drivers/staging/batman-adv/hash.h

   1 /*
   2  * Copyright (C) 2006-2010 B.A.T.M.A.N. contributors:
   3  *
   4  * Simon Wunderlich, Marek Lindner
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of version 2 of the GNU General Public
   8  * License as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  13  * General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  18  * 02110-1301, USA
  19  *
  20  */
  21
  22 #ifndef _NET_BATMAN_ADV_HASH_H_
  23 #define _NET_BATMAN_ADV_HASH_H_
  24
  25 #define HASHIT(name) struct hash_it_t name = { \
  26                 .index = -1, .bucket = NULL, \
  27                 .prev_bucket = NULL, \
  28                 .first_bucket = NULL }
  29
  30
  31 typedef int (*hashdata_compare_cb)(void *, void *);
  32 typedef int (*hashdata_choose_cb)(void *, int);
  33 typedef void (*hashdata_free_cb)(void *, void *);
  34
  35 struct element_t {
  36         void *data;             /* pointer to the data */
  37         struct element_t *next; /* overflow bucket pointer */
  38 };
  39
  40 struct hash_it_t {
  41         int index;
  42         struct element_t *bucket;
  43         struct element_t *prev_bucket;
  44         struct element_t **first_bucket;
  45 };
  46
  47 struct hashtable_t {
  48         struct element_t **table;   /* the hashtable itself, with the buckets */
  49         int elements;               /* number of elements registered */
  50         int size;                   /* size of hashtable */
  51         hashdata_compare_cb compare;/* callback to a compare function.  should
  52                                      * compare 2 element datas for their keys,
  53                                      * return 0 if same and not 0 if not
  54                                      * same */
  55         hashdata_choose_cb choose;  /* the hashfunction, should return an index
  56                                      * based on the key in the data of the first
  57                                      * argument and the size the second */
  58 };
  59
  60 /* allocates and clears the hash */
  61 struct hashtable_t *hash_new(int size, hashdata_compare_cb compare,
  62                              hashdata_choose_cb choose);
  63
  64 /* remove bucket (this might be used in hash_iterate() if you already found the
  65  * bucket you want to delete and don't need the overhead to find it again with
  66  * hash_remove().  But usually, you don't want to use this function, as it
  67  * fiddles with hash-internals. */
  68 void *hash_remove_bucket(struct hashtable_t *hash, struct hash_it_t *hash_it_t);
  69
  70 /* remove the hash structure. if hashdata_free_cb != NULL, this function will be
  71  * called to remove the elements inside of the hash.  if you don't remove the
  72  * elements, memory might be leaked. */
  73 void hash_delete(struct hashtable_t *hash, hashdata_free_cb free_cb, void *arg);
  74
  75 /* free only the hashtable and the hash itself. */
  76 void hash_destroy(struct hashtable_t *hash);
  77
  78 /* adds data to the hashtable. returns 0 on success, -1 on error */
  79 int hash_add(struct hashtable_t *hash, void *data);
  80
  81 /* removes data from hash, if found. returns pointer do data on success, so you
  82  * can remove the used structure yourself, or NULL on error .  data could be the
  83  * structure you use with just the key filled, we just need the key for
  84  * comparing. */
  85 void *hash_remove(struct hashtable_t *hash, void *data);
  86
  87 /* finds data, based on the key in keydata. returns the found data on success,
  88  * or NULL on error */
  89 void *hash_find(struct hashtable_t *hash, void *keydata);
  90
  91 /* resize the hash, returns the pointer to the new hash or NULL on
  92  * error. removes the old hash on success */
  93 struct hashtable_t *hash_resize(struct hashtable_t *hash, int size);
  94
  95 /* iterate though the hash. first element is selected with iter_in NULL.  use
  96  * the returned iterator to access the elements until hash_it_t returns NULL. */
  97 struct hash_it_t *hash_iterate(struct hashtable_t *hash,
  98                                struct hash_it_t *iter_in);
  99
 100 #endif /* _NET_BATMAN_ADV_HASH_H_ */