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Rev | Author | Line No. | Line |
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996 | cejka | 1 | /* |
2759 | jermar | 2 | * Copyright (c) 2008 Jakub Jermar |
996 | cejka | 3 | * All rights reserved. |
4 | * |
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5 | * Redistribution and use in source and binary forms, with or without |
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6 | * modification, are permitted provided that the following conditions |
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7 | * are met: |
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8 | * |
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9 | * - Redistributions of source code must retain the above copyright |
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10 | * notice, this list of conditions and the following disclaimer. |
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11 | * - Redistributions in binary form must reproduce the above copyright |
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12 | * notice, this list of conditions and the following disclaimer in the |
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13 | * documentation and/or other materials provided with the distribution. |
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14 | * - The name of the author may not be used to endorse or promote products |
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15 | * derived from this software without specific prior written permission. |
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16 | * |
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17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
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18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
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20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
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21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
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26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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27 | */ |
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28 | |||
1866 | jermar | 29 | /** @addtogroup libc |
1653 | cejka | 30 | * @{ |
31 | */ |
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32 | /** @file |
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33 | */ |
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34 | |||
996 | cejka | 35 | /* |
36 | * This is an implementation of generic chained hash table. |
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37 | */ |
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38 | |||
4509 | decky | 39 | #include <adt/hash_table.h> |
40 | #include <adt/list.h> |
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996 | cejka | 41 | #include <unistd.h> |
42 | #include <malloc.h> |
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43 | #include <assert.h> |
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997 | cejka | 44 | #include <stdio.h> |
45 | #include <string.h> |
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996 | cejka | 46 | |
47 | /** Create chained hash table. |
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48 | * |
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2759 | jermar | 49 | * @param h Hash table structure. Will be initialized by this call. |
50 | * @param m Number of hash table buckets. |
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51 | * @param max_keys Maximal number of keys needed to identify an item. |
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52 | * @param op Hash table operations structure. |
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53 | * @return True on success |
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996 | cejka | 54 | */ |
2759 | jermar | 55 | int hash_table_create(hash_table_t *h, hash_count_t m, hash_count_t max_keys, |
56 | hash_table_operations_t *op) |
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996 | cejka | 57 | { |
997 | cejka | 58 | hash_count_t i; |
996 | cejka | 59 | |
997 | cejka | 60 | assert(h); |
61 | assert(op && op->hash && op->compare); |
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62 | assert(max_keys > 0); |
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996 | cejka | 63 | |
1202 | jermar | 64 | h->entry = malloc(m * sizeof(link_t)); |
996 | cejka | 65 | if (!h->entry) { |
997 | cejka | 66 | printf("cannot allocate memory for hash table\n"); |
67 | return false; |
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996 | cejka | 68 | } |
1202 | jermar | 69 | memset((void *) h->entry, 0, m * sizeof(link_t)); |
996 | cejka | 70 | |
71 | for (i = 0; i < m; i++) |
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72 | list_initialize(&h->entry[i]); |
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73 | |||
74 | h->entries = m; |
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75 | h->max_keys = max_keys; |
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76 | h->op = op; |
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997 | cejka | 77 | return true; |
996 | cejka | 78 | } |
79 | |||
2759 | jermar | 80 | /** Destroy a hash table instance. |
996 | cejka | 81 | * |
2759 | jermar | 82 | * @param h Hash table to be destroyed. |
996 | cejka | 83 | */ |
2759 | jermar | 84 | void hash_table_destroy(hash_table_t *h) |
85 | { |
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86 | assert(h); |
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87 | assert(h->entry); |
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88 | free(h->entry); |
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89 | } |
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90 | |||
91 | /** Insert item into a hash table. |
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92 | * |
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93 | * @param h Hash table. |
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94 | * @param key Array of all keys necessary to compute hash index. |
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95 | * @param item Item to be inserted into the hash table. |
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96 | */ |
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997 | cejka | 97 | void hash_table_insert(hash_table_t *h, unsigned long key[], link_t *item) |
996 | cejka | 98 | { |
99 | hash_index_t chain; |
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100 | |||
997 | cejka | 101 | assert(item); |
102 | assert(h && h->op && h->op->hash && h->op->compare); |
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996 | cejka | 103 | |
104 | chain = h->op->hash(key); |
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997 | cejka | 105 | assert(chain < h->entries); |
996 | cejka | 106 | |
107 | list_append(item, &h->entry[chain]); |
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108 | } |
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109 | |||
110 | /** Search hash table for an item matching keys. |
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111 | * |
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2759 | jermar | 112 | * @param h Hash table. |
113 | * @param key Array of all keys needed to compute hash index. |
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996 | cejka | 114 | * |
2759 | jermar | 115 | * @return Matching item on success, NULL if there is no such item. |
996 | cejka | 116 | */ |
997 | cejka | 117 | link_t *hash_table_find(hash_table_t *h, unsigned long key[]) |
996 | cejka | 118 | { |
119 | link_t *cur; |
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120 | hash_index_t chain; |
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121 | |||
997 | cejka | 122 | assert(h && h->op && h->op->hash && h->op->compare); |
996 | cejka | 123 | |
124 | chain = h->op->hash(key); |
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997 | cejka | 125 | assert(chain < h->entries); |
996 | cejka | 126 | |
2759 | jermar | 127 | for (cur = h->entry[chain].next; cur != &h->entry[chain]; |
128 | cur = cur->next) { |
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996 | cejka | 129 | if (h->op->compare(key, h->max_keys, cur)) { |
130 | /* |
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131 | * The entry is there. |
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132 | */ |
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133 | return cur; |
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134 | } |
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135 | } |
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136 | |||
137 | return NULL; |
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138 | } |
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139 | |||
140 | /** Remove all matching items from hash table. |
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141 | * |
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142 | * For each removed item, h->remove_callback() is called. |
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143 | * |
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2759 | jermar | 144 | * @param h Hash table. |
145 | * @param key Array of keys that will be compared against items of |
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146 | * the hash table. |
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147 | * @param keys Number of keys in the 'key' array. |
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996 | cejka | 148 | */ |
997 | cejka | 149 | void hash_table_remove(hash_table_t *h, unsigned long key[], hash_count_t keys) |
996 | cejka | 150 | { |
151 | hash_index_t chain; |
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152 | link_t *cur; |
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153 | |||
2759 | jermar | 154 | assert(h && h->op && h->op->hash && h->op->compare && |
155 | h->op->remove_callback); |
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997 | cejka | 156 | assert(keys <= h->max_keys); |
996 | cejka | 157 | |
158 | if (keys == h->max_keys) { |
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159 | |||
160 | /* |
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2759 | jermar | 161 | * All keys are known, hash_table_find() can be used to find the |
162 | * entry. |
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996 | cejka | 163 | */ |
164 | |||
165 | cur = hash_table_find(h, key); |
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166 | if (cur) { |
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167 | list_remove(cur); |
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168 | h->op->remove_callback(cur); |
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169 | } |
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170 | return; |
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171 | } |
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172 | |||
173 | /* |
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174 | * Fewer keys were passed. |
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175 | * Any partially matching entries are to be removed. |
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176 | */ |
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177 | for (chain = 0; chain < h->entries; chain++) { |
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2759 | jermar | 178 | for (cur = h->entry[chain].next; cur != &h->entry[chain]; |
179 | cur = cur->next) { |
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996 | cejka | 180 | if (h->op->compare(key, keys, cur)) { |
181 | link_t *hlp; |
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182 | |||
183 | hlp = cur; |
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184 | cur = cur->prev; |
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185 | |||
186 | list_remove(hlp); |
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187 | h->op->remove_callback(hlp); |
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188 | |||
189 | continue; |
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190 | } |
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191 | } |
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192 | } |
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193 | } |
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1653 | cejka | 194 | |
1866 | jermar | 195 | /** @} |
1653 | cejka | 196 | */ |