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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 | #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 | /* remove element if you already found the element you want to delete and don't | |
53 | * need the overhead to find it again with hash_remove(). But usually, you | |
54 | * don't want to use this function, as it fiddles with hash-internals. */ | |
55 | void *hash_remove_element(struct hashtable_t *hash, struct element_t *elem); | |
56 | ||
57 | /* free only the hashtable and the hash itself. */ | |
58 | void hash_destroy(struct hashtable_t *hash); | |
59 | ||
60 | /* remove the hash structure. if hashdata_free_cb != NULL, this function will be | |
61 | * called to remove the elements inside of the hash. if you don't remove the | |
62 | * elements, memory might be leaked. */ | |
63 | static inline void hash_delete(struct hashtable_t *hash, | |
64 | hashdata_free_cb free_cb, void *arg) | |
65 | { | |
66 | struct hlist_head *head; | |
67 | struct hlist_node *walk, *safe; | |
68 | struct element_t *bucket; | |
69 | int i; | |
70 | ||
71 | for (i = 0; i < hash->size; i++) { | |
72 | head = &hash->table[i]; | |
73 | ||
74 | hlist_for_each_safe(walk, safe, head) { | |
75 | bucket = hlist_entry(walk, struct element_t, hlist); | |
76 | if (free_cb) | |
77 | free_cb(bucket->data, arg); | |
78 | ||
79 | hlist_del(walk); | |
80 | kfree(bucket); | |
81 | } | |
82 | } | |
83 | ||
84 | hash_destroy(hash); | |
85 | } | |
86 | ||
87 | /* adds data to the hashtable. returns 0 on success, -1 on error */ | |
88 | static inline int hash_add(struct hashtable_t *hash, | |
89 | hashdata_compare_cb compare, | |
90 | hashdata_choose_cb choose, void *data) | |
91 | { | |
92 | int index; | |
93 | struct hlist_head *head; | |
94 | struct hlist_node *walk, *safe; | |
95 | struct element_t *bucket; | |
96 | ||
97 | if (!hash) | |
98 | return -1; | |
99 | ||
100 | index = choose(data, hash->size); | |
101 | head = &hash->table[index]; | |
102 | ||
103 | hlist_for_each_safe(walk, safe, head) { | |
104 | bucket = hlist_entry(walk, struct element_t, hlist); | |
105 | if (compare(bucket->data, data)) | |
106 | return -1; | |
107 | } | |
108 | ||
109 | /* no duplicate found in list, add new element */ | |
110 | bucket = kmalloc(sizeof(struct element_t), GFP_ATOMIC); | |
111 | ||
112 | if (!bucket) | |
113 | return -1; | |
114 | ||
115 | bucket->data = data; | |
116 | hlist_add_head(&bucket->hlist, head); | |
117 | ||
118 | return 0; | |
119 | } | |
120 | ||
121 | /* removes data from hash, if found. returns pointer do data on success, so you | |
122 | * can remove the used structure yourself, or NULL on error . data could be the | |
123 | * structure you use with just the key filled, we just need the key for | |
124 | * comparing. */ | |
125 | static inline void *hash_remove(struct hashtable_t *hash, | |
126 | hashdata_compare_cb compare, | |
127 | hashdata_choose_cb choose, void *data) | |
128 | { | |
129 | size_t index; | |
130 | struct hlist_node *walk; | |
131 | struct element_t *bucket; | |
132 | struct hlist_head *head; | |
133 | void *data_save; | |
134 | ||
135 | index = choose(data, hash->size); | |
136 | head = &hash->table[index]; | |
137 | ||
138 | hlist_for_each_entry(bucket, walk, head, hlist) { | |
139 | if (compare(bucket->data, data)) { | |
140 | data_save = bucket->data; | |
141 | hlist_del(walk); | |
142 | kfree(bucket); | |
143 | return data_save; | |
144 | } | |
145 | } | |
146 | ||
147 | return NULL; | |
148 | } | |
149 | ||
150 | /* finds data, based on the key in keydata. returns the found data on success, | |
151 | * or NULL on error */ | |
152 | static inline void *hash_find(struct hashtable_t *hash, | |
153 | hashdata_compare_cb compare, | |
154 | hashdata_choose_cb choose, void *keydata) | |
155 | { | |
156 | int index; | |
157 | struct hlist_head *head; | |
158 | struct hlist_node *walk; | |
159 | struct element_t *bucket; | |
160 | ||
161 | if (!hash) | |
162 | return NULL; | |
163 | ||
164 | index = choose(keydata , hash->size); | |
165 | head = &hash->table[index]; | |
166 | ||
167 | hlist_for_each(walk, head) { | |
168 | bucket = hlist_entry(walk, struct element_t, hlist); | |
169 | if (compare(bucket->data, keydata)) | |
170 | return bucket->data; | |
171 | } | |
172 | ||
173 | return NULL; | |
174 | } | |
175 | ||
176 | #endif /* _NET_BATMAN_ADV_HASH_H_ */ |