1 /* hash.c - hash tables for opkg
3 Steven M. Ayer, Jamey Hicks
5 Copyright (C) 2002 Compaq Computer Corporation
7 This program is free software; you can redistribute it and/or
8 modify it under the terms of the GNU General Public License as
9 published by the Free Software Foundation; either version 2, or (at
10 your option) any later version.
12 This program is distributed in the hope that it will be useful, but
13 WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 General Public License for more details.
22 #include "hash_table.h"
23 #include "opkg_message.h"
26 static int hash_index(hash_table_t *hash, const char *pkg_name);
27 static int rotating(const char *key, int len, int prime);
29 static int hash_index(hash_table_t *hash, const char *pkg_name)
31 return rotating(pkg_name, strlen(pkg_name), hash->n_entries);
34 static int rotating(const char *key, int len, int prime)
37 for (hash=len, i=0; i<len; ++i)
38 hash = (hash<<4)^(hash>>28)^key[i];
39 return (hash % prime);
44 * this is an open table keyed by strings
46 int hash_table_init(const char *name, hash_table_t *hash, int len)
48 static int primes_table[] = {
49 379, 761, 983, 1423, 2711, 3361, 3931, 4679, 5519, 6701, 9587,
50 19471, 23143, 33961, 46499, 49727, 99529, 0
54 if (hash->entries != NULL) {
55 /* we have been here already */
62 hash->hash_entry_key = NULL;
64 picker = primes_table;
65 while(*picker && (*picker++ < len));
67 fprintf(stderr, "%s: primes table might not be big enough (! << %d)\n", __FUNCTION__, len);
70 hash->n_entries = *picker;
71 hash->entries = (hash_entry_t *)calloc(hash->n_entries, sizeof(hash_entry_t));
72 if (hash->entries == NULL) {
73 fprintf(stderr, "%s: Out of memory.\n", __FUNCTION__);
79 void hash_table_deinit(hash_table_t *hash)
86 void *hash_table_get(hash_table_t *hash, const char *key)
88 int ndx= hash_index(hash, key);
89 hash_entry_t *hash_entry = hash->entries + ndx;
94 if (strcmp(key, hash_entry->key) == 0) {
95 // opkg_message(NULL, OPKG_DEBUG, "Function: %s. Key found for '%s' \n", __FUNCTION__, key);
96 return hash_entry->data;
99 hash_entry = hash_entry->next;
104 int hash_table_insert(hash_table_t *hash, const char *key, void *value)
106 int ndx= hash_index(hash, key);
107 hash_entry_t *hash_entry = hash->entries + ndx;
108 if (0) opkg_message(NULL, OPKG_DEBUG2, "Function: %s. Inserting in hash for '%s' \n", __FUNCTION__, key);
109 if (hash_entry->key) {
110 if (strcmp(hash_entry->key, key) == 0) {
111 /* alread in table, update the value */
112 if (0) opkg_message(NULL, OPKG_DEBUG2, "Function: %s. Value already in hash for '%s' \n", __FUNCTION__, key);
113 hash_entry->data = value;
117 * if this is a collision, we have to go to the end of the ll,
118 * then add a new entry
119 * before we can hook up the value
121 if (0) opkg_message(NULL, OPKG_DEBUG2, "Function: %s. Value already in hash by collision for '%s' \n", __FUNCTION__, key);
122 while (hash_entry->next)
123 hash_entry = hash_entry->next;
124 hash_entry->next = (hash_entry_t *)malloc(sizeof(hash_entry_t));
125 if (!hash_entry->next) {
128 hash_entry = hash_entry->next;
129 hash_entry->next = NULL;
133 hash_entry->key = strdup(key);
134 hash_entry->data = value;
140 void hash_table_foreach(hash_table_t *hash, void (*f)(const char *key, void *entry, void *data), void *data)
146 for (i = 0; i < hash->n_entries; i++) {
147 hash_entry_t *hash_entry = (hash->entries + i);
149 if(hash_entry->key) {
150 f(hash_entry->key, hash_entry->data, data);
152 } while((hash_entry = hash_entry->next));