1 /**************************************************************************
2 *
3 * Copyright 2007 VMware, Inc.
4 * All Rights Reserved.
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a
7 * copy of this software and associated documentation files (the
8 * "Software"), to deal in the Software without restriction, including
9 * without limitation the rights to use, copy, modify, merge, publish,
10 * distribute, sub license, and/or sell copies of the Software, and to
11 * permit persons to whom the Software is furnished to do so, subject to
12 * the following conditions:
13 *
14 * The above copyright notice and this permission notice (including the
15 * next paragraph) shall be included in all copies or substantial portions
16 * of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
19 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
20 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
21 * IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
22 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
23 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
24 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
25 *
26 **************************************************************************/
27
28 /**
29 * @file
30 * Hash table implementation.
31 *
32 * This file provides a hash implementation that is capable of dealing
33 * with collisions. It stores colliding entries in linked list. All
34 * functions operating on the hash return an iterator. The iterator
35 * itself points to the collision list. If there wasn't any collision
36 * the list will have just one entry, otherwise client code should
37 * iterate over the entries to find the exact entry among ones that
38 * had the same key (e.g. memcmp could be used on the data to check
39 * that)
40 *
41 * @author Zack Rusin <zackr@vmware.com>
42 */
43
44 #ifndef CSO_HASH_H
45 #define CSO_HASH_H
46
47 #include "util/compiler.h"
48
49 #ifdef __cplusplus
50 extern "C" {
51 #endif
52
53
54 struct cso_node {
55 struct cso_node *next;
56 void *value;
57 unsigned key;
58 };
59
60 struct cso_hash_iter {
61 struct cso_hash *hash;
62 struct cso_node *node;
63 };
64
65 struct cso_hash {
66 struct cso_node *fakeNext;
67 struct cso_node **buckets;
68 struct cso_node *end;
69 int size;
70 short userNumBits;
71 short numBits;
72 int numBuckets;
73 };
74
75
76 void
77 cso_hash_init(struct cso_hash *hash);
78
79 void
80 cso_hash_deinit(struct cso_hash *hash);
81
82 int
83 cso_hash_size(const struct cso_hash *hash);
84
85
86 /**
87 * Adds a data with the given key to the hash. If entry with the given
88 * key is already in the hash, this current entry is instered before it
89 * in the collision list.
90 * Function returns iterator pointing to the inserted item in the hash.
91 */
92 struct cso_hash_iter
93 cso_hash_insert(struct cso_hash *hash, unsigned key, void *data);
94
95
96 /**
97 * Removes the item pointed to by the current iterator from the hash.
98 * Note that the data itself is not erased and if it was a malloc'ed pointer
99 * it will have to be freed after calling this function by the callee.
100 * Function returns iterator pointing to the item after the removed one in
101 * the hash.
102 */
103 struct cso_hash_iter
104 cso_hash_erase(struct cso_hash *hash, struct cso_hash_iter iter);
105
106 void *
107 cso_hash_take(struct cso_hash *hash, unsigned key);
108
109 struct cso_hash_iter
110 cso_hash_first_node(struct cso_hash *hash);
111
112 /**
113 * Returns true if a value with the given key exists in the hash
114 */
115 bool
116 cso_hash_contains(struct cso_hash *hash, unsigned key);
117
118 unsigned
119 cso_hash_iter_key(struct cso_hash_iter iter);
120
121
122 /**
123 * Convenience routine to iterate over the collision list while doing a memory
124 * comparison to see which entry in the list is a direct copy of our template
125 * and returns that entry.
126 */
127 void *
128 cso_hash_find_data_from_template(struct cso_hash *hash,
129 unsigned hash_key,
130 void *templ,
131 int size);
132
133 struct cso_node *
134 cso_hash_data_next(struct cso_node *node);
135
136
137 static inline bool
cso_hash_iter_is_null(struct cso_hash_iter iter)138 cso_hash_iter_is_null(struct cso_hash_iter iter)
139 {
140 return !iter.node || iter.node == iter.hash->end;
141 }
142
143
144 static inline void *
cso_hash_iter_data(struct cso_hash_iter iter)145 cso_hash_iter_data(struct cso_hash_iter iter)
146 {
147 if (!iter.node || iter.hash->end == iter.node)
148 return NULL;
149 return iter.node->value;
150 }
151
152
153 static inline struct cso_node **
cso_hash_find_node(struct cso_hash * hash,unsigned akey)154 cso_hash_find_node(struct cso_hash *hash, unsigned akey)
155 {
156 struct cso_node **node;
157
158 if (hash->numBuckets) {
159 node = &hash->buckets[akey % hash->numBuckets];
160 assert(*node == hash->end || (*node)->next);
161 while (*node != hash->end && (*node)->key != akey)
162 node = &(*node)->next;
163 } else {
164 node = &hash->end;
165 }
166 return node;
167 }
168
169
170 /**
171 * Return an iterator pointing to the first entry in the collision list.
172 */
173 static inline struct cso_hash_iter
cso_hash_find(struct cso_hash * hash,unsigned key)174 cso_hash_find(struct cso_hash *hash, unsigned key)
175 {
176 struct cso_node **nextNode = cso_hash_find_node(hash, key);
177 struct cso_hash_iter iter = {hash, *nextNode};
178 return iter;
179 }
180
181
182 static inline struct cso_hash_iter
cso_hash_iter_next(struct cso_hash_iter iter)183 cso_hash_iter_next(struct cso_hash_iter iter)
184 {
185 struct cso_hash_iter next = {iter.hash, cso_hash_data_next(iter.node)};
186 return next;
187 }
188
189 #ifdef __cplusplus
190 }
191 #endif
192
193 #endif
194