| /* |
| * Copyright (C) 2006-2010 B.A.T.M.A.N. contributors: |
| * |
| * Simon Wunderlich, Marek Lindner |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of version 2 of the GNU General Public |
| * License as published by the Free Software Foundation. |
| * |
| * 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 "main.h" |
| #include "hash.h" |
| |
| /* clears the hash */ |
| void hash_init(struct hashtable_t *hash) |
| { |
| int i; |
| |
| hash->elements = 0; |
| |
| for (i = 0 ; i < hash->size; i++) |
| hash->table[i] = NULL; |
| } |
| |
| /* remove the hash structure. if hashdata_free_cb != NULL, this function will be |
| * called to remove the elements inside of the hash. if you don't remove the |
| * elements, memory might be leaked. */ |
| void hash_delete(struct hashtable_t *hash, hashdata_free_cb free_cb) |
| { |
| struct element_t *bucket, *last_bucket; |
| int i; |
| |
| for (i = 0; i < hash->size; i++) { |
| bucket = hash->table[i]; |
| |
| while (bucket != NULL) { |
| if (free_cb != NULL) |
| free_cb(bucket->data); |
| |
| last_bucket = bucket; |
| bucket = bucket->next; |
| kfree(last_bucket); |
| } |
| } |
| |
| hash_destroy(hash); |
| } |
| |
| /* free only the hashtable and the hash itself. */ |
| void hash_destroy(struct hashtable_t *hash) |
| { |
| kfree(hash->table); |
| kfree(hash); |
| } |
| |
| /* iterate though the hash. First element is selected if an iterator |
| * initialized with HASHIT() is supplied as iter. Use the returned |
| * (or supplied) iterator to access the elements until hash_iterate returns |
| * NULL. */ |
| |
| struct hash_it_t *hash_iterate(struct hashtable_t *hash, |
| struct hash_it_t *iter) |
| { |
| if (!hash) |
| return NULL; |
| if (!iter) |
| return NULL; |
| |
| /* sanity checks first (if our bucket got deleted in the last |
| * iteration): */ |
| if (iter->bucket != NULL) { |
| if (iter->first_bucket != NULL) { |
| /* we're on the first element and it got removed after |
| * the last iteration. */ |
| if ((*iter->first_bucket) != iter->bucket) { |
| /* there are still other elements in the list */ |
| if ((*iter->first_bucket) != NULL) { |
| iter->prev_bucket = NULL; |
| iter->bucket = (*iter->first_bucket); |
| iter->first_bucket = |
| &hash->table[iter->index]; |
| return iter; |
| } else { |
| iter->bucket = NULL; |
| } |
| } |
| } else if (iter->prev_bucket != NULL) { |
| /* |
| * we're not on the first element, and the bucket got |
| * removed after the last iteration. the last bucket's |
| * next pointer is not pointing to our actual bucket |
| * anymore. select the next. |
| */ |
| if (iter->prev_bucket->next != iter->bucket) |
| iter->bucket = iter->prev_bucket; |
| } |
| } |
| |
| /* now as we are sane, select the next one if there is some */ |
| if (iter->bucket != NULL) { |
| if (iter->bucket->next != NULL) { |
| iter->prev_bucket = iter->bucket; |
| iter->bucket = iter->bucket->next; |
| iter->first_bucket = NULL; |
| return iter; |
| } |
| } |
| |
| /* if not returned yet, we've reached the last one on the index and have |
| * to search forward */ |
| iter->index++; |
| /* go through the entries of the hash table */ |
| while (iter->index < hash->size) { |
| if ((hash->table[iter->index]) != NULL) { |
| iter->prev_bucket = NULL; |
| iter->bucket = hash->table[iter->index]; |
| iter->first_bucket = &hash->table[iter->index]; |
| return iter; |
| } else { |
| iter->index++; |
| } |
| } |
| |
| /* nothing to iterate over anymore */ |
| return NULL; |
| } |
| |
| /* allocates and clears the hash */ |
| struct hashtable_t *hash_new(int size, hashdata_compare_cb compare, |
| hashdata_choose_cb choose) |
| { |
| struct hashtable_t *hash; |
| |
| hash = kmalloc(sizeof(struct hashtable_t) , GFP_ATOMIC); |
| |
| if (hash == NULL) |
| return NULL; |
| |
| hash->size = size; |
| hash->table = kmalloc(sizeof(struct element_t *) * size, GFP_ATOMIC); |
| |
| if (hash->table == NULL) { |
| kfree(hash); |
| return NULL; |
| } |
| |
| hash_init(hash); |
| |
| hash->compare = compare; |
| hash->choose = choose; |
| |
| return hash; |
| } |
| |
| /* adds data to the hashtable. returns 0 on success, -1 on error */ |
| int hash_add(struct hashtable_t *hash, void *data) |
| { |
| int index; |
| struct element_t *bucket, *prev_bucket = NULL; |
| |
| if (!hash) |
| return -1; |
| |
| index = hash->choose(data, hash->size); |
| bucket = hash->table[index]; |
| |
| while (bucket != NULL) { |
| if (hash->compare(bucket->data, data)) |
| return -1; |
| |
| prev_bucket = bucket; |
| bucket = bucket->next; |
| } |
| |
| /* found the tail of the list, add new element */ |
| bucket = kmalloc(sizeof(struct element_t), GFP_ATOMIC); |
| |
| if (bucket == NULL) |
| return -1; |
| |
| bucket->data = data; |
| bucket->next = NULL; |
| |
| /* and link it */ |
| if (prev_bucket == NULL) |
| hash->table[index] = bucket; |
| else |
| prev_bucket->next = bucket; |
| |
| hash->elements++; |
| return 0; |
| } |
| |
| /* finds data, based on the key in keydata. returns the found data on success, |
| * or NULL on error */ |
| void *hash_find(struct hashtable_t *hash, void *keydata) |
| { |
| int index; |
| struct element_t *bucket; |
| |
| if (!hash) |
| return NULL; |
| |
| index = hash->choose(keydata , hash->size); |
| bucket = hash->table[index]; |
| |
| while (bucket != NULL) { |
| if (hash->compare(bucket->data, keydata)) |
| return bucket->data; |
| |
| bucket = bucket->next; |
| } |
| |
| return NULL; |
| } |
| |
| /* remove bucket (this might be used in hash_iterate() if you already found the |
| * bucket you want to delete and don't need the overhead to find it again with |
| * hash_remove(). But usually, you don't want to use this function, as it |
| * fiddles with hash-internals. */ |
| void *hash_remove_bucket(struct hashtable_t *hash, struct hash_it_t *hash_it_t) |
| { |
| void *data_save; |
| |
| data_save = hash_it_t->bucket->data; |
| |
| if (hash_it_t->prev_bucket != NULL) |
| hash_it_t->prev_bucket->next = hash_it_t->bucket->next; |
| else if (hash_it_t->first_bucket != NULL) |
| (*hash_it_t->first_bucket) = hash_it_t->bucket->next; |
| |
| kfree(hash_it_t->bucket); |
| hash->elements--; |
| |
| return data_save; |
| } |
| |
| /* removes data from hash, if found. returns pointer do data on success, so you |
| * can remove the used structure yourself, or NULL on error . data could be the |
| * structure you use with just the key filled, we just need the key for |
| * comparing. */ |
| void *hash_remove(struct hashtable_t *hash, void *data) |
| { |
| struct hash_it_t hash_it_t; |
| |
| hash_it_t.index = hash->choose(data, hash->size); |
| hash_it_t.bucket = hash->table[hash_it_t.index]; |
| hash_it_t.prev_bucket = NULL; |
| |
| while (hash_it_t.bucket != NULL) { |
| if (hash->compare(hash_it_t.bucket->data, data)) { |
| hash_it_t.first_bucket = |
| (hash_it_t.bucket == |
| hash->table[hash_it_t.index] ? |
| &hash->table[hash_it_t.index] : NULL); |
| return hash_remove_bucket(hash, &hash_it_t); |
| } |
| |
| hash_it_t.prev_bucket = hash_it_t.bucket; |
| hash_it_t.bucket = hash_it_t.bucket->next; |
| } |
| |
| return NULL; |
| } |
| |
| /* resize the hash, returns the pointer to the new hash or NULL on |
| * error. removes the old hash on success. */ |
| struct hashtable_t *hash_resize(struct hashtable_t *hash, int size) |
| { |
| struct hashtable_t *new_hash; |
| struct element_t *bucket; |
| int i; |
| |
| /* initialize a new hash with the new size */ |
| new_hash = hash_new(size, hash->compare, hash->choose); |
| |
| if (new_hash == NULL) |
| return NULL; |
| |
| /* copy the elements */ |
| for (i = 0; i < hash->size; i++) { |
| bucket = hash->table[i]; |
| |
| while (bucket != NULL) { |
| hash_add(new_hash, bucket->data); |
| bucket = bucket->next; |
| } |
| } |
| |
| /* remove hash and eventual overflow buckets but not the content |
| * itself. */ |
| hash_delete(hash, NULL); |
| |
| return new_hash; |
| } |