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/* David Leonard, 2002. Public domain. */
/* $Id: hash.c 978 2006-01-27 15:01:08Z d $ */
/*
* Simple hash tables of linked lists. Each hash table
* has to provide a hashing function, and a more precise
* comparison function. These routines do the rest.
*/
#if HAVE_CONFIG_H
# include "config.h"
#endif
#if STDC_HEADERS
# include <stdlib.h>
#endif
#include "compat.h"
#include "hash.h"
struct hashelt {
struct hashelt *next;
const void *key;
const void *data;
};
static struct hashelt **
find(struct hash *h, const void *key)
{
unsigned int hash = (*h->hashfn)(key);
struct hashelt **he;
for (he = &h->list[hash % HASHSZ]; *he; he = &(*he)->next)
if ((*h->cmp)(key, (*he)->key) == 0)
break;
return he;
}
/* Find the data associated with a key. Returns 0 if not found. */
const void *
hash_lookup(struct hash *h, const void *key)
{
struct hashelt **he = find(h, key);
if (*he)
return (*he)->data;
else
return (void *)0;
}
/*
* Store a key and data in the hash table. The key & data pointers
* are now owned by the hash table. They will be freed later during
* hash_del() or hash_clear() using the freedata and freekey function
* pointers.
*/
void
hash_store(struct hash *h, const void *key, const void *data)
{
struct hashelt **he = find(h, key);
struct hashelt *e;
if (*he) {
if (h->freedata)
(*h->freedata)((*he)->data);
if (h->freekey)
(*h->freekey)((*he)->key);
e = *he;
} else {
e = (struct hashelt *)malloc(sizeof (struct hashelt));
if (e == NULL)
errx(1, "malloc");
e->next = *he;
*he = e;
}
(*he)->key = key;
(*he)->data = data;
}
/* Free a hashed value */
void
hash_del(struct hash *h, const void *key)
{
struct hashelt **he = find(h, key);
if (*he) {
struct hashelt *e = *he;
*he = (*he)->next;
if (h->freekey)
(*h->freekey)(e->key);
if (h->freedata)
(*h->freedata)(e->key);
free(e);
}
}
/* Free all the values stored in a hash table */
void
hash_clear(struct hash *h)
{
int i;
for (i = 0; i < HASHSZ; i++)
while (h->list[i]) {
struct hashelt *he = h->list[i];
h->list[i] = he->next;
if (h->freekey)
(*h->freekey)(he->key);
if (h->freedata)
(*h->freedata)(he->data);
free((void *)he);
}
}
/* A generic hashing function for binary data */
unsigned int
hash_generic( const void *data, size_t sz)
{
unsigned int hash = 0;
const unsigned char *p = (const unsigned char *)data;
int i;
for (i = 0; i < sz; i ++)
hash = (hash << 4) ^ *p++;
return hash;
}
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