/*
* 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_ */
