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Diffstat (limited to 'net/batman-adv/hash.h')
| -rw-r--r-- | net/batman-adv/hash.h | 176 |
1 files changed, 176 insertions, 0 deletions
diff --git a/net/batman-adv/hash.h b/net/batman-adv/hash.h new file mode 100644 index 00000000000..09216ade16f --- /dev/null +++ b/net/batman-adv/hash.h @@ -0,0 +1,176 @@ +/* + * 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 + * + */ + +#ifndef _NET_BATMAN_ADV_HASH_H_ +#define _NET_BATMAN_ADV_HASH_H_ + +#include <linux/list.h> + +/* callback to a compare function. should + * compare 2 element datas for their keys, + * return 0 if same and not 0 if not + * same */ +typedef int (*hashdata_compare_cb)(void *, void *); + +/* the hashfunction, should return an index + * based on the key in the data of the first + * argument and the size the second */ +typedef int (*hashdata_choose_cb)(void *, int); +typedef void (*hashdata_free_cb)(void *, void *); + +struct element_t { + void *data; /* pointer to the data */ + struct hlist_node hlist; /* bucket list pointer */ +}; + +struct hashtable_t { + struct hlist_head *table; /* the hashtable itself, with the buckets */ + int size; /* size of hashtable */ +}; + +/* allocates and clears the hash */ +struct hashtable_t *hash_new(int size); + +/* remove element if you already found the element 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_element(struct hashtable_t *hash, struct element_t *elem); + +/* free only the hashtable and the hash itself. */ +void hash_destroy(struct hashtable_t *hash); + +/* 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. */ +static inline void hash_delete(struct hashtable_t *hash, + hashdata_free_cb free_cb, void *arg) +{ + struct hlist_head *head; + struct hlist_node *walk, *safe; + struct element_t *bucket; + int i; + + for (i = 0; i < hash->size; i++) { + head = &hash->table[i]; + + hlist_for_each_safe(walk, safe, head) { + bucket = hlist_entry(walk, struct element_t, hlist); + if (free_cb) + free_cb(bucket->data, arg); + + hlist_del(walk); + kfree(bucket); + } + } + + hash_destroy(hash); +} + +/* adds data to the hashtable. returns 0 on success, -1 on error */ +static inline int hash_add(struct hashtable_t *hash, + hashdata_compare_cb compare, + hashdata_choose_cb choose, void *data) +{ + int index; + struct hlist_head *head; + struct hlist_node *walk, *safe; + struct element_t *bucket; + + if (!hash) + return -1; + + index = choose(data, hash->size); + head = &hash->table[index]; + + hlist_for_each_safe(walk, safe, head) { + bucket = hlist_entry(walk, struct element_t, hlist); + if (compare(bucket->data, data)) + return -1; + } + + /* no duplicate found in list, add new element */ + bucket = kmalloc(sizeof(struct element_t), GFP_ATOMIC); + + if (!bucket) + return -1; + + bucket->data = data; + hlist_add_head(&bucket->hlist, head); + + return 0; +} + +/* 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. */ +static inline void *hash_remove(struct hashtable_t *hash, + hashdata_compare_cb compare, + hashdata_choose_cb choose, void *data) +{ + size_t index; + struct hlist_node *walk; + struct element_t *bucket; + struct hlist_head *head; + void *data_save; + + index = choose(data, hash->size); + head = &hash->table[index]; + + hlist_for_each_entry(bucket, walk, head, hlist) { + if (compare(bucket->data, data)) { + data_save = bucket->data; + hlist_del(walk); + kfree(bucket); + return data_save; + } + } + + return NULL; +} + +/* finds data, based on the key in keydata. returns the found data on success, + * or NULL on error */ +static inline void *hash_find(struct hashtable_t *hash, + hashdata_compare_cb compare, + hashdata_choose_cb choose, void *keydata) +{ + int index; + struct hlist_head *head; + struct hlist_node *walk; + struct element_t *bucket; + + if (!hash) + return NULL; + + index = choose(keydata , hash->size); + head = &hash->table[index]; + + hlist_for_each(walk, head) { + bucket = hlist_entry(walk, struct element_t, hlist); + if (compare(bucket->data, keydata)) + return bucket->data; + } + + return NULL; +} + +#endif /* _NET_BATMAN_ADV_HASH_H_ */ |