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"
24 #include "libbb/libbb.h"
27 static int hash_index(hash_table_t *hash, const char *pkg_name);
28 static int rotating(const char *key, int len, int prime);
30 static int hash_index(hash_table_t *hash, const char *pkg_name)
32 return rotating(pkg_name, strlen(pkg_name), hash->n_entries);
35 static int rotating(const char *key, int len, int prime)
38 for (hash=len, i=0; i<len; ++i)
39 hash = (hash<<4)^(hash>>28)^key[i];
40 return (hash % prime);
45 * this is an open table keyed by strings
47 int hash_table_init(const char *name, hash_table_t *hash, int len)
49 static int primes_table[] = {
50 379, 761, 983, 1423, 2711, 3361, 3931, 4679, 5519, 6701, 9587,
51 19471, 23143, 33961, 46499, 49727, 99529, 0
55 if (hash->entries != NULL) {
56 /* we have been here already */
63 hash->hash_entry_key = NULL;
65 picker = primes_table;
66 while(*picker && (*picker++ < len));
68 fprintf(stderr, "%s: primes table might not be big enough (! << %d)\n", __FUNCTION__, len);
71 hash->n_entries = *picker;
72 hash->entries = xcalloc(hash->n_entries, sizeof(hash_entry_t));
77 void hash_table_deinit(hash_table_t *hash)
83 /* free the reminaing entries */
84 for (i = 0; i < hash->n_entries; i++) {
85 hash_entry_t *hash_entry = (hash->entries + i);
86 free (hash_entry->key);
87 /* skip the first entry as this is part of the array */
88 hash_entry = hash_entry->next;
91 hash_entry_t *old = hash_entry;
92 hash_entry = hash_entry->next;
100 hash->entries = NULL;
104 void *hash_table_get(hash_table_t *hash, const char *key)
106 int ndx= hash_index(hash, key);
107 hash_entry_t *hash_entry = hash->entries + ndx;
112 if (strcmp(key, hash_entry->key) == 0) {
113 // opkg_message(NULL, OPKG_DEBUG, "Function: %s. Key found for '%s' \n", __FUNCTION__, key);
114 return hash_entry->data;
117 hash_entry = hash_entry->next;
122 int hash_table_insert(hash_table_t *hash, const char *key, void *value)
124 int ndx= hash_index(hash, key);
125 hash_entry_t *hash_entry = hash->entries + ndx;
126 if (hash_entry->key) {
127 if (strcmp(hash_entry->key, key) == 0) {
128 /* alread in table, update the value */
129 hash_entry->data = value;
133 * if this is a collision, we have to go to the end of the ll,
134 * then add a new entry
135 * before we can hook up the value
137 while (hash_entry->next) {
138 hash_entry = hash_entry->next;
139 if (strcmp(hash_entry->key, key) == 0) {
140 hash_entry->data = value;
144 hash_entry->next = xcalloc(1, sizeof(hash_entry_t));
145 hash_entry = hash_entry->next;
146 hash_entry->next = NULL;
150 hash_entry->key = xstrdup(key);
151 hash_entry->data = value;
156 int hash_table_remove(hash_table_t *hash, const char *key)
158 int ndx= hash_index(hash, key);
159 hash_entry_t *hash_entry = hash->entries + ndx;
160 hash_entry_t *next_entry=NULL, *last_entry=NULL;
165 if (strcmp(key, hash_entry->key) == 0) {
166 free(hash_entry->key);
168 last_entry->next = hash_entry->next;
171 next_entry = hash_entry->next;
173 memmove(hash_entry, next_entry, sizeof(hash_entry_t));
176 memset(hash_entry, 0 , sizeof(hash_entry_t));
182 last_entry = hash_entry;
183 hash_entry = hash_entry->next;
188 void hash_table_foreach(hash_table_t *hash, void (*f)(const char *key, void *entry, void *data), void *data)
194 for (i = 0; i < hash->n_entries; i++) {
195 hash_entry_t *hash_entry = (hash->entries + i);
197 if(hash_entry->key) {
198 f(hash_entry->key, hash_entry->data, data);
200 } while((hash_entry = hash_entry->next));