1 /* infcodes.c -- process literals and length/distance pairs |
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2 * Copyright (C) 1995-2002 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 |
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12 /* simplify the use of the inflate_huft type with some defines */ |
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13 #define exop word.what.Exop |
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14 #define bits word.what.Bits |
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15 |
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16 typedef enum { /* waiting for "i:"=input, "o:"=output, "x:"=nothing */ |
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17 START, /* x: set up for LEN */ |
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18 LEN, /* i: get length/literal/eob next */ |
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19 LENEXT, /* i: getting length extra (have base) */ |
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20 DIST, /* i: get distance next */ |
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21 DISTEXT, /* i: getting distance extra */ |
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22 COPY, /* o: copying bytes in window, waiting for space */ |
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23 LIT, /* o: got literal, waiting for output space */ |
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24 WASH, /* o: got eob, possibly still output waiting */ |
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25 END, /* x: got eob and all data flushed */ |
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26 BADCODE} /* x: got error */ |
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27 inflate_codes_mode; |
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28 |
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29 /* inflate codes private state */ |
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30 struct inflate_codes_state { |
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31 |
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32 /* mode */ |
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33 inflate_codes_mode 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 local inflate_codes_statef *inflate_codes_new( /* bl, bd, tl, td, z) */ |
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59 uInt bl, uInt bd, |
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60 inflate_huft *tl, |
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61 inflate_huft *td, /* need separate declaration for Borland C++ */ |
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62 z_streamp z ) |
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63 { |
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64 inflate_codes_statef *c; |
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65 |
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66 if ((c = (inflate_codes_statef *) |
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67 ZALLOC(z,1,sizeof(struct inflate_codes_state))) != Z_NULL) |
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68 { |
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69 c->mode = START; |
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70 c->lbits = (Byte)bl; |
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71 c->dbits = (Byte)bd; |
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72 c->ltree = tl; |
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73 c->dtree = td; |
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74 Tracev((stderr, "inflate: codes new\n")); |
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75 } |
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76 return c; |
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77 } |
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78 |
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79 |
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80 local int inflate_codes( /* s, z, r) */ |
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81 inflate_blocks_statef *s, |
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82 z_streamp z, |
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83 int r ) |
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84 { |
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85 uInt j; /* temporary storage */ |
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86 inflate_huft *t; /* temporary pointer */ |
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87 uInt e; /* extra bits or operation */ |
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88 uLong b; /* bit buffer */ |
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89 uInt k; /* bits in bit buffer */ |
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90 Bytef *p; /* input data pointer */ |
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91 uInt n; /* bytes available there */ |
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92 Bytef *q; /* output window write pointer */ |
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93 uInt m; /* bytes to end of window or read pointer */ |
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94 Bytef *f; /* pointer to copy strings from */ |
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95 inflate_codes_statef *c = s->sub.decode.codes; /* codes state */ |
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96 |
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97 /* copy input/output information to locals (UPDATE macro restores) */ |
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98 LOAD |
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99 |
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100 /* process input and output based on current state */ |
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101 while (1) switch (c->mode) |
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102 { /* waiting for "i:"=input, "o:"=output, "x:"=nothing */ |
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103 case START: /* x: set up for LEN */ |
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104 #ifndef SLOW |
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105 if (m >= 258 && n >= 10) |
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106 { |
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107 UPDATE |
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108 r = inflate_fast(c->lbits, c->dbits, c->ltree, c->dtree, s, z); |
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109 LOAD |
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110 if (r != Z_OK) |
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111 { |
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112 c->mode = r == Z_STREAM_END ? WASH : BADCODE; |
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113 break; |
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114 } |
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115 } |
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116 #endif /* !SLOW */ |
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117 c->sub.code.need = c->lbits; |
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118 c->sub.code.tree = c->ltree; |
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119 c->mode = LEN; |
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120 case LEN: /* i: get length/literal/eob next */ |
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121 j = c->sub.code.need; |
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122 NEEDBITS(j) |
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123 t = c->sub.code.tree + ((uInt)b & inflate_mask[j]); |
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124 DUMPBITS(t->bits) |
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125 e = (uInt)(t->exop); |
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126 if (e == 0) /* literal */ |
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127 { |
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128 c->sub.lit = t->base; |
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129 Tracevv((stderr, t->base >= 0x20 && t->base < 0x7f ? |
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130 "inflate: literal '%c'\n" : |
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131 "inflate: literal 0x%02x\n", t->base)); |
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132 c->mode = LIT; |
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133 break; |
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134 } |
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135 if (e & 16) /* length */ |
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136 { |
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137 c->sub.copy.get = e & 15; |
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138 c->len = t->base; |
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139 c->mode = LENEXT; |
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140 break; |
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141 } |
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142 if ((e & 64) == 0) /* next table */ |
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143 { |
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144 c->sub.code.need = e; |
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145 c->sub.code.tree = t + t->base; |
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146 break; |
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147 } |
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148 if (e & 32) /* end of block */ |
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149 { |
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150 Tracevv((stderr, "inflate: end of block\n")); |
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151 c->mode = WASH; |
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152 break; |
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153 } |
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154 c->mode = BADCODE; /* invalid code */ |
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155 z->msg = (char*)"invalid literal/length code"; |
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156 r = Z_DATA_ERROR; |
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157 LEAVE |
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158 case LENEXT: /* i: getting length extra (have base) */ |
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159 j = c->sub.copy.get; |
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160 NEEDBITS(j) |
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161 c->len += (uInt)b & inflate_mask[j]; |
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162 DUMPBITS(j) |
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163 c->sub.code.need = c->dbits; |
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164 c->sub.code.tree = c->dtree; |
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165 Tracevv((stderr, "inflate: length %u\n", c->len)); |
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166 c->mode = DIST; |
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167 case DIST: /* i: get distance next */ |
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168 j = c->sub.code.need; |
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169 NEEDBITS(j) |
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170 t = c->sub.code.tree + ((uInt)b & inflate_mask[j]); |
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171 DUMPBITS(t->bits) |
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172 e = (uInt)(t->exop); |
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173 if (e & 16) /* distance */ |
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174 { |
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175 c->sub.copy.get = e & 15; |
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176 c->sub.copy.dist = t->base; |
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177 c->mode = DISTEXT; |
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178 break; |
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179 } |
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180 if ((e & 64) == 0) /* next table */ |
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181 { |
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182 c->sub.code.need = e; |
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183 c->sub.code.tree = t + t->base; |
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184 break; |
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185 } |
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186 c->mode = BADCODE; /* invalid code */ |
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187 z->msg = (char*)"invalid distance code"; |
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188 r = Z_DATA_ERROR; |
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189 LEAVE |
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190 case DISTEXT: /* i: getting distance extra */ |
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191 j = c->sub.copy.get; |
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192 NEEDBITS(j) |
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193 c->sub.copy.dist += (uInt)b & inflate_mask[j]; |
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194 DUMPBITS(j) |
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195 Tracevv((stderr, "inflate: distance %u\n", c->sub.copy.dist)); |
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196 c->mode = COPY; |
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197 case COPY: /* o: copying bytes in window, waiting for space */ |
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198 f = q - c->sub.copy.dist; |
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199 while (f < s->window) /* modulo window size-"while" instead */ |
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200 f += s->end - s->window; /* of "if" handles invalid distances */ |
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201 while (c->len) |
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202 { |
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203 NEEDOUT |
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204 OUTBYTE(*f++) |
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205 if (f == s->end) |
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206 f = s->window; |
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207 c->len--; |
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208 } |
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209 c->mode = START; |
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210 break; |
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211 case LIT: /* o: got literal, waiting for output space */ |
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212 NEEDOUT |
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213 OUTBYTE(c->sub.lit) |
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214 c->mode = START; |
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215 break; |
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216 case WASH: /* o: got eob, possibly more output */ |
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217 if (k > 7) /* return unused byte, if any */ |
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218 { |
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219 Assert(k < 16, "inflate_codes grabbed too many bytes") |
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220 k -= 8; |
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221 n++; |
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222 p--; /* can always return one */ |
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223 } |
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224 FLUSH |
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225 if (s->read != s->write) |
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226 LEAVE |
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227 c->mode = END; |
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228 case END: |
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229 r = Z_STREAM_END; |
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230 LEAVE |
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231 case BADCODE: /* x: got error */ |
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232 r = Z_DATA_ERROR; |
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233 LEAVE |
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234 default: |
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235 r = Z_STREAM_ERROR; |
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236 LEAVE |
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237 } |
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238 #ifdef NEED_DUMMY_RETURN |
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239 return Z_STREAM_ERROR; /* Some dumb compilers complain without this */ |
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240 #endif |
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241 } |
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242 |
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243 |
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244 local void inflate_codes_free( /* c, z) */ |
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245 inflate_codes_statef *c, |
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246 z_streamp z ) |
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247 { |
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248 ZFREE(z, c); |
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249 Tracev((stderr, "inflate: codes free\n")); |
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250 } |
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