1 /* trees.c -- output deflated data using Huffman coding
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2 * Copyright (C) 1995-2005 Jean-loup Gailly
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3 * For conditions of distribution and use, see copyright notice in zlib.h
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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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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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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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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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29 * Addison-Wesley, 1983. ISBN 0-201-06672-6.
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34 /* #define GEN_TREES_H */
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36 #include "deflate.h"
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42 /* ===========================================================================
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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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49 #define END_BLOCK 256
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50 /* end of block literal code */
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53 /* repeat previous bit length 3-6 times (2 bits of repeat count) */
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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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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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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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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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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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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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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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81 /* ===========================================================================
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82 * Local data. These are initialized only once.
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85 #define DIST_CODE_LEN 512 /* see definition of array dist_code below */
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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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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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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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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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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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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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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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118 # include "trees.h"
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119 #endif /* GEN_TREES_H */
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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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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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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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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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138 /* ===========================================================================
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139 * Local (static) routines in this file.
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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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153 local void compress_block OF((deflate_state *s, ct_data *ltree,
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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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163 local void gen_trees_header OF((void));
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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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171 # define send_code(s, c, tree) \
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172 { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
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173 send_bits(s, tree[c].Code, tree[c].Len); }
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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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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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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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190 local void send_bits OF((deflate_state *s, int value, int length));
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192 local void send_bits(s, value, length)
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194 int value; /* value to send */
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195 int length; /* number of bits */
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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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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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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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211 s->bi_buf |= value << s->bi_valid;
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212 s->bi_valid += length;
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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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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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226 s->bi_buf |= (value) << s->bi_valid;\
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227 s->bi_valid += len;\
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233 /* the arguments must not have side effects */
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235 /* ===========================================================================
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236 * Initialize the various 'constant' tables.
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238 local void tr_static_init()
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240 #if defined(GEN_TREES_H) || !defined(STDC)
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241 static int static_init_done = 0;
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242 int n; /* iterates over tree elements */
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243 int bits; /* bit counter */
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244 int length; /* length value */
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245 int code; /* code value */
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246 int dist; /* distance index */
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247 ush bl_count[MAX_BITS+1];
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248 /* number of codes at each bit length for an optimal tree */
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250 if (static_init_done) return;
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252 /* For some embedded targets, global variables are not initialized: */
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253 static_l_desc.static_tree = static_ltree;
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254 static_l_desc.extra_bits = extra_lbits;
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255 static_d_desc.static_tree = static_dtree;
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256 static_d_desc.extra_bits = extra_dbits;
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257 static_bl_desc.extra_bits = extra_blbits;
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259 /* Initialize the mapping length (0..255) -> length code (0..28) */
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261 for (code = 0; code < LENGTH_CODES-1; code++) {
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262 base_length[code] = length;
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263 for (n = 0; n < (1<<extra_lbits[code]); n++) {
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264 _length_code[length++] = (uch)code;
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267 Assert (length == 256, "tr_static_init: length != 256");
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268 /* Note that the length 255 (match length 258) can be represented
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269 * in two different ways: code 284 + 5 bits or code 285, so we
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270 * overwrite length_code[255] to use the best encoding:
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272 _length_code[length-1] = (uch)code;
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274 /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
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276 for (code = 0 ; code < 16; code++) {
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277 base_dist[code] = dist;
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278 for (n = 0; n < (1<<extra_dbits[code]); n++) {
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279 _dist_code[dist++] = (uch)code;
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282 Assert (dist == 256, "tr_static_init: dist != 256");
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283 dist >>= 7; /* from now on, all distances are divided by 128 */
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284 for ( ; code < D_CODES; code++) {
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285 base_dist[code] = dist << 7;
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286 for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
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287 _dist_code[256 + dist++] = (uch)code;
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290 Assert (dist == 256, "tr_static_init: 256+dist != 512");
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292 /* Construct the codes of the static literal tree */
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293 for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
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295 while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
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296 while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
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297 while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
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298 while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
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299 /* Codes 286 and 287 do not exist, but we must include them in the
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300 * tree construction to get a canonical Huffman tree (longest code
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303 gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);
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305 /* The static distance tree is trivial: */
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306 for (n = 0; n < D_CODES; n++) {
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307 static_dtree[n].Len = 5;
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308 static_dtree[n].Code = bi_reverse((unsigned)n, 5);
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310 static_init_done = 1;
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312 # ifdef GEN_TREES_H
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313 gen_trees_header();
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315 #endif /* defined(GEN_TREES_H) || !defined(STDC) */
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318 /* ===========================================================================
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319 * Genererate the file trees.h describing the static trees.
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323 # include <stdio.h>
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326 # define SEPARATOR(i, last, width) \
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327 ((i) == (last)? "\n};\n\n" : \
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328 ((i) % (width) == (width)-1 ? ",\n" : ", "))
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330 void gen_trees_header()
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332 FILE *header = fopen("trees.h", "w");
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335 Assert (header != NULL, "Can't open trees.h");
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337 "/* header created automatically with -DGEN_TREES_H */\n\n");
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339 fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n");
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340 for (i = 0; i < L_CODES+2; i++) {
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341 fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code,
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342 static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5));
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345 fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n");
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346 for (i = 0; i < D_CODES; i++) {
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347 fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code,
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348 static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5));
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351 fprintf(header, "const uch _dist_code[DIST_CODE_LEN] = {\n");
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352 for (i = 0; i < DIST_CODE_LEN; i++) {
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353 fprintf(header, "%2u%s", _dist_code[i],
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354 SEPARATOR(i, DIST_CODE_LEN-1, 20));
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357 fprintf(header, "const uch _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");
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358 for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) {
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359 fprintf(header, "%2u%s", _length_code[i],
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360 SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));
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363 fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");
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364 for (i = 0; i < LENGTH_CODES; i++) {
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365 fprintf(header, "%1u%s", base_length[i],
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366 SEPARATOR(i, LENGTH_CODES-1, 20));
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369 fprintf(header, "local const int base_dist[D_CODES] = {\n");
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370 for (i = 0; i < D_CODES; i++) {
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371 fprintf(header, "%5u%s", base_dist[i],
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372 SEPARATOR(i, D_CODES-1, 10));
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377 #endif /* GEN_TREES_H */
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379 /* ===========================================================================
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380 * Initialize the tree data structures for a new zlib stream.
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387 s->l_desc.dyn_tree = s->dyn_ltree;
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388 s->l_desc.stat_desc = &static_l_desc;
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390 s->d_desc.dyn_tree = s->dyn_dtree;
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391 s->d_desc.stat_desc = &static_d_desc;
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393 s->bl_desc.dyn_tree = s->bl_tree;
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394 s->bl_desc.stat_desc = &static_bl_desc;
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398 s->last_eob_len = 8; /* enough lookahead for inflate */
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400 s->compressed_len = 0L;
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404 /* Initialize the first block of the first file: */
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408 /* ===========================================================================
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409 * Initialize a new block.
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411 local void init_block(s)
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414 int n; /* iterates over tree elements */
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416 /* Initialize the trees. */
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417 for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0;
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418 for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0;
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419 for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;
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421 s->dyn_ltree[END_BLOCK].Freq = 1;
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422 s->opt_len = s->static_len = 0L;
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423 s->last_lit = s->matches = 0;
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427 /* Index within the heap array of least frequent node in the Huffman tree */
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430 /* ===========================================================================
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431 * Remove the smallest element from the heap and recreate the heap with
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432 * one less element. Updates heap and heap_len.
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434 #define pqremove(s, tree, top) \
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436 top = s->heap[SMALLEST]; \
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437 s->heap[SMALLEST] = s->heap[s->heap_len--]; \
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438 pqdownheap(s, tree, SMALLEST); \
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441 /* ===========================================================================
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442 * Compares to subtrees, using the tree depth as tie breaker when
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443 * the subtrees have equal frequency. This minimizes the worst case length.
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445 #define smaller(tree, n, m, depth) \
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446 (tree[n].Freq < tree[m].Freq || \
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447 (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
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449 /* ===========================================================================
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450 * Restore the heap property by moving down the tree starting at node k,
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451 * exchanging a node with the smallest of its two sons if necessary, stopping
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452 * when the heap property is re-established (each father smaller than its
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455 local void pqdownheap(s, tree, k)
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457 ct_data *tree; /* the tree to restore */
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458 int k; /* node to move down */
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460 int v = s->heap[k];
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461 int j = k << 1; /* left son of k */
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462 while (j <= s->heap_len) {
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463 /* Set j to the smallest of the two sons: */
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464 if (j < s->heap_len &&
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465 smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
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468 /* Exit if v is smaller than both sons */
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469 if (smaller(tree, v, s->heap[j], s->depth)) break;
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471 /* Exchange v with the smallest son */
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472 s->heap[k] = s->heap[j]; k = j;
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474 /* And continue down the tree, setting j to the left son of k */
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480 /* ===========================================================================
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481 * Compute the optimal bit lengths for a tree and update the total bit length
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482 * for the current block.
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483 * IN assertion: the fields freq and dad are set, heap[heap_max] and
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484 * above are the tree nodes sorted by increasing frequency.
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485 * OUT assertions: the field len is set to the optimal bit length, the
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486 * array bl_count contains the frequencies for each bit length.
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487 * The length opt_len is updated; static_len is also updated if stree is
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490 local void gen_bitlen(s, desc)
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492 tree_desc *desc; /* the tree descriptor */
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494 ct_data *tree = desc->dyn_tree;
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495 int max_code = desc->max_code;
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496 const ct_data *stree = desc->stat_desc->static_tree;
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497 const intf *extra = desc->stat_desc->extra_bits;
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498 int base = desc->stat_desc->extra_base;
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499 int max_length = desc->stat_desc->max_length;
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500 int h; /* heap index */
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501 int n, m; /* iterate over the tree elements */
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502 int bits; /* bit length */
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503 int xbits; /* extra bits */
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504 ush f; /* frequency */
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505 int overflow = 0; /* number of elements with bit length too large */
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507 for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
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509 /* In a first pass, compute the optimal bit lengths (which may
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510 * overflow in the case of the bit length tree).
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512 tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
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514 for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
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516 bits = tree[tree[n].Dad].Len + 1;
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517 if (bits > max_length) bits = max_length, overflow++;
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518 tree[n].Len = (ush)bits;
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519 /* We overwrite tree[n].Dad which is no longer needed */
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521 if (n > max_code) continue; /* not a leaf node */
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523 s->bl_count[bits]++;
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525 if (n >= base) xbits = extra[n-base];
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527 s->opt_len += (ulg)f * (bits + xbits);
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528 if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits);
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530 if (overflow == 0) return;
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532 Trace((stderr,"\nbit length overflow\n"));
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533 /* This happens for example on obj2 and pic of the Calgary corpus */
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535 /* Find the first bit length which could increase: */
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537 bits = max_length-1;
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538 while (s->bl_count[bits] == 0) bits--;
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539 s->bl_count[bits]--; /* move one leaf down the tree */
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540 s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
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541 s->bl_count[max_length]--;
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542 /* The brother of the overflow item also moves one step up,
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543 * but this does not affect bl_count[max_length]
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546 } while (overflow > 0);
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548 /* Now recompute all bit lengths, scanning in increasing frequency.
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549 * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
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550 * lengths instead of fixing only the wrong ones. This idea is taken
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551 * from 'ar' written by Haruhiko Okumura.)
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553 for (bits = max_length; bits != 0; bits--) {
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554 n = s->bl_count[bits];
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557 if (m > max_code) continue;
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558 if ((unsigned) tree[m].Len != (unsigned) bits) {
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559 Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
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560 s->opt_len += ((long)bits - (long)tree[m].Len)
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561 *(long)tree[m].Freq;
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562 tree[m].Len = (ush)bits;
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569 /* ===========================================================================
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570 * Generate the codes for a given tree and bit counts (which need not be
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572 * IN assertion: the array bl_count contains the bit length statistics for
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573 * the given tree and the field len is set for all tree elements.
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574 * OUT assertion: the field code is set for all tree elements of non
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575 * zero code length.
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577 local void gen_codes (tree, max_code, bl_count)
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578 ct_data *tree; /* the tree to decorate */
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579 int max_code; /* largest code with non zero frequency */
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580 ushf *bl_count; /* number of codes at each bit length */
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582 ush next_code[MAX_BITS+1]; /* next code value for each bit length */
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583 ush code = 0; /* running code value */
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584 int bits; /* bit index */
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585 int n; /* code index */
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587 /* The distribution counts are first used to generate the code values
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588 * without bit reversal.
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590 for (bits = 1; bits <= MAX_BITS; bits++) {
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591 next_code[bits] = code = (code + bl_count[bits-1]) << 1;
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593 /* Check that the bit counts in bl_count are consistent. The last code
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594 * must be all ones.
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596 Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
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597 "inconsistent bit counts");
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598 Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
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600 for (n = 0; n <= max_code; n++) {
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601 int len = tree[n].Len;
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602 if (len == 0) continue;
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603 /* Now reverse the bits */
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604 tree[n].Code = bi_reverse(next_code[len]++, len);
\r
606 Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
\r
607 n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
\r
611 /* ===========================================================================
\r
612 * Construct one Huffman tree and assigns the code bit strings and lengths.
\r
613 * Update the total bit length for the current block.
\r
614 * IN assertion: the field freq is set for all tree elements.
\r
615 * OUT assertions: the fields len and code are set to the optimal bit length
\r
616 * and corresponding code. The length opt_len is updated; static_len is
\r
617 * also updated if stree is not null. The field max_code is set.
\r
619 local void build_tree(s, desc)
\r
621 tree_desc *desc; /* the tree descriptor */
\r
623 ct_data *tree = desc->dyn_tree;
\r
624 const ct_data *stree = desc->stat_desc->static_tree;
\r
625 int elems = desc->stat_desc->elems;
\r
626 int n, m; /* iterate over heap elements */
\r
627 int max_code = -1; /* largest code with non zero frequency */
\r
628 int node; /* new node being created */
\r
630 /* Construct the initial heap, with least frequent element in
\r
631 * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
\r
632 * heap[0] is not used.
\r
634 s->heap_len = 0, s->heap_max = HEAP_SIZE;
\r
636 for (n = 0; n < elems; n++) {
\r
637 if (tree[n].Freq != 0) {
\r
638 s->heap[++(s->heap_len)] = max_code = n;
\r
645 /* The pkzip format requires that at least one distance code exists,
\r
646 * and that at least one bit should be sent even if there is only one
\r
647 * possible code. So to avoid special checks later on we force at least
\r
648 * two codes of non zero frequency.
\r
650 while (s->heap_len < 2) {
\r
651 node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
\r
652 tree[node].Freq = 1;
\r
653 s->depth[node] = 0;
\r
654 s->opt_len--; if (stree) s->static_len -= stree[node].Len;
\r
655 /* node is 0 or 1 so it does not have extra bits */
\r
657 desc->max_code = max_code;
\r
659 /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
\r
660 * establish sub-heaps of increasing lengths:
\r
662 for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
\r
664 /* Construct the Huffman tree by repeatedly combining the least two
\r
667 node = elems; /* next internal node of the tree */
\r
669 pqremove(s, tree, n); /* n = node of least frequency */
\r
670 m = s->heap[SMALLEST]; /* m = node of next least frequency */
\r
672 s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
\r
673 s->heap[--(s->heap_max)] = m;
\r
675 /* Create a new node father of n and m */
\r
676 tree[node].Freq = tree[n].Freq + tree[m].Freq;
\r
677 s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?
\r
678 s->depth[n] : s->depth[m]) + 1);
\r
679 tree[n].Dad = tree[m].Dad = (ush)node;
\r
680 #ifdef DUMP_BL_TREE
\r
681 if (tree == s->bl_tree) {
\r
682 fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
\r
683 node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
\r
686 /* and insert the new node in the heap */
\r
687 s->heap[SMALLEST] = node++;
\r
688 pqdownheap(s, tree, SMALLEST);
\r
690 } while (s->heap_len >= 2);
\r
692 s->heap[--(s->heap_max)] = s->heap[SMALLEST];
\r
694 /* At this point, the fields freq and dad are set. We can now
\r
695 * generate the bit lengths.
\r
697 gen_bitlen(s, (tree_desc *)desc);
\r
699 /* The field len is now set, we can generate the bit codes */
\r
700 gen_codes ((ct_data *)tree, max_code, s->bl_count);
\r
703 /* ===========================================================================
\r
704 * Scan a literal or distance tree to determine the frequencies of the codes
\r
705 * in the bit length tree.
\r
707 local void scan_tree (s, tree, max_code)
\r
709 ct_data *tree; /* the tree to be scanned */
\r
710 int max_code; /* and its largest code of non zero frequency */
\r
712 int n; /* iterates over all tree elements */
\r
713 int prevlen = -1; /* last emitted length */
\r
714 int curlen; /* length of current code */
\r
715 int nextlen = tree[0].Len; /* length of next code */
\r
716 int count = 0; /* repeat count of the current code */
\r
717 int max_count = 7; /* max repeat count */
\r
718 int min_count = 4; /* min repeat count */
\r
720 if (nextlen == 0) max_count = 138, min_count = 3;
\r
721 tree[max_code+1].Len = (ush)0xffff; /* guard */
\r
723 for (n = 0; n <= max_code; n++) {
\r
724 curlen = nextlen; nextlen = tree[n+1].Len;
\r
725 if (++count < max_count && curlen == nextlen) {
\r
727 } else if (count < min_count) {
\r
728 s->bl_tree[curlen].Freq += count;
\r
729 } else if (curlen != 0) {
\r
730 if (curlen != prevlen) s->bl_tree[curlen].Freq++;
\r
731 s->bl_tree[REP_3_6].Freq++;
\r
732 } else if (count <= 10) {
\r
733 s->bl_tree[REPZ_3_10].Freq++;
\r
735 s->bl_tree[REPZ_11_138].Freq++;
\r
737 count = 0; prevlen = curlen;
\r
738 if (nextlen == 0) {
\r
739 max_count = 138, min_count = 3;
\r
740 } else if (curlen == nextlen) {
\r
741 max_count = 6, min_count = 3;
\r
743 max_count = 7, min_count = 4;
\r
748 /* ===========================================================================
\r
749 * Send a literal or distance tree in compressed form, using the codes in
\r
752 local void send_tree (s, tree, max_code)
\r
754 ct_data *tree; /* the tree to be scanned */
\r
755 int max_code; /* and its largest code of non zero frequency */
\r
757 int n; /* iterates over all tree elements */
\r
758 int prevlen = -1; /* last emitted length */
\r
759 int curlen; /* length of current code */
\r
760 int nextlen = tree[0].Len; /* length of next code */
\r
761 int count = 0; /* repeat count of the current code */
\r
762 int max_count = 7; /* max repeat count */
\r
763 int min_count = 4; /* min repeat count */
\r
765 /* tree[max_code+1].Len = -1; */ /* guard already set */
\r
766 if (nextlen == 0) max_count = 138, min_count = 3;
\r
768 for (n = 0; n <= max_code; n++) {
\r
769 curlen = nextlen; nextlen = tree[n+1].Len;
\r
770 if (++count < max_count && curlen == nextlen) {
\r
772 } else if (count < min_count) {
\r
773 do { send_code(s, curlen, s->bl_tree); } while (--count != 0);
\r
775 } else if (curlen != 0) {
\r
776 if (curlen != prevlen) {
\r
777 send_code(s, curlen, s->bl_tree); count--;
\r
779 Assert(count >= 3 && count <= 6, " 3_6?");
\r
780 send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);
\r
782 } else if (count <= 10) {
\r
783 send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);
\r
786 send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
\r
788 count = 0; prevlen = curlen;
\r
789 if (nextlen == 0) {
\r
790 max_count = 138, min_count = 3;
\r
791 } else if (curlen == nextlen) {
\r
792 max_count = 6, min_count = 3;
\r
794 max_count = 7, min_count = 4;
\r
799 /* ===========================================================================
\r
800 * Construct the Huffman tree for the bit lengths and return the index in
\r
801 * bl_order of the last bit length code to send.
\r
803 local int build_bl_tree(s)
\r
806 int max_blindex; /* index of last bit length code of non zero freq */
\r
808 /* Determine the bit length frequencies for literal and distance trees */
\r
809 scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
\r
810 scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);
\r
812 /* Build the bit length tree: */
\r
813 build_tree(s, (tree_desc *)(&(s->bl_desc)));
\r
814 /* opt_len now includes the length of the tree representations, except
\r
815 * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
\r
818 /* Determine the number of bit length codes to send. The pkzip format
\r
819 * requires that at least 4 bit length codes be sent. (appnote.txt says
\r
820 * 3 but the actual value used is 4.)
\r
822 for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
\r
823 if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
\r
825 /* Update opt_len to include the bit length tree and counts */
\r
826 s->opt_len += 3*(max_blindex+1) + 5+5+4;
\r
827 Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
\r
828 s->opt_len, s->static_len));
\r
830 return max_blindex;
\r
833 /* ===========================================================================
\r
834 * Send the header for a block using dynamic Huffman trees: the counts, the
\r
835 * lengths of the bit length codes, the literal tree and the distance tree.
\r
836 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
\r
838 local void send_all_trees(s, lcodes, dcodes, blcodes)
\r
840 int lcodes, dcodes, blcodes; /* number of codes for each tree */
\r
842 int rank; /* index in bl_order */
\r
844 Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
\r
845 Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
\r
847 Tracev((stderr, "\nbl counts: "));
\r
848 send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
\r
849 send_bits(s, dcodes-1, 5);
\r
850 send_bits(s, blcodes-4, 4); /* not -3 as stated in appnote.txt */
\r
851 for (rank = 0; rank < blcodes; rank++) {
\r
852 Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
\r
853 send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
\r
855 Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));
\r
857 send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
\r
858 Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));
\r
860 send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
\r
861 Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
\r
864 /* ===========================================================================
\r
865 * Send a stored block
\r
867 void _tr_stored_block(s, buf, stored_len, eof)
\r
869 charf *buf; /* input block */
\r
870 ulg stored_len; /* length of input block */
\r
871 int eof; /* true if this is the last block for a file */
\r
873 send_bits(s, (STORED_BLOCK<<1)+eof, 3); /* send block type */
\r
875 s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
\r
876 s->compressed_len += (stored_len + 4) << 3;
\r
878 copy_block(s, buf, (unsigned)stored_len, 1); /* with header */
\r
881 /* ===========================================================================
\r
882 * Send one empty static block to give enough lookahead for inflate.
\r
883 * This takes 10 bits, of which 7 may remain in the bit buffer.
\r
884 * The current inflate code requires 9 bits of lookahead. If the
\r
885 * last two codes for the previous block (real code plus EOB) were coded
\r
886 * on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode
\r
887 * the last real code. In this case we send two empty static blocks instead
\r
888 * of one. (There are no problems if the previous block is stored or fixed.)
\r
889 * To simplify the code, we assume the worst case of last real code encoded
\r
895 send_bits(s, STATIC_TREES<<1, 3);
\r
896 send_code(s, END_BLOCK, static_ltree);
\r
898 s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
\r
901 /* Of the 10 bits for the empty block, we have already sent
\r
902 * (10 - bi_valid) bits. The lookahead for the last real code (before
\r
903 * the EOB of the previous block) was thus at least one plus the length
\r
904 * of the EOB plus what we have just sent of the empty static block.
\r
906 if (1 + s->last_eob_len + 10 - s->bi_valid < 9) {
\r
907 send_bits(s, STATIC_TREES<<1, 3);
\r
908 send_code(s, END_BLOCK, static_ltree);
\r
910 s->compressed_len += 10L;
\r
914 s->last_eob_len = 7;
\r
917 /* ===========================================================================
\r
918 * Determine the best encoding for the current block: dynamic trees, static
\r
919 * trees or store, and output the encoded block to the zip file.
\r
921 void _tr_flush_block(s, buf, stored_len, eof)
\r
923 charf *buf; /* input block, or NULL if too old */
\r
924 ulg stored_len; /* length of input block */
\r
925 int eof; /* true if this is the last block for a file */
\r
927 ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
\r
928 int max_blindex = 0; /* index of last bit length code of non zero freq */
\r
930 /* Build the Huffman trees unless a stored block is forced */
\r
931 if (s->level > 0) {
\r
933 /* Check if the file is binary or text */
\r
934 if (stored_len > 0 && s->strm->data_type == Z_UNKNOWN)
\r
937 /* Construct the literal and distance trees */
\r
938 build_tree(s, (tree_desc *)(&(s->l_desc)));
\r
939 Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
\r
942 build_tree(s, (tree_desc *)(&(s->d_desc)));
\r
943 Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
\r
945 /* At this point, opt_len and static_len are the total bit lengths of
\r
946 * the compressed block data, excluding the tree representations.
\r
949 /* Build the bit length tree for the above two trees, and get the index
\r
950 * in bl_order of the last bit length code to send.
\r
952 max_blindex = build_bl_tree(s);
\r
954 /* Determine the best encoding. Compute the block lengths in bytes. */
\r
955 opt_lenb = (s->opt_len+3+7)>>3;
\r
956 static_lenb = (s->static_len+3+7)>>3;
\r
958 Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
\r
959 opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
\r
962 if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
\r
965 Assert(buf != (char*)0, "lost buf");
\r
966 opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
\r
969 #ifdef FORCE_STORED
\r
970 if (buf != (char*)0) { /* force stored block */
\r
972 if (stored_len+4 <= opt_lenb && buf != (char*)0) {
\r
973 /* 4: two words for the lengths */
\r
975 /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
\r
976 * Otherwise we can't have processed more than WSIZE input bytes since
\r
977 * the last block flush, because compression would have been
\r
978 * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
\r
979 * transform a block into a stored block.
\r
981 _tr_stored_block(s, buf, stored_len, eof);
\r
983 #ifdef FORCE_STATIC
\r
984 } else if (static_lenb >= 0) { /* force static trees */
\r
986 } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) {
\r
988 send_bits(s, (STATIC_TREES<<1)+eof, 3);
\r
989 compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree);
\r
991 s->compressed_len += 3 + s->static_len;
\r
994 send_bits(s, (DYN_TREES<<1)+eof, 3);
\r
995 send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
\r
997 compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree);
\r
999 s->compressed_len += 3 + s->opt_len;
\r
1002 Assert (s->compressed_len == s->bits_sent, "bad compressed size");
\r
1003 /* The above check is made mod 2^32, for files larger than 512 MB
\r
1004 * and uLong implemented on 32 bits.
\r
1011 s->compressed_len += 7; /* align on byte boundary */
\r
1014 Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
\r
1015 s->compressed_len-7*eof));
\r
1018 /* ===========================================================================
\r
1019 * Save the match info and tally the frequency counts. Return true if
\r
1020 * the current block must be flushed.
\r
1022 int _tr_tally (s, dist, lc)
\r
1024 unsigned dist; /* distance of matched string */
\r
1025 unsigned lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */
\r
1027 s->d_buf[s->last_lit] = (ush)dist;
\r
1028 s->l_buf[s->last_lit++] = (uch)lc;
\r
1030 /* lc is the unmatched char */
\r
1031 s->dyn_ltree[lc].Freq++;
\r
1034 /* Here, lc is the match length - MIN_MATCH */
\r
1035 dist--; /* dist = match distance - 1 */
\r
1036 Assert((ush)dist < (ush)MAX_DIST(s) &&
\r
1037 (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
\r
1038 (ush)d_code(dist) < (ush)D_CODES, "_tr_tally: bad match");
\r
1040 s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
\r
1041 s->dyn_dtree[d_code(dist)].Freq++;
\r
1044 #ifdef TRUNCATE_BLOCK
\r
1045 /* Try to guess if it is profitable to stop the current block here */
\r
1046 if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
\r
1047 /* Compute an upper bound for the compressed length */
\r
1048 ulg out_length = (ulg)s->last_lit*8L;
\r
1049 ulg in_length = (ulg)((long)s->strstart - s->block_start);
\r
1051 for (dcode = 0; dcode < D_CODES; dcode++) {
\r
1052 out_length += (ulg)s->dyn_dtree[dcode].Freq *
\r
1053 (5L+extra_dbits[dcode]);
\r
1056 Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
\r
1057 s->last_lit, in_length, out_length,
\r
1058 100L - out_length*100L/in_length));
\r
1059 if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
\r
1062 return (s->last_lit == s->lit_bufsize-1);
\r
1063 /* We avoid equality with lit_bufsize because of wraparound at 64K
\r
1064 * on 16 bit machines and because stored blocks are restricted to
\r
1069 /* ===========================================================================
\r
1070 * Send the block data compressed using the given Huffman trees
\r
1072 local void compress_block(s, ltree, dtree)
\r
1074 ct_data *ltree; /* literal tree */
\r
1075 ct_data *dtree; /* distance tree */
\r
1077 unsigned dist; /* distance of matched string */
\r
1078 int lc; /* match length or unmatched char (if dist == 0) */
\r
1079 unsigned lx = 0; /* running index in l_buf */
\r
1080 unsigned code; /* the code to send */
\r
1081 int extra; /* number of extra bits to send */
\r
1083 if (s->last_lit != 0) do {
\r
1084 dist = s->d_buf[lx];
\r
1085 lc = s->l_buf[lx++];
\r
1087 send_code(s, lc, ltree); /* send a literal byte */
\r
1088 Tracecv(isgraph(lc), (stderr," '%c' ", lc));
\r
1090 /* Here, lc is the match length - MIN_MATCH */
\r
1091 code = _length_code[lc];
\r
1092 send_code(s, code+LITERALS+1, ltree); /* send the length code */
\r
1093 extra = extra_lbits[code];
\r
1095 lc -= base_length[code];
\r
1096 send_bits(s, lc, extra); /* send the extra length bits */
\r
1098 dist--; /* dist is now the match distance - 1 */
\r
1099 code = d_code(dist);
\r
1100 Assert (code < D_CODES, "bad d_code");
\r
1102 send_code(s, code, dtree); /* send the distance code */
\r
1103 extra = extra_dbits[code];
\r
1105 dist -= base_dist[code];
\r
1106 send_bits(s, dist, extra); /* send the extra distance bits */
\r
1108 } /* literal or match pair ? */
\r
1110 /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
\r
1111 Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx,
\r
1112 "pendingBuf overflow");
\r
1114 } while (lx < s->last_lit);
\r
1116 send_code(s, END_BLOCK, ltree);
\r
1117 s->last_eob_len = ltree[END_BLOCK].Len;
\r
1120 /* ===========================================================================
\r
1121 * Set the data type to BINARY or TEXT, using a crude approximation:
\r
1122 * set it to Z_TEXT if all symbols are either printable characters (33 to 255)
\r
1123 * or white spaces (9 to 13, or 32); or set it to Z_BINARY otherwise.
\r
1124 * IN assertion: the fields Freq of dyn_ltree are set.
\r
1126 local void set_data_type(s)
\r
1131 for (n = 0; n < 9; n++)
\r
1132 if (s->dyn_ltree[n].Freq != 0)
\r
1135 for (n = 14; n < 32; n++)
\r
1136 if (s->dyn_ltree[n].Freq != 0)
\r
1138 s->strm->data_type = (n == 32) ? Z_TEXT : Z_BINARY;
\r
1141 /* ===========================================================================
\r
1142 * Reverse the first len bits of a code, using straightforward code (a faster
\r
1143 * method would use a table)
\r
1144 * IN assertion: 1 <= len <= 15
\r
1146 local unsigned bi_reverse(code, len)
\r
1147 unsigned code; /* the value to invert */
\r
1148 int len; /* its bit length */
\r
1150 register unsigned res = 0;
\r
1153 code >>= 1, res <<= 1;
\r
1154 } while (--len > 0);
\r
1158 /* ===========================================================================
\r
1159 * Flush the bit buffer, keeping at most 7 bits in it.
\r
1161 local void bi_flush(s)
\r
1164 if (s->bi_valid == 16) {
\r
1165 put_short(s, s->bi_buf);
\r
1168 } else if (s->bi_valid >= 8) {
\r
1169 put_byte(s, (Byte)s->bi_buf);
\r
1175 /* ===========================================================================
\r
1176 * Flush the bit buffer and align the output on a byte boundary
\r
1178 local void bi_windup(s)
\r
1181 if (s->bi_valid > 8) {
\r
1182 put_short(s, s->bi_buf);
\r
1183 } else if (s->bi_valid > 0) {
\r
1184 put_byte(s, (Byte)s->bi_buf);
\r
1189 s->bits_sent = (s->bits_sent+7) & ~7;
\r
1193 /* ===========================================================================
\r
1194 * Copy a stored block, storing first the length and its
\r
1195 * one's complement if requested.
\r
1197 local void copy_block(s, buf, len, header)
\r
1199 charf *buf; /* the input data */
\r
1200 unsigned len; /* its length */
\r
1201 int header; /* true if block header must be written */
\r
1203 bi_windup(s); /* align on byte boundary */
\r
1204 s->last_eob_len = 8; /* enough lookahead for inflate */
\r
1207 put_short(s, (ush)len);
\r
1208 put_short(s, (ush)~len);
\r
1210 s->bits_sent += 2*16;
\r
1214 s->bits_sent += (ulg)len<<3;
\r
1217 put_byte(s, *buf++);
\r