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1 /* infcodes.c -- process literals and length/distance pairs
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2 * Copyright (C) 1995-1998 Mark Adler
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3 * For conditions of distribution and use, see copyright notice in zlib.h
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4 */
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5
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6 #include "zutil.h"
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7 #include "inftrees.h"
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8 #include "infblock.h"
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9 #include "infcodes.h"
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10 #include "infutil.h"
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11 #include "inffast.h"
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12
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13 /* simplify the use of the inflate_huft type with some defines */
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14 #define exop word.what.Exop
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15 #define bits word.what.Bits
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16
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17 typedef enum { /* waiting for "i:"=input, "o:"=output, "x:"=nothing */
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18 START, /* x: set up for LEN */
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19 LEN, /* i: get length/literal/eob next */
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20 LENEXT, /* i: getting length extra (have base) */
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21 DIST, /* i: get distance next */
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22 DISTEXT, /* i: getting distance extra */
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23 COPY, /* o: copying bytes in window, waiting for space */
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24 LIT, /* o: got literal, waiting for output space */
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25 WASH, /* o: got eob, possibly still output waiting */
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26 END, /* x: got eob and all data flushed */
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27 BADCODE} /* x: got error */
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28 inflate_codes_mode;
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29
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30 /* inflate codes private state */
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31 struct inflate_codes_state {
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32
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33 /* mode */
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34 inflate_codes_mode mode; /* current inflate_codes mode */
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35
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36 /* mode dependent information */
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37 uInt len;
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38 union {
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39 struct {
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40 inflate_huft *tree; /* pointer into tree */
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41 uInt need; /* bits needed */
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42 } code; /* if LEN or DIST, where in tree */
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43 uInt lit; /* if LIT, literal */
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44 struct {
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45 uInt get; /* bits to get for extra */
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46 uInt dist; /* distance back to copy from */
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47 } copy; /* if EXT or COPY, where and how much */
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48 } sub; /* submode */
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49
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50 /* mode independent information */
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51 Byte lbits; /* ltree bits decoded per branch */
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52 Byte dbits; /* dtree bits decoder per branch */
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53 inflate_huft *ltree; /* literal/length/eob tree */
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54 inflate_huft *dtree; /* distance tree */
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55
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56 };
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57
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58
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59 inflate_codes_statef *inflate_codes_new(bl, bd, tl, td, z)
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60 uInt bl, bd;
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61 inflate_huft *tl;
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62 inflate_huft *td; /* need separate declaration for Borland C++ */
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63 z_streamp z;
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64 {
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65 inflate_codes_statef *c;
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66
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67 if ((c = (inflate_codes_statef *)
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68 ZALLOC(z,1,sizeof(struct inflate_codes_state))) != Z_NULL)
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69 {
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70 c->mode = START;
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71 c->lbits = (Byte)bl;
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72 c->dbits = (Byte)bd;
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73 c->ltree = tl;
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74 c->dtree = td;
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75 Tracev((stderr, "inflate: codes new\n"));
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76 }
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77 return c;
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78 }
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79
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80
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81 int inflate_codes(s, z, r)
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82 inflate_blocks_statef *s;
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83 z_streamp z;
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84 int r;
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85 {
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86 uInt j; /* temporary storage */
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87 inflate_huft *t; /* temporary pointer */
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88 uInt e; /* extra bits or operation */
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89 uLong b; /* bit buffer */
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90 uInt k; /* bits in bit buffer */
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91 Bytef *p; /* input data pointer */
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92 uInt n; /* bytes available there */
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93 Bytef *q; /* output window write pointer */
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94 uInt m; /* bytes to end of window or read pointer */
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95 Bytef *f; /* pointer to copy strings from */
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96 inflate_codes_statef *c = s->sub.decode.codes; /* codes state */
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97
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98 /* copy input/output information to locals (UPDATE macro restores) */
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99 LOAD
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100
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101 /* process input and output based on current state */
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102 while (1) switch (c->mode)
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103 { /* waiting for "i:"=input, "o:"=output, "x:"=nothing */
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104 case START: /* x: set up for LEN */
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105 #ifndef SLOW
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106 if (m >= 258 && n >= 10)
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107 {
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108 UPDATE
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109 r = inflate_fast(c->lbits, c->dbits, c->ltree, c->dtree, s, z);
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110 LOAD
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111 if (r != Z_OK)
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112 {
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113 c->mode = r == Z_STREAM_END ? WASH : BADCODE;
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114 break;
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115 }
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116 }
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117 #endif /* !SLOW */
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118 c->sub.code.need = c->lbits;
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119 c->sub.code.tree = c->ltree;
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120 c->mode = LEN;
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121 case LEN: /* i: get length/literal/eob next */
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122 j = c->sub.code.need;
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123 NEEDBITS(j)
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124 t = c->sub.code.tree + ((uInt)b & inflate_mask[j]);
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125 DUMPBITS(t->bits)
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126 e = (uInt)(t->exop);
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127 if (e == 0) /* literal */
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128 {
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129 c->sub.lit = t->base;
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130 Tracevv((stderr, t->base >= 0x20 && t->base < 0x7f ?
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131 "inflate: literal '%c'\n" :
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132 "inflate: literal 0x%02x\n", t->base));
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133 c->mode = LIT;
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134 break;
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135 }
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136 if (e & 16) /* length */
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137 {
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138 c->sub.copy.get = e & 15;
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139 c->len = t->base;
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140 c->mode = LENEXT;
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141 break;
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142 }
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143 if ((e & 64) == 0) /* next table */
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144 {
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145 c->sub.code.need = e;
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146 c->sub.code.tree = t + t->base;
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147 break;
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148 }
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149 if (e & 32) /* end of block */
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150 {
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151 Tracevv((stderr, "inflate: end of block\n"));
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152 c->mode = WASH;
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153 break;
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154 }
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155 c->mode = BADCODE; /* invalid code */
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156 z->msg = (char*)"invalid literal/length code";
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157 r = Z_DATA_ERROR;
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158 LEAVE
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159 case LENEXT: /* i: getting length extra (have base) */
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160 j = c->sub.copy.get;
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161 NEEDBITS(j)
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162 c->len += (uInt)b & inflate_mask[j];
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163 DUMPBITS(j)
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164 c->sub.code.need = c->dbits;
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165 c->sub.code.tree = c->dtree;
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166 Tracevv((stderr, "inflate: length %u\n", c->len));
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167 c->mode = DIST;
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168 case DIST: /* i: get distance next */
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169 j = c->sub.code.need;
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170 NEEDBITS(j)
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171 t = c->sub.code.tree + ((uInt)b & inflate_mask[j]);
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172 DUMPBITS(t->bits)
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173 e = (uInt)(t->exop);
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174 if (e & 16) /* distance */
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175 {
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176 c->sub.copy.get = e & 15;
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177 c->sub.copy.dist = t->base;
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178 c->mode = DISTEXT;
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179 break;
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180 }
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181 if ((e & 64) == 0) /* next table */
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182 {
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183 c->sub.code.need = e;
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184 c->sub.code.tree = t + t->base;
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185 break;
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186 }
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187 c->mode = BADCODE; /* invalid code */
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188 z->msg = (char*)"invalid distance code";
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189 r = Z_DATA_ERROR;
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190 LEAVE
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191 case DISTEXT: /* i: getting distance extra */
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192 j = c->sub.copy.get;
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193 NEEDBITS(j)
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194 c->sub.copy.dist += (uInt)b & inflate_mask[j];
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195 DUMPBITS(j)
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196 Tracevv((stderr, "inflate: distance %u\n", c->sub.copy.dist));
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197 c->mode = COPY;
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198 case COPY: /* o: copying bytes in window, waiting for space */
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199 #ifndef __TURBOC__ /* Turbo C bug for following expression */
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200 f = (uInt)(q - s->window) < c->sub.copy.dist ?
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201 s->end - (c->sub.copy.dist - (q - s->window)) :
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202 q - c->sub.copy.dist;
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203 #else
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204 f = q - c->sub.copy.dist;
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205 if ((uInt)(q - s->window) < c->sub.copy.dist)
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206 f = s->end - (c->sub.copy.dist - (uInt)(q - s->window));
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207 #endif
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208 while (c->len)
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209 {
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210 NEEDOUT
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211 OUTBYTE(*f++)
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212 if (f == s->end)
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213 f = s->window;
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214 c->len--;
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215 }
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216 c->mode = START;
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217 break;
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218 case LIT: /* o: got literal, waiting for output space */
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219 NEEDOUT
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220 OUTBYTE(c->sub.lit)
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221 c->mode = START;
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222 break;
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223 case WASH: /* o: got eob, possibly more output */
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224 if (k > 7) /* return unused byte, if any */
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225 {
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226 Assert(k < 16, "inflate_codes grabbed too many bytes")
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227 k -= 8;
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228 n++;
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229 p--; /* can always return one */
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230 }
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231 FLUSH
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232 if (s->read != s->write)
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233 LEAVE
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234 c->mode = END;
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235 case END:
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236 r = Z_STREAM_END;
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237 LEAVE
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238 case BADCODE: /* x: got error */
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239 r = Z_DATA_ERROR;
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240 LEAVE
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241 default:
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242 r = Z_STREAM_ERROR;
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243 LEAVE
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244 }
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245 #ifdef NEED_DUMMY_RETURN
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246 return Z_STREAM_ERROR; /* Some dumb compilers complain without this */
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247 #endif
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248 }
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249
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250
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251 void inflate_codes_free(c, z)
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252 inflate_codes_statef *c;
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253 z_streamp z;
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254 {
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255 ZFREE(z, c);
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256 Tracev((stderr, "inflate: codes free\n"));
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257 }
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