+++ /dev/null
-/*
- hash.c -- hash table management
- Copyright (C) 2012-2013 Guus Sliepen <guus@tinc-vpn.org>
-
- 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 "system.h"
-
-#include "hash.h"
-#include "xalloc.h"
-
-/* Generic hash function */
-
-static uint32_t hash_function(const void *p, size_t len) {
- const uint8_t *q = p;
- uint32_t hash = 0;
-
- while(true) {
- for(size_t i = len > 4 ? 4 : len; --i;) {
- hash += (uint32_t)q[len - i] << (8 * i);
- }
-
- hash = (uint32_t)(hash * 0x9e370001UL); // Golden ratio prime.
-
- if(len <= 4) {
- break;
- }
-
- len -= 4;
- }
-
- return hash;
-}
-
-/* Map 32 bits int onto 0..n-1, without throwing away too many bits if n is 2^8 or 2^16 */
-
-static uint32_t modulo(uint32_t hash, size_t n) {
- if(n == 0x100) {
- return (hash >> 24) ^ ((hash >> 16) & 0xff) ^ ((hash >> 8) & 0xff) ^ (hash & 0xff);
- } else if(n == 0x10000) {
- return (hash >> 16) ^ (hash & 0xffff);
- } else {
- return hash % n;
- }
-}
-
-/* (De)allocation */
-
-hash_t *hash_alloc(size_t n, size_t size) {
- hash_t *hash = xzalloc(sizeof(*hash));
- hash->n = n;
- hash->size = size;
- hash->keys = xzalloc(hash->n * hash->size);
- hash->values = xzalloc(hash->n * sizeof(*hash->values));
- return hash;
-}
-
-void hash_free(hash_t *hash) {
- free(hash->keys);
- free(hash->values);
- free(hash);
-}
-
-/* Searching and inserting */
-
-void hash_insert(hash_t *hash, const void *key, const void *value) {
- uint32_t i = modulo(hash_function(key, hash->size), hash->n);
- memcpy(hash->keys + i * hash->size, key, hash->size);
- hash->values[i] = value;
-}
-
-void *hash_search(const hash_t *hash, const void *key) {
- uint32_t i = modulo(hash_function(key, hash->size), hash->n);
-
- if(hash->values[i] && !memcmp(key, hash->keys + i * hash->size, hash->size)) {
- return (void *)hash->values[i];
- }
-
- return NULL;
-}
-
-void *hash_search_or_insert(hash_t *hash, const void *key, const void *value) {
- uint32_t i = modulo(hash_function(key, hash->size), hash->n);
-
- if(hash->values[i] && !memcmp(key, hash->keys + i * hash->size, hash->size)) {
- return (void *)hash->values[i];
- }
-
- memcpy(hash->keys + i * hash->size, key, hash->size);
- hash->values[i] = value;
- return NULL;
-}
-
-/* Deleting */
-
-void hash_delete(hash_t *hash, const void *key) {
- uint32_t i = modulo(hash_function(key, hash->size), hash->n);
- hash->values[i] = NULL;
-}
-
-/* Utility functions */
-
-void hash_clear(hash_t *hash) {
- memset(hash->values, 0, hash->n * sizeof(*hash->values));
-}
-
-void hash_resize(hash_t *hash, size_t n) {
- hash->keys = xrealloc(hash->keys, n * hash->size);
- hash->values = xrealloc(hash->values, n * sizeof(*hash->values));
-
- if(n > hash->n) {
- memset(hash->keys + hash->n * hash->size, 0, (n - hash->n) * hash->size);
- memset(hash->values + hash->n, 0, (n - hash->n) * sizeof(*hash->values));
- }
-}