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10
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1 /* trees.c -- output deflated data using Huffman coding
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2 * Copyright (C) 1995 Jean-loup Gailly
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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 /*
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7 * ALGORITHM
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8 *
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9 * The "deflation" process uses several Huffman trees. The more
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10 * common source values are represented by shorter bit sequences.
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11 *
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12 * Each code tree is stored in a compressed form which is itself
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13 * a Huffman encoding of the lengths of all the code strings (in
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14 * ascending order by source values). The actual code strings are
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15 * reconstructed from the lengths in the inflate process, as described
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16 * in the deflate specification.
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17 *
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18 * REFERENCES
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19 *
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20 * Deutsch, L.P.,"'Deflate' Compressed Data Format Specification".
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21 * Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc
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22 *
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23 * Storer, James A.
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24 * Data Compression: Methods and Theory, pp. 49-50.
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25 * Computer Science Press, 1988. ISBN 0-7167-8156-5.
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26 *
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27 * Sedgewick, R.
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28 * Algorithms, p290.
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29 * Addison-Wesley, 1983. ISBN 0-201-06672-6.
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30 */
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31
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32 /* $Id: trees.c,v 1.1.1.1 1997/12/06 04:37:18 darius Exp $ */
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33
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34 #include "deflate.h"
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35
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36 #ifdef DEBUG
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37 # include <ctype.h>
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38 #endif
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39
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40 /* ===========================================================================
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41 * Constants
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42 */
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43
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44 #define MAX_BL_BITS 7
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45 /* Bit length codes must not exceed MAX_BL_BITS bits */
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46
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47 #define END_BLOCK 256
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48 /* end of block literal code */
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49
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50 #define REP_3_6 16
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51 /* repeat previous bit length 3-6 times (2 bits of repeat count) */
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52
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53 #define REPZ_3_10 17
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54 /* repeat a zero length 3-10 times (3 bits of repeat count) */
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55
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56 #define REPZ_11_138 18
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57 /* repeat a zero length 11-138 times (7 bits of repeat count) */
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58
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59 local int extra_lbits[LENGTH_CODES] /* extra bits for each length code */
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60 = {0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5,0};
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61
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62 local int extra_dbits[D_CODES] /* extra bits for each distance code */
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63 = {0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13};
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64
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65 local int extra_blbits[BL_CODES]/* extra bits for each bit length code */
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66 = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};
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67
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68 local uch bl_order[BL_CODES]
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69 = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};
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70 /* The lengths of the bit length codes are sent in order of decreasing
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71 * probability, to avoid transmitting the lengths for unused bit length codes.
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72 */
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73
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74 #define Buf_size (8 * 2*sizeof(char))
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75 /* Number of bits used within bi_buf. (bi_buf might be implemented on
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76 * more than 16 bits on some systems.)
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77 */
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78
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79 /* ===========================================================================
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80 * Local data. These are initialized only once.
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81 * To do: initialize at compile time to be completely reentrant. ???
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82 */
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83
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84 local ct_data static_ltree[L_CODES+2];
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85 /* The static literal tree. Since the bit lengths are imposed, there is no
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86 * need for the L_CODES extra codes used during heap construction. However
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87 * The codes 286 and 287 are needed to build a canonical tree (see ct_init
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88 * below).
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89 */
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90
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91 local ct_data static_dtree[D_CODES];
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92 /* The static distance tree. (Actually a trivial tree since all codes use
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93 * 5 bits.)
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94 */
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95
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96 local uch dist_code[512];
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97 /* distance codes. The first 256 values correspond to the distances
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98 * 3 .. 258, the last 256 values correspond to the top 8 bits of
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99 * the 15 bit distances.
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100 */
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101
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102 local uch length_code[MAX_MATCH-MIN_MATCH+1];
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103 /* length code for each normalized match length (0 == MIN_MATCH) */
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104
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105 local int base_length[LENGTH_CODES];
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106 /* First normalized length for each code (0 = MIN_MATCH) */
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107
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108 local int base_dist[D_CODES];
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109 /* First normalized distance for each code (0 = distance of 1) */
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110
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111 struct static_tree_desc_s {
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112 ct_data *static_tree; /* static tree or NULL */
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113 intf *extra_bits; /* extra bits for each code or NULL */
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114 int extra_base; /* base index for extra_bits */
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115 int elems; /* max number of elements in the tree */
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116 int max_length; /* max bit length for the codes */
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117 };
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118
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119 local static_tree_desc static_l_desc =
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120 {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};
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121
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122 local static_tree_desc static_d_desc =
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123 {static_dtree, extra_dbits, 0, D_CODES, MAX_BITS};
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124
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125 local static_tree_desc static_bl_desc =
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126 {(ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS};
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127
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128 /* ===========================================================================
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129 * Local (static) routines in this file.
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130 */
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131
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132 local void ct_static_init OF((void));
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133 local void init_block OF((deflate_state *s));
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134 local void pqdownheap OF((deflate_state *s, ct_data *tree, int k));
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135 local void gen_bitlen OF((deflate_state *s, tree_desc *desc));
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136 local void gen_codes OF((ct_data *tree, int max_code, ushf *bl_count));
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137 local void build_tree OF((deflate_state *s, tree_desc *desc));
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138 local void scan_tree OF((deflate_state *s, ct_data *tree, int max_code));
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139 local void send_tree OF((deflate_state *s, ct_data *tree, int max_code));
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140 local int build_bl_tree OF((deflate_state *s));
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141 local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes,
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142 int blcodes));
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143 local void compress_block OF((deflate_state *s, ct_data *ltree,
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144 ct_data *dtree));
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145 local void set_data_type OF((deflate_state *s));
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146 local unsigned bi_reverse OF((unsigned value, int length));
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147 local void bi_windup OF((deflate_state *s));
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148 local void bi_flush OF((deflate_state *s));
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149 local void copy_block OF((deflate_state *s, charf *buf, unsigned len,
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150 int header));
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151
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152 #ifndef DEBUG
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153 # define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
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154 /* Send a code of the given tree. c and tree must not have side effects */
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155
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156 #else /* DEBUG */
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157 # define send_code(s, c, tree) \
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158 { if (verbose>1) fprintf(stderr,"\ncd %3d ",(c)); \
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159 send_bits(s, tree[c].Code, tree[c].Len); }
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160 #endif
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161
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162 #define d_code(dist) \
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163 ((dist) < 256 ? dist_code[dist] : dist_code[256+((dist)>>7)])
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164 /* Mapping from a distance to a distance code. dist is the distance - 1 and
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165 * must not have side effects. dist_code[256] and dist_code[257] are never
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166 * used.
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167 */
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168
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169 /* ===========================================================================
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170 * Output a short LSB first on the stream.
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171 * IN assertion: there is enough room in pendingBuf.
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172 */
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173 #define put_short(s, w) { \
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174 put_byte(s, (uch)((w) & 0xff)); \
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175 put_byte(s, (uch)((ush)(w) >> 8)); \
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176 }
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177
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178 /* ===========================================================================
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179 * Send a value on a given number of bits.
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180 * IN assertion: length <= 16 and value fits in length bits.
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181 */
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182 #ifdef DEBUG
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183 local void send_bits OF((deflate_state *s, int value, int length));
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184
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185 local void send_bits(s, value, length)
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186 deflate_state *s;
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187 int value; /* value to send */
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188 int length; /* number of bits */
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189 {
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190 Tracev((stderr," l %2d v %4x ", length, value));
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191 Assert(length > 0 && length <= 15, "invalid length");
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192 s->bits_sent += (ulg)length;
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193
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194 /* If not enough room in bi_buf, use (valid) bits from bi_buf and
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195 * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
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196 * unused bits in value.
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197 */
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198 if (s->bi_valid > (int)Buf_size - length) {
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199 s->bi_buf |= (value << s->bi_valid);
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200 put_short(s, s->bi_buf);
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201 s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);
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202 s->bi_valid += length - Buf_size;
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203 } else {
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204 s->bi_buf |= value << s->bi_valid;
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205 s->bi_valid += length;
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206 }
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207 }
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208 #else /* !DEBUG */
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209
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210 #define send_bits(s, value, length) \
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211 { int len = length;\
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212 if (s->bi_valid > (int)Buf_size - len) {\
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213 int val = value;\
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214 s->bi_buf |= (val << s->bi_valid);\
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215 put_short(s, s->bi_buf);\
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216 s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
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217 s->bi_valid += len - Buf_size;\
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218 } else {\
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219 s->bi_buf |= (value) << s->bi_valid;\
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220 s->bi_valid += len;\
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221 }\
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222 }
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223 #endif /* DEBUG */
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224
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225
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226 #define MAX(a,b) (a >= b ? a : b)
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227 /* the arguments must not have side effects */
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228
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229 /* ===========================================================================
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230 * Initialize the various 'constant' tables.
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231 * To do: do this at compile time.
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232 */
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233 local void ct_static_init()
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234 {
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235 int n; /* iterates over tree elements */
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236 int bits; /* bit counter */
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237 int length; /* length value */
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238 int code; /* code value */
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239 int dist; /* distance index */
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240 ush bl_count[MAX_BITS+1];
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241 /* number of codes at each bit length for an optimal tree */
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242
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243 /* Initialize the mapping length (0..255) -> length code (0..28) */
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244 length = 0;
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245 for (code = 0; code < LENGTH_CODES-1; code++) {
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246 base_length[code] = length;
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247 for (n = 0; n < (1<<extra_lbits[code]); n++) {
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248 length_code[length++] = (uch)code;
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249 }
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250 }
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251 Assert (length == 256, "ct_static_init: length != 256");
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252 /* Note that the length 255 (match length 258) can be represented
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253 * in two different ways: code 284 + 5 bits or code 285, so we
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254 * overwrite length_code[255] to use the best encoding:
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255 */
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256 length_code[length-1] = (uch)code;
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257
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258 /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
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259 dist = 0;
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260 for (code = 0 ; code < 16; code++) {
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261 base_dist[code] = dist;
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262 for (n = 0; n < (1<<extra_dbits[code]); n++) {
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263 dist_code[dist++] = (uch)code;
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264 }
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265 }
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266 Assert (dist == 256, "ct_static_init: dist != 256");
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267 dist >>= 7; /* from now on, all distances are divided by 128 */
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268 for ( ; code < D_CODES; code++) {
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269 base_dist[code] = dist << 7;
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270 for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
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271 dist_code[256 + dist++] = (uch)code;
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272 }
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273 }
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274 Assert (dist == 256, "ct_static_init: 256+dist != 512");
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275
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276 /* Construct the codes of the static literal tree */
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277 for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
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278 n = 0;
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279 while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
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280 while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
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281 while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
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282 while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
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283 /* Codes 286 and 287 do not exist, but we must include them in the
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284 * tree construction to get a canonical Huffman tree (longest code
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285 * all ones)
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286 */
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287 gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);
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288
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289 /* The static distance tree is trivial: */
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290 for (n = 0; n < D_CODES; n++) {
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291 static_dtree[n].Len = 5;
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292 static_dtree[n].Code = bi_reverse(n, 5);
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293 }
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294 }
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295
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296 /* ===========================================================================
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297 * Initialize the tree data structures for a new zlib stream.
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298 */
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299 void ct_init(s)
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300 deflate_state *s;
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301 {
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302 if (static_dtree[0].Len == 0) {
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303 ct_static_init(); /* To do: at compile time */
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304 }
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305
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306 s->compressed_len = 0L;
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307
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308 s->l_desc.dyn_tree = s->dyn_ltree;
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309 s->l_desc.stat_desc = &static_l_desc;
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310
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311 s->d_desc.dyn_tree = s->dyn_dtree;
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312 s->d_desc.stat_desc = &static_d_desc;
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313
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314 s->bl_desc.dyn_tree = s->bl_tree;
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315 s->bl_desc.stat_desc = &static_bl_desc;
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316
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317 s->bi_buf = 0;
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318 s->bi_valid = 0;
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319 s->last_eob_len = 8; /* enough lookahead for inflate */
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320 #ifdef DEBUG
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321 s->bits_sent = 0L;
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322 #endif
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323
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324 /* Initialize the first block of the first file: */
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325 init_block(s);
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326 }
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327
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328 /* ===========================================================================
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329 * Initialize a new block.
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330 */
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331 local void init_block(s)
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332 deflate_state *s;
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333 {
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334 int n; /* iterates over tree elements */
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335
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336 /* Initialize the trees. */
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337 for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0;
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338 for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0;
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339 for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;
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340
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341 s->dyn_ltree[END_BLOCK].Freq = 1;
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342 s->opt_len = s->static_len = 0L;
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343 s->last_lit = s->matches = 0;
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344 }
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345
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346 #define SMALLEST 1
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347 /* Index within the heap array of least frequent node in the Huffman tree */
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348
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349
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350 /* ===========================================================================
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351 * Remove the smallest element from the heap and recreate the heap with
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352 * one less element. Updates heap and heap_len.
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353 */
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354 #define pqremove(s, tree, top) \
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355 {\
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356 top = s->heap[SMALLEST]; \
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357 s->heap[SMALLEST] = s->heap[s->heap_len--]; \
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358 pqdownheap(s, tree, SMALLEST); \
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359 }
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360
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361 /* ===========================================================================
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362 * Compares to subtrees, using the tree depth as tie breaker when
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363 * the subtrees have equal frequency. This minimizes the worst case length.
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364 */
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365 #define smaller(tree, n, m, depth) \
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366 (tree[n].Freq < tree[m].Freq || \
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367 (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
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368
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369 /* ===========================================================================
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370 * Restore the heap property by moving down the tree starting at node k,
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371 * exchanging a node with the smallest of its two sons if necessary, stopping
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372 * when the heap property is re-established (each father smaller than its
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373 * two sons).
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|
|
374 */
|
|
|
375 local void pqdownheap(s, tree, k)
|
|
|
376 deflate_state *s;
|
|
|
377 ct_data *tree; /* the tree to restore */
|
|
|
378 int k; /* node to move down */
|
|
|
379 {
|
|
|
380 int v = s->heap[k];
|
|
|
381 int j = k << 1; /* left son of k */
|
|
|
382 while (j <= s->heap_len) {
|
|
|
383 /* Set j to the smallest of the two sons: */
|
|
|
384 if (j < s->heap_len &&
|
|
|
385 smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
|
|
|
386 j++;
|
|
|
387 }
|
|
|
388 /* Exit if v is smaller than both sons */
|
|
|
389 if (smaller(tree, v, s->heap[j], s->depth)) break;
|
|
|
390
|
|
|
391 /* Exchange v with the smallest son */
|
|
|
392 s->heap[k] = s->heap[j]; k = j;
|
|
|
393
|
|
|
394 /* And continue down the tree, setting j to the left son of k */
|
|
|
395 j <<= 1;
|
|
|
396 }
|
|
|
397 s->heap[k] = v;
|
|
|
398 }
|
|
|
399
|
|
|
400 /* ===========================================================================
|
|
|
401 * Compute the optimal bit lengths for a tree and update the total bit length
|
|
|
402 * for the current block.
|
|
|
403 * IN assertion: the fields freq and dad are set, heap[heap_max] and
|
|
|
404 * above are the tree nodes sorted by increasing frequency.
|
|
|
405 * OUT assertions: the field len is set to the optimal bit length, the
|
|
|
406 * array bl_count contains the frequencies for each bit length.
|
|
|
407 * The length opt_len is updated; static_len is also updated if stree is
|
|
|
408 * not null.
|
|
|
409 */
|
|
|
410 local void gen_bitlen(s, desc)
|
|
|
411 deflate_state *s;
|
|
|
412 tree_desc *desc; /* the tree descriptor */
|
|
|
413 {
|
|
|
414 ct_data *tree = desc->dyn_tree;
|
|
|
415 int max_code = desc->max_code;
|
|
|
416 ct_data *stree = desc->stat_desc->static_tree;
|
|
|
417 intf *extra = desc->stat_desc->extra_bits;
|
|
|
418 int base = desc->stat_desc->extra_base;
|
|
|
419 int max_length = desc->stat_desc->max_length;
|
|
|
420 int h; /* heap index */
|
|
|
421 int n, m; /* iterate over the tree elements */
|
|
|
422 int bits; /* bit length */
|
|
|
423 int xbits; /* extra bits */
|
|
|
424 ush f; /* frequency */
|
|
|
425 int overflow = 0; /* number of elements with bit length too large */
|
|
|
426
|
|
|
427 for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
|
|
|
428
|
|
|
429 /* In a first pass, compute the optimal bit lengths (which may
|
|
|
430 * overflow in the case of the bit length tree).
|
|
|
431 */
|
|
|
432 tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
|
|
|
433
|
|
|
434 for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
|
|
|
435 n = s->heap[h];
|
|
|
436 bits = tree[tree[n].Dad].Len + 1;
|
|
|
437 if (bits > max_length) bits = max_length, overflow++;
|
|
|
438 tree[n].Len = (ush)bits;
|
|
|
439 /* We overwrite tree[n].Dad which is no longer needed */
|
|
|
440
|
|
|
441 if (n > max_code) continue; /* not a leaf node */
|
|
|
442
|
|
|
443 s->bl_count[bits]++;
|
|
|
444 xbits = 0;
|
|
|
445 if (n >= base) xbits = extra[n-base];
|
|
|
446 f = tree[n].Freq;
|
|
|
447 s->opt_len += (ulg)f * (bits + xbits);
|
|
|
448 if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits);
|
|
|
449 }
|
|
|
450 if (overflow == 0) return;
|
|
|
451
|
|
|
452 Trace((stderr,"\nbit length overflow\n"));
|
|
|
453 /* This happens for example on obj2 and pic of the Calgary corpus */
|
|
|
454
|
|
|
455 /* Find the first bit length which could increase: */
|
|
|
456 do {
|
|
|
457 bits = max_length-1;
|
|
|
458 while (s->bl_count[bits] == 0) bits--;
|
|
|
459 s->bl_count[bits]--; /* move one leaf down the tree */
|
|
|
460 s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
|
|
|
461 s->bl_count[max_length]--;
|
|
|
462 /* The brother of the overflow item also moves one step up,
|
|
|
463 * but this does not affect bl_count[max_length]
|
|
|
464 */
|
|
|
465 overflow -= 2;
|
|
|
466 } while (overflow > 0);
|
|
|
467
|
|
|
468 /* Now recompute all bit lengths, scanning in increasing frequency.
|
|
|
469 * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
|
|
|
470 * lengths instead of fixing only the wrong ones. This idea is taken
|
|
|
471 * from 'ar' written by Haruhiko Okumura.)
|
|
|
472 */
|
|
|
473 for (bits = max_length; bits != 0; bits--) {
|
|
|
474 n = s->bl_count[bits];
|
|
|
475 while (n != 0) {
|
|
|
476 m = s->heap[--h];
|
|
|
477 if (m > max_code) continue;
|
|
|
478 if (tree[m].Len != (unsigned) bits) {
|
|
|
479 Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
|
|
|
480 s->opt_len += ((long)bits - (long)tree[m].Len)
|
|
|
481 *(long)tree[m].Freq;
|
|
|
482 tree[m].Len = (ush)bits;
|
|
|
483 }
|
|
|
484 n--;
|
|
|
485 }
|
|
|
486 }
|
|
|
487 }
|
|
|
488
|
|
|
489 /* ===========================================================================
|
|
|
490 * Generate the codes for a given tree and bit counts (which need not be
|
|
|
491 * optimal).
|
|
|
492 * IN assertion: the array bl_count contains the bit length statistics for
|
|
|
493 * the given tree and the field len is set for all tree elements.
|
|
|
494 * OUT assertion: the field code is set for all tree elements of non
|
|
|
495 * zero code length.
|
|
|
496 */
|
|
|
497 local void gen_codes (tree, max_code, bl_count)
|
|
|
498 ct_data *tree; /* the tree to decorate */
|
|
|
499 int max_code; /* largest code with non zero frequency */
|
|
|
500 ushf *bl_count; /* number of codes at each bit length */
|
|
|
501 {
|
|
|
502 ush next_code[MAX_BITS+1]; /* next code value for each bit length */
|
|
|
503 ush code = 0; /* running code value */
|
|
|
504 int bits; /* bit index */
|
|
|
505 int n; /* code index */
|
|
|
506
|
|
|
507 /* The distribution counts are first used to generate the code values
|
|
|
508 * without bit reversal.
|
|
|
509 */
|
|
|
510 for (bits = 1; bits <= MAX_BITS; bits++) {
|
|
|
511 next_code[bits] = code = (code + bl_count[bits-1]) << 1;
|
|
|
512 }
|
|
|
513 /* Check that the bit counts in bl_count are consistent. The last code
|
|
|
514 * must be all ones.
|
|
|
515 */
|
|
|
516 Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
|
|
|
517 "inconsistent bit counts");
|
|
|
518 Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
|
|
|
519
|
|
|
520 for (n = 0; n <= max_code; n++) {
|
|
|
521 int len = tree[n].Len;
|
|
|
522 if (len == 0) continue;
|
|
|
523 /* Now reverse the bits */
|
|
|
524 tree[n].Code = bi_reverse(next_code[len]++, len);
|
|
|
525
|
|
|
526 Tracec(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
|
|
|
527 n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
|
|
|
528 }
|
|
|
529 }
|
|
|
530
|
|
|
531 /* ===========================================================================
|
|
|
532 * Construct one Huffman tree and assigns the code bit strings and lengths.
|
|
|
533 * Update the total bit length for the current block.
|
|
|
534 * IN assertion: the field freq is set for all tree elements.
|
|
|
535 * OUT assertions: the fields len and code are set to the optimal bit length
|
|
|
536 * and corresponding code. The length opt_len is updated; static_len is
|
|
|
537 * also updated if stree is not null. The field max_code is set.
|
|
|
538 */
|
|
|
539 local void build_tree(s, desc)
|
|
|
540 deflate_state *s;
|
|
|
541 tree_desc *desc; /* the tree descriptor */
|
|
|
542 {
|
|
|
543 ct_data *tree = desc->dyn_tree;
|
|
|
544 ct_data *stree = desc->stat_desc->static_tree;
|
|
|
545 int elems = desc->stat_desc->elems;
|
|
|
546 int n, m; /* iterate over heap elements */
|
|
|
547 int max_code = -1; /* largest code with non zero frequency */
|
|
|
548 int node; /* new node being created */
|
|
|
549
|
|
|
550 /* Construct the initial heap, with least frequent element in
|
|
|
551 * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
|
|
|
552 * heap[0] is not used.
|
|
|
553 */
|
|
|
554 s->heap_len = 0, s->heap_max = HEAP_SIZE;
|
|
|
555
|
|
|
556 for (n = 0; n < elems; n++) {
|
|
|
557 if (tree[n].Freq != 0) {
|
|
|
558 s->heap[++(s->heap_len)] = max_code = n;
|
|
|
559 s->depth[n] = 0;
|
|
|
560 } else {
|
|
|
561 tree[n].Len = 0;
|
|
|
562 }
|
|
|
563 }
|
|
|
564
|
|
|
565 /* The pkzip format requires that at least one distance code exists,
|
|
|
566 * and that at least one bit should be sent even if there is only one
|
|
|
567 * possible code. So to avoid special checks later on we force at least
|
|
|
568 * two codes of non zero frequency.
|
|
|
569 */
|
|
|
570 while (s->heap_len < 2) {
|
|
|
571 node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
|
|
|
572 tree[node].Freq = 1;
|
|
|
573 s->depth[node] = 0;
|
|
|
574 s->opt_len--; if (stree) s->static_len -= stree[node].Len;
|
|
|
575 /* node is 0 or 1 so it does not have extra bits */
|
|
|
576 }
|
|
|
577 desc->max_code = max_code;
|
|
|
578
|
|
|
579 /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
|
|
|
580 * establish sub-heaps of increasing lengths:
|
|
|
581 */
|
|
|
582 for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
|
|
|
583
|
|
|
584 /* Construct the Huffman tree by repeatedly combining the least two
|
|
|
585 * frequent nodes.
|
|
|
586 */
|
|
|
587 node = elems; /* next internal node of the tree */
|
|
|
588 do {
|
|
|
589 pqremove(s, tree, n); /* n = node of least frequency */
|
|
|
590 m = s->heap[SMALLEST]; /* m = node of next least frequency */
|
|
|
591
|
|
|
592 s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
|
|
|
593 s->heap[--(s->heap_max)] = m;
|
|
|
594
|
|
|
595 /* Create a new node father of n and m */
|
|
|
596 tree[node].Freq = tree[n].Freq + tree[m].Freq;
|
|
|
597 s->depth[node] = (uch) (MAX(s->depth[n], s->depth[m]) + 1);
|
|
|
598 tree[n].Dad = tree[m].Dad = (ush)node;
|
|
|
599 #ifdef DUMP_BL_TREE
|
|
|
600 if (tree == s->bl_tree) {
|
|
|
601 fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
|
|
|
602 node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
|
|
|
603 }
|
|
|
604 #endif
|
|
|
605 /* and insert the new node in the heap */
|
|
|
606 s->heap[SMALLEST] = node++;
|
|
|
607 pqdownheap(s, tree, SMALLEST);
|
|
|
608
|
|
|
609 } while (s->heap_len >= 2);
|
|
|
610
|
|
|
611 s->heap[--(s->heap_max)] = s->heap[SMALLEST];
|
|
|
612
|
|
|
613 /* At this point, the fields freq and dad are set. We can now
|
|
|
614 * generate the bit lengths.
|
|
|
615 */
|
|
|
616 gen_bitlen(s, (tree_desc *)desc);
|
|
|
617
|
|
|
618 /* The field len is now set, we can generate the bit codes */
|
|
|
619 gen_codes ((ct_data *)tree, max_code, s->bl_count);
|
|
|
620 }
|
|
|
621
|
|
|
622 /* ===========================================================================
|
|
|
623 * Scan a literal or distance tree to determine the frequencies of the codes
|
|
|
624 * in the bit length tree.
|
|
|
625 */
|
|
|
626 local void scan_tree (s, tree, max_code)
|
|
|
627 deflate_state *s;
|
|
|
628 ct_data *tree; /* the tree to be scanned */
|
|
|
629 int max_code; /* and its largest code of non zero frequency */
|
|
|
630 {
|
|
|
631 int n; /* iterates over all tree elements */
|
|
|
632 int prevlen = -1; /* last emitted length */
|
|
|
633 int curlen; /* length of current code */
|
|
|
634 int nextlen = tree[0].Len; /* length of next code */
|
|
|
635 int count = 0; /* repeat count of the current code */
|
|
|
636 int max_count = 7; /* max repeat count */
|
|
|
637 int min_count = 4; /* min repeat count */
|
|
|
638
|
|
|
639 if (nextlen == 0) max_count = 138, min_count = 3;
|
|
|
640 tree[max_code+1].Len = (ush)0xffff; /* guard */
|
|
|
641
|
|
|
642 for (n = 0; n <= max_code; n++) {
|
|
|
643 curlen = nextlen; nextlen = tree[n+1].Len;
|
|
|
644 if (++count < max_count && curlen == nextlen) {
|
|
|
645 continue;
|
|
|
646 } else if (count < min_count) {
|
|
|
647 s->bl_tree[curlen].Freq += count;
|
|
|
648 } else if (curlen != 0) {
|
|
|
649 if (curlen != prevlen) s->bl_tree[curlen].Freq++;
|
|
|
650 s->bl_tree[REP_3_6].Freq++;
|
|
|
651 } else if (count <= 10) {
|
|
|
652 s->bl_tree[REPZ_3_10].Freq++;
|
|
|
653 } else {
|
|
|
654 s->bl_tree[REPZ_11_138].Freq++;
|
|
|
655 }
|
|
|
656 count = 0; prevlen = curlen;
|
|
|
657 if (nextlen == 0) {
|
|
|
658 max_count = 138, min_count = 3;
|
|
|
659 } else if (curlen == nextlen) {
|
|
|
660 max_count = 6, min_count = 3;
|
|
|
661 } else {
|
|
|
662 max_count = 7, min_count = 4;
|
|
|
663 }
|
|
|
664 }
|
|
|
665 }
|
|
|
666
|
|
|
667 /* ===========================================================================
|
|
|
668 * Send a literal or distance tree in compressed form, using the codes in
|
|
|
669 * bl_tree.
|
|
|
670 */
|
|
|
671 local void send_tree (s, tree, max_code)
|
|
|
672 deflate_state *s;
|
|
|
673 ct_data *tree; /* the tree to be scanned */
|
|
|
674 int max_code; /* and its largest code of non zero frequency */
|
|
|
675 {
|
|
|
676 int n; /* iterates over all tree elements */
|
|
|
677 int prevlen = -1; /* last emitted length */
|
|
|
678 int curlen; /* length of current code */
|
|
|
679 int nextlen = tree[0].Len; /* length of next code */
|
|
|
680 int count = 0; /* repeat count of the current code */
|
|
|
681 int max_count = 7; /* max repeat count */
|
|
|
682 int min_count = 4; /* min repeat count */
|
|
|
683
|
|
|
684 /* tree[max_code+1].Len = -1; */ /* guard already set */
|
|
|
685 if (nextlen == 0) max_count = 138, min_count = 3;
|
|
|
686
|
|
|
687 for (n = 0; n <= max_code; n++) {
|
|
|
688 curlen = nextlen; nextlen = tree[n+1].Len;
|
|
|
689 if (++count < max_count && curlen == nextlen) {
|
|
|
690 continue;
|
|
|
691 } else if (count < min_count) {
|
|
|
692 do { send_code(s, curlen, s->bl_tree); } while (--count != 0);
|
|
|
693
|
|
|
694 } else if (curlen != 0) {
|
|
|
695 if (curlen != prevlen) {
|
|
|
696 send_code(s, curlen, s->bl_tree); count--;
|
|
|
697 }
|
|
|
698 Assert(count >= 3 && count <= 6, " 3_6?");
|
|
|
699 send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);
|
|
|
700
|
|
|
701 } else if (count <= 10) {
|
|
|
702 send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);
|
|
|
703
|
|
|
704 } else {
|
|
|
705 send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
|
|
|
706 }
|
|
|
707 count = 0; prevlen = curlen;
|
|
|
708 if (nextlen == 0) {
|
|
|
709 max_count = 138, min_count = 3;
|
|
|
710 } else if (curlen == nextlen) {
|
|
|
711 max_count = 6, min_count = 3;
|
|
|
712 } else {
|
|
|
713 max_count = 7, min_count = 4;
|
|
|
714 }
|
|
|
715 }
|
|
|
716 }
|
|
|
717
|
|
|
718 /* ===========================================================================
|
|
|
719 * Construct the Huffman tree for the bit lengths and return the index in
|
|
|
720 * bl_order of the last bit length code to send.
|
|
|
721 */
|
|
|
722 local int build_bl_tree(s)
|
|
|
723 deflate_state *s;
|
|
|
724 {
|
|
|
725 int max_blindex; /* index of last bit length code of non zero freq */
|
|
|
726
|
|
|
727 /* Determine the bit length frequencies for literal and distance trees */
|
|
|
728 scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
|
|
|
729 scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);
|
|
|
730
|
|
|
731 /* Build the bit length tree: */
|
|
|
732 build_tree(s, (tree_desc *)(&(s->bl_desc)));
|
|
|
733 /* opt_len now includes the length of the tree representations, except
|
|
|
734 * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
|
|
|
735 */
|
|
|
736
|
|
|
737 /* Determine the number of bit length codes to send. The pkzip format
|
|
|
738 * requires that at least 4 bit length codes be sent. (appnote.txt says
|
|
|
739 * 3 but the actual value used is 4.)
|
|
|
740 */
|
|
|
741 for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
|
|
|
742 if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
|
|
|
743 }
|
|
|
744 /* Update opt_len to include the bit length tree and counts */
|
|
|
745 s->opt_len += 3*(max_blindex+1) + 5+5+4;
|
|
|
746 Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
|
|
|
747 s->opt_len, s->static_len));
|
|
|
748
|
|
|
749 return max_blindex;
|
|
|
750 }
|
|
|
751
|
|
|
752 /* ===========================================================================
|
|
|
753 * Send the header for a block using dynamic Huffman trees: the counts, the
|
|
|
754 * lengths of the bit length codes, the literal tree and the distance tree.
|
|
|
755 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
|
|
|
756 */
|
|
|
757 local void send_all_trees(s, lcodes, dcodes, blcodes)
|
|
|
758 deflate_state *s;
|
|
|
759 int lcodes, dcodes, blcodes; /* number of codes for each tree */
|
|
|
760 {
|
|
|
761 int rank; /* index in bl_order */
|
|
|
762
|
|
|
763 Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
|
|
|
764 Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
|
|
|
765 "too many codes");
|
|
|
766 Tracev((stderr, "\nbl counts: "));
|
|
|
767 send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
|
|
|
768 send_bits(s, dcodes-1, 5);
|
|
|
769 send_bits(s, blcodes-4, 4); /* not -3 as stated in appnote.txt */
|
|
|
770 for (rank = 0; rank < blcodes; rank++) {
|
|
|
771 Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
|
|
|
772 send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
|
|
|
773 }
|
|
|
774 Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));
|
|
|
775
|
|
|
776 send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
|
|
|
777 Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));
|
|
|
778
|
|
|
779 send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
|
|
|
780 Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
|
|
|
781 }
|
|
|
782
|
|
|
783 /* ===========================================================================
|
|
|
784 * Send a stored block
|
|
|
785 */
|
|
|
786 void ct_stored_block(s, buf, stored_len, eof)
|
|
|
787 deflate_state *s;
|
|
|
788 charf *buf; /* input block */
|
|
|
789 ulg stored_len; /* length of input block */
|
|
|
790 int eof; /* true if this is the last block for a file */
|
|
|
791 {
|
|
|
792 send_bits(s, (STORED_BLOCK<<1)+eof, 3); /* send block type */
|
|
|
793 s->compressed_len = (s->compressed_len + 3 + 7) & ~7L;
|
|
|
794 s->compressed_len += (stored_len + 4) << 3;
|
|
|
795
|
|
|
796 copy_block(s, buf, (unsigned)stored_len, 1); /* with header */
|
|
|
797 }
|
|
|
798
|
|
|
799 /* ===========================================================================
|
|
|
800 * Send one empty static block to give enough lookahead for inflate.
|
|
|
801 * This takes 10 bits, of which 7 may remain in the bit buffer.
|
|
|
802 * The current inflate code requires 9 bits of lookahead. If the EOB
|
|
|
803 * code for the previous block was coded on 5 bits or less, inflate
|
|
|
804 * may have only 5+3 bits of lookahead to decode this EOB.
|
|
|
805 * (There are no problems if the previous block is stored or fixed.)
|
|
|
806 */
|
|
|
807 void ct_align(s)
|
|
|
808 deflate_state *s;
|
|
|
809 {
|
|
|
810 send_bits(s, STATIC_TREES<<1, 3);
|
|
|
811 send_code(s, END_BLOCK, static_ltree);
|
|
|
812 s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
|
|
|
813 bi_flush(s);
|
|
|
814 /* Of the 10 bits for the empty block, we have already sent
|
|
|
815 * (10 - bi_valid) bits. The lookahead for the EOB of the previous
|
|
|
816 * block was thus its length plus what we have just sent.
|
|
|
817 */
|
|
|
818 if (s->last_eob_len + 10 - s->bi_valid < 9) {
|
|
|
819 send_bits(s, STATIC_TREES<<1, 3);
|
|
|
820 send_code(s, END_BLOCK, static_ltree);
|
|
|
821 s->compressed_len += 10L;
|
|
|
822 bi_flush(s);
|
|
|
823 }
|
|
|
824 s->last_eob_len = 7;
|
|
|
825 }
|
|
|
826
|
|
|
827 /* ===========================================================================
|
|
|
828 * Determine the best encoding for the current block: dynamic trees, static
|
|
|
829 * trees or store, and output the encoded block to the zip file. This function
|
|
|
830 * returns the total compressed length for the file so far.
|
|
|
831 */
|
|
|
832 ulg ct_flush_block(s, buf, stored_len, eof)
|
|
|
833 deflate_state *s;
|
|
|
834 charf *buf; /* input block, or NULL if too old */
|
|
|
835 ulg stored_len; /* length of input block */
|
|
|
836 int eof; /* true if this is the last block for a file */
|
|
|
837 {
|
|
|
838 ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
|
|
|
839 int max_blindex; /* index of last bit length code of non zero freq */
|
|
|
840
|
|
|
841 /* Check if the file is ascii or binary */
|
|
|
842 if (s->data_type == UNKNOWN) set_data_type(s);
|
|
|
843
|
|
|
844 /* Construct the literal and distance trees */
|
|
|
845 build_tree(s, (tree_desc *)(&(s->l_desc)));
|
|
|
846 Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
|
|
|
847 s->static_len));
|
|
|
848
|
|
|
849 build_tree(s, (tree_desc *)(&(s->d_desc)));
|
|
|
850 Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
|
|
|
851 s->static_len));
|
|
|
852 /* At this point, opt_len and static_len are the total bit lengths of
|
|
|
853 * the compressed block data, excluding the tree representations.
|
|
|
854 */
|
|
|
855
|
|
|
856 /* Build the bit length tree for the above two trees, and get the index
|
|
|
857 * in bl_order of the last bit length code to send.
|
|
|
858 */
|
|
|
859 max_blindex = build_bl_tree(s);
|
|
|
860
|
|
|
861 /* Determine the best encoding. Compute first the block length in bytes */
|
|
|
862 opt_lenb = (s->opt_len+3+7)>>3;
|
|
|
863 static_lenb = (s->static_len+3+7)>>3;
|
|
|
864
|
|
|
865 Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
|
|
|
866 opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
|
|
|
867 s->last_lit));
|
|
|
868
|
|
|
869 if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
|
|
|
870
|
|
|
871 /* If compression failed and this is the first and last block,
|
|
|
872 * and if the .zip file can be seeked (to rewrite the local header),
|
|
|
873 * the whole file is transformed into a stored file:
|
|
|
874 */
|
|
|
875 #ifdef STORED_FILE_OK
|
|
|
876 # ifdef FORCE_STORED_FILE
|
|
|
877 if (eof && compressed_len == 0L) { /* force stored file */
|
|
|
878 # else
|
|
|
879 if (stored_len <= opt_lenb && eof && s->compressed_len==0L && seekable()) {
|
|
|
880 # endif
|
|
|
881 /* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */
|
|
|
882 if (buf == (charf*)0) error ("block vanished");
|
|
|
883
|
|
|
884 copy_block(buf, (unsigned)stored_len, 0); /* without header */
|
|
|
885 s->compressed_len = stored_len << 3;
|
|
|
886 s->method = STORED;
|
|
|
887 } else
|
|
|
888 #endif /* STORED_FILE_OK */
|
|
|
889
|
|
|
890 #ifdef FORCE_STORED
|
|
|
891 if (buf != (char*)0) { /* force stored block */
|
|
|
892 #else
|
|
|
893 if (stored_len+4 <= opt_lenb && buf != (char*)0) {
|
|
|
894 /* 4: two words for the lengths */
|
|
|
895 #endif
|
|
|
896 /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
|
|
|
897 * Otherwise we can't have processed more than WSIZE input bytes since
|
|
|
898 * the last block flush, because compression would have been
|
|
|
899 * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
|
|
|
900 * transform a block into a stored block.
|
|
|
901 */
|
|
|
902 ct_stored_block(s, buf, stored_len, eof);
|
|
|
903
|
|
|
904 #ifdef FORCE_STATIC
|
|
|
905 } else if (static_lenb >= 0) { /* force static trees */
|
|
|
906 #else
|
|
|
907 } else if (static_lenb == opt_lenb) {
|
|
|
908 #endif
|
|
|
909 send_bits(s, (STATIC_TREES<<1)+eof, 3);
|
|
|
910 compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree);
|
|
|
911 s->compressed_len += 3 + s->static_len;
|
|
|
912 } else {
|
|
|
913 send_bits(s, (DYN_TREES<<1)+eof, 3);
|
|
|
914 send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
|
|
|
915 max_blindex+1);
|
|
|
916 compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree);
|
|
|
917 s->compressed_len += 3 + s->opt_len;
|
|
|
918 }
|
|
|
919 Assert (s->compressed_len == s->bits_sent, "bad compressed size");
|
|
|
920 init_block(s);
|
|
|
921
|
|
|
922 if (eof) {
|
|
|
923 bi_windup(s);
|
|
|
924 s->compressed_len += 7; /* align on byte boundary */
|
|
|
925 }
|
|
|
926 Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
|
|
|
927 s->compressed_len-7*eof));
|
|
|
928
|
|
|
929 return s->compressed_len >> 3;
|
|
|
930 }
|
|
|
931
|
|
|
932 /* ===========================================================================
|
|
|
933 * Save the match info and tally the frequency counts. Return true if
|
|
|
934 * the current block must be flushed.
|
|
|
935 */
|
|
|
936 int ct_tally (s, dist, lc)
|
|
|
937 deflate_state *s;
|
|
|
938 int dist; /* distance of matched string */
|
|
|
939 int lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */
|
|
|
940 {
|
|
|
941 s->d_buf[s->last_lit] = (ush)dist;
|
|
|
942 s->l_buf[s->last_lit++] = (uch)lc;
|
|
|
943 if (dist == 0) {
|
|
|
944 /* lc is the unmatched char */
|
|
|
945 s->dyn_ltree[lc].Freq++;
|
|
|
946 } else {
|
|
|
947 s->matches++;
|
|
|
948 /* Here, lc is the match length - MIN_MATCH */
|
|
|
949 dist--; /* dist = match distance - 1 */
|
|
|
950 Assert((ush)dist < (ush)MAX_DIST(s) &&
|
|
|
951 (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
|
|
|
952 (ush)d_code(dist) < (ush)D_CODES, "ct_tally: bad match");
|
|
|
953
|
|
|
954 s->dyn_ltree[length_code[lc]+LITERALS+1].Freq++;
|
|
|
955 s->dyn_dtree[d_code(dist)].Freq++;
|
|
|
956 }
|
|
|
957
|
|
|
958 /* Try to guess if it is profitable to stop the current block here */
|
|
|
959 if (s->level > 2 && (s->last_lit & 0xfff) == 0) {
|
|
|
960 /* Compute an upper bound for the compressed length */
|
|
|
961 ulg out_length = (ulg)s->last_lit*8L;
|
|
|
962 ulg in_length = (ulg)s->strstart - s->block_start;
|
|
|
963 int dcode;
|
|
|
964 for (dcode = 0; dcode < D_CODES; dcode++) {
|
|
|
965 out_length += (ulg)s->dyn_dtree[dcode].Freq *
|
|
|
966 (5L+extra_dbits[dcode]);
|
|
|
967 }
|
|
|
968 out_length >>= 3;
|
|
|
969 Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
|
|
|
970 s->last_lit, in_length, out_length,
|
|
|
971 100L - out_length*100L/in_length));
|
|
|
972 if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
|
|
|
973 }
|
|
|
974 return (s->last_lit == s->lit_bufsize-1);
|
|
|
975 /* We avoid equality with lit_bufsize because of wraparound at 64K
|
|
|
976 * on 16 bit machines and because stored blocks are restricted to
|
|
|
977 * 64K-1 bytes.
|
|
|
978 */
|
|
|
979 }
|
|
|
980
|
|
|
981 /* ===========================================================================
|
|
|
982 * Send the block data compressed using the given Huffman trees
|
|
|
983 */
|
|
|
984 local void compress_block(s, ltree, dtree)
|
|
|
985 deflate_state *s;
|
|
|
986 ct_data *ltree; /* literal tree */
|
|
|
987 ct_data *dtree; /* distance tree */
|
|
|
988 {
|
|
|
989 unsigned dist; /* distance of matched string */
|
|
|
990 int lc; /* match length or unmatched char (if dist == 0) */
|
|
|
991 unsigned lx = 0; /* running index in l_buf */
|
|
|
992 unsigned code; /* the code to send */
|
|
|
993 int extra; /* number of extra bits to send */
|
|
|
994
|
|
|
995 if (s->last_lit != 0) do {
|
|
|
996 dist = s->d_buf[lx];
|
|
|
997 lc = s->l_buf[lx++];
|
|
|
998 if (dist == 0) {
|
|
|
999 send_code(s, lc, ltree); /* send a literal byte */
|
|
|
1000 Tracecv(isgraph(lc), (stderr," '%c' ", lc));
|
|
|
1001 } else {
|
|
|
1002 /* Here, lc is the match length - MIN_MATCH */
|
|
|
1003 code = length_code[lc];
|
|
|
1004 send_code(s, code+LITERALS+1, ltree); /* send the length code */
|
|
|
1005 extra = extra_lbits[code];
|
|
|
1006 if (extra != 0) {
|
|
|
1007 lc -= base_length[code];
|
|
|
1008 send_bits(s, lc, extra); /* send the extra length bits */
|
|
|
1009 }
|
|
|
1010 dist--; /* dist is now the match distance - 1 */
|
|
|
1011 code = d_code(dist);
|
|
|
1012 Assert (code < D_CODES, "bad d_code");
|
|
|
1013
|
|
|
1014 send_code(s, code, dtree); /* send the distance code */
|
|
|
1015 extra = extra_dbits[code];
|
|
|
1016 if (extra != 0) {
|
|
|
1017 dist -= base_dist[code];
|
|
|
1018 send_bits(s, dist, extra); /* send the extra distance bits */
|
|
|
1019 }
|
|
|
1020 } /* literal or match pair ? */
|
|
|
1021
|
|
|
1022 /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
|
|
|
1023 Assert(s->pending < s->lit_bufsize + 2*lx, "pendingBuf overflow");
|
|
|
1024
|
|
|
1025 } while (lx < s->last_lit);
|
|
|
1026
|
|
|
1027 send_code(s, END_BLOCK, ltree);
|
|
|
1028 s->last_eob_len = ltree[END_BLOCK].Len;
|
|
|
1029 }
|
|
|
1030
|
|
|
1031 /* ===========================================================================
|
|
|
1032 * Set the data type to ASCII or BINARY, using a crude approximation:
|
|
|
1033 * binary if more than 20% of the bytes are <= 6 or >= 128, ascii otherwise.
|
|
|
1034 * IN assertion: the fields freq of dyn_ltree are set and the total of all
|
|
|
1035 * frequencies does not exceed 64K (to fit in an int on 16 bit machines).
|
|
|
1036 */
|
|
|
1037 local void set_data_type(s)
|
|
|
1038 deflate_state *s;
|
|
|
1039 {
|
|
|
1040 int n = 0;
|
|
|
1041 unsigned ascii_freq = 0;
|
|
|
1042 unsigned bin_freq = 0;
|
|
|
1043 while (n < 7) bin_freq += s->dyn_ltree[n++].Freq;
|
|
|
1044 while (n < 128) ascii_freq += s->dyn_ltree[n++].Freq;
|
|
|
1045 while (n < LITERALS) bin_freq += s->dyn_ltree[n++].Freq;
|
|
|
1046 s->data_type = (Byte)(bin_freq > (ascii_freq >> 2) ? BINARY : ASCII);
|
|
|
1047 }
|
|
|
1048
|
|
|
1049 /* ===========================================================================
|
|
|
1050 * Reverse the first len bits of a code, using straightforward code (a faster
|
|
|
1051 * method would use a table)
|
|
|
1052 * IN assertion: 1 <= len <= 15
|
|
|
1053 */
|
|
|
1054 local unsigned bi_reverse(code, len)
|
|
|
1055 unsigned code; /* the value to invert */
|
|
|
1056 int len; /* its bit length */
|
|
|
1057 {
|
|
|
1058 register unsigned res = 0;
|
|
|
1059 do {
|
|
|
1060 res |= code & 1;
|
|
|
1061 code >>= 1, res <<= 1;
|
|
|
1062 } while (--len > 0);
|
|
|
1063 return res >> 1;
|
|
|
1064 }
|
|
|
1065
|
|
|
1066 /* ===========================================================================
|
|
|
1067 * Flush the bit buffer, keeping at most 7 bits in it.
|
|
|
1068 */
|
|
|
1069 local void bi_flush(s)
|
|
|
1070 deflate_state *s;
|
|
|
1071 {
|
|
|
1072 if (s->bi_valid == 16) {
|
|
|
1073 put_short(s, s->bi_buf);
|
|
|
1074 s->bi_buf = 0;
|
|
|
1075 s->bi_valid = 0;
|
|
|
1076 } else if (s->bi_valid >= 8) {
|
|
|
1077 put_byte(s, (Byte)s->bi_buf);
|
|
|
1078 s->bi_buf >>= 8;
|
|
|
1079 s->bi_valid -= 8;
|
|
|
1080 }
|
|
|
1081 }
|
|
|
1082
|
|
|
1083 /* ===========================================================================
|
|
|
1084 * Flush the bit buffer and align the output on a byte boundary
|
|
|
1085 */
|
|
|
1086 local void bi_windup(s)
|
|
|
1087 deflate_state *s;
|
|
|
1088 {
|
|
|
1089 if (s->bi_valid > 8) {
|
|
|
1090 put_short(s, s->bi_buf);
|
|
|
1091 } else if (s->bi_valid > 0) {
|
|
|
1092 put_byte(s, (Byte)s->bi_buf);
|
|
|
1093 }
|
|
|
1094 s->bi_buf = 0;
|
|
|
1095 s->bi_valid = 0;
|
|
|
1096 #ifdef DEBUG
|
|
|
1097 s->bits_sent = (s->bits_sent+7) & ~7;
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1098 #endif
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1099 }
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1100
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1101 /* ===========================================================================
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1102 * Copy a stored block, storing first the length and its
|
|
|
1103 * one's complement if requested.
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|
|
1104 */
|
|
|
1105 local void copy_block(s, buf, len, header)
|
|
|
1106 deflate_state *s;
|
|
|
1107 charf *buf; /* the input data */
|
|
|
1108 unsigned len; /* its length */
|
|
|
1109 int header; /* true if block header must be written */
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|
|
1110 {
|
|
|
1111 bi_windup(s); /* align on byte boundary */
|
|
|
1112 s->last_eob_len = 8; /* enough lookahead for inflate */
|
|
|
1113
|
|
|
1114 if (header) {
|
|
|
1115 put_short(s, (ush)len);
|
|
|
1116 put_short(s, (ush)~len);
|
|
|
1117 #ifdef DEBUG
|
|
|
1118 s->bits_sent += 2*16;
|
|
|
1119 #endif
|
|
|
1120 }
|
|
|
1121 #ifdef DEBUG
|
|
|
1122 s->bits_sent += (ulg)len<<3;
|
|
|
1123 #endif
|
|
|
1124 while (len--) {
|
|
|
1125 put_byte(s, *buf++);
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|
|
1126 }
|
|
|
1127 }
|
