1 | /**************************************************************************
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2 | *
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3 | * locallib.cpp -- Misc functions
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4 | * Copyright (C) 1994 Gary Eddy, Alistair Moffat and 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 | **************************************************************************/
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21 |
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22 | #include "sysfuncs.h"
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23 |
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24 | #include "memlib.h"
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25 | #include "bitio_gen.h"
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26 | #include "huffman.h"
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27 | #include "netorder.h" /* [RPAP - Jan 97: Endian Ordering] */
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28 |
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29 | #include "locallib.h"
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30 | #include "text.h"
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31 |
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32 | int
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33 | vecentropy (int *A, int n)
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34 | {
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35 | int total = 0, i;
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36 | double bits = 0.0;
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37 |
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38 | for (i = 0; i < n; ++i)
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39 | total += A[i];
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40 | for (i = 0; i < n; ++i)
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41 | if (A[i])
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42 | bits += A[i] * log2 (1.0 * total / A[i]);
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43 | return ((int) (bits + 0.9999));
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44 |
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45 | }
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46 |
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47 | static void
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48 | siftdown (int *A, int i, int n)
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49 | {
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50 | int ms, t;
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51 |
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52 | while (2 * i + 1 <= n - 1)
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53 | {
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54 | if (2 * i + 1 == n - 1 || A[2 * i + 1] < A[2 * i + 2])
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55 | ms = 2 * i + 1;
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56 | else
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57 | ms = 2 * i + 2;
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58 | if (A[i] > A[ms])
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59 | {
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60 | t = A[i];
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61 | A[i] = A[ms];
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62 | A[ms] = t;
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63 | }
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64 | i = ms;
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65 | }
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66 | }
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67 |
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68 | static void
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69 | buildheap (int *A, int n)
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70 | {
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71 | int i;
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72 | for (i = n / 2 - 1; i >= 0; --i)
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73 | siftdown (A, i, n);
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74 | }
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75 |
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76 | int
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77 | huffcodebits (unsigned long *A, int n)
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78 | {
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79 | int i, j, tot = 0, bits = 0, v1, v2, *B;
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80 |
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81 | B = (int *) Xmalloc (n * sizeof (int));
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82 | j = 0;
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83 | for (i = 0; i < n; ++i)
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84 | {
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85 | if (A[i])
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86 | {
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87 | tot += (B[j++] = A[i]);
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88 | }
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89 | }
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90 | n = j;
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91 |
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92 | if (n == 0 || tot == 0)
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93 | return (0);
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94 |
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95 | buildheap (B, n);
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96 | while (n > 1)
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97 | {
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98 | v1 = B[0];
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99 | B[0] = B[n - 1];
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100 | --n;
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101 | siftdown (B, 0, n);
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102 | v2 = B[0];
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103 | B[0] = v1 + v2;
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104 | siftdown (B, 0, n);
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105 | bits += v1 + v2;
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106 | }
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107 | Xfree (B);
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108 | return (bits);
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109 | }
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110 |
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111 |
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112 | int
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113 | modelbits (unsigned long *A, int n)
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114 | {
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115 | int i, bits = 0, last, N = 0;
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116 |
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117 | last = -1;
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118 | for (i = 0; i < n; ++i)
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119 | {
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120 | if (A[i])
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121 | {
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122 | bits += BIO_Gamma_Length (i - last) + BIO_Gamma_Length (A[i]);
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123 | last = i;
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124 | ++N;
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125 | }
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126 | }
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127 | if (N == 0)
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128 | return (0);
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129 | bits += BIO_Gamma_Length (N);
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130 | return (bits);
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131 | }
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132 |
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133 |
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134 |
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135 |
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136 |
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137 | /* Find the next prime number larger than p */
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138 | int
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139 | prime (int p)
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140 | {
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141 | int limit;
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142 | p += (p & 1) + 1;
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143 | limit = (int) sqrt ((double) p) + 1;
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144 | do
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145 | {
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146 | int j;
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147 | while (limit * limit < p)
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148 | ++limit;
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149 | for (j = 3; j <= limit && p % j; j += 2)
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150 | ; /* NULLBODY */
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151 | if (j > limit)
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152 | break;
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153 | p += 2;
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154 | }
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155 | while (1);
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156 | return (p);
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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 | int Read_cdh (FILE * f, compression_dict_header * cdh, u_long * /*mem*/,
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162 | u_long * disk) {
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163 | if (disk)
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164 | (*disk) += sizeof (*cdh);
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165 |
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166 | /* [RPAP - Jan 97: Endian Ordering] */
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167 | if (fread (cdh, sizeof (*cdh), 1, f) == 1)
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168 | {
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169 | int i;
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170 | NTOHUL(cdh->dict_type);
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171 | NTOHUL(cdh->novel_method);
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172 | for (i = 0; i < TEXT_PARAMS; ++i)
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173 | NTOHUL(cdh->params[i]);
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174 | NTOHUL(cdh->num_words[0]);
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175 | NTOHUL(cdh->num_words[1]);
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176 | NTOHUL(cdh->num_word_chars[0]);
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177 | NTOHUL(cdh->num_word_chars[1]);
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178 | NTOHUL(cdh->lookback);
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179 | return 0;
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180 | }
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181 | else
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182 | return -1;
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183 | }
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184 |
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185 |
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186 | int
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187 | Read_cfh (FILE * f, comp_frags_header * cfh, u_long * mem, u_long * disk)
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188 | {
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189 | int i; /* [RPAP - Jan 97: Endian Ordering] */
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190 |
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191 | if (Read_Huffman_Data (f, &cfh->hd, mem, disk) == -1)
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192 | return -1;
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193 | if (fread (&cfh->uncompressed_size,
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194 | sizeof (cfh->uncompressed_size), 1, f) != 1)
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195 | return -1;
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196 | NTOHUL(cfh->uncompressed_size); /* [RPAP - Jan 97: Endian Ordering] */
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197 |
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198 | if (disk)
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199 | (*disk) += sizeof (cfh->uncompressed_size);
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200 |
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201 | memset (cfh->huff_words_size, '\0', sizeof (cfh->huff_words_size));
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202 |
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203 | if ((int)fread (cfh->huff_words_size + cfh->hd.mincodelen,
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204 | sizeof (*cfh->huff_words_size),
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205 | cfh->hd.maxcodelen - cfh->hd.mincodelen + 1, f) !=
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206 | cfh->hd.maxcodelen - cfh->hd.mincodelen + 1)
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207 | return -1;
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208 |
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209 | /* [RPAP - Jan 97: Endian Ordering] */
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210 | for (i = cfh->hd.mincodelen; i < cfh->hd.maxcodelen + 1; ++i)
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211 | NTOHUL(cfh->huff_words_size[i]);
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212 |
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213 | if (disk)
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214 | (*disk) += sizeof (*cfh->huff_words_size) *
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215 | (cfh->hd.maxcodelen - cfh->hd.mincodelen + 1);
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216 | return 0;
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217 | }
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218 |
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