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Rev | Author | Line No. | Line |
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96 | giacomo | 1 | /* trees.c -- output deflated data using Huffman coding |
2 | * Copyright (C) 1995-2002 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 | |||
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 | |||
32 | /* @(#) $Id: trees.c,v 1.1 2003-03-20 13:08:13 giacomo Exp $ */ |
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33 | |||
34 | /* #define GEN_TREES_H */ |
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35 | |||
36 | #include "deflate.h" |
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37 | |||
38 | #ifdef DEBUG |
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39 | # include <ctype.h> |
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40 | #endif |
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41 | |||
42 | /* =========================================================================== |
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43 | * Constants |
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44 | */ |
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45 | |||
46 | #define MAX_BL_BITS 7 |
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47 | /* Bit length codes must not exceed MAX_BL_BITS bits */ |
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48 | |||
49 | #define END_BLOCK 256 |
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50 | /* end of block literal code */ |
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51 | |||
52 | #define REP_3_6 16 |
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53 | /* repeat previous bit length 3-6 times (2 bits of repeat count) */ |
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54 | |||
55 | #define REPZ_3_10 17 |
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56 | /* repeat a zero length 3-10 times (3 bits of repeat count) */ |
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57 | |||
58 | #define REPZ_11_138 18 |
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59 | /* repeat a zero length 11-138 times (7 bits of repeat count) */ |
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60 | |||
61 | local const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */ |
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62 | = {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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63 | |||
64 | local const int extra_dbits[D_CODES] /* extra bits for each distance code */ |
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65 | = {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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66 | |||
67 | local const int extra_blbits[BL_CODES]/* extra bits for each bit length code */ |
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68 | = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7}; |
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69 | |||
70 | local const uch bl_order[BL_CODES] |
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71 | = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15}; |
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72 | /* The lengths of the bit length codes are sent in order of decreasing |
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73 | * probability, to avoid transmitting the lengths for unused bit length codes. |
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74 | */ |
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75 | |||
76 | #define Buf_size (8 * 2*sizeof(char)) |
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77 | /* Number of bits used within bi_buf. (bi_buf might be implemented on |
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78 | * more than 16 bits on some systems.) |
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79 | */ |
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80 | |||
81 | /* =========================================================================== |
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82 | * Local data. These are initialized only once. |
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83 | */ |
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84 | |||
85 | #define DIST_CODE_LEN 512 /* see definition of array dist_code below */ |
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86 | |||
87 | #if defined(GEN_TREES_H) || !defined(STDC) |
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88 | /* non ANSI compilers may not accept trees.h */ |
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89 | |||
90 | local ct_data static_ltree[L_CODES+2]; |
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91 | /* The static literal tree. Since the bit lengths are imposed, there is no |
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92 | * need for the L_CODES extra codes used during heap construction. However |
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93 | * The codes 286 and 287 are needed to build a canonical tree (see _tr_init |
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94 | * below). |
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95 | */ |
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96 | |||
97 | local ct_data static_dtree[D_CODES]; |
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98 | /* The static distance tree. (Actually a trivial tree since all codes use |
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99 | * 5 bits.) |
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100 | */ |
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101 | |||
102 | uch _dist_code[DIST_CODE_LEN]; |
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103 | /* Distance codes. The first 256 values correspond to the distances |
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104 | * 3 .. 258, the last 256 values correspond to the top 8 bits of |
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105 | * the 15 bit distances. |
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106 | */ |
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107 | |||
108 | uch _length_code[MAX_MATCH-MIN_MATCH+1]; |
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109 | /* length code for each normalized match length (0 == MIN_MATCH) */ |
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110 | |||
111 | local int base_length[LENGTH_CODES]; |
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112 | /* First normalized length for each code (0 = MIN_MATCH) */ |
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113 | |||
114 | local int base_dist[D_CODES]; |
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115 | /* First normalized distance for each code (0 = distance of 1) */ |
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116 | |||
117 | #else |
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118 | # include "trees.h" |
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119 | #endif /* GEN_TREES_H */ |
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120 | |||
121 | struct static_tree_desc_s { |
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122 | const ct_data *static_tree; /* static tree or NULL */ |
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123 | const intf *extra_bits; /* extra bits for each code or NULL */ |
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124 | int extra_base; /* base index for extra_bits */ |
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125 | int elems; /* max number of elements in the tree */ |
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126 | int max_length; /* max bit length for the codes */ |
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127 | }; |
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128 | |||
129 | local static_tree_desc static_l_desc = |
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130 | {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS}; |
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131 | |||
132 | local static_tree_desc static_d_desc = |
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133 | {static_dtree, extra_dbits, 0, D_CODES, MAX_BITS}; |
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134 | |||
135 | local static_tree_desc static_bl_desc = |
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136 | {(const ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS}; |
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137 | |||
138 | /* =========================================================================== |
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139 | * Local (static) routines in this file. |
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140 | */ |
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141 | |||
142 | local void tr_static_init OF((void)); |
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143 | local void init_block OF((deflate_state *s)); |
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144 | local void pqdownheap OF((deflate_state *s, ct_data *tree, int k)); |
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145 | local void gen_bitlen OF((deflate_state *s, tree_desc *desc)); |
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146 | local void gen_codes OF((ct_data *tree, int max_code, ushf *bl_count)); |
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147 | local void build_tree OF((deflate_state *s, tree_desc *desc)); |
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148 | local void scan_tree OF((deflate_state *s, ct_data *tree, int max_code)); |
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149 | local void send_tree OF((deflate_state *s, ct_data *tree, int max_code)); |
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150 | local int build_bl_tree OF((deflate_state *s)); |
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151 | local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes, |
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152 | int blcodes)); |
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153 | local void compress_block OF((deflate_state *s, ct_data *ltree, |
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154 | ct_data *dtree)); |
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155 | local void set_data_type OF((deflate_state *s)); |
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156 | local unsigned bi_reverse OF((unsigned value, int length)); |
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157 | local void bi_windup OF((deflate_state *s)); |
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158 | local void bi_flush OF((deflate_state *s)); |
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159 | local void copy_block OF((deflate_state *s, charf *buf, unsigned len, |
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160 | int header)); |
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161 | |||
162 | #ifdef GEN_TREES_H |
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163 | local void gen_trees_header OF((void)); |
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164 | #endif |
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165 | |||
166 | #ifndef DEBUG |
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167 | # define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len) |
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168 | /* Send a code of the given tree. c and tree must not have side effects */ |
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169 | |||
170 | #else /* DEBUG */ |
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171 | # define send_code(s, c, tree) \ |
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172 | { if (z_verbose>2) cprintf("\ncd %3d ",(c)); \ |
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173 | send_bits(s, tree[c].Code, tree[c].Len); } |
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174 | #endif |
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175 | |||
176 | /* =========================================================================== |
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177 | * Output a short LSB first on the stream. |
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178 | * IN assertion: there is enough room in pendingBuf. |
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179 | */ |
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180 | #define put_short(s, w) { \ |
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181 | put_byte(s, (uch)((w) & 0xff)); \ |
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182 | put_byte(s, (uch)((ush)(w) >> 8)); \ |
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183 | } |
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184 | |||
185 | /* =========================================================================== |
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186 | * Send a value on a given number of bits. |
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187 | * IN assertion: length <= 16 and value fits in length bits. |
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188 | */ |
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189 | #ifdef DEBUG |
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190 | local void send_bits OF((deflate_state *s, int value, int length)); |
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191 | |||
192 | local void send_bits(s, value, length) |
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193 | deflate_state *s; |
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194 | int value; /* value to send */ |
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195 | int length; /* number of bits */ |
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196 | { |
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197 | Tracevv((stderr," l %2d v %4x ", length, value)); |
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198 | Assert(length > 0 && length <= 15, "invalid length"); |
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199 | s->bits_sent += (ulg)length; |
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200 | |||
201 | /* If not enough room in bi_buf, use (valid) bits from bi_buf and |
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202 | * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid)) |
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203 | * unused bits in value. |
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204 | */ |
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205 | if (s->bi_valid > (int)Buf_size - length) { |
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206 | s->bi_buf |= (value << s->bi_valid); |
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207 | put_short(s, s->bi_buf); |
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208 | s->bi_buf = (ush)value >> (Buf_size - s->bi_valid); |
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209 | s->bi_valid += length - Buf_size; |
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210 | } else { |
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211 | s->bi_buf |= value << s->bi_valid; |
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212 | s->bi_valid += length; |
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213 | } |
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214 | } |
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215 | #else /* !DEBUG */ |
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216 | |||
217 | #define send_bits(s, value, length) \ |
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218 | { int len = length;\ |
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219 | if (s->bi_valid > (int)Buf_size - len) {\ |
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220 | int val = value;\ |
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221 | s->bi_buf |= (val << s->bi_valid);\ |
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222 | put_short(s, s->bi_buf);\ |
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223 | s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\ |
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224 | s->bi_valid += len - Buf_size;\ |
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225 | } else {\ |
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226 | s->bi_buf |= (value) << s->bi_valid;\ |
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227 | s->bi_valid += len;\ |
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228 | }\ |
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229 | } |
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230 | #endif /* DEBUG */ |
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231 | |||
232 | |||
233 | #define MAX(a,b) (a >= b ? a : b) |
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234 | /* the arguments must not have side effects */ |
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235 | |||
236 | /* =========================================================================== |
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237 | * Initialize the various 'constant' tables. |
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238 | */ |
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239 | local void tr_static_init() |
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240 | { |
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241 | #if defined(GEN_TREES_H) || !defined(STDC) |
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242 | static int static_init_done = 0; |
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243 | int n; /* iterates over tree elements */ |
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244 | int bits; /* bit counter */ |
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245 | int length; /* length value */ |
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246 | int code; /* code value */ |
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247 | int dist; /* distance index */ |
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248 | ush bl_count[MAX_BITS+1]; |
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249 | /* number of codes at each bit length for an optimal tree */ |
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250 | |||
251 | if (static_init_done) return; |
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252 | |||
253 | /* For some embedded targets, global variables are not initialized: */ |
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254 | static_l_desc.static_tree = static_ltree; |
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255 | static_l_desc.extra_bits = extra_lbits; |
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256 | static_d_desc.static_tree = static_dtree; |
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257 | static_d_desc.extra_bits = extra_dbits; |
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258 | static_bl_desc.extra_bits = extra_blbits; |
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259 | |||
260 | /* Initialize the mapping length (0..255) -> length code (0..28) */ |
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261 | length = 0; |
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262 | for (code = 0; code < LENGTH_CODES-1; code++) { |
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263 | base_length[code] = length; |
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264 | for (n = 0; n < (1<<extra_lbits[code]); n++) { |
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265 | _length_code[length++] = (uch)code; |
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266 | } |
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267 | } |
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268 | Assert (length == 256, "tr_static_init: length != 256"); |
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269 | /* Note that the length 255 (match length 258) can be represented |
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270 | * in two different ways: code 284 + 5 bits or code 285, so we |
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271 | * overwrite length_code[255] to use the best encoding: |
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272 | */ |
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273 | _length_code[length-1] = (uch)code; |
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274 | |||
275 | /* Initialize the mapping dist (0..32K) -> dist code (0..29) */ |
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276 | dist = 0; |
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277 | for (code = 0 ; code < 16; code++) { |
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278 | base_dist[code] = dist; |
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279 | for (n = 0; n < (1<<extra_dbits[code]); n++) { |
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280 | _dist_code[dist++] = (uch)code; |
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281 | } |
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282 | } |
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283 | Assert (dist == 256, "tr_static_init: dist != 256"); |
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284 | dist >>= 7; /* from now on, all distances are divided by 128 */ |
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285 | for ( ; code < D_CODES; code++) { |
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286 | base_dist[code] = dist << 7; |
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287 | for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) { |
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288 | _dist_code[256 + dist++] = (uch)code; |
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289 | } |
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290 | } |
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291 | Assert (dist == 256, "tr_static_init: 256+dist != 512"); |
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292 | |||
293 | /* Construct the codes of the static literal tree */ |
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294 | for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0; |
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295 | n = 0; |
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296 | while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++; |
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297 | while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++; |
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298 | while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++; |
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299 | while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++; |
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300 | /* Codes 286 and 287 do not exist, but we must include them in the |
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301 | * tree construction to get a canonical Huffman tree (longest code |
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302 | * all ones) |
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303 | */ |
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304 | gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count); |
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305 | |||
306 | /* The static distance tree is trivial: */ |
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307 | for (n = 0; n < D_CODES; n++) { |
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308 | static_dtree[n].Len = 5; |
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309 | static_dtree[n].Code = bi_reverse((unsigned)n, 5); |
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310 | } |
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311 | static_init_done = 1; |
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312 | |||
313 | # ifdef GEN_TREES_H |
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314 | gen_trees_header(); |
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315 | # endif |
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316 | #endif /* defined(GEN_TREES_H) || !defined(STDC) */ |
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317 | } |
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318 | |||
319 | /* =========================================================================== |
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320 | * Genererate the file trees.h describing the static trees. |
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321 | */ |
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322 | #ifdef GEN_TREES_H |
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323 | # ifndef DEBUG |
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324 | # include <stdio.h> |
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325 | # endif |
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326 | |||
327 | # define SEPARATOR(i, last, width) \ |
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328 | ((i) == (last)? "\n};\n\n" : \ |
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329 | ((i) % (width) == (width)-1 ? ",\n" : ", ")) |
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330 | |||
331 | void gen_trees_header() |
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332 | { |
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333 | FILE *header = fopen("trees.h", "w"); |
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334 | int i; |
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335 | |||
336 | Assert (header != NULL, "Can't open trees.h"); |
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337 | fprintf(header, |
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338 | "/* header created automatically with -DGEN_TREES_H */\n\n"); |
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339 | |||
340 | fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n"); |
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341 | for (i = 0; i < L_CODES+2; i++) { |
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342 | fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code, |
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343 | static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5)); |
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344 | } |
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345 | |||
346 | fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n"); |
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347 | for (i = 0; i < D_CODES; i++) { |
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348 | fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code, |
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349 | static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5)); |
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350 | } |
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351 | |||
352 | fprintf(header, "const uch _dist_code[DIST_CODE_LEN] = {\n"); |
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353 | for (i = 0; i < DIST_CODE_LEN; i++) { |
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354 | fprintf(header, "%2u%s", _dist_code[i], |
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355 | SEPARATOR(i, DIST_CODE_LEN-1, 20)); |
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356 | } |
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357 | |||
358 | fprintf(header, "const uch _length_code[MAX_MATCH-MIN_MATCH+1]= {\n"); |
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359 | for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) { |
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360 | fprintf(header, "%2u%s", _length_code[i], |
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361 | SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20)); |
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362 | } |
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363 | |||
364 | fprintf(header, "local const int base_length[LENGTH_CODES] = {\n"); |
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365 | for (i = 0; i < LENGTH_CODES; i++) { |
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366 | fprintf(header, "%1u%s", base_length[i], |
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367 | SEPARATOR(i, LENGTH_CODES-1, 20)); |
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368 | } |
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369 | |||
370 | fprintf(header, "local const int base_dist[D_CODES] = {\n"); |
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371 | for (i = 0; i < D_CODES; i++) { |
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372 | fprintf(header, "%5u%s", base_dist[i], |
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373 | SEPARATOR(i, D_CODES-1, 10)); |
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374 | } |
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375 | |||
376 | fclose(header); |
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377 | } |
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378 | #endif /* GEN_TREES_H */ |
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379 | |||
380 | /* =========================================================================== |
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381 | * Initialize the tree data structures for a new zlib stream. |
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382 | */ |
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383 | void _tr_init(s) |
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384 | deflate_state *s; |
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385 | { |
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386 | tr_static_init(); |
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387 | |||
388 | s->l_desc.dyn_tree = s->dyn_ltree; |
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389 | s->l_desc.stat_desc = &static_l_desc; |
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390 | |||
391 | s->d_desc.dyn_tree = s->dyn_dtree; |
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392 | s->d_desc.stat_desc = &static_d_desc; |
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393 | |||
394 | s->bl_desc.dyn_tree = s->bl_tree; |
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395 | s->bl_desc.stat_desc = &static_bl_desc; |
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396 | |||
397 | s->bi_buf = 0; |
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398 | s->bi_valid = 0; |
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399 | s->last_eob_len = 8; /* enough lookahead for inflate */ |
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400 | #ifdef DEBUG |
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401 | s->compressed_len = 0L; |
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402 | s->bits_sent = 0L; |
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403 | #endif |
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404 | |||
405 | /* Initialize the first block of the first file: */ |
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406 | init_block(s); |
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407 | } |
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408 | |||
409 | /* =========================================================================== |
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410 | * Initialize a new block. |
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411 | */ |
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412 | local void init_block(s) |
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413 | deflate_state *s; |
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414 | { |
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415 | int n; /* iterates over tree elements */ |
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416 | |||
417 | /* Initialize the trees. */ |
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418 | for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0; |
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419 | for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0; |
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420 | for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0; |
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421 | |||
422 | s->dyn_ltree[END_BLOCK].Freq = 1; |
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423 | s->opt_len = s->static_len = 0L; |
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424 | s->last_lit = s->matches = 0; |
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425 | } |
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426 | |||
427 | #define SMALLEST 1 |
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428 | /* Index within the heap array of least frequent node in the Huffman tree */ |
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429 | |||
430 | |||
431 | /* =========================================================================== |
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432 | * Remove the smallest element from the heap and recreate the heap with |
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433 | * one less element. Updates heap and heap_len. |
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434 | */ |
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435 | #define pqremove(s, tree, top) \ |
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436 | {\ |
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437 | top = s->heap[SMALLEST]; \ |
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438 | s->heap[SMALLEST] = s->heap[s->heap_len--]; \ |
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439 | pqdownheap(s, tree, SMALLEST); \ |
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440 | } |
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441 | |||
442 | /* =========================================================================== |
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443 | * Compares to subtrees, using the tree depth as tie breaker when |
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444 | * the subtrees have equal frequency. This minimizes the worst case length. |
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445 | */ |
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446 | #define smaller(tree, n, m, depth) \ |
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447 | (tree[n].Freq < tree[m].Freq || \ |
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448 | (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m])) |
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449 | |||
450 | /* =========================================================================== |
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451 | * Restore the heap property by moving down the tree starting at node k, |
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452 | * exchanging a node with the smallest of its two sons if necessary, stopping |
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453 | * when the heap property is re-established (each father smaller than its |
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454 | * two sons). |
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455 | */ |
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456 | local void pqdownheap(s, tree, k) |
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457 | deflate_state *s; |
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458 | ct_data *tree; /* the tree to restore */ |
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459 | int k; /* node to move down */ |
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460 | { |
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461 | int v = s->heap[k]; |
||
462 | int j = k << 1; /* left son of k */ |
||
463 | while (j <= s->heap_len) { |
||
464 | /* Set j to the smallest of the two sons: */ |
||
465 | if (j < s->heap_len && |
||
466 | smaller(tree, s->heap[j+1], s->heap[j], s->depth)) { |
||
467 | j++; |
||
468 | } |
||
469 | /* Exit if v is smaller than both sons */ |
||
470 | if (smaller(tree, v, s->heap[j], s->depth)) break; |
||
471 | |||
472 | /* Exchange v with the smallest son */ |
||
473 | s->heap[k] = s->heap[j]; k = j; |
||
474 | |||
475 | /* And continue down the tree, setting j to the left son of k */ |
||
476 | j <<= 1; |
||
477 | } |
||
478 | s->heap[k] = v; |
||
479 | } |
||
480 | |||
481 | /* =========================================================================== |
||
482 | * Compute the optimal bit lengths for a tree and update the total bit length |
||
483 | * for the current block. |
||
484 | * IN assertion: the fields freq and dad are set, heap[heap_max] and |
||
485 | * above are the tree nodes sorted by increasing frequency. |
||
486 | * OUT assertions: the field len is set to the optimal bit length, the |
||
487 | * array bl_count contains the frequencies for each bit length. |
||
488 | * The length opt_len is updated; static_len is also updated if stree is |
||
489 | * not null. |
||
490 | */ |
||
491 | local void gen_bitlen(s, desc) |
||
492 | deflate_state *s; |
||
493 | tree_desc *desc; /* the tree descriptor */ |
||
494 | { |
||
495 | ct_data *tree = desc->dyn_tree; |
||
496 | int max_code = desc->max_code; |
||
497 | const ct_data *stree = desc->stat_desc->static_tree; |
||
498 | const intf *extra = desc->stat_desc->extra_bits; |
||
499 | int base = desc->stat_desc->extra_base; |
||
500 | int max_length = desc->stat_desc->max_length; |
||
501 | int h; /* heap index */ |
||
502 | int n, m; /* iterate over the tree elements */ |
||
503 | int bits; /* bit length */ |
||
504 | int xbits; /* extra bits */ |
||
505 | ush f; /* frequency */ |
||
506 | int overflow = 0; /* number of elements with bit length too large */ |
||
507 | |||
508 | for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0; |
||
509 | |||
510 | /* In a first pass, compute the optimal bit lengths (which may |
||
511 | * overflow in the case of the bit length tree). |
||
512 | */ |
||
513 | tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */ |
||
514 | |||
515 | for (h = s->heap_max+1; h < HEAP_SIZE; h++) { |
||
516 | n = s->heap[h]; |
||
517 | bits = tree[tree[n].Dad].Len + 1; |
||
518 | if (bits > max_length) bits = max_length, overflow++; |
||
519 | tree[n].Len = (ush)bits; |
||
520 | /* We overwrite tree[n].Dad which is no longer needed */ |
||
521 | |||
522 | if (n > max_code) continue; /* not a leaf node */ |
||
523 | |||
524 | s->bl_count[bits]++; |
||
525 | xbits = 0; |
||
526 | if (n >= base) xbits = extra[n-base]; |
||
527 | f = tree[n].Freq; |
||
528 | s->opt_len += (ulg)f * (bits + xbits); |
||
529 | if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits); |
||
530 | } |
||
531 | if (overflow == 0) return; |
||
532 | |||
533 | Trace((stderr,"\nbit length overflow\n")); |
||
534 | /* This happens for example on obj2 and pic of the Calgary corpus */ |
||
535 | |||
536 | /* Find the first bit length which could increase: */ |
||
537 | do { |
||
538 | bits = max_length-1; |
||
539 | while (s->bl_count[bits] == 0) bits--; |
||
540 | s->bl_count[bits]--; /* move one leaf down the tree */ |
||
541 | s->bl_count[bits+1] += 2; /* move one overflow item as its brother */ |
||
542 | s->bl_count[max_length]--; |
||
543 | /* The brother of the overflow item also moves one step up, |
||
544 | * but this does not affect bl_count[max_length] |
||
545 | */ |
||
546 | overflow -= 2; |
||
547 | } while (overflow > 0); |
||
548 | |||
549 | /* Now recompute all bit lengths, scanning in increasing frequency. |
||
550 | * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all |
||
551 | * lengths instead of fixing only the wrong ones. This idea is taken |
||
552 | * from 'ar' written by Haruhiko Okumura.) |
||
553 | */ |
||
554 | for (bits = max_length; bits != 0; bits--) { |
||
555 | n = s->bl_count[bits]; |
||
556 | while (n != 0) { |
||
557 | m = s->heap[--h]; |
||
558 | if (m > max_code) continue; |
||
559 | if (tree[m].Len != (unsigned) bits) { |
||
560 | Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits)); |
||
561 | s->opt_len += ((long)bits - (long)tree[m].Len) |
||
562 | *(long)tree[m].Freq; |
||
563 | tree[m].Len = (ush)bits; |
||
564 | } |
||
565 | n--; |
||
566 | } |
||
567 | } |
||
568 | } |
||
569 | |||
570 | /* =========================================================================== |
||
571 | * Generate the codes for a given tree and bit counts (which need not be |
||
572 | * optimal). |
||
573 | * IN assertion: the array bl_count contains the bit length statistics for |
||
574 | * the given tree and the field len is set for all tree elements. |
||
575 | * OUT assertion: the field code is set for all tree elements of non |
||
576 | * zero code length. |
||
577 | */ |
||
578 | local void gen_codes (tree, max_code, bl_count) |
||
579 | ct_data *tree; /* the tree to decorate */ |
||
580 | int max_code; /* largest code with non zero frequency */ |
||
581 | ushf *bl_count; /* number of codes at each bit length */ |
||
582 | { |
||
583 | ush next_code[MAX_BITS+1]; /* next code value for each bit length */ |
||
584 | ush code = 0; /* running code value */ |
||
585 | int bits; /* bit index */ |
||
586 | int n; /* code index */ |
||
587 | |||
588 | /* The distribution counts are first used to generate the code values |
||
589 | * without bit reversal. |
||
590 | */ |
||
591 | for (bits = 1; bits <= MAX_BITS; bits++) { |
||
592 | next_code[bits] = code = (code + bl_count[bits-1]) << 1; |
||
593 | } |
||
594 | /* Check that the bit counts in bl_count are consistent. The last code |
||
595 | * must be all ones. |
||
596 | */ |
||
597 | Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1, |
||
598 | "inconsistent bit counts"); |
||
599 | Tracev((stderr,"\ngen_codes: max_code %d ", max_code)); |
||
600 | |||
601 | for (n = 0; n <= max_code; n++) { |
||
602 | int len = tree[n].Len; |
||
603 | if (len == 0) continue; |
||
604 | /* Now reverse the bits */ |
||
605 | tree[n].Code = bi_reverse(next_code[len]++, len); |
||
606 | |||
607 | Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ", |
||
608 | n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1)); |
||
609 | } |
||
610 | } |
||
611 | |||
612 | /* =========================================================================== |
||
613 | * Construct one Huffman tree and assigns the code bit strings and lengths. |
||
614 | * Update the total bit length for the current block. |
||
615 | * IN assertion: the field freq is set for all tree elements. |
||
616 | * OUT assertions: the fields len and code are set to the optimal bit length |
||
617 | * and corresponding code. The length opt_len is updated; static_len is |
||
618 | * also updated if stree is not null. The field max_code is set. |
||
619 | */ |
||
620 | local void build_tree(s, desc) |
||
621 | deflate_state *s; |
||
622 | tree_desc *desc; /* the tree descriptor */ |
||
623 | { |
||
624 | ct_data *tree = desc->dyn_tree; |
||
625 | const ct_data *stree = desc->stat_desc->static_tree; |
||
626 | int elems = desc->stat_desc->elems; |
||
627 | int n, m; /* iterate over heap elements */ |
||
628 | int max_code = -1; /* largest code with non zero frequency */ |
||
629 | int node; /* new node being created */ |
||
630 | |||
631 | /* Construct the initial heap, with least frequent element in |
||
632 | * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1]. |
||
633 | * heap[0] is not used. |
||
634 | */ |
||
635 | s->heap_len = 0, s->heap_max = HEAP_SIZE; |
||
636 | |||
637 | for (n = 0; n < elems; n++) { |
||
638 | if (tree[n].Freq != 0) { |
||
639 | s->heap[++(s->heap_len)] = max_code = n; |
||
640 | s->depth[n] = 0; |
||
641 | } else { |
||
642 | tree[n].Len = 0; |
||
643 | } |
||
644 | } |
||
645 | |||
646 | /* The pkzip format requires that at least one distance code exists, |
||
647 | * and that at least one bit should be sent even if there is only one |
||
648 | * possible code. So to avoid special checks later on we force at least |
||
649 | * two codes of non zero frequency. |
||
650 | */ |
||
651 | while (s->heap_len < 2) { |
||
652 | node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0); |
||
653 | tree[node].Freq = 1; |
||
654 | s->depth[node] = 0; |
||
655 | s->opt_len--; if (stree) s->static_len -= stree[node].Len; |
||
656 | /* node is 0 or 1 so it does not have extra bits */ |
||
657 | } |
||
658 | desc->max_code = max_code; |
||
659 | |||
660 | /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree, |
||
661 | * establish sub-heaps of increasing lengths: |
||
662 | */ |
||
663 | for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n); |
||
664 | |||
665 | /* Construct the Huffman tree by repeatedly combining the least two |
||
666 | * frequent nodes. |
||
667 | */ |
||
668 | node = elems; /* next internal node of the tree */ |
||
669 | do { |
||
670 | pqremove(s, tree, n); /* n = node of least frequency */ |
||
671 | m = s->heap[SMALLEST]; /* m = node of next least frequency */ |
||
672 | |||
673 | s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */ |
||
674 | s->heap[--(s->heap_max)] = m; |
||
675 | |||
676 | /* Create a new node father of n and m */ |
||
677 | tree[node].Freq = tree[n].Freq + tree[m].Freq; |
||
678 | s->depth[node] = (uch) (MAX(s->depth[n], s->depth[m]) + 1); |
||
679 | tree[n].Dad = tree[m].Dad = (ush)node; |
||
680 | #ifdef DUMP_BL_TREE |
||
681 | if (tree == s->bl_tree) { |
||
682 | cprintf("\nnode %d(%d), sons %d(%d) %d(%d)", |
||
683 | node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq); |
||
684 | } |
||
685 | #endif |
||
686 | /* and insert the new node in the heap */ |
||
687 | s->heap[SMALLEST] = node++; |
||
688 | pqdownheap(s, tree, SMALLEST); |
||
689 | |||
690 | } while (s->heap_len >= 2); |
||
691 | |||
692 | s->heap[--(s->heap_max)] = s->heap[SMALLEST]; |
||
693 | |||
694 | /* At this point, the fields freq and dad are set. We can now |
||
695 | * generate the bit lengths. |
||
696 | */ |
||
697 | gen_bitlen(s, (tree_desc *)desc); |
||
698 | |||
699 | /* The field len is now set, we can generate the bit codes */ |
||
700 | gen_codes ((ct_data *)tree, max_code, s->bl_count); |
||
701 | } |
||
702 | |||
703 | /* =========================================================================== |
||
704 | * Scan a literal or distance tree to determine the frequencies of the codes |
||
705 | * in the bit length tree. |
||
706 | */ |
||
707 | local void scan_tree (s, tree, max_code) |
||
708 | deflate_state *s; |
||
709 | ct_data *tree; /* the tree to be scanned */ |
||
710 | int max_code; /* and its largest code of non zero frequency */ |
||
711 | { |
||
712 | int n; /* iterates over all tree elements */ |
||
713 | int prevlen = -1; /* last emitted length */ |
||
714 | int curlen; /* length of current code */ |
||
715 | int nextlen = tree[0].Len; /* length of next code */ |
||
716 | int count = 0; /* repeat count of the current code */ |
||
717 | int max_count = 7; /* max repeat count */ |
||
718 | int min_count = 4; /* min repeat count */ |
||
719 | |||
720 | if (nextlen == 0) max_count = 138, min_count = 3; |
||
721 | tree[max_code+1].Len = (ush)0xffff; /* guard */ |
||
722 | |||
723 | for (n = 0; n <= max_code; n++) { |
||
724 | curlen = nextlen; nextlen = tree[n+1].Len; |
||
725 | if (++count < max_count && curlen == nextlen) { |
||
726 | continue; |
||
727 | } else if (count < min_count) { |
||
728 | s->bl_tree[curlen].Freq += count; |
||
729 | } else if (curlen != 0) { |
||
730 | if (curlen != prevlen) s->bl_tree[curlen].Freq++; |
||
731 | s->bl_tree[REP_3_6].Freq++; |
||
732 | } else if (count <= 10) { |
||
733 | s->bl_tree[REPZ_3_10].Freq++; |
||
734 | } else { |
||
735 | s->bl_tree[REPZ_11_138].Freq++; |
||
736 | } |
||
737 | count = 0; prevlen = curlen; |
||
738 | if (nextlen == 0) { |
||
739 | max_count = 138, min_count = 3; |
||
740 | } else if (curlen == nextlen) { |
||
741 | max_count = 6, min_count = 3; |
||
742 | } else { |
||
743 | max_count = 7, min_count = 4; |
||
744 | } |
||
745 | } |
||
746 | } |
||
747 | |||
748 | /* =========================================================================== |
||
749 | * Send a literal or distance tree in compressed form, using the codes in |
||
750 | * bl_tree. |
||
751 | */ |
||
752 | local void send_tree (s, tree, max_code) |
||
753 | deflate_state *s; |
||
754 | ct_data *tree; /* the tree to be scanned */ |
||
755 | int max_code; /* and its largest code of non zero frequency */ |
||
756 | { |
||
757 | int n; /* iterates over all tree elements */ |
||
758 | int prevlen = -1; /* last emitted length */ |
||
759 | int curlen; /* length of current code */ |
||
760 | int nextlen = tree[0].Len; /* length of next code */ |
||
761 | int count = 0; /* repeat count of the current code */ |
||
762 | int max_count = 7; /* max repeat count */ |
||
763 | int min_count = 4; /* min repeat count */ |
||
764 | |||
765 | /* tree[max_code+1].Len = -1; */ /* guard already set */ |
||
766 | if (nextlen == 0) max_count = 138, min_count = 3; |
||
767 | |||
768 | for (n = 0; n <= max_code; n++) { |
||
769 | curlen = nextlen; nextlen = tree[n+1].Len; |
||
770 | if (++count < max_count && curlen == nextlen) { |
||
771 | continue; |
||
772 | } else if (count < min_count) { |
||
773 | do { send_code(s, curlen, s->bl_tree); } while (--count != 0); |
||
774 | |||
775 | } else if (curlen != 0) { |
||
776 | if (curlen != prevlen) { |
||
777 | send_code(s, curlen, s->bl_tree); count--; |
||
778 | } |
||
779 | Assert(count >= 3 && count <= 6, " 3_6?"); |
||
780 | send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2); |
||
781 | |||
782 | } else if (count <= 10) { |
||
783 | send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3); |
||
784 | |||
785 | } else { |
||
786 | send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7); |
||
787 | } |
||
788 | count = 0; prevlen = curlen; |
||
789 | if (nextlen == 0) { |
||
790 | max_count = 138, min_count = 3; |
||
791 | } else if (curlen == nextlen) { |
||
792 | max_count = 6, min_count = 3; |
||
793 | } else { |
||
794 | max_count = 7, min_count = 4; |
||
795 | } |
||
796 | } |
||
797 | } |
||
798 | |||
799 | /* =========================================================================== |
||
800 | * Construct the Huffman tree for the bit lengths and return the index in |
||
801 | * bl_order of the last bit length code to send. |
||
802 | */ |
||
803 | local int build_bl_tree(s) |
||
804 | deflate_state *s; |
||
805 | { |
||
806 | int max_blindex; /* index of last bit length code of non zero freq */ |
||
807 | |||
808 | /* Determine the bit length frequencies for literal and distance trees */ |
||
809 | scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code); |
||
810 | scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code); |
||
811 | |||
812 | /* Build the bit length tree: */ |
||
813 | build_tree(s, (tree_desc *)(&(s->bl_desc))); |
||
814 | /* opt_len now includes the length of the tree representations, except |
||
815 | * the lengths of the bit lengths codes and the 5+5+4 bits for the counts. |
||
816 | */ |
||
817 | |||
818 | /* Determine the number of bit length codes to send. The pkzip format |
||
819 | * requires that at least 4 bit length codes be sent. (appnote.txt says |
||
820 | * 3 but the actual value used is 4.) |
||
821 | */ |
||
822 | for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) { |
||
823 | if (s->bl_tree[bl_order[max_blindex]].Len != 0) break; |
||
824 | } |
||
825 | /* Update opt_len to include the bit length tree and counts */ |
||
826 | s->opt_len += 3*(max_blindex+1) + 5+5+4; |
||
827 | Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", |
||
828 | s->opt_len, s->static_len)); |
||
829 | |||
830 | return max_blindex; |
||
831 | } |
||
832 | |||
833 | /* =========================================================================== |
||
834 | * Send the header for a block using dynamic Huffman trees: the counts, the |
||
835 | * lengths of the bit length codes, the literal tree and the distance tree. |
||
836 | * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4. |
||
837 | */ |
||
838 | local void send_all_trees(s, lcodes, dcodes, blcodes) |
||
839 | deflate_state *s; |
||
840 | int lcodes, dcodes, blcodes; /* number of codes for each tree */ |
||
841 | { |
||
842 | int rank; /* index in bl_order */ |
||
843 | |||
844 | Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes"); |
||
845 | Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES, |
||
846 | "too many codes"); |
||
847 | Tracev((stderr, "\nbl counts: ")); |
||
848 | send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */ |
||
849 | send_bits(s, dcodes-1, 5); |
||
850 | send_bits(s, blcodes-4, 4); /* not -3 as stated in appnote.txt */ |
||
851 | for (rank = 0; rank < blcodes; rank++) { |
||
852 | Tracev((stderr, "\nbl code %2d ", bl_order[rank])); |
||
853 | send_bits(s, s->bl_tree[bl_order[rank]].Len, 3); |
||
854 | } |
||
855 | Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent)); |
||
856 | |||
857 | send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */ |
||
858 | Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent)); |
||
859 | |||
860 | send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */ |
||
861 | Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent)); |
||
862 | } |
||
863 | |||
864 | /* =========================================================================== |
||
865 | * Send a stored block |
||
866 | */ |
||
867 | void _tr_stored_block(s, buf, stored_len, eof) |
||
868 | deflate_state *s; |
||
869 | charf *buf; /* input block */ |
||
870 | ulg stored_len; /* length of input block */ |
||
871 | int eof; /* true if this is the last block for a file */ |
||
872 | { |
||
873 | send_bits(s, (STORED_BLOCK<<1)+eof, 3); /* send block type */ |
||
874 | #ifdef DEBUG |
||
875 | s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L; |
||
876 | s->compressed_len += (stored_len + 4) << 3; |
||
877 | #endif |
||
878 | copy_block(s, buf, (unsigned)stored_len, 1); /* with header */ |
||
879 | } |
||
880 | |||
881 | /* =========================================================================== |
||
882 | * Send one empty static block to give enough lookahead for inflate. |
||
883 | * This takes 10 bits, of which 7 may remain in the bit buffer. |
||
884 | * The current inflate code requires 9 bits of lookahead. If the |
||
885 | * last two codes for the previous block (real code plus EOB) were coded |
||
886 | * on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode |
||
887 | * the last real code. In this case we send two empty static blocks instead |
||
888 | * of one. (There are no problems if the previous block is stored or fixed.) |
||
889 | * To simplify the code, we assume the worst case of last real code encoded |
||
890 | * on one bit only. |
||
891 | */ |
||
892 | void _tr_align(s) |
||
893 | deflate_state *s; |
||
894 | { |
||
895 | send_bits(s, STATIC_TREES<<1, 3); |
||
896 | send_code(s, END_BLOCK, static_ltree); |
||
897 | #ifdef DEBUG |
||
898 | s->compressed_len += 10L; /* 3 for block type, 7 for EOB */ |
||
899 | #endif |
||
900 | bi_flush(s); |
||
901 | /* Of the 10 bits for the empty block, we have already sent |
||
902 | * (10 - bi_valid) bits. The lookahead for the last real code (before |
||
903 | * the EOB of the previous block) was thus at least one plus the length |
||
904 | * of the EOB plus what we have just sent of the empty static block. |
||
905 | */ |
||
906 | if (1 + s->last_eob_len + 10 - s->bi_valid < 9) { |
||
907 | send_bits(s, STATIC_TREES<<1, 3); |
||
908 | send_code(s, END_BLOCK, static_ltree); |
||
909 | #ifdef DEBUG |
||
910 | s->compressed_len += 10L; |
||
911 | #endif |
||
912 | bi_flush(s); |
||
913 | } |
||
914 | s->last_eob_len = 7; |
||
915 | } |
||
916 | |||
917 | /* =========================================================================== |
||
918 | * Determine the best encoding for the current block: dynamic trees, static |
||
919 | * trees or store, and output the encoded block to the zip file. |
||
920 | */ |
||
921 | void _tr_flush_block(s, buf, stored_len, eof) |
||
922 | deflate_state *s; |
||
923 | charf *buf; /* input block, or NULL if too old */ |
||
924 | ulg stored_len; /* length of input block */ |
||
925 | int eof; /* true if this is the last block for a file */ |
||
926 | { |
||
927 | ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */ |
||
928 | int max_blindex = 0; /* index of last bit length code of non zero freq */ |
||
929 | |||
930 | /* Build the Huffman trees unless a stored block is forced */ |
||
931 | if (s->level > 0) { |
||
932 | |||
933 | /* Check if the file is ascii or binary */ |
||
934 | if (s->data_type == Z_UNKNOWN) set_data_type(s); |
||
935 | |||
936 | /* Construct the literal and distance trees */ |
||
937 | build_tree(s, (tree_desc *)(&(s->l_desc))); |
||
938 | Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len, |
||
939 | s->static_len)); |
||
940 | |||
941 | build_tree(s, (tree_desc *)(&(s->d_desc))); |
||
942 | Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len, |
||
943 | s->static_len)); |
||
944 | /* At this point, opt_len and static_len are the total bit lengths of |
||
945 | * the compressed block data, excluding the tree representations. |
||
946 | */ |
||
947 | |||
948 | /* Build the bit length tree for the above two trees, and get the index |
||
949 | * in bl_order of the last bit length code to send. |
||
950 | */ |
||
951 | max_blindex = build_bl_tree(s); |
||
952 | |||
953 | /* Determine the best encoding. Compute first the block length in bytes*/ |
||
954 | opt_lenb = (s->opt_len+3+7)>>3; |
||
955 | static_lenb = (s->static_len+3+7)>>3; |
||
956 | |||
957 | Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ", |
||
958 | opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len, |
||
959 | s->last_lit)); |
||
960 | |||
961 | if (static_lenb <= opt_lenb) opt_lenb = static_lenb; |
||
962 | |||
963 | } else { |
||
964 | Assert(buf != (char*)0, "lost buf"); |
||
965 | opt_lenb = static_lenb = stored_len + 5; /* force a stored block */ |
||
966 | } |
||
967 | |||
968 | #ifdef FORCE_STORED |
||
969 | if (buf != (char*)0) { /* force stored block */ |
||
970 | #else |
||
971 | if (stored_len+4 <= opt_lenb && buf != (char*)0) { |
||
972 | /* 4: two words for the lengths */ |
||
973 | #endif |
||
974 | /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE. |
||
975 | * Otherwise we can't have processed more than WSIZE input bytes since |
||
976 | * the last block flush, because compression would have been |
||
977 | * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to |
||
978 | * transform a block into a stored block. |
||
979 | */ |
||
980 | _tr_stored_block(s, buf, stored_len, eof); |
||
981 | |||
982 | #ifdef FORCE_STATIC |
||
983 | } else if (static_lenb >= 0) { /* force static trees */ |
||
984 | #else |
||
985 | } else if (static_lenb == opt_lenb) { |
||
986 | #endif |
||
987 | send_bits(s, (STATIC_TREES<<1)+eof, 3); |
||
988 | compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree); |
||
989 | #ifdef DEBUG |
||
990 | s->compressed_len += 3 + s->static_len; |
||
991 | #endif |
||
992 | } else { |
||
993 | send_bits(s, (DYN_TREES<<1)+eof, 3); |
||
994 | send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1, |
||
995 | max_blindex+1); |
||
996 | compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree); |
||
997 | #ifdef DEBUG |
||
998 | s->compressed_len += 3 + s->opt_len; |
||
999 | #endif |
||
1000 | } |
||
1001 | Assert (s->compressed_len == s->bits_sent, "bad compressed size"); |
||
1002 | /* The above check is made mod 2^32, for files larger than 512 MB |
||
1003 | * and uLong implemented on 32 bits. |
||
1004 | */ |
||
1005 | init_block(s); |
||
1006 | |||
1007 | if (eof) { |
||
1008 | bi_windup(s); |
||
1009 | #ifdef DEBUG |
||
1010 | s->compressed_len += 7; /* align on byte boundary */ |
||
1011 | #endif |
||
1012 | } |
||
1013 | Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3, |
||
1014 | s->compressed_len-7*eof)); |
||
1015 | } |
||
1016 | |||
1017 | /* =========================================================================== |
||
1018 | * Save the match info and tally the frequency counts. Return true if |
||
1019 | * the current block must be flushed. |
||
1020 | */ |
||
1021 | int _tr_tally (s, dist, lc) |
||
1022 | deflate_state *s; |
||
1023 | unsigned dist; /* distance of matched string */ |
||
1024 | unsigned lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */ |
||
1025 | { |
||
1026 | s->d_buf[s->last_lit] = (ush)dist; |
||
1027 | s->l_buf[s->last_lit++] = (uch)lc; |
||
1028 | if (dist == 0) { |
||
1029 | /* lc is the unmatched char */ |
||
1030 | s->dyn_ltree[lc].Freq++; |
||
1031 | } else { |
||
1032 | s->matches++; |
||
1033 | /* Here, lc is the match length - MIN_MATCH */ |
||
1034 | dist--; /* dist = match distance - 1 */ |
||
1035 | Assert((ush)dist < (ush)MAX_DIST(s) && |
||
1036 | (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) && |
||
1037 | (ush)d_code(dist) < (ush)D_CODES, "_tr_tally: bad match"); |
||
1038 | |||
1039 | s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++; |
||
1040 | s->dyn_dtree[d_code(dist)].Freq++; |
||
1041 | } |
||
1042 | |||
1043 | #ifdef TRUNCATE_BLOCK |
||
1044 | /* Try to guess if it is profitable to stop the current block here */ |
||
1045 | if ((s->last_lit & 0x1fff) == 0 && s->level > 2) { |
||
1046 | /* Compute an upper bound for the compressed length */ |
||
1047 | ulg out_length = (ulg)s->last_lit*8L; |
||
1048 | ulg in_length = (ulg)((long)s->strstart - s->block_start); |
||
1049 | int dcode; |
||
1050 | for (dcode = 0; dcode < D_CODES; dcode++) { |
||
1051 | out_length += (ulg)s->dyn_dtree[dcode].Freq * |
||
1052 | (5L+extra_dbits[dcode]); |
||
1053 | } |
||
1054 | out_length >>= 3; |
||
1055 | Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ", |
||
1056 | s->last_lit, in_length, out_length, |
||
1057 | 100L - out_length*100L/in_length)); |
||
1058 | if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1; |
||
1059 | } |
||
1060 | #endif |
||
1061 | return (s->last_lit == s->lit_bufsize-1); |
||
1062 | /* We avoid equality with lit_bufsize because of wraparound at 64K |
||
1063 | * on 16 bit machines and because stored blocks are restricted to |
||
1064 | * 64K-1 bytes. |
||
1065 | */ |
||
1066 | } |
||
1067 | |||
1068 | /* =========================================================================== |
||
1069 | * Send the block data compressed using the given Huffman trees |
||
1070 | */ |
||
1071 | local void compress_block(s, ltree, dtree) |
||
1072 | deflate_state *s; |
||
1073 | ct_data *ltree; /* literal tree */ |
||
1074 | ct_data *dtree; /* distance tree */ |
||
1075 | { |
||
1076 | unsigned dist; /* distance of matched string */ |
||
1077 | int lc; /* match length or unmatched char (if dist == 0) */ |
||
1078 | unsigned lx = 0; /* running index in l_buf */ |
||
1079 | unsigned code; /* the code to send */ |
||
1080 | int extra; /* number of extra bits to send */ |
||
1081 | |||
1082 | if (s->last_lit != 0) do { |
||
1083 | dist = s->d_buf[lx]; |
||
1084 | lc = s->l_buf[lx++]; |
||
1085 | if (dist == 0) { |
||
1086 | send_code(s, lc, ltree); /* send a literal byte */ |
||
1087 | Tracecv(isgraph(lc), (stderr," '%c' ", lc)); |
||
1088 | } else { |
||
1089 | /* Here, lc is the match length - MIN_MATCH */ |
||
1090 | code = _length_code[lc]; |
||
1091 | send_code(s, code+LITERALS+1, ltree); /* send the length code */ |
||
1092 | extra = extra_lbits[code]; |
||
1093 | if (extra != 0) { |
||
1094 | lc -= base_length[code]; |
||
1095 | send_bits(s, lc, extra); /* send the extra length bits */ |
||
1096 | } |
||
1097 | dist--; /* dist is now the match distance - 1 */ |
||
1098 | code = d_code(dist); |
||
1099 | Assert (code < D_CODES, "bad d_code"); |
||
1100 | |||
1101 | send_code(s, code, dtree); /* send the distance code */ |
||
1102 | extra = extra_dbits[code]; |
||
1103 | if (extra != 0) { |
||
1104 | dist -= base_dist[code]; |
||
1105 | send_bits(s, dist, extra); /* send the extra distance bits */ |
||
1106 | } |
||
1107 | } /* literal or match pair ? */ |
||
1108 | |||
1109 | /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */ |
||
1110 | Assert(s->pending < s->lit_bufsize + 2*lx, "pendingBuf overflow"); |
||
1111 | |||
1112 | } while (lx < s->last_lit); |
||
1113 | |||
1114 | send_code(s, END_BLOCK, ltree); |
||
1115 | s->last_eob_len = ltree[END_BLOCK].Len; |
||
1116 | } |
||
1117 | |||
1118 | /* =========================================================================== |
||
1119 | * Set the data type to ASCII or BINARY, using a crude approximation: |
||
1120 | * binary if more than 20% of the bytes are <= 6 or >= 128, ascii otherwise. |
||
1121 | * IN assertion: the fields freq of dyn_ltree are set and the total of all |
||
1122 | * frequencies does not exceed 64K (to fit in an int on 16 bit machines). |
||
1123 | */ |
||
1124 | local void set_data_type(s) |
||
1125 | deflate_state *s; |
||
1126 | { |
||
1127 | int n = 0; |
||
1128 | unsigned ascii_freq = 0; |
||
1129 | unsigned bin_freq = 0; |
||
1130 | while (n < 7) bin_freq += s->dyn_ltree[n++].Freq; |
||
1131 | while (n < 128) ascii_freq += s->dyn_ltree[n++].Freq; |
||
1132 | while (n < LITERALS) bin_freq += s->dyn_ltree[n++].Freq; |
||
1133 | s->data_type = (Byte)(bin_freq > (ascii_freq >> 2) ? Z_BINARY : Z_ASCII); |
||
1134 | } |
||
1135 | |||
1136 | /* =========================================================================== |
||
1137 | * Reverse the first len bits of a code, using straightforward code (a faster |
||
1138 | * method would use a table) |
||
1139 | * IN assertion: 1 <= len <= 15 |
||
1140 | */ |
||
1141 | local unsigned bi_reverse(code, len) |
||
1142 | unsigned code; /* the value to invert */ |
||
1143 | int len; /* its bit length */ |
||
1144 | { |
||
1145 | register unsigned res = 0; |
||
1146 | do { |
||
1147 | res |= code & 1; |
||
1148 | code >>= 1, res <<= 1; |
||
1149 | } while (--len > 0); |
||
1150 | return res >> 1; |
||
1151 | } |
||
1152 | |||
1153 | /* =========================================================================== |
||
1154 | * Flush the bit buffer, keeping at most 7 bits in it. |
||
1155 | */ |
||
1156 | local void bi_flush(s) |
||
1157 | deflate_state *s; |
||
1158 | { |
||
1159 | if (s->bi_valid == 16) { |
||
1160 | put_short(s, s->bi_buf); |
||
1161 | s->bi_buf = 0; |
||
1162 | s->bi_valid = 0; |
||
1163 | } else if (s->bi_valid >= 8) { |
||
1164 | put_byte(s, (Byte)s->bi_buf); |
||
1165 | s->bi_buf >>= 8; |
||
1166 | s->bi_valid -= 8; |
||
1167 | } |
||
1168 | } |
||
1169 | |||
1170 | /* =========================================================================== |
||
1171 | * Flush the bit buffer and align the output on a byte boundary |
||
1172 | */ |
||
1173 | local void bi_windup(s) |
||
1174 | deflate_state *s; |
||
1175 | { |
||
1176 | if (s->bi_valid > 8) { |
||
1177 | put_short(s, s->bi_buf); |
||
1178 | } else if (s->bi_valid > 0) { |
||
1179 | put_byte(s, (Byte)s->bi_buf); |
||
1180 | } |
||
1181 | s->bi_buf = 0; |
||
1182 | s->bi_valid = 0; |
||
1183 | #ifdef DEBUG |
||
1184 | s->bits_sent = (s->bits_sent+7) & ~7; |
||
1185 | #endif |
||
1186 | } |
||
1187 | |||
1188 | /* =========================================================================== |
||
1189 | * Copy a stored block, storing first the length and its |
||
1190 | * one's complement if requested. |
||
1191 | */ |
||
1192 | local void copy_block(s, buf, len, header) |
||
1193 | deflate_state *s; |
||
1194 | charf *buf; /* the input data */ |
||
1195 | unsigned len; /* its length */ |
||
1196 | int header; /* true if block header must be written */ |
||
1197 | { |
||
1198 | bi_windup(s); /* align on byte boundary */ |
||
1199 | s->last_eob_len = 8; /* enough lookahead for inflate */ |
||
1200 | |||
1201 | if (header) { |
||
1202 | put_short(s, (ush)len); |
||
1203 | put_short(s, (ush)~len); |
||
1204 | #ifdef DEBUG |
||
1205 | s->bits_sent += 2*16; |
||
1206 | #endif |
||
1207 | } |
||
1208 | #ifdef DEBUG |
||
1209 | s->bits_sent += (ulg)len<<3; |
||
1210 | #endif |
||
1211 | while (len--) { |
||
1212 | put_byte(s, *buf++); |
||
1213 | } |
||
1214 | } |