1 /* 2 * Copyright (C) 2006-2011 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 #include <linux/list.h> 26 27 /* callback to a compare function. should 28 * compare 2 element datas for their keys, 29 * return 0 if same and not 0 if not 30 * same */ 31 typedef int (*hashdata_compare_cb)(void *, void *); 32 33 /* the hashfunction, should return an index 34 * based on the key in the data of the first 35 * argument and the size the second */ 36 typedef int (*hashdata_choose_cb)(void *, int); 37 typedef void (*hashdata_free_cb)(void *, void *); 38 39 struct element_t { 40 void *data; /* pointer to the data */ 41 struct hlist_node hlist; /* bucket list pointer */ 42 }; 43 44 struct hashtable_t { 45 struct hlist_head *table; /* the hashtable itself, with the buckets */ 46 int size; /* size of hashtable */ 47 }; 48 49 /* allocates and clears the hash */ 50 struct hashtable_t *hash_new(int size); 51 52 /* free only the hashtable and the hash itself. */ 53 void hash_destroy(struct hashtable_t *hash); 54 55 /* remove the hash structure. if hashdata_free_cb != NULL, this function will be 56 * called to remove the elements inside of the hash. if you don't remove the 57 * elements, memory might be leaked. */ 58 static inline void hash_delete(struct hashtable_t *hash, 59 hashdata_free_cb free_cb, void *arg) 60 { 61 struct hlist_head *head; 62 struct hlist_node *walk, *safe; 63 struct element_t *bucket; 64 int i; 65 66 for (i = 0; i < hash->size; i++) { 67 head = &hash->table[i]; 68 69 hlist_for_each_safe(walk, safe, head) { 70 bucket = hlist_entry(walk, struct element_t, hlist); 71 if (free_cb) 72 free_cb(bucket->data, arg); 73 74 hlist_del(walk); 75 kfree(bucket); 76 } 77 } 78 79 hash_destroy(hash); 80 } 81 82 /* adds data to the hashtable. returns 0 on success, -1 on error */ 83 static inline int hash_add(struct hashtable_t *hash, 84 hashdata_compare_cb compare, 85 hashdata_choose_cb choose, void *data) 86 { 87 int index; 88 struct hlist_head *head; 89 struct hlist_node *walk, *safe; 90 struct element_t *bucket; 91 92 if (!hash) 93 return -1; 94 95 index = choose(data, hash->size); 96 head = &hash->table[index]; 97 98 hlist_for_each_safe(walk, safe, head) { 99 bucket = hlist_entry(walk, struct element_t, hlist); 100 if (compare(bucket->data, data)) 101 return -1; 102 } 103 104 /* no duplicate found in list, add new element */ 105 bucket = kmalloc(sizeof(struct element_t), GFP_ATOMIC); 106 107 if (!bucket) 108 return -1; 109 110 bucket->data = data; 111 hlist_add_head(&bucket->hlist, head); 112 113 return 0; 114 } 115 116 /* removes data from hash, if found. returns pointer do data on success, so you 117 * can remove the used structure yourself, or NULL on error . data could be the 118 * structure you use with just the key filled, we just need the key for 119 * comparing. */ 120 static inline void *hash_remove(struct hashtable_t *hash, 121 hashdata_compare_cb compare, 122 hashdata_choose_cb choose, void *data) 123 { 124 size_t index; 125 struct hlist_node *walk; 126 struct element_t *bucket; 127 struct hlist_head *head; 128 void *data_save; 129 130 index = choose(data, hash->size); 131 head = &hash->table[index]; 132 133 hlist_for_each_entry(bucket, walk, head, hlist) { 134 if (compare(bucket->data, data)) { 135 data_save = bucket->data; 136 hlist_del(walk); 137 kfree(bucket); 138 return data_save; 139 } 140 } 141 142 return NULL; 143 } 144 145 /* finds data, based on the key in keydata. returns the found data on success, 146 * or NULL on error */ 147 static inline void *hash_find(struct hashtable_t *hash, 148 hashdata_compare_cb compare, 149 hashdata_choose_cb choose, void *keydata) 150 { 151 int index; 152 struct hlist_head *head; 153 struct hlist_node *walk; 154 struct element_t *bucket; 155 156 if (!hash) 157 return NULL; 158 159 index = choose(keydata , hash->size); 160 head = &hash->table[index]; 161 162 hlist_for_each(walk, head) { 163 bucket = hlist_entry(walk, struct element_t, hlist); 164 if (compare(bucket->data, keydata)) 165 return bucket->data; 166 } 167 168 return NULL; 169 } 170 171 #endif /* _NET_BATMAN_ADV_HASH_H_ */ 172