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10
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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 "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 base more.Base
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15 #define next more.Next
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16 #define exop word.what.Exop
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17 #define bits word.what.Bits
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18
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19 /* inflate codes private state */
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20 struct inflate_codes_state {
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21
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22 /* mode */
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23 enum { /* waiting for "i:"=input, "o:"=output, "x:"=nothing */
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24 START, /* x: set up for LEN */
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25 LEN, /* i: get length/literal/eob next */
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26 LENEXT, /* i: getting length extra (have base) */
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27 DIST, /* i: get distance next */
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28 DISTEXT, /* i: getting distance extra */
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29 COPY, /* o: copying bytes in window, waiting for space */
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30 LIT, /* o: got literal, waiting for output space */
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31 WASH, /* o: got eob, possibly still output waiting */
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32 END, /* x: got eob and all data flushed */
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33 BADCODE} /* x: got error */
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34 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, *td;
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62 z_stream *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 int inflate_codes(s, z, r)
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81 inflate_blocks_statef *s;
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82 z_stream *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->next;
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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 = "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->next;
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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 = "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 #ifndef __TURBOC__ /* Turbo C bug for following expression */
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199 f = (uInt)(q - s->window) < c->sub.copy.dist ?
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200 s->end - (c->sub.copy.dist - (q - s->window)) :
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201 q - c->sub.copy.dist;
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202 #else
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203 f = q - c->sub.copy.dist;
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204 if ((uInt)(q - s->window) < c->sub.copy.dist)
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205 f = s->end - (c->sub.copy.dist - (q - s->window));
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206 #endif
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207 while (c->len)
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208 {
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209 NEEDOUT
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210 OUTBYTE(*f++)
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211 if (f == s->end)
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212 f = s->window;
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213 c->len--;
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214 }
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215 c->mode = START;
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216 break;
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217 case LIT: /* o: got literal, waiting for output space */
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218 NEEDOUT
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219 OUTBYTE(c->sub.lit)
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220 c->mode = START;
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221 break;
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222 case WASH: /* o: got eob, possibly more output */
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223 FLUSH
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224 if (s->read != s->write)
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225 LEAVE
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226 c->mode = END;
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227 case END:
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228 r = Z_STREAM_END;
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229 LEAVE
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230 case BADCODE: /* x: got error */
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231 r = Z_DATA_ERROR;
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232 LEAVE
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233 default:
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234 r = Z_STREAM_ERROR;
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235 LEAVE
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236 }
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237 }
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238
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239
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240 void inflate_codes_free(c, z)
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241 inflate_codes_statef *c;
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242 z_stream *z;
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243 {
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244 ZFREE(z, c);
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245 Tracev((stderr, "inflate: codes free\n"));
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246 }
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