval = ht_hash_code(key, ht->size);
for (node = ht->table[hashval]; node; node = node->next) {
if (!strcmp(key, node->key)) {
return node->data;
}
}
errno = ENOENT;
return NULL;
}
int ht_remove(char *key, ht_t *ht)
{
ht_entry_t **pn;
unsigned hashval;
if (!ht || !ht->table) {
return -1;
}
hashval = ht_hash_code(key, ht->size);
for (pn = &(ht->table[hashval]); *pn; pn = &((*pn)->next)) {
if (!strcmp(key, (*pn)->key)) {
(*pn) = (*pn)->next;
return 0;
}
}
errno = ENOENT;
return -1;
}
int ht_update(char *key, void *data, ht_t *ht)
{
while (ht_match(key, ht) != NULL) {
ht_remove(key, ht);
}
return ht_add(key, data, ht);
}
void ht_free(ht_t **ht)
{
if (!ht || !(*ht))
return;
if ((*ht)->table)
free((*ht)->table);
if ((*ht)->chunk)
ch_free((*ht)->chunk);
free((*ht));
(*ht) = NULL;
}
/* end of hashtable.c */
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