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