linuxptp/hash.c

114 lines
2.3 KiB
C

/**
* @file hash.c
* @brief Implements a simple hash table.
* @note Copyright (C) 2015 Richard Cochran <richardcochran@gmail.com>
*
* This program 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 of the License, or
* (at your option) any later version.
*
* This program 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 this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <stdlib.h>
#include <string.h>
#include "hash.h"
#define HASH_TABLE_SIZE 200
struct node {
char *key;
void *data;
struct node *next;
};
struct hash {
struct node *table[HASH_TABLE_SIZE];
};
static unsigned int hash_function(const char* s)
{
unsigned int i;
for (i = 0; *s; s++) {
i = 131 * i + *s;
}
return i % HASH_TABLE_SIZE;
}
struct hash *hash_create(void)
{
struct hash *ht = calloc(1, sizeof(*ht));
return ht;
}
void hash_destroy(struct hash *ht, void (*func)(void *))
{
unsigned int i;
struct node *n, *next, **table = ht->table;
for (i = 0; i < HASH_TABLE_SIZE; i++) {
for (n = table[i] ; n; n = next) {
next = n->next;
if (func) {
func(n->data);
}
free(n->key);
free(n);
}
}
free(ht);
}
int hash_insert(struct hash *ht, const char* key, void *data)
{
unsigned int h;
struct node *n, **table = ht->table;
h = hash_function(key);
for (n = table[h] ; n; n = n->next) {
if (!strcmp(n->key, key)) {
/* reject duplicate keys */
return -1;
}
}
n = calloc(1, sizeof(*n));
if (!n) {
return -1;
}
n->key = strdup(key);
if (!n->key) {
free(n);
return -1;
}
n->data = data;
n->next = table[h];
table[h] = n;
return 0;
}
void *hash_lookup(struct hash *ht, const char* key)
{
unsigned int h;
struct node *n, **table = ht->table;
h = hash_function(key);
for (n = table[h] ; n; n = n->next) {
if (!strcmp(n->key, key)) {
return n->data;
}
}
return NULL;
}