1 | /* |
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2 | * htable.c - Generic, embedded hash table implementation. |
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3 | * |
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4 | * Author Alain Greiner (2016,2017) |
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5 | * |
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6 | * Copyright (c) UPMC Sorbonne Universites |
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7 | * |
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8 | * This file is part of ALMOS-MKH. |
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9 | * |
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10 | * ALMOS-MKH is free software; you can redistribute it and/or modify it |
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11 | * under the terms of the GNU General Public License as published by |
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12 | * the Free Software Foundation; version 2.0 of the License. |
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13 | * |
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14 | * ALMOS-MKH is distributed in the hope that it will be useful, but |
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15 | * WITHOUT ANY WARRANTY; without even the implied warranty of |
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16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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17 | * General Public License for more details. |
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18 | * |
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19 | * You should have received a copy of the GNU General Public License |
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20 | * along with ALMOS-MKH; if not, write to the Free Software Foundation, |
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21 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
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22 | */ |
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23 | |
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24 | #include <kernel_config.h> |
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25 | #include <hal_kernel_types.h> |
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26 | #include <hal_special.h> |
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27 | #include <htab.h> |
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28 | #include <busylock.h> |
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29 | #include <list.h> |
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30 | #include <printk.h> |
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31 | #include <vfs.h> |
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32 | |
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33 | |
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34 | /////////////////////////////////////////////////////////////////////////////////////////// |
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35 | // Item type specific (static) functions (two functions for each item type). |
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36 | // Example below if for <bloup_t> type, where the identifier is an uint32_t field. |
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37 | /////////////////////////////////////////////////////////////////////////////////////////// |
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38 | |
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39 | typedef struct bloup_s |
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40 | { |
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41 | uint32_t key; |
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42 | list_entry_t list; |
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43 | } |
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44 | bloup_t; |
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45 | |
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46 | /////////////////////////////////////////////////////////////////////////////////////////// |
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47 | // This static function computes the hash index from the key. |
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48 | /////////////////////////////////////////////////////////////////////////////////////////// |
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49 | // @ key : local pointer on key. |
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50 | // @ return the index value, from 0 to (HASHTAB_SIZE - 1) |
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51 | /////////////////////////////////////////////////////////////////////////////////////////// |
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52 | static uint32_t htab_bloup_index( void * key ) |
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53 | { |
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54 | return (*(uint32_t *)key) % HASHTAB_SIZE; |
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55 | } |
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56 | |
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57 | /////////////////////////////////////////////////////////////////////////////////////// |
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58 | // This static function is used by htab_lookup(), htab_insert(), and htab_remove(). |
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59 | // They scan one sub-list identified by <index> to find an item identified by <key>. |
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60 | // The sub-list is not modified, but the lock must have been taken by the caller. |
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61 | /////////////////////////////////////////////////////////////////////////////////////// |
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62 | // @ htab : pointer on hash table. |
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63 | // @ index : index of sub-list to be scanned. |
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64 | // @ key : pointer on item identifier. |
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65 | // @ return pointer on item if found / return NULL if not found. |
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66 | /////////////////////////////////////////////////////////////////////////////////////// |
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67 | static void * htab_bloup_scan( htab_t * htab, |
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68 | uint32_t index, |
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69 | void * key ) |
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70 | { |
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71 | list_entry_t * list_entry; // pointer on list_entry_t (iterator) |
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72 | bloup_t * bloup; // pointer on item |
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73 | |
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74 | LIST_FOREACH( &htab->roots[index] , list_entry ) |
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75 | { |
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76 | bloup = (bloup_t *)LIST_ELEMENT( list_entry , bloup_t , list ); |
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77 | if( bloup->key == *(uint32_t *)key ) return bloup; |
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78 | } |
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79 | |
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80 | // no matching item found |
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81 | return NULL; |
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82 | } |
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83 | |
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84 | //////////////////////////////////////////////////////////////////////////////////////// |
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85 | // Generic access functions |
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86 | //////////////////////////////////////////////////////////////////////////////////////// |
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87 | |
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88 | //////////////////////////////////////// |
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89 | void htab_init( htab_t * htab, |
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90 | htab_item_type_t type ) |
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91 | { |
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92 | uint32_t i; |
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93 | |
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94 | // initialize readlock |
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95 | busylock_init( &htab->lock , LOCK_HTAB_STATE ); |
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96 | |
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97 | htab->items = 0; |
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98 | |
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99 | if( type == HTAB_BLOUP_TYPE ) |
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100 | { |
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101 | htab->scan = &htab_bloup_scan; |
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102 | htab->index = &htab_bloup_index; |
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103 | } |
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104 | else |
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105 | { |
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106 | assert( __FUNCTION__, false , "undefined item type\n" ); |
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107 | } |
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108 | |
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109 | // initialize partial lists |
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110 | for( i = 0 ; i < HASHTAB_SIZE ; i++ ) |
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111 | { |
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112 | list_root_init( &htab->roots[i] ); |
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113 | } |
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114 | } |
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115 | |
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116 | ///////////////////////////////////////// |
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117 | error_t htab_insert( htab_t * htab, |
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118 | void * key, |
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119 | list_entry_t * list_entry ) |
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120 | { |
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121 | // compute index from key |
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122 | uint32_t index = htab->index( key ); |
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123 | |
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124 | // take the lock |
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125 | busylock_acquire( &htab->lock ); |
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126 | |
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127 | // scan sub-list to check if item exist |
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128 | void * item = htab->scan( htab , index , key ); |
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129 | |
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130 | if( item != NULL ) // item exist => return error |
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131 | { |
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132 | // release lock |
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133 | busylock_release( &htab->lock ); |
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134 | |
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135 | return 0xFFFFFFFF; |
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136 | } |
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137 | else // item doesn't exist => register |
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138 | { |
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139 | // register item in hash table |
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140 | list_add_last( &htab->roots[index] , list_entry ); |
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141 | |
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142 | // update items number |
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143 | htab->items++; |
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144 | |
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145 | // release lock |
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146 | busylock_release( &htab->lock ); |
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147 | |
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148 | return 0; |
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149 | } |
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150 | } |
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151 | |
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152 | ///////////////////////////////////////// |
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153 | error_t htab_remove( htab_t * htab, |
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154 | void * key, |
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155 | list_entry_t * list_entry ) |
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156 | { |
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157 | // compute index from key |
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158 | uint32_t index = htab->index( key ); |
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159 | |
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160 | // take the lock |
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161 | busylock_acquire( &htab->lock ); |
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162 | |
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163 | // scan sub-list to chek if item exist |
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164 | void * item = htab->scan( htab , index , key ); |
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165 | |
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166 | if( item == NULL ) // item doesn't exist |
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167 | { |
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168 | // release lock |
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169 | busylock_release( &htab->lock ); |
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170 | |
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171 | return 0xFFFFFFFF; |
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172 | } |
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173 | else // item exist => remove it |
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174 | { |
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175 | // remove item from hash table |
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176 | list_unlink( list_entry ); |
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177 | |
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178 | // update items number |
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179 | htab->items--; |
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180 | |
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181 | // release lock |
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182 | busylock_release( &htab->lock ); |
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183 | |
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184 | return 0; |
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185 | } |
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186 | } |
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187 | |
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188 | ////////////////////////////////// |
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189 | void * htab_lookup( htab_t * htab, |
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190 | void * key ) |
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191 | { |
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192 | // compute index from key |
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193 | uint32_t index = htab->index( key ); |
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194 | |
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195 | // take the lock |
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196 | busylock_acquire( &htab->lock ); |
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197 | |
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198 | // scan sub-list |
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199 | void * item = htab->scan( htab , index , key ); |
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200 | |
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201 | // release lock |
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202 | busylock_release( &htab->lock ); |
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203 | |
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204 | return item; |
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205 | } |
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206 | |
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207 | |
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208 | |
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