1 | /**************************************************************************
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2 | *
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3 | * huffman.c -- Huffman coding functions
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4 | * Copyright (C) 1994 Neil Sharman
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5 | *
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6 | * This program is free software; you can redistribute it and/or modify
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7 | * it under the terms of the GNU General Public License as published by
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8 | * the Free Software Foundation; either version 2 of the License, or
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9 | * (at your option) any later version.
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10 | *
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11 | * This program is distributed in the hope that it will be useful,
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12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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14 | * GNU General Public License 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 this program; if not, write to the Free Software
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18 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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19 | *
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20 | * $Id: huffman.c 3745 2003-02-20 21:20:24Z mdewsnip $
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21 | *
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22 | **************************************************************************/
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23 |
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24 | /*
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25 | $Log$
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26 | Revision 1.1 2003/02/20 21:14:16 mdewsnip
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27 | Addition of MG package for search and retrieval
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28 |
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29 | Revision 1.1 1999/08/10 21:16:51 sjboddie
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30 | renamed mg-1.3d directory mg
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31 |
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32 | Revision 1.1 1998/11/17 09:32:03 rjmcnab
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33 | *** empty log message ***
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34 |
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35 | * Revision 1.1 1994/08/22 00:24:44 tes
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36 | * Initial placement under CVS.
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37 | *
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38 | */
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39 |
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40 | static char *RCSID = "$Id: huffman.c 3745 2003-02-20 21:20:24Z mdewsnip $";
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41 |
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42 | #include "sysfuncs.h"
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43 | #include "memlib.h"
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44 | #include "huffman.h"
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45 | #include "messages.h"
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46 | #include "netorder.h" /* [RPAP - Jan 97: Endian Ordering] */
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47 |
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48 | /* ->data on success,
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49 | NULL on error
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50 | */
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51 | huff_data *
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52 | Generate_Huffman_Data (int num, long *freqs, huff_data * data,
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53 | u_long * mem)
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54 | {
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55 | int HNum, i, count;
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56 | unsigned long *heap;
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57 | huff_data *hd = data;
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58 | if (!hd)
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59 | {
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60 | if (!(hd = Xmalloc (sizeof (huff_data))))
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61 | goto error0;
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62 | }
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63 | if (!(heap = Xmalloc (num * 2 * sizeof (*heap))))
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64 | goto error1;
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65 | if (!(hd->clens = Xmalloc (num * sizeof (char))))
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66 | goto error2;
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67 | hd->num_codes = num;
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68 | if (mem)
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69 | {
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70 | if (hd != data)
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71 | *mem += sizeof (huff_data);
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72 | *mem += num * sizeof (char);
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73 | }
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74 | bcopy ((char *) freqs, (char *) &heap[num], num * sizeof (*heap));
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75 | bzero ((char *) heap, num * sizeof (*heap));
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76 |
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77 | /* Initialise the pointers to the leaves */
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78 | for (count = i = 0; i < num; i++)
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79 | if (heap[num + i])
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80 | heap[count++] = num + i;
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81 |
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82 | /* Reorganise the pointers so that it is a heap */
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83 | HNum = count;
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84 | for (i = HNum / 2; i > 0; i--)
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85 | {
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86 | register int curr, child;
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87 | curr = i;
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88 | child = curr * 2;
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89 | while (child <= HNum)
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90 | {
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91 | if (child < HNum && heap[heap[child]] < heap[heap[child - 1]])
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92 | child++;
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93 | if (heap[heap[curr - 1]] > heap[heap[child - 1]])
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94 | {
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95 | register u_long temp;
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96 | temp = heap[child - 1];
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97 | heap[child - 1] = heap[curr - 1];
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98 | heap[curr - 1] = temp;
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99 | curr = child;
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100 | child = 2 * curr;
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101 | }
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102 | else
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103 | break;
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104 | }
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105 | }
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106 |
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107 |
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108 | /* Form the huffman tree */
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109 | while (HNum > 1)
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110 | {
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111 | int pos[2];
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112 |
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113 | for (i = 0; i < 2; i++)
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114 | {
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115 | register int curr, child;
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116 | pos[i] = heap[0];
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117 | heap[0] = heap[--HNum];
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118 | curr = 1;
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119 | child = 2;
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120 | while (child <= HNum)
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121 | {
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122 | if (child < HNum &&
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123 | heap[heap[child]] < heap[heap[child - 1]])
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124 | child++;
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125 | if (heap[heap[curr - 1]] > heap[heap[child - 1]])
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126 | {
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127 | register int temp;
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128 | temp = heap[child - 1];
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129 | heap[child - 1] = heap[curr - 1];
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130 | heap[curr - 1] = temp;
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131 | curr = child;
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132 | child = 2 * curr;
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133 | }
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134 | else
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135 | break;
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136 | }
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137 | }
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138 |
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139 | heap[HNum + 1] = heap[pos[0]] + heap[pos[1]];
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140 | heap[pos[0]] = heap[pos[1]] = HNum + 1;
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141 |
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142 | heap[HNum] = HNum + 1;
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143 |
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144 | {
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145 | register int parent, curr;
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146 | HNum++;
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147 | curr = HNum;
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148 | parent = curr >> 1;
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149 | while (parent && heap[heap[parent - 1]] > heap[heap[curr - 1]])
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150 | {
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151 | register int temp;
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152 | temp = heap[parent - 1];
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153 | heap[parent - 1] = heap[curr - 1];
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154 | heap[curr - 1] = temp;
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155 | curr = parent;
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156 | parent = curr >> 1;
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157 | }
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158 | }
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159 | }
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160 |
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161 |
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162 | /* Calculate the code lens */
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163 | heap[0] = -1UL;
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164 | heap[1] = 0;
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165 | for (i = 2; i < num * 2; i++)
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166 | heap[i] = heap[heap[i]] + 1;
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167 |
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168 | /* zero the lencount's array */
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169 | bzero ((char *) hd->lencount, sizeof (hd->lencount));
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170 | hd->maxcodelen = 0;
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171 | hd->mincodelen = 100;
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172 |
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173 | /* Set the code length of each leaf in the huffman tree */
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174 | for (i = 0; i < num; i++)
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175 | {
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176 | register u_long codelen = heap[i + num];
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177 | hd->clens[i] = (char) codelen;
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178 | if (!codelen)
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179 | continue;
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180 | if (codelen > hd->maxcodelen)
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181 | hd->maxcodelen = codelen;
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182 | if (codelen < hd->mincodelen)
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183 | hd->mincodelen = codelen;
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184 | hd->lencount[codelen]++;
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185 | }
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186 |
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187 |
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188 | if (hd->maxcodelen == 0 && hd->mincodelen == 100)
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189 | {
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190 | hd->num_codes = 0;
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191 | }
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192 | else
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193 | {
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194 | /* Calculate the current codes for each different code length */
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195 | hd->min_code[hd->maxcodelen] = 0;
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196 | for (i = hd->maxcodelen - 1; i>=0; i--)
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197 | hd->min_code[i] = (hd->min_code[i + 1] + hd->lencount[i + 1]) >> 1;
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198 | }
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199 | free (heap);
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200 | return (hd);
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201 |
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202 | error2:
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203 | free (heap);
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204 | error1:
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205 | if (!data)
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206 | free (hd);
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207 | error0:
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208 | return (NULL);
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209 |
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210 | }
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211 |
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212 | unsigned long *
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213 | Generate_Huffman_Codes (huff_data * data, u_long * mem)
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214 | {
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215 | int i;
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216 | unsigned long *codes;
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217 | unsigned long mc[MAX_HUFFCODE_LEN + 1];
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218 |
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219 | if (!data)
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220 | return (NULL);
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221 | if (!(codes = Xmalloc (data->num_codes * sizeof (*codes))))
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222 | return (NULL);
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223 | if (mem)
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224 | *mem += data->num_codes * sizeof (*codes);
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225 | bcopy ((char *) data->min_code, (char *) mc, sizeof (mc));
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226 | for (i = 0; i < data->num_codes; i++)
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227 | if (data->clens[i])
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228 | codes[i] = mc[(int) (data->clens[i])]++;
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229 |
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230 | return (codes);
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231 | }
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232 |
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233 |
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234 | unsigned long **
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235 | Generate_Huffman_Vals (huff_data * data, u_long * mem)
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236 | {
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237 | int i;
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238 | unsigned long *fcode[MAX_HUFFCODE_LEN + 1];
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239 | unsigned long **values;
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240 | unsigned long *vals;
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241 |
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242 | if (!data)
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243 | return (NULL);
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244 | if (!(vals = Xmalloc (data->num_codes * sizeof (*vals))))
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245 | return (NULL);
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246 | if (!(values = Xmalloc ((MAX_HUFFCODE_LEN + 1) * sizeof (unsigned long *))))
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247 | {
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248 | free (vals);
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249 | return (NULL);
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250 | }
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251 |
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252 | bzero ((char *) values, (MAX_HUFFCODE_LEN + 1) * sizeof (unsigned long *));
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253 |
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254 | if (mem)
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255 | *mem += data->num_codes * sizeof (*vals) +
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256 | (MAX_HUFFCODE_LEN + 1) * sizeof (unsigned long *);
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257 |
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258 | fcode[0] = values[0] = &vals[0];
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259 | for (i = 1; i <= data->maxcodelen; i++)
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260 | fcode[i] = values[i] = &vals[(values[i - 1] - vals) + data->lencount[i - 1]];
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261 |
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262 | for (i = 0; i < data->num_codes; i++)
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263 | if (data->clens[i])
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264 | *fcode[(int) (data->clens[i])]++ = i;
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265 | return (values);
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266 | }
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267 |
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268 |
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269 |
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270 | double
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271 | Calculate_Huffman_Size (int num, long *freqs, long *counts)
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272 | {
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273 | double size = 0;
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274 | huff_data hd;
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275 | int i;
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276 | if (!Generate_Huffman_Data (num, freqs, &hd, NULL))
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277 | return -1;
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278 | for (i = 0; i < num; i++)
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279 | size += counts[i] * hd.clens[i];
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280 | Xfree (hd.clens);
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281 | return size;
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282 | }
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283 |
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284 |
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285 |
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286 | int
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287 | Write_Huffman_Data (FILE * f, huff_data * hd)
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288 | {
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289 | /* [RPAP - Jan 97: Endian Ordering] */
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290 | HTONSI(hd->num_codes);
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291 | HTONSI(hd->mincodelen);
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292 | HTONSI(hd->maxcodelen);
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293 |
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294 | if (fwrite (&hd->num_codes, sizeof (hd->num_codes), 1, f) != 1)
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295 | return -1;
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296 |
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297 | if (fwrite (&hd->mincodelen, sizeof (hd->mincodelen), 1, f) != 1)
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298 | return -1;
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299 |
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300 | if (fwrite (&hd->maxcodelen, sizeof (hd->maxcodelen), 1, f) != 1)
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301 | return -1;
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302 |
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303 | /* [RPAP - Jan 97: Endian Ordering] */
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304 | NTOHSI(hd->num_codes);
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305 | NTOHSI(hd->mincodelen);
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306 | NTOHSI(hd->maxcodelen);
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307 |
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308 | if (hd->num_codes)
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309 | {
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310 | /* [RPAP - Jan 97: Endian Ordering] */
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311 | int i;
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312 | for (i = hd->mincodelen; i < hd->maxcodelen + 1; i++)
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313 | HTONSI(hd->lencount[i]);
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314 | for (i = 0; i < hd->maxcodelen + 1; i++)
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315 | HTONUL(hd->min_code[i]);
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316 |
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317 | if (fwrite (hd->lencount + hd->mincodelen, sizeof (*hd->lencount),
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318 | hd->maxcodelen - hd->mincodelen + 1, f) !=
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319 | hd->maxcodelen - hd->mincodelen + 1)
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320 | return -1;
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321 |
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322 | if (fwrite (hd->min_code, sizeof (*hd->min_code), hd->maxcodelen + 1, f) !=
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323 | hd->maxcodelen + 1)
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324 | return -1;
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325 |
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326 | if (fwrite (hd->clens, sizeof (*hd->clens), hd->num_codes, f) != hd->num_codes)
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327 | return -1;
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328 |
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329 | /* [RPAP - Jan 97: Endian Ordering] */
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330 | for (i = hd->mincodelen; i < hd->maxcodelen + 1; i++)
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331 | NTOHSI(hd->lencount[i]);
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332 | for (i = 0; i < hd->maxcodelen + 1; i++)
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333 | NTOHUL(hd->min_code[i]);
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334 | }
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335 | return 0;
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336 | }
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337 |
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338 |
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339 |
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340 |
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341 | static int
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342 | General_Read_Huffman_Data (size_t (*rd) (), void *f,
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343 | huff_data * hd, u_long * mem, u_long * disk)
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344 | {
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345 | if (rd (&hd->num_codes, sizeof (hd->num_codes), 1, f) != 1)
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346 | return -1;
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347 |
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348 | if (rd (&hd->mincodelen, sizeof (hd->mincodelen), 1, f) != 1)
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349 | return -1;
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350 |
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351 | if (rd (&hd->maxcodelen, sizeof (hd->maxcodelen), 1, f) != 1)
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352 | return -1;
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353 |
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354 | /* [RPAP - Jan 97: Endian Ordering] */
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355 | NTOHSI(hd->num_codes);
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356 | NTOHSI(hd->mincodelen);
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357 | NTOHSI(hd->maxcodelen);
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358 |
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359 | if (disk)
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360 | (*disk) += sizeof (hd->num_codes) + sizeof (hd->mincodelen) +
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361 | sizeof (hd->maxcodelen);
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362 |
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363 | hd->clens = NULL;
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364 |
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365 | if (hd->num_codes)
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366 | {
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367 | int i; /* [RPAP - Jan 97: Endian Ordering] */
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368 |
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369 | bzero ((char *) (hd->lencount), sizeof (hd->lencount));
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370 | if (rd (hd->lencount + hd->mincodelen, sizeof (*hd->lencount),
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371 | hd->maxcodelen - hd->mincodelen + 1, f) !=
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372 | hd->maxcodelen - hd->mincodelen + 1)
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373 | return -1;
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374 |
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375 | /* [RPAP - Jan 97: Endian Ordering] */
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376 | for (i = hd->mincodelen; i < hd->maxcodelen + 1; i++)
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377 | NTOHSI(hd->lencount[i]);
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378 |
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379 | if (disk)
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380 | (*disk) += sizeof (*hd->lencount) * (hd->maxcodelen - hd->mincodelen + 1);
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381 |
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382 | bzero ((char *) (hd->min_code), sizeof (hd->min_code));
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383 |
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384 | if (rd (hd->min_code, sizeof (*hd->min_code), hd->maxcodelen + 1, f) !=
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385 | hd->maxcodelen + 1)
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386 | return -1;
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387 |
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388 | /* [RPAP - Jan 97: Endian Ordering] */
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389 | for (i = 0; i < hd->maxcodelen + 1; i++)
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390 | NTOHUL(hd->min_code[i]);
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391 |
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392 | if (disk)
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393 | (*disk) += sizeof (*hd->min_code) * (hd->maxcodelen + 1);
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394 |
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395 | if (!(hd->clens = Xmalloc (sizeof (*hd->clens) * hd->num_codes)))
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396 | return -1;
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397 |
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398 |
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399 | if (rd (hd->clens, sizeof (*hd->clens), hd->num_codes, f) != hd->num_codes)
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400 | return -1;
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401 |
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402 | if (disk)
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403 | (*disk) += sizeof (*hd->clens) * hd->num_codes;
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404 | }
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405 |
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406 | if (mem)
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407 | *mem += sizeof (*hd->clens) * hd->num_codes;
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408 | return 0;
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409 | }
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410 |
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411 |
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412 |
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413 | int
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414 | Read_Huffman_Data (FILE * f, huff_data * hd, u_long * mem, u_long * disk)
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415 | {
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416 | return General_Read_Huffman_Data (fread, f, hd, mem, disk);
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417 | }
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418 |
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419 |
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420 |
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421 |
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422 | int
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423 | F_Read_Huffman_Data (File * f, huff_data * hd, u_long * mem, u_long * disk)
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424 | {
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425 | return General_Read_Huffman_Data (Fread, f, hd, mem, disk);
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426 | }
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