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428
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1 /* Hash tables.
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2 Copyright (C) 1992, 1993, 1994 Free Software Foundation, Inc.
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3
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4 This file is part of XEmacs.
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5
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6 XEmacs is free software; you can redistribute it and/or modify it
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7 under the terms of the GNU General Public License as published by the
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8 Free Software Foundation; either version 2, or (at your option) any
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9 later version.
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10
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11 XEmacs is distributed in the hope that it will be useful, but WITHOUT
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12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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14 for more details.
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15
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16 You should have received a copy of the GNU General Public License
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17 along with XEmacs; see the file COPYING. If not, write to
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18 the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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19 Boston, MA 02111-1307, USA. */
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20
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21 /* Synched up with: Not in FSF. */
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22
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23 #include <config.h>
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24 #include "lisp.h"
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25 #include "hash.h"
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26
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27 #define NULL_ENTRY ((void *) 0xdeadbeef)
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28
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29 #define COMFORTABLE_SIZE(size) (21 * (size) / 16)
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30
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31 #define KEYS_DIFFER_P(old, new, testfun) \
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32 (((old) != (new)) && (!(testfun) || !(testfun) ((old),(new))))
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33
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34 static void rehash (hentry *harray, struct hash_table *ht, hash_size_t size);
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35
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36 unsigned long
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37 memory_hash (CONST void *xv, size_t size)
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38 {
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39 unsigned int h = 0;
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40 unsigned CONST char *x = (unsigned CONST char *) xv;
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41
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42 if (!x) return 0;
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43
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44 while (size--)
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45 {
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46 unsigned int g;
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47 h = (h << 4) + *x++;
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48 if ((g = h & 0xf0000000) != 0)
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49 h = (h ^ (g >> 24)) ^ g;
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50 }
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51
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52 return h;
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53 }
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54
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55 /* Return a suitable size for a hash table, with at least SIZE slots. */
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56 static size_t
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57 hash_table_size (size_t requested_size)
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58 {
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59 /* Return some prime near, but greater than or equal to, SIZE.
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60 Decades from the time of writing, someone will have a system large
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61 enough that the list below will be too short... */
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62 static CONST size_t primes [] =
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63 {
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64 19, 29, 41, 59, 79, 107, 149, 197, 263, 347, 457, 599, 787, 1031,
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65 1361, 1777, 2333, 3037, 3967, 5167, 6719, 8737, 11369, 14783,
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66 19219, 24989, 32491, 42257, 54941, 71429, 92861, 120721, 156941,
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67 204047, 265271, 344857, 448321, 582821, 757693, 985003, 1280519,
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68 1664681, 2164111, 2813353, 3657361, 4754591, 6180989, 8035301,
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69 10445899, 13579681, 17653589, 22949669, 29834603, 38784989,
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70 50420551, 65546729, 85210757, 110774011, 144006217, 187208107,
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71 243370577, 316381771, 411296309, 534685237, 695090819, 903618083,
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72 1174703521, 1527114613, 1985248999, 2580823717UL, 3355070839UL
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73 };
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74 /* We've heard of binary search. */
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75 int low, high;
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76 for (low = 0, high = countof (primes) - 1; high - low > 1;)
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77 {
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78 /* Loop Invariant: size < primes [high] */
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79 int mid = (low + high) / 2;
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80 if (primes [mid] < requested_size)
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81 low = mid;
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82 else
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83 high = mid;
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84 }
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85 return primes [high];
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86 }
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87
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88 CONST void *
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89 gethash (CONST void *key, struct hash_table *hash_table, CONST void **ret_value)
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90 {
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91 if (!key)
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92 {
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93 *ret_value = hash_table->zero_entry;
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94 return (void *) hash_table->zero_set;
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95 }
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96 else
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97 {
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98 hentry *harray = hash_table->harray;
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99 hash_table_test_function test_function = hash_table->test_function;
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100 hash_size_t size = hash_table->size;
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101 unsigned int hcode_initial =
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102 hash_table->hash_function ?
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103 hash_table->hash_function (key) :
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104 (unsigned long) key;
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105 unsigned int hcode = hcode_initial % size;
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106 hentry *e = &harray [hcode];
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107 CONST void *e_key = e->key;
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108
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109 if (e_key ?
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110 KEYS_DIFFER_P (e_key, key, test_function) :
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111 e->contents == NULL_ENTRY)
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112 {
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113 size_t h2 = size - 2;
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114 unsigned int incr = 1 + (hcode_initial % h2);
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115 do
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116 {
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117 hcode += incr; if (hcode >= size) hcode -= size;
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118 e = &harray [hcode];
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119 e_key = e->key;
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120 }
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121 while (e_key ?
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122 KEYS_DIFFER_P (e_key, key, test_function) :
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123 e->contents == NULL_ENTRY);
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124 }
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125
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126 *ret_value = e->contents;
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127 return e->key;
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128 }
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129 }
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130
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131 void
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132 clrhash (struct hash_table *hash_table)
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133 {
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134 memset (hash_table->harray, 0, sizeof (hentry) * hash_table->size);
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135 hash_table->zero_entry = 0;
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136 hash_table->zero_set = 0;
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137 hash_table->fullness = 0;
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138 }
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139
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140 void
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141 free_hash_table (struct hash_table *hash_table)
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142 {
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143 xfree (hash_table->harray);
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144 xfree (hash_table);
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145 }
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146
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147 struct hash_table*
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148 make_hash_table (hash_size_t size)
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149 {
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150 struct hash_table *hash_table = xnew_and_zero (struct hash_table);
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151 hash_table->size = hash_table_size (COMFORTABLE_SIZE (size));
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152 hash_table->harray = xnew_array (hentry, hash_table->size);
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153 clrhash (hash_table);
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154 return hash_table;
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155 }
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156
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157 struct hash_table *
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158 make_general_hash_table (hash_size_t size,
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159 hash_table_hash_function hash_function,
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160 hash_table_test_function test_function)
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161 {
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162 struct hash_table* hash_table = make_hash_table (size);
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163 hash_table->hash_function = hash_function;
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164 hash_table->test_function = test_function;
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165 return hash_table;
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166 }
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167
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168 static void
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169 grow_hash_table (struct hash_table *hash_table, hash_size_t new_size)
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170 {
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171 hash_size_t old_size = hash_table->size;
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172 hentry *old_harray = hash_table->harray;
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173
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174 hash_table->size = hash_table_size (new_size);
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175 hash_table->harray = xnew_array (hentry, hash_table->size);
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176
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177 /* do the rehash on the "grown" table */
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178 {
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179 long old_zero_set = hash_table->zero_set;
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180 void *old_zero_entry = hash_table->zero_entry;
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181 clrhash (hash_table);
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182 hash_table->zero_set = old_zero_set;
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183 hash_table->zero_entry = old_zero_entry;
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184 rehash (old_harray, hash_table, old_size);
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185 }
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186
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187 xfree (old_harray);
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188 }
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189
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190 void
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191 puthash (CONST void *key, void *contents, struct hash_table *hash_table)
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192 {
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193 if (!key)
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194 {
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195 hash_table->zero_entry = contents;
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196 hash_table->zero_set = 1;
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197 }
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198 else
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199 {
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200 hash_table_test_function test_function = hash_table->test_function;
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201 hash_size_t size = hash_table->size;
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202 hentry *harray = hash_table->harray;
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203 unsigned int hcode_initial =
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204 hash_table->hash_function ?
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205 hash_table->hash_function (key) :
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206 (unsigned long) key;
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207 unsigned int hcode = hcode_initial % size;
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208 size_t h2 = size - 2;
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209 unsigned int incr = 1 + (hcode_initial % h2);
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210 CONST void *e_key = harray [hcode].key;
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211 CONST void *oldcontents;
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212
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213 if (e_key && KEYS_DIFFER_P (e_key, key, test_function))
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214 {
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215 do
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216 {
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217 hcode += incr; if (hcode >= size) hcode -= size;
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218 e_key = harray [hcode].key;
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219 }
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220 while (e_key && KEYS_DIFFER_P (e_key, key, test_function));
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221 }
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222 oldcontents = harray [hcode].contents;
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223 harray [hcode].key = key;
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224 harray [hcode].contents = contents;
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225 /* If the entry that we used was a deleted entry,
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226 check for a non deleted entry of the same key,
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227 then delete it. */
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228 if (!e_key && oldcontents == NULL_ENTRY)
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229 {
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230 hentry *e;
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231
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232 do
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233 {
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234 hcode += incr; if (hcode >= size) hcode -= size;
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235 e = &harray [hcode];
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236 e_key = e->key;
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237 }
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238 while (e_key ?
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239 KEYS_DIFFER_P (e_key, key, test_function):
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240 e->contents == NULL_ENTRY);
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241
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242 if (e_key)
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243 {
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244 e->key = 0;
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245 e->contents = NULL_ENTRY;
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246 }
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247 }
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248
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249 /* only increment the fullness when we used up a new hentry */
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250 if (!e_key || KEYS_DIFFER_P (e_key, key, test_function))
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251 {
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252 hash_size_t comfortable_size = COMFORTABLE_SIZE (++(hash_table->fullness));
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253 if (hash_table->size < comfortable_size)
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254 grow_hash_table (hash_table, comfortable_size + 1);
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255 }
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256 }
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257 }
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258
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259 static void
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260 rehash (hentry *harray, struct hash_table *hash_table, hash_size_t size)
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261 {
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262 hentry *limit = harray + size;
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263 hentry *e;
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264 for (e = harray; e < limit; e++)
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265 {
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266 if (e->key)
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267 puthash (e->key, e->contents, hash_table);
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268 }
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269 }
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270
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271 void
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272 remhash (CONST void *key, struct hash_table *hash_table)
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273 {
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274 if (!key)
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275 {
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276 hash_table->zero_entry = 0;
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277 hash_table->zero_set = 0;
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278 }
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279 else
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280 {
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281 hentry *harray = hash_table->harray;
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282 hash_table_test_function test_function = hash_table->test_function;
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283 hash_size_t size = hash_table->size;
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284 unsigned int hcode_initial =
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285 (hash_table->hash_function) ?
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286 (hash_table->hash_function (key)) :
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287 ((unsigned long) key);
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288 unsigned int hcode = hcode_initial % size;
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289 hentry *e = &harray [hcode];
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290 CONST void *e_key = e->key;
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291
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292 if (e_key ?
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293 KEYS_DIFFER_P (e_key, key, test_function) :
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294 e->contents == NULL_ENTRY)
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295 {
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296 size_t h2 = size - 2;
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297 unsigned int incr = 1 + (hcode_initial % h2);
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298 do
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299 {
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300 hcode += incr; if (hcode >= size) hcode -= size;
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301 e = &harray [hcode];
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302 e_key = e->key;
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303 }
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304 while (e_key?
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305 KEYS_DIFFER_P (e_key, key, test_function):
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306 e->contents == NULL_ENTRY);
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307 }
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308 if (e_key)
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309 {
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310 e->key = 0;
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311 e->contents = NULL_ENTRY;
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312 /* Note: you can't do fullness-- here, it breaks the world. */
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313 }
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314 }
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315 }
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316
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317 void
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318 maphash (maphash_function mf, struct hash_table *hash_table, void *arg)
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319 {
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320 hentry *e;
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321 hentry *limit;
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322
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323 if (hash_table->zero_set)
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324 {
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325 if (mf (0, hash_table->zero_entry, arg))
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326 return;
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327 }
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328
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329 for (e = hash_table->harray, limit = e + hash_table->size; e < limit; e++)
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330 {
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331 if (e->key && mf (e->key, e->contents, arg))
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332 return;
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333 }
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334 }
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335
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336 void
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337 map_remhash (remhash_predicate predicate, struct hash_table *hash_table, void *arg)
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338 {
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339 hentry *e;
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340 hentry *limit;
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341
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342 if (hash_table->zero_set && predicate (0, hash_table->zero_entry, arg))
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343 {
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344 hash_table->zero_set = 0;
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345 hash_table->zero_entry = 0;
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346 }
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347
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348 for (e = hash_table->harray, limit = e + hash_table->size; e < limit; e++)
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349 if (predicate (e->key, e->contents, arg))
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350 {
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351 e->key = 0;
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352 e->contents = NULL_ENTRY;
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353 }
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354 }
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