diff options
Diffstat (limited to 'src/lib/hashtable.c')
| -rw-r--r-- | src/lib/hashtable.c | 188 |
1 files changed, 188 insertions, 0 deletions
diff --git a/src/lib/hashtable.c b/src/lib/hashtable.c new file mode 100644 index 00000000..cc73d6a0 --- /dev/null +++ b/src/lib/hashtable.c @@ -0,0 +1,188 @@ +/* + * Ouroboros - Copyright (C) 2016 + * + * Hash table with separate chaining on collisions + * + * Sander Vrijders <sander.vrijders@intec.ugent.be> + * + * 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., 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +#include <ouroboros/config.h> +#include <ouroboros/hashtable.h> +#include <ouroboros/list.h> +#include <ouroboros/errno.h> + +#include <assert.h> + +struct htable_entry { + struct list_head next; + uint64_t key; + void * val; +}; + +struct htable { + struct list_head * buckets; + bool hash_key; + uint64_t buckets_size; +}; + +struct htable * htable_create(uint64_t buckets, bool hash_key) +{ + struct htable * tmp; + unsigned int i; + + if (buckets == 0) + return NULL; + + buckets--; + buckets |= buckets >> 1; + buckets |= buckets >> 2; + buckets |= buckets >> 4; + buckets |= buckets >> 8; + buckets |= buckets >> 16; + buckets |= buckets >> 32; + buckets++; + + tmp = malloc(sizeof(*tmp)); + if (tmp == NULL) + return NULL; + + tmp->hash_key = hash_key; + tmp->buckets_size = buckets; + + tmp->buckets = malloc(buckets * sizeof(*tmp->buckets)); + if (tmp->buckets == NULL) { + free(tmp); + return NULL; + } + + for (i = 0; i < buckets; i++) + INIT_LIST_HEAD(&(tmp->buckets[i])); + + return tmp; +} + +int htable_destroy(struct htable * table) +{ + unsigned int i; + struct list_head * pos = NULL; + struct list_head * n = NULL; + struct htable_entry * entry; + + assert(table); + + for (i = 0; i < table->buckets_size; i++) { + list_for_each_safe(pos, n, &(table->buckets[i])) { + entry = list_entry(pos, struct htable_entry, next); + free(entry->val); + free(entry); + } + } + + free(table->buckets); + free(table); + + return 0; +} + +static uint64_t hash(uint64_t x) +{ + x = (x ^ (x >> 30)) * UINT64_C(0xbf58476d1ce4e5b9); + x = (x ^ (x >> 27)) * UINT64_C(0x94d049bb133111eb); + x = x ^ (x >> 31); + + return x; +} + +static uint64_t calc_key(struct htable * table, uint64_t key) +{ + if (table->hash_key == true) + key = hash(key); + + return (key & (table->buckets_size - 1)); +} + +int htable_insert(struct htable * table, uint64_t key, void * val) +{ + struct htable_entry * entry; + uint64_t lookup_key; + struct list_head * pos = NULL; + + assert(table); + + lookup_key = calc_key(table, key); + + list_for_each(pos, &(table->buckets[lookup_key])) { + entry = list_entry(pos, struct htable_entry, next); + if (entry->key == key) + return -1; + } + + entry = malloc(sizeof(*entry)); + if (entry == NULL) + return -ENOMEM; + + entry->key = key; + entry->val = val; + INIT_LIST_HEAD(&entry->next); + + list_add(&entry->next, &(table->buckets[lookup_key])); + + return 0; +} + +void * htable_lookup(struct htable * table, uint64_t key) +{ + struct htable_entry * entry; + struct list_head * pos = NULL; + uint64_t lookup_key; + + assert(table); + + lookup_key = calc_key(table, key); + + list_for_each(pos, &(table->buckets[lookup_key])) { + entry = list_entry(pos, struct htable_entry, next); + if (entry->key == key) + return entry->val; + } + + return NULL; +} + +int htable_delete(struct htable * table, uint64_t key) +{ + struct htable_entry * entry; + uint64_t lookup_key; + struct list_head * pos = NULL; + struct list_head * n = NULL; + + assert(table); + + lookup_key = calc_key(table, key); + + list_for_each_safe(pos, n, &(table->buckets[lookup_key])) { + entry = list_entry(pos, struct htable_entry, next); + if (entry->key == key) { + list_del(&entry->next); + free(entry->val); + free(entry); + return 0; + } + } + + return -1; +} |