/* * Copyright © 2009 Intel Corporation * Copyright © 1988-2004 Keith Packard and Bart Massey. * * Permission is hereby granted, free of charge, to any person obtaining a * copy of this software and associated documentation files (the "Software"), * to deal in the Software without restriction, including without limitation * the rights to use, copy, modify, merge, publish, distribute, sublicense, * and/or sell copies of the Software, and to permit persons to whom the * Software is furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice (including the next * paragraph) shall be included in all copies or substantial portions of the * Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS * IN THE SOFTWARE. * * Except as contained in this notice, the names of the authors * or their institutions shall not be used in advertising or * otherwise to promote the sale, use or other dealings in this * Software without prior written authorization from the * authors. * * Authors: * Eric Anholt * Keith Packard */ #include #include "hash_table.h" /* * From Knuth -- a good choice for hash/rehash values is p, p-2 where * p and p-2 are both prime. These tables are sized to have an extra 10% * free to avoid exponential performance degradation as the hash table fills */ uint32_t deleted_key_value; const void *deleted_key = &deleted_key_value; static const struct { uint32_t max_entries, size, rehash; } hash_sizes[] = { { 2, 5, 3 }, { 4, 7, 5 }, { 8, 13, 11 }, { 16, 19, 17 }, { 32, 43, 41 }, { 64, 73, 71 }, { 128, 151, 149 }, { 256, 283, 281 }, { 512, 571, 569 }, { 1024, 1153, 1151 }, { 2048, 2269, 2267 }, { 4096, 4519, 4517 }, { 8192, 9013, 9011 }, { 16384, 18043, 18041 }, { 32768, 36109, 36107 }, { 65536, 72091, 72089 }, { 131072, 144409, 144407 }, { 262144, 288361, 288359 }, { 524288, 576883, 576881 }, { 1048576, 1153459, 1153457 }, { 2097152, 2307163, 2307161 }, { 4194304, 4613893, 4613891 }, { 8388608, 9227641, 9227639 }, { 16777216, 18455029, 18455027 }, { 33554432, 36911011, 36911009 }, { 67108864, 73819861, 73819859 }, { 134217728, 147639589, 147639587 }, { 268435456, 295279081, 295279079 }, { 536870912, 590559793, 590559791 }, { 1073741824, 1181116273, 1181116271}, { 2147483648ul, 2362232233ul, 2362232231ul} }; static int entry_is_free(struct hash_entry *entry) { return entry->key == NULL; } static int entry_is_present(struct hash_entry *entry) { return entry->key != NULL && entry->key != deleted_key; } struct hash_table * hash_table_create(uint32_t (*hash_function)(const void *key), int key_equals_function(const void *a, const void *b)) { struct hash_table *ht; ht = malloc(sizeof(*ht)); if (ht == NULL) return NULL; ht->size_index = 0; ht->size = hash_sizes[ht->size_index].size; ht->rehash = hash_sizes[ht->size_index].rehash; ht->max_entries = hash_sizes[ht->size_index].max_entries; ht->hash_function = hash_function; ht->table = calloc(ht->size, sizeof(*ht->table)); if (ht->table == NULL) { free(ht); return NULL; } return ht; } /** * Frees the given hash table. * * If delete_function is passed, it gets called on each entry present before * freeing. */ void hash_table_destroy(struct hash_table *ht, void (*delete_function)(struct hash_entry *entry)) { if (!ht) return; if (delete_function) { struct hash_entry *entry; for (entry = ht->table; entry != NULL; entry = hash_table_next_entry(ht, entry)) { delete_function(entry); } } free(ht); } struct hash_entry * hash_table_search(struct hash_table *ht, const void *key) { uint32_t hash, hash_address; hash = ht->hash_function(key); hash_address = hash & ht->size; do { struct hash_entry *entry = ht->table + hash_address; if (entry_is_free(entry)) { return NULL; } else if (entry_is_present(entry) && hash == hash) { if (ht->key_equals_function(key, entry->key)) { return entry; } } hash_address = (hash_address + ht->rehash) & ht->size; } while (hash_address != hash % ht->size); return NULL; } static void hash_table_expand(struct hash_table *ht) { /* XXX */ } struct hash_entry * hash_table_insert(struct hash_table *ht, const void *key, void *data) { uint32_t hash, hash_address; if (ht->entries + 1 > ht->max_entries) { hash_table_expand(ht); } hash = ht->hash_function(key); hash_address = hash & ht->size; do { struct hash_entry *entry = ht->table + hash_address; if (!entry_is_present(entry)) { entry->hash = hash; entry->key = key; entry->data = data; ht->entries++; return entry; } hash_address = (hash_address + ht->rehash) & ht->size; } while (hash_address != hash % ht->size); /* We could hit here if a required resize failed. An unchecked-malloc * application could ignore this result. */ return NULL; } /** * This function deletes the given hash table entry. * * Note that deletion doesn't otherwise modify the table, so an iteration over * the table deleting entries is safe. */ void hash_table_delete_entry(struct hash_table *ht, struct hash_entry *entry) { entry->key = deleted_key; ht->entries--; } /** * This function is an iterator over the hash table. * * Pass in NULL for the first entry, as in the start of a for loop. Note that * an iteration over the table is O(table_size) not O(entries). */ struct hash_entry * hash_table_next_entry(struct hash_table *ht, struct hash_entry *entry) { if (entry == NULL) entry = ht->table; else entry = entry + 1; for (; entry != ht->table + ht->size; entry++) { if (entry_is_present(entry)) { return entry; } } return NULL; }