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