Fossil SCM

fossil-scm / compat / zlib / trees.c
Source Blame History 1119 lines
7ef7284… drh 1 /* trees.c -- output deflated data using Huffman coding
6ea30fb… florian 2 * Copyright (C) 1995-2026 Jean-loup Gailly
7ef7284… drh 3 * detect_data_type() function provided freely by Cosmin Truta, 2006
7ef7284… drh 4 * For conditions of distribution and use, see copyright notice in zlib.h
7ef7284… drh 5 */
7ef7284… drh 6
7ef7284… drh 7 /*
7ef7284… drh 8 * ALGORITHM
7ef7284… drh 9 *
7ef7284… drh 10 * The "deflation" process uses several Huffman trees. The more
7ef7284… drh 11 * common source values are represented by shorter bit sequences.
7ef7284… drh 12 *
7ef7284… drh 13 * Each code tree is stored in a compressed form which is itself
7ef7284… drh 14 * a Huffman encoding of the lengths of all the code strings (in
7ef7284… drh 15 * ascending order by source values). The actual code strings are
7ef7284… drh 16 * reconstructed from the lengths in the inflate process, as described
7ef7284… drh 17 * in the deflate specification.
7ef7284… drh 18 *
7ef7284… drh 19 * REFERENCES
7ef7284… drh 20 *
7ef7284… drh 21 * Deutsch, L.P.,"'Deflate' Compressed Data Format Specification".
7ef7284… drh 22 * Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc
7ef7284… drh 23 *
7ef7284… drh 24 * Storer, James A.
7ef7284… drh 25 * Data Compression: Methods and Theory, pp. 49-50.
7ef7284… drh 26 * Computer Science Press, 1988. ISBN 0-7167-8156-5.
7ef7284… drh 27 *
7ef7284… drh 28 * Sedgewick, R.
7ef7284… drh 29 * Algorithms, p290.
7ef7284… drh 30 * Addison-Wesley, 1983. ISBN 0-201-06672-6.
7ef7284… drh 31 */
7ef7284… drh 32
7ef7284… drh 33 /* @(#) $Id$ */
7ef7284… drh 34
7ef7284… drh 35 /* #define GEN_TREES_H */
7ef7284… drh 36
7ef7284… drh 37 #include "deflate.h"
7ef7284… drh 38
e38d5e1… jan.nijtmans 39 #ifdef ZLIB_DEBUG
7ef7284… drh 40 # include <ctype.h>
7ef7284… drh 41 #endif
7ef7284… drh 42
7ef7284… drh 43 /* ===========================================================================
7ef7284… drh 44 * Constants
7ef7284… drh 45 */
7ef7284… drh 46
7ef7284… drh 47 #define MAX_BL_BITS 7
7ef7284… drh 48 /* Bit length codes must not exceed MAX_BL_BITS bits */
7ef7284… drh 49
7ef7284… drh 50 #define END_BLOCK 256
7ef7284… drh 51 /* end of block literal code */
7ef7284… drh 52
7ef7284… drh 53 #define REP_3_6 16
7ef7284… drh 54 /* repeat previous bit length 3-6 times (2 bits of repeat count) */
7ef7284… drh 55
7ef7284… drh 56 #define REPZ_3_10 17
7ef7284… drh 57 /* repeat a zero length 3-10 times (3 bits of repeat count) */
7ef7284… drh 58
7ef7284… drh 59 #define REPZ_11_138 18
7ef7284… drh 60 /* repeat a zero length 11-138 times (7 bits of repeat count) */
7ef7284… drh 61
7ef7284… drh 62 local const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */
7ef7284… drh 63 = {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};
7ef7284… drh 64
7ef7284… drh 65 local const int extra_dbits[D_CODES] /* extra bits for each distance code */
7ef7284… drh 66 = {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};
7ef7284… drh 67
7ef7284… drh 68 local const int extra_blbits[BL_CODES]/* extra bits for each bit length code */
7ef7284… drh 69 = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};
7ef7284… drh 70
7ef7284… drh 71 local const uch bl_order[BL_CODES]
7ef7284… drh 72 = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};
7ef7284… drh 73 /* The lengths of the bit length codes are sent in order of decreasing
7ef7284… drh 74 * probability, to avoid transmitting the lengths for unused bit length codes.
7ef7284… drh 75 */
7ef7284… drh 76
7ef7284… drh 77 /* ===========================================================================
7ef7284… drh 78 * Local data. These are initialized only once.
7ef7284… drh 79 */
7ef7284… drh 80
7ef7284… drh 81 #define DIST_CODE_LEN 512 /* see definition of array dist_code below */
7ef7284… drh 82
7ef7284… drh 83 #if defined(GEN_TREES_H) || !defined(STDC)
7ef7284… drh 84 /* non ANSI compilers may not accept trees.h */
7ef7284… drh 85
7ef7284… drh 86 local ct_data static_ltree[L_CODES+2];
7ef7284… drh 87 /* The static literal tree. Since the bit lengths are imposed, there is no
7ef7284… drh 88 * need for the L_CODES extra codes used during heap construction. However
7ef7284… drh 89 * The codes 286 and 287 are needed to build a canonical tree (see _tr_init
7ef7284… drh 90 * below).
7ef7284… drh 91 */
7ef7284… drh 92
7ef7284… drh 93 local ct_data static_dtree[D_CODES];
7ef7284… drh 94 /* The static distance tree. (Actually a trivial tree since all codes use
7ef7284… drh 95 * 5 bits.)
7ef7284… drh 96 */
7ef7284… drh 97
7ef7284… drh 98 uch _dist_code[DIST_CODE_LEN];
7ef7284… drh 99 /* Distance codes. The first 256 values correspond to the distances
7ef7284… drh 100 * 3 .. 258, the last 256 values correspond to the top 8 bits of
7ef7284… drh 101 * the 15 bit distances.
7ef7284… drh 102 */
7ef7284… drh 103
7ef7284… drh 104 uch _length_code[MAX_MATCH-MIN_MATCH+1];
7ef7284… drh 105 /* length code for each normalized match length (0 == MIN_MATCH) */
7ef7284… drh 106
7ef7284… drh 107 local int base_length[LENGTH_CODES];
7ef7284… drh 108 /* First normalized length for each code (0 = MIN_MATCH) */
7ef7284… drh 109
7ef7284… drh 110 local int base_dist[D_CODES];
7ef7284… drh 111 /* First normalized distance for each code (0 = distance of 1) */
7ef7284… drh 112
7ef7284… drh 113 #else
7ef7284… drh 114 # include "trees.h"
6ea30fb… florian 115 #endif /* defined(GEN_TREES_H) || !defined(STDC) */
7ef7284… drh 116
7ef7284… drh 117 struct static_tree_desc_s {
7ef7284… drh 118 const ct_data *static_tree; /* static tree or NULL */
7ef7284… drh 119 const intf *extra_bits; /* extra bits for each code or NULL */
7ef7284… drh 120 int extra_base; /* base index for extra_bits */
7ef7284… drh 121 int elems; /* max number of elements in the tree */
7ef7284… drh 122 int max_length; /* max bit length for the codes */
7ef7284… drh 123 };
7ef7284… drh 124
f1f1d6c… drh 125 #ifdef NO_INIT_GLOBAL_POINTERS
f1f1d6c… drh 126 # define TCONST
f1f1d6c… drh 127 #else
f1f1d6c… drh 128 # define TCONST const
f1f1d6c… drh 129 #endif
f1f1d6c… drh 130
f1f1d6c… drh 131 local TCONST static_tree_desc static_l_desc =
7ef7284… drh 132 {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};
7ef7284… drh 133
f1f1d6c… drh 134 local TCONST static_tree_desc static_d_desc =
7ef7284… drh 135 {static_dtree, extra_dbits, 0, D_CODES, MAX_BITS};
7ef7284… drh 136
f1f1d6c… drh 137 local TCONST static_tree_desc static_bl_desc =
7ef7284… drh 138 {(const ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS};
7ef7284… drh 139
7ef7284… drh 140 /* ===========================================================================
f1f1d6c… drh 141 * Output a short LSB first on the stream.
f1f1d6c… drh 142 * IN assertion: there is enough room in pendingBuf.
f1f1d6c… drh 143 */
f1f1d6c… drh 144 #define put_short(s, w) { \
f1f1d6c… drh 145 put_byte(s, (uch)((w) & 0xff)); \
f1f1d6c… drh 146 put_byte(s, (uch)((ush)(w) >> 8)); \
f1f1d6c… drh 147 }
f1f1d6c… drh 148
f1f1d6c… drh 149 /* ===========================================================================
f1f1d6c… drh 150 * Reverse the first len bits of a code, using straightforward code (a faster
f1f1d6c… drh 151 * method would use a table)
f1f1d6c… drh 152 * IN assertion: 1 <= len <= 15
f1f1d6c… drh 153 */
f1f1d6c… drh 154 local unsigned bi_reverse(unsigned code, int len) {
6ea30fb… florian 155 unsigned res = 0;
f1f1d6c… drh 156 do {
f1f1d6c… drh 157 res |= code & 1;
f1f1d6c… drh 158 code >>= 1, res <<= 1;
f1f1d6c… drh 159 } while (--len > 0);
f1f1d6c… drh 160 return res >> 1;
f1f1d6c… drh 161 }
f1f1d6c… drh 162
f1f1d6c… drh 163 /* ===========================================================================
f1f1d6c… drh 164 * Flush the bit buffer, keeping at most 7 bits in it.
f1f1d6c… drh 165 */
f1f1d6c… drh 166 local void bi_flush(deflate_state *s) {
f1f1d6c… drh 167 if (s->bi_valid == 16) {
f1f1d6c… drh 168 put_short(s, s->bi_buf);
f1f1d6c… drh 169 s->bi_buf = 0;
f1f1d6c… drh 170 s->bi_valid = 0;
f1f1d6c… drh 171 } else if (s->bi_valid >= 8) {
f1f1d6c… drh 172 put_byte(s, (Byte)s->bi_buf);
f1f1d6c… drh 173 s->bi_buf >>= 8;
f1f1d6c… drh 174 s->bi_valid -= 8;
f1f1d6c… drh 175 }
f1f1d6c… drh 176 }
f1f1d6c… drh 177
f1f1d6c… drh 178 /* ===========================================================================
f1f1d6c… drh 179 * Flush the bit buffer and align the output on a byte boundary
f1f1d6c… drh 180 */
f1f1d6c… drh 181 local void bi_windup(deflate_state *s) {
f1f1d6c… drh 182 if (s->bi_valid > 8) {
f1f1d6c… drh 183 put_short(s, s->bi_buf);
f1f1d6c… drh 184 } else if (s->bi_valid > 0) {
f1f1d6c… drh 185 put_byte(s, (Byte)s->bi_buf);
f1f1d6c… drh 186 }
6ea30fb… florian 187 s->bi_used = ((s->bi_valid - 1) & 7) + 1;
f1f1d6c… drh 188 s->bi_buf = 0;
f1f1d6c… drh 189 s->bi_valid = 0;
f1f1d6c… drh 190 #ifdef ZLIB_DEBUG
6ea30fb… florian 191 s->bits_sent = (s->bits_sent + 7) & ~(ulg)7;
f1f1d6c… drh 192 #endif
f1f1d6c… drh 193 }
f1f1d6c… drh 194
f1f1d6c… drh 195 /* ===========================================================================
f1f1d6c… drh 196 * Generate the codes for a given tree and bit counts (which need not be
f1f1d6c… drh 197 * optimal).
f1f1d6c… drh 198 * IN assertion: the array bl_count contains the bit length statistics for
f1f1d6c… drh 199 * the given tree and the field len is set for all tree elements.
f1f1d6c… drh 200 * OUT assertion: the field code is set for all tree elements of non
f1f1d6c… drh 201 * zero code length.
e38d5e1… jan.nijtmans 202 */
f1f1d6c… drh 203 local void gen_codes(ct_data *tree, int max_code, ushf *bl_count) {
f1f1d6c… drh 204 ush next_code[MAX_BITS+1]; /* next code value for each bit length */
f1f1d6c… drh 205 unsigned code = 0; /* running code value */
f1f1d6c… drh 206 int bits; /* bit index */
f1f1d6c… drh 207 int n; /* code index */
f1f1d6c… drh 208
f1f1d6c… drh 209 /* The distribution counts are first used to generate the code values
f1f1d6c… drh 210 * without bit reversal.
f1f1d6c… drh 211 */
f1f1d6c… drh 212 for (bits = 1; bits <= MAX_BITS; bits++) {
f1f1d6c… drh 213 code = (code + bl_count[bits - 1]) << 1;
f1f1d6c… drh 214 next_code[bits] = (ush)code;
f1f1d6c… drh 215 }
f1f1d6c… drh 216 /* Check that the bit counts in bl_count are consistent. The last code
f1f1d6c… drh 217 * must be all ones.
f1f1d6c… drh 218 */
f1f1d6c… drh 219 Assert (code + bl_count[MAX_BITS] - 1 == (1 << MAX_BITS) - 1,
f1f1d6c… drh 220 "inconsistent bit counts");
f1f1d6c… drh 221 Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
f1f1d6c… drh 222
f1f1d6c… drh 223 for (n = 0; n <= max_code; n++) {
f1f1d6c… drh 224 int len = tree[n].Len;
f1f1d6c… drh 225 if (len == 0) continue;
f1f1d6c… drh 226 /* Now reverse the bits */
f1f1d6c… drh 227 tree[n].Code = (ush)bi_reverse(next_code[len]++, len);
f1f1d6c… drh 228
f1f1d6c… drh 229 Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
f1f1d6c… drh 230 n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len] - 1));
f1f1d6c… drh 231 }
f1f1d6c… drh 232 }
e38d5e1… jan.nijtmans 233
e38d5e1… jan.nijtmans 234 #ifdef GEN_TREES_H
f1f1d6c… drh 235 local void gen_trees_header(void);
e38d5e1… jan.nijtmans 236 #endif
e38d5e1… jan.nijtmans 237
e38d5e1… jan.nijtmans 238 #ifndef ZLIB_DEBUG
e38d5e1… jan.nijtmans 239 # define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
e38d5e1… jan.nijtmans 240 /* Send a code of the given tree. c and tree must not have side effects */
e38d5e1… jan.nijtmans 241
e38d5e1… jan.nijtmans 242 #else /* !ZLIB_DEBUG */
e38d5e1… jan.nijtmans 243 # define send_code(s, c, tree) \
e38d5e1… jan.nijtmans 244 { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
e38d5e1… jan.nijtmans 245 send_bits(s, tree[c].Code, tree[c].Len); }
e38d5e1… jan.nijtmans 246 #endif
e38d5e1… jan.nijtmans 247
e38d5e1… jan.nijtmans 248 /* ===========================================================================
7ef7284… drh 249 * Send a value on a given number of bits.
7ef7284… drh 250 * IN assertion: length <= 16 and value fits in length bits.
7ef7284… drh 251 */
e38d5e1… jan.nijtmans 252 #ifdef ZLIB_DEBUG
f1f1d6c… drh 253 local void send_bits(deflate_state *s, int value, int length) {
7ef7284… drh 254 Tracevv((stderr," l %2d v %4x ", length, value));
7ef7284… drh 255 Assert(length > 0 && length <= 15, "invalid length");
7ef7284… drh 256 s->bits_sent += (ulg)length;
7ef7284… drh 257
7ef7284… drh 258 /* If not enough room in bi_buf, use (valid) bits from bi_buf and
a9e589c… florian 259 * (16 - bi_valid) bits from value, leaving (width - (16 - bi_valid))
7ef7284… drh 260 * unused bits in value.
7ef7284… drh 261 */
7ef7284… drh 262 if (s->bi_valid > (int)Buf_size - length) {
7ef7284… drh 263 s->bi_buf |= (ush)value << s->bi_valid;
7ef7284… drh 264 put_short(s, s->bi_buf);
7ef7284… drh 265 s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);
7ef7284… drh 266 s->bi_valid += length - Buf_size;
7ef7284… drh 267 } else {
7ef7284… drh 268 s->bi_buf |= (ush)value << s->bi_valid;
7ef7284… drh 269 s->bi_valid += length;
7ef7284… drh 270 }
7ef7284… drh 271 }
e38d5e1… jan.nijtmans 272 #else /* !ZLIB_DEBUG */
7ef7284… drh 273
7ef7284… drh 274 #define send_bits(s, value, length) \
7ef7284… drh 275 { int len = length;\
7ef7284… drh 276 if (s->bi_valid > (int)Buf_size - len) {\
e38d5e1… jan.nijtmans 277 int val = (int)value;\
7ef7284… drh 278 s->bi_buf |= (ush)val << s->bi_valid;\
7ef7284… drh 279 put_short(s, s->bi_buf);\
7ef7284… drh 280 s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
7ef7284… drh 281 s->bi_valid += len - Buf_size;\
7ef7284… drh 282 } else {\
7ef7284… drh 283 s->bi_buf |= (ush)(value) << s->bi_valid;\
7ef7284… drh 284 s->bi_valid += len;\
7ef7284… drh 285 }\
7ef7284… drh 286 }
e38d5e1… jan.nijtmans 287 #endif /* ZLIB_DEBUG */
7ef7284… drh 288
7ef7284… drh 289
7ef7284… drh 290 /* the arguments must not have side effects */
7ef7284… drh 291
7ef7284… drh 292 /* ===========================================================================
7ef7284… drh 293 * Initialize the various 'constant' tables.
7ef7284… drh 294 */
f1f1d6c… drh 295 local void tr_static_init(void) {
7ef7284… drh 296 #if defined(GEN_TREES_H) || !defined(STDC)
7ef7284… drh 297 static int static_init_done = 0;
7ef7284… drh 298 int n; /* iterates over tree elements */
7ef7284… drh 299 int bits; /* bit counter */
7ef7284… drh 300 int length; /* length value */
7ef7284… drh 301 int code; /* code value */
7ef7284… drh 302 int dist; /* distance index */
7ef7284… drh 303 ush bl_count[MAX_BITS+1];
7ef7284… drh 304 /* number of codes at each bit length for an optimal tree */
7ef7284… drh 305
7ef7284… drh 306 if (static_init_done) return;
7ef7284… drh 307
7ef7284… drh 308 /* For some embedded targets, global variables are not initialized: */
7ef7284… drh 309 #ifdef NO_INIT_GLOBAL_POINTERS
7ef7284… drh 310 static_l_desc.static_tree = static_ltree;
7ef7284… drh 311 static_l_desc.extra_bits = extra_lbits;
7ef7284… drh 312 static_d_desc.static_tree = static_dtree;
7ef7284… drh 313 static_d_desc.extra_bits = extra_dbits;
7ef7284… drh 314 static_bl_desc.extra_bits = extra_blbits;
7ef7284… drh 315 #endif
7ef7284… drh 316
7ef7284… drh 317 /* Initialize the mapping length (0..255) -> length code (0..28) */
7ef7284… drh 318 length = 0;
7ef7284… drh 319 for (code = 0; code < LENGTH_CODES-1; code++) {
7ef7284… drh 320 base_length[code] = length;
a9e589c… florian 321 for (n = 0; n < (1 << extra_lbits[code]); n++) {
7ef7284… drh 322 _length_code[length++] = (uch)code;
7ef7284… drh 323 }
7ef7284… drh 324 }
7ef7284… drh 325 Assert (length == 256, "tr_static_init: length != 256");
7ef7284… drh 326 /* Note that the length 255 (match length 258) can be represented
7ef7284… drh 327 * in two different ways: code 284 + 5 bits or code 285, so we
7ef7284… drh 328 * overwrite length_code[255] to use the best encoding:
7ef7284… drh 329 */
a9e589c… florian 330 _length_code[length - 1] = (uch)code;
7ef7284… drh 331
7ef7284… drh 332 /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
7ef7284… drh 333 dist = 0;
7ef7284… drh 334 for (code = 0 ; code < 16; code++) {
7ef7284… drh 335 base_dist[code] = dist;
a9e589c… florian 336 for (n = 0; n < (1 << extra_dbits[code]); n++) {
7ef7284… drh 337 _dist_code[dist++] = (uch)code;
7ef7284… drh 338 }
7ef7284… drh 339 }
7ef7284… drh 340 Assert (dist == 256, "tr_static_init: dist != 256");
7ef7284… drh 341 dist >>= 7; /* from now on, all distances are divided by 128 */
7ef7284… drh 342 for ( ; code < D_CODES; code++) {
7ef7284… drh 343 base_dist[code] = dist << 7;
a9e589c… florian 344 for (n = 0; n < (1 << (extra_dbits[code] - 7)); n++) {
7ef7284… drh 345 _dist_code[256 + dist++] = (uch)code;
7ef7284… drh 346 }
7ef7284… drh 347 }
a9e589c… florian 348 Assert (dist == 256, "tr_static_init: 256 + dist != 512");
7ef7284… drh 349
7ef7284… drh 350 /* Construct the codes of the static literal tree */
7ef7284… drh 351 for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
7ef7284… drh 352 n = 0;
7ef7284… drh 353 while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
7ef7284… drh 354 while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
7ef7284… drh 355 while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
7ef7284… drh 356 while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
7ef7284… drh 357 /* Codes 286 and 287 do not exist, but we must include them in the
7ef7284… drh 358 * tree construction to get a canonical Huffman tree (longest code
7ef7284… drh 359 * all ones)
7ef7284… drh 360 */
7ef7284… drh 361 gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);
7ef7284… drh 362
7ef7284… drh 363 /* The static distance tree is trivial: */
7ef7284… drh 364 for (n = 0; n < D_CODES; n++) {
7ef7284… drh 365 static_dtree[n].Len = 5;
7ef7284… drh 366 static_dtree[n].Code = bi_reverse((unsigned)n, 5);
7ef7284… drh 367 }
7ef7284… drh 368 static_init_done = 1;
7ef7284… drh 369
7ef7284… drh 370 # ifdef GEN_TREES_H
7ef7284… drh 371 gen_trees_header();
7ef7284… drh 372 # endif
7ef7284… drh 373 #endif /* defined(GEN_TREES_H) || !defined(STDC) */
7ef7284… drh 374 }
7ef7284… drh 375
7ef7284… drh 376 /* ===========================================================================
a9e589c… florian 377 * Generate the file trees.h describing the static trees.
7ef7284… drh 378 */
7ef7284… drh 379 #ifdef GEN_TREES_H
e38d5e1… jan.nijtmans 380 # ifndef ZLIB_DEBUG
7ef7284… drh 381 # include <stdio.h>
7ef7284… drh 382 # endif
7ef7284… drh 383
7ef7284… drh 384 # define SEPARATOR(i, last, width) \
7ef7284… drh 385 ((i) == (last)? "\n};\n\n" : \
a9e589c… florian 386 ((i) % (width) == (width) - 1 ? ",\n" : ", "))
7ef7284… drh 387
f1f1d6c… drh 388 void gen_trees_header(void) {
7ef7284… drh 389 FILE *header = fopen("trees.h", "w");
7ef7284… drh 390 int i;
7ef7284… drh 391
7ef7284… drh 392 Assert (header != NULL, "Can't open trees.h");
7ef7284… drh 393 fprintf(header,
7ef7284… drh 394 "/* header created automatically with -DGEN_TREES_H */\n\n");
7ef7284… drh 395
7ef7284… drh 396 fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n");
7ef7284… drh 397 for (i = 0; i < L_CODES+2; i++) {
7ef7284… drh 398 fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code,
7ef7284… drh 399 static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5));
7ef7284… drh 400 }
7ef7284… drh 401
7ef7284… drh 402 fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n");
7ef7284… drh 403 for (i = 0; i < D_CODES; i++) {
7ef7284… drh 404 fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code,
7ef7284… drh 405 static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5));
7ef7284… drh 406 }
7ef7284… drh 407
7ef7284… drh 408 fprintf(header, "const uch ZLIB_INTERNAL _dist_code[DIST_CODE_LEN] = {\n");
7ef7284… drh 409 for (i = 0; i < DIST_CODE_LEN; i++) {
7ef7284… drh 410 fprintf(header, "%2u%s", _dist_code[i],
7ef7284… drh 411 SEPARATOR(i, DIST_CODE_LEN-1, 20));
7ef7284… drh 412 }
7ef7284… drh 413
7ef7284… drh 414 fprintf(header,
7ef7284… drh 415 "const uch ZLIB_INTERNAL _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");
7ef7284… drh 416 for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) {
7ef7284… drh 417 fprintf(header, "%2u%s", _length_code[i],
7ef7284… drh 418 SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));
7ef7284… drh 419 }
7ef7284… drh 420
7ef7284… drh 421 fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");
7ef7284… drh 422 for (i = 0; i < LENGTH_CODES; i++) {
7ef7284… drh 423 fprintf(header, "%1u%s", base_length[i],
7ef7284… drh 424 SEPARATOR(i, LENGTH_CODES-1, 20));
7ef7284… drh 425 }
7ef7284… drh 426
7ef7284… drh 427 fprintf(header, "local const int base_dist[D_CODES] = {\n");
7ef7284… drh 428 for (i = 0; i < D_CODES; i++) {
7ef7284… drh 429 fprintf(header, "%5u%s", base_dist[i],
7ef7284… drh 430 SEPARATOR(i, D_CODES-1, 10));
7ef7284… drh 431 }
7ef7284… drh 432
7ef7284… drh 433 fclose(header);
7ef7284… drh 434 }
7ef7284… drh 435 #endif /* GEN_TREES_H */
7ef7284… drh 436
7ef7284… drh 437 /* ===========================================================================
f1f1d6c… drh 438 * Initialize a new block.
f1f1d6c… drh 439 */
f1f1d6c… drh 440 local void init_block(deflate_state *s) {
f1f1d6c… drh 441 int n; /* iterates over tree elements */
f1f1d6c… drh 442
f1f1d6c… drh 443 /* Initialize the trees. */
f1f1d6c… drh 444 for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0;
f1f1d6c… drh 445 for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0;
f1f1d6c… drh 446 for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;
f1f1d6c… drh 447
f1f1d6c… drh 448 s->dyn_ltree[END_BLOCK].Freq = 1;
f1f1d6c… drh 449 s->opt_len = s->static_len = 0L;
f1f1d6c… drh 450 s->sym_next = s->matches = 0;
f1f1d6c… drh 451 }
f1f1d6c… drh 452
f1f1d6c… drh 453 /* ===========================================================================
7ef7284… drh 454 * Initialize the tree data structures for a new zlib stream.
7ef7284… drh 455 */
f1f1d6c… drh 456 void ZLIB_INTERNAL _tr_init(deflate_state *s) {
7ef7284… drh 457 tr_static_init();
7ef7284… drh 458
7ef7284… drh 459 s->l_desc.dyn_tree = s->dyn_ltree;
7ef7284… drh 460 s->l_desc.stat_desc = &static_l_desc;
7ef7284… drh 461
7ef7284… drh 462 s->d_desc.dyn_tree = s->dyn_dtree;
7ef7284… drh 463 s->d_desc.stat_desc = &static_d_desc;
7ef7284… drh 464
7ef7284… drh 465 s->bl_desc.dyn_tree = s->bl_tree;
7ef7284… drh 466 s->bl_desc.stat_desc = &static_bl_desc;
7ef7284… drh 467
7ef7284… drh 468 s->bi_buf = 0;
7ef7284… drh 469 s->bi_valid = 0;
6ea30fb… florian 470 s->bi_used = 0;
e38d5e1… jan.nijtmans 471 #ifdef ZLIB_DEBUG
7ef7284… drh 472 s->compressed_len = 0L;
7ef7284… drh 473 s->bits_sent = 0L;
7ef7284… drh 474 #endif
7ef7284… drh 475
7ef7284… drh 476 /* Initialize the first block of the first file: */
7ef7284… drh 477 init_block(s);
7ef7284… drh 478 }
7ef7284… drh 479
7ef7284… drh 480 #define SMALLEST 1
7ef7284… drh 481 /* Index within the heap array of least frequent node in the Huffman tree */
7ef7284… drh 482
7ef7284… drh 483
7ef7284… drh 484 /* ===========================================================================
7ef7284… drh 485 * Remove the smallest element from the heap and recreate the heap with
7ef7284… drh 486 * one less element. Updates heap and heap_len.
7ef7284… drh 487 */
7ef7284… drh 488 #define pqremove(s, tree, top) \
7ef7284… drh 489 {\
7ef7284… drh 490 top = s->heap[SMALLEST]; \
7ef7284… drh 491 s->heap[SMALLEST] = s->heap[s->heap_len--]; \
7ef7284… drh 492 pqdownheap(s, tree, SMALLEST); \
7ef7284… drh 493 }
7ef7284… drh 494
7ef7284… drh 495 /* ===========================================================================
7ef7284… drh 496 * Compares to subtrees, using the tree depth as tie breaker when
7ef7284… drh 497 * the subtrees have equal frequency. This minimizes the worst case length.
7ef7284… drh 498 */
7ef7284… drh 499 #define smaller(tree, n, m, depth) \
7ef7284… drh 500 (tree[n].Freq < tree[m].Freq || \
7ef7284… drh 501 (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
7ef7284… drh 502
7ef7284… drh 503 /* ===========================================================================
7ef7284… drh 504 * Restore the heap property by moving down the tree starting at node k,
7ef7284… drh 505 * exchanging a node with the smallest of its two sons if necessary, stopping
7ef7284… drh 506 * when the heap property is re-established (each father smaller than its
7ef7284… drh 507 * two sons).
7ef7284… drh 508 */
f1f1d6c… drh 509 local void pqdownheap(deflate_state *s, ct_data *tree, int k) {
7ef7284… drh 510 int v = s->heap[k];
7ef7284… drh 511 int j = k << 1; /* left son of k */
7ef7284… drh 512 while (j <= s->heap_len) {
7ef7284… drh 513 /* Set j to the smallest of the two sons: */
7ef7284… drh 514 if (j < s->heap_len &&
a9e589c… florian 515 smaller(tree, s->heap[j + 1], s->heap[j], s->depth)) {
7ef7284… drh 516 j++;
7ef7284… drh 517 }
7ef7284… drh 518 /* Exit if v is smaller than both sons */
7ef7284… drh 519 if (smaller(tree, v, s->heap[j], s->depth)) break;
7ef7284… drh 520
7ef7284… drh 521 /* Exchange v with the smallest son */
7ef7284… drh 522 s->heap[k] = s->heap[j]; k = j;
7ef7284… drh 523
7ef7284… drh 524 /* And continue down the tree, setting j to the left son of k */
7ef7284… drh 525 j <<= 1;
7ef7284… drh 526 }
7ef7284… drh 527 s->heap[k] = v;
7ef7284… drh 528 }
7ef7284… drh 529
7ef7284… drh 530 /* ===========================================================================
7ef7284… drh 531 * Compute the optimal bit lengths for a tree and update the total bit length
7ef7284… drh 532 * for the current block.
7ef7284… drh 533 * IN assertion: the fields freq and dad are set, heap[heap_max] and
7ef7284… drh 534 * above are the tree nodes sorted by increasing frequency.
7ef7284… drh 535 * OUT assertions: the field len is set to the optimal bit length, the
7ef7284… drh 536 * array bl_count contains the frequencies for each bit length.
7ef7284… drh 537 * The length opt_len is updated; static_len is also updated if stree is
7ef7284… drh 538 * not null.
7ef7284… drh 539 */
f1f1d6c… drh 540 local void gen_bitlen(deflate_state *s, tree_desc *desc) {
7ef7284… drh 541 ct_data *tree = desc->dyn_tree;
7ef7284… drh 542 int max_code = desc->max_code;
7ef7284… drh 543 const ct_data *stree = desc->stat_desc->static_tree;
7ef7284… drh 544 const intf *extra = desc->stat_desc->extra_bits;
7ef7284… drh 545 int base = desc->stat_desc->extra_base;
7ef7284… drh 546 int max_length = desc->stat_desc->max_length;
7ef7284… drh 547 int h; /* heap index */
7ef7284… drh 548 int n, m; /* iterate over the tree elements */
7ef7284… drh 549 int bits; /* bit length */
7ef7284… drh 550 int xbits; /* extra bits */
7ef7284… drh 551 ush f; /* frequency */
7ef7284… drh 552 int overflow = 0; /* number of elements with bit length too large */
7ef7284… drh 553
7ef7284… drh 554 for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
7ef7284… drh 555
7ef7284… drh 556 /* In a first pass, compute the optimal bit lengths (which may
7ef7284… drh 557 * overflow in the case of the bit length tree).
7ef7284… drh 558 */
7ef7284… drh 559 tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
7ef7284… drh 560
a9e589c… florian 561 for (h = s->heap_max + 1; h < HEAP_SIZE; h++) {
7ef7284… drh 562 n = s->heap[h];
7ef7284… drh 563 bits = tree[tree[n].Dad].Len + 1;
7ef7284… drh 564 if (bits > max_length) bits = max_length, overflow++;
7ef7284… drh 565 tree[n].Len = (ush)bits;
7ef7284… drh 566 /* We overwrite tree[n].Dad which is no longer needed */
7ef7284… drh 567
7ef7284… drh 568 if (n > max_code) continue; /* not a leaf node */
7ef7284… drh 569
7ef7284… drh 570 s->bl_count[bits]++;
7ef7284… drh 571 xbits = 0;
a9e589c… florian 572 if (n >= base) xbits = extra[n - base];
7ef7284… drh 573 f = tree[n].Freq;
e38d5e1… jan.nijtmans 574 s->opt_len += (ulg)f * (unsigned)(bits + xbits);
e38d5e1… jan.nijtmans 575 if (stree) s->static_len += (ulg)f * (unsigned)(stree[n].Len + xbits);
7ef7284… drh 576 }
7ef7284… drh 577 if (overflow == 0) return;
7ef7284… drh 578
e38d5e1… jan.nijtmans 579 Tracev((stderr,"\nbit length overflow\n"));
7ef7284… drh 580 /* This happens for example on obj2 and pic of the Calgary corpus */
7ef7284… drh 581
7ef7284… drh 582 /* Find the first bit length which could increase: */
7ef7284… drh 583 do {
a9e589c… florian 584 bits = max_length - 1;
7ef7284… drh 585 while (s->bl_count[bits] == 0) bits--;
a9e589c… florian 586 s->bl_count[bits]--; /* move one leaf down the tree */
a9e589c… florian 587 s->bl_count[bits + 1] += 2; /* move one overflow item as its brother */
7ef7284… drh 588 s->bl_count[max_length]--;
7ef7284… drh 589 /* The brother of the overflow item also moves one step up,
7ef7284… drh 590 * but this does not affect bl_count[max_length]
7ef7284… drh 591 */
7ef7284… drh 592 overflow -= 2;
7ef7284… drh 593 } while (overflow > 0);
7ef7284… drh 594
7ef7284… drh 595 /* Now recompute all bit lengths, scanning in increasing frequency.
7ef7284… drh 596 * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
7ef7284… drh 597 * lengths instead of fixing only the wrong ones. This idea is taken
7ef7284… drh 598 * from 'ar' written by Haruhiko Okumura.)
7ef7284… drh 599 */
7ef7284… drh 600 for (bits = max_length; bits != 0; bits--) {
7ef7284… drh 601 n = s->bl_count[bits];
7ef7284… drh 602 while (n != 0) {
7ef7284… drh 603 m = s->heap[--h];
7ef7284… drh 604 if (m > max_code) continue;
7ef7284… drh 605 if ((unsigned) tree[m].Len != (unsigned) bits) {
e38d5e1… jan.nijtmans 606 Tracev((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
e38d5e1… jan.nijtmans 607 s->opt_len += ((ulg)bits - tree[m].Len) * tree[m].Freq;
7ef7284… drh 608 tree[m].Len = (ush)bits;
7ef7284… drh 609 }
7ef7284… drh 610 n--;
7ef7284… drh 611 }
7ef7284… drh 612 }
7ef7284… drh 613 }
7ef7284… drh 614
f1f1d6c… drh 615 #ifdef DUMP_BL_TREE
f1f1d6c… drh 616 # include <stdio.h>
f1f1d6c… drh 617 #endif
7ef7284… drh 618
7ef7284… drh 619 /* ===========================================================================
7ef7284… drh 620 * Construct one Huffman tree and assigns the code bit strings and lengths.
7ef7284… drh 621 * Update the total bit length for the current block.
7ef7284… drh 622 * IN assertion: the field freq is set for all tree elements.
7ef7284… drh 623 * OUT assertions: the fields len and code are set to the optimal bit length
7ef7284… drh 624 * and corresponding code. The length opt_len is updated; static_len is
7ef7284… drh 625 * also updated if stree is not null. The field max_code is set.
7ef7284… drh 626 */
f1f1d6c… drh 627 local void build_tree(deflate_state *s, tree_desc *desc) {
7ef7284… drh 628 ct_data *tree = desc->dyn_tree;
7ef7284… drh 629 const ct_data *stree = desc->stat_desc->static_tree;
7ef7284… drh 630 int elems = desc->stat_desc->elems;
7ef7284… drh 631 int n, m; /* iterate over heap elements */
7ef7284… drh 632 int max_code = -1; /* largest code with non zero frequency */
7ef7284… drh 633 int node; /* new node being created */
7ef7284… drh 634
7ef7284… drh 635 /* Construct the initial heap, with least frequent element in
a9e589c… florian 636 * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n + 1].
7ef7284… drh 637 * heap[0] is not used.
7ef7284… drh 638 */
7ef7284… drh 639 s->heap_len = 0, s->heap_max = HEAP_SIZE;
7ef7284… drh 640
7ef7284… drh 641 for (n = 0; n < elems; n++) {
7ef7284… drh 642 if (tree[n].Freq != 0) {
7ef7284… drh 643 s->heap[++(s->heap_len)] = max_code = n;
7ef7284… drh 644 s->depth[n] = 0;
7ef7284… drh 645 } else {
7ef7284… drh 646 tree[n].Len = 0;
7ef7284… drh 647 }
7ef7284… drh 648 }
7ef7284… drh 649
7ef7284… drh 650 /* The pkzip format requires that at least one distance code exists,
7ef7284… drh 651 * and that at least one bit should be sent even if there is only one
7ef7284… drh 652 * possible code. So to avoid special checks later on we force at least
7ef7284… drh 653 * two codes of non zero frequency.
7ef7284… drh 654 */
7ef7284… drh 655 while (s->heap_len < 2) {
7ef7284… drh 656 node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
7ef7284… drh 657 tree[node].Freq = 1;
7ef7284… drh 658 s->depth[node] = 0;
7ef7284… drh 659 s->opt_len--; if (stree) s->static_len -= stree[node].Len;
7ef7284… drh 660 /* node is 0 or 1 so it does not have extra bits */
7ef7284… drh 661 }
7ef7284… drh 662 desc->max_code = max_code;
7ef7284… drh 663
a9e589c… florian 664 /* The elements heap[heap_len/2 + 1 .. heap_len] are leaves of the tree,
7ef7284… drh 665 * establish sub-heaps of increasing lengths:
7ef7284… drh 666 */
7ef7284… drh 667 for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
7ef7284… drh 668
7ef7284… drh 669 /* Construct the Huffman tree by repeatedly combining the least two
7ef7284… drh 670 * frequent nodes.
7ef7284… drh 671 */
7ef7284… drh 672 node = elems; /* next internal node of the tree */
7ef7284… drh 673 do {
7ef7284… drh 674 pqremove(s, tree, n); /* n = node of least frequency */
7ef7284… drh 675 m = s->heap[SMALLEST]; /* m = node of next least frequency */
7ef7284… drh 676
7ef7284… drh 677 s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
7ef7284… drh 678 s->heap[--(s->heap_max)] = m;
7ef7284… drh 679
7ef7284… drh 680 /* Create a new node father of n and m */
7ef7284… drh 681 tree[node].Freq = tree[n].Freq + tree[m].Freq;
7ef7284… drh 682 s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?
7ef7284… drh 683 s->depth[n] : s->depth[m]) + 1);
7ef7284… drh 684 tree[n].Dad = tree[m].Dad = (ush)node;
7ef7284… drh 685 #ifdef DUMP_BL_TREE
7ef7284… drh 686 if (tree == s->bl_tree) {
7ef7284… drh 687 fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
7ef7284… drh 688 node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
7ef7284… drh 689 }
7ef7284… drh 690 #endif
7ef7284… drh 691 /* and insert the new node in the heap */
7ef7284… drh 692 s->heap[SMALLEST] = node++;
7ef7284… drh 693 pqdownheap(s, tree, SMALLEST);
7ef7284… drh 694
7ef7284… drh 695 } while (s->heap_len >= 2);
7ef7284… drh 696
7ef7284… drh 697 s->heap[--(s->heap_max)] = s->heap[SMALLEST];
7ef7284… drh 698
7ef7284… drh 699 /* At this point, the fields freq and dad are set. We can now
7ef7284… drh 700 * generate the bit lengths.
7ef7284… drh 701 */
7ef7284… drh 702 gen_bitlen(s, (tree_desc *)desc);
7ef7284… drh 703
7ef7284… drh 704 /* The field len is now set, we can generate the bit codes */
7ef7284… drh 705 gen_codes ((ct_data *)tree, max_code, s->bl_count);
7ef7284… drh 706 }
7ef7284… drh 707
7ef7284… drh 708 /* ===========================================================================
7ef7284… drh 709 * Scan a literal or distance tree to determine the frequencies of the codes
7ef7284… drh 710 * in the bit length tree.
7ef7284… drh 711 */
f1f1d6c… drh 712 local void scan_tree(deflate_state *s, ct_data *tree, int max_code) {
7ef7284… drh 713 int n; /* iterates over all tree elements */
7ef7284… drh 714 int prevlen = -1; /* last emitted length */
7ef7284… drh 715 int curlen; /* length of current code */
7ef7284… drh 716 int nextlen = tree[0].Len; /* length of next code */
7ef7284… drh 717 int count = 0; /* repeat count of the current code */
7ef7284… drh 718 int max_count = 7; /* max repeat count */
7ef7284… drh 719 int min_count = 4; /* min repeat count */
7ef7284… drh 720
7ef7284… drh 721 if (nextlen == 0) max_count = 138, min_count = 3;
a9e589c… florian 722 tree[max_code + 1].Len = (ush)0xffff; /* guard */
7ef7284… drh 723
7ef7284… drh 724 for (n = 0; n <= max_code; n++) {
a9e589c… florian 725 curlen = nextlen; nextlen = tree[n + 1].Len;
7ef7284… drh 726 if (++count < max_count && curlen == nextlen) {
7ef7284… drh 727 continue;
7ef7284… drh 728 } else if (count < min_count) {
6ea30fb… florian 729 s->bl_tree[curlen].Freq += (ush)count;
7ef7284… drh 730 } else if (curlen != 0) {
7ef7284… drh 731 if (curlen != prevlen) s->bl_tree[curlen].Freq++;
7ef7284… drh 732 s->bl_tree[REP_3_6].Freq++;
7ef7284… drh 733 } else if (count <= 10) {
7ef7284… drh 734 s->bl_tree[REPZ_3_10].Freq++;
7ef7284… drh 735 } else {
7ef7284… drh 736 s->bl_tree[REPZ_11_138].Freq++;
7ef7284… drh 737 }
7ef7284… drh 738 count = 0; prevlen = curlen;
7ef7284… drh 739 if (nextlen == 0) {
7ef7284… drh 740 max_count = 138, min_count = 3;
7ef7284… drh 741 } else if (curlen == nextlen) {
7ef7284… drh 742 max_count = 6, min_count = 3;
7ef7284… drh 743 } else {
7ef7284… drh 744 max_count = 7, min_count = 4;
7ef7284… drh 745 }
7ef7284… drh 746 }
7ef7284… drh 747 }
7ef7284… drh 748
7ef7284… drh 749 /* ===========================================================================
7ef7284… drh 750 * Send a literal or distance tree in compressed form, using the codes in
7ef7284… drh 751 * bl_tree.
7ef7284… drh 752 */
f1f1d6c… drh 753 local void send_tree(deflate_state *s, ct_data *tree, int max_code) {
7ef7284… drh 754 int n; /* iterates over all tree elements */
7ef7284… drh 755 int prevlen = -1; /* last emitted length */
7ef7284… drh 756 int curlen; /* length of current code */
7ef7284… drh 757 int nextlen = tree[0].Len; /* length of next code */
7ef7284… drh 758 int count = 0; /* repeat count of the current code */
7ef7284… drh 759 int max_count = 7; /* max repeat count */
7ef7284… drh 760 int min_count = 4; /* min repeat count */
7ef7284… drh 761
a9e589c… florian 762 /* tree[max_code + 1].Len = -1; */ /* guard already set */
7ef7284… drh 763 if (nextlen == 0) max_count = 138, min_count = 3;
7ef7284… drh 764
7ef7284… drh 765 for (n = 0; n <= max_code; n++) {
a9e589c… florian 766 curlen = nextlen; nextlen = tree[n + 1].Len;
7ef7284… drh 767 if (++count < max_count && curlen == nextlen) {
7ef7284… drh 768 continue;
7ef7284… drh 769 } else if (count < min_count) {
7ef7284… drh 770 do { send_code(s, curlen, s->bl_tree); } while (--count != 0);
7ef7284… drh 771
7ef7284… drh 772 } else if (curlen != 0) {
7ef7284… drh 773 if (curlen != prevlen) {
7ef7284… drh 774 send_code(s, curlen, s->bl_tree); count--;
7ef7284… drh 775 }
7ef7284… drh 776 Assert(count >= 3 && count <= 6, " 3_6?");
a9e589c… florian 777 send_code(s, REP_3_6, s->bl_tree); send_bits(s, count - 3, 2);
7ef7284… drh 778
7ef7284… drh 779 } else if (count <= 10) {
a9e589c… florian 780 send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count - 3, 3);
7ef7284… drh 781
7ef7284… drh 782 } else {
a9e589c… florian 783 send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count - 11, 7);
7ef7284… drh 784 }
7ef7284… drh 785 count = 0; prevlen = curlen;
7ef7284… drh 786 if (nextlen == 0) {
7ef7284… drh 787 max_count = 138, min_count = 3;
7ef7284… drh 788 } else if (curlen == nextlen) {
7ef7284… drh 789 max_count = 6, min_count = 3;
7ef7284… drh 790 } else {
7ef7284… drh 791 max_count = 7, min_count = 4;
7ef7284… drh 792 }
7ef7284… drh 793 }
7ef7284… drh 794 }
7ef7284… drh 795
7ef7284… drh 796 /* ===========================================================================
7ef7284… drh 797 * Construct the Huffman tree for the bit lengths and return the index in
7ef7284… drh 798 * bl_order of the last bit length code to send.
7ef7284… drh 799 */
f1f1d6c… drh 800 local int build_bl_tree(deflate_state *s) {
7ef7284… drh 801 int max_blindex; /* index of last bit length code of non zero freq */
7ef7284… drh 802
7ef7284… drh 803 /* Determine the bit length frequencies for literal and distance trees */
7ef7284… drh 804 scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
7ef7284… drh 805 scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);
7ef7284… drh 806
7ef7284… drh 807 /* Build the bit length tree: */
7ef7284… drh 808 build_tree(s, (tree_desc *)(&(s->bl_desc)));
a9e589c… florian 809 /* opt_len now includes the length of the tree representations, except the
a9e589c… florian 810 * lengths of the bit lengths codes and the 5 + 5 + 4 bits for the counts.
7ef7284… drh 811 */
7ef7284… drh 812
7ef7284… drh 813 /* Determine the number of bit length codes to send. The pkzip format
7ef7284… drh 814 * requires that at least 4 bit length codes be sent. (appnote.txt says
7ef7284… drh 815 * 3 but the actual value used is 4.)
7ef7284… drh 816 */
7ef7284… drh 817 for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
7ef7284… drh 818 if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
7ef7284… drh 819 }
7ef7284… drh 820 /* Update opt_len to include the bit length tree and counts */
a9e589c… florian 821 s->opt_len += 3*((ulg)max_blindex + 1) + 5 + 5 + 4;
6ea30fb… florian 822 Tracev((stderr, "\ndyn trees: dyn %lu, stat %lu",
7ef7284… drh 823 s->opt_len, s->static_len));
7ef7284… drh 824
7ef7284… drh 825 return max_blindex;
7ef7284… drh 826 }
7ef7284… drh 827
7ef7284… drh 828 /* ===========================================================================
7ef7284… drh 829 * Send the header for a block using dynamic Huffman trees: the counts, the
7ef7284… drh 830 * lengths of the bit length codes, the literal tree and the distance tree.
7ef7284… drh 831 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
7ef7284… drh 832 */
f1f1d6c… drh 833 local void send_all_trees(deflate_state *s, int lcodes, int dcodes,
f1f1d6c… drh 834 int blcodes) {
7ef7284… drh 835 int rank; /* index in bl_order */
7ef7284… drh 836
7ef7284… drh 837 Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
7ef7284… drh 838 Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
7ef7284… drh 839 "too many codes");
7ef7284… drh 840 Tracev((stderr, "\nbl counts: "));
a9e589c… florian 841 send_bits(s, lcodes - 257, 5); /* not +255 as stated in appnote.txt */
a9e589c… florian 842 send_bits(s, dcodes - 1, 5);
a9e589c… florian 843 send_bits(s, blcodes - 4, 4); /* not -3 as stated in appnote.txt */
7ef7284… drh 844 for (rank = 0; rank < blcodes; rank++) {
7ef7284… drh 845 Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
7ef7284… drh 846 send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
7ef7284… drh 847 }
6ea30fb… florian 848 Tracev((stderr, "\nbl tree: sent %lu", s->bits_sent));
7ef7284… drh 849
a9e589c… florian 850 send_tree(s, (ct_data *)s->dyn_ltree, lcodes - 1); /* literal tree */
6ea30fb… florian 851 Tracev((stderr, "\nlit tree: sent %lu", s->bits_sent));
7ef7284… drh 852
a9e589c… florian 853 send_tree(s, (ct_data *)s->dyn_dtree, dcodes - 1); /* distance tree */
6ea30fb… florian 854 Tracev((stderr, "\ndist tree: sent %lu", s->bits_sent));
7ef7284… drh 855 }
7ef7284… drh 856
7ef7284… drh 857 /* ===========================================================================
7ef7284… drh 858 * Send a stored block
7ef7284… drh 859 */
f1f1d6c… drh 860 void ZLIB_INTERNAL _tr_stored_block(deflate_state *s, charf *buf,
f1f1d6c… drh 861 ulg stored_len, int last) {
a9e589c… florian 862 send_bits(s, (STORED_BLOCK<<1) + last, 3); /* send block type */
e38d5e1… jan.nijtmans 863 bi_windup(s); /* align on byte boundary */
e38d5e1… jan.nijtmans 864 put_short(s, (ush)stored_len);
e38d5e1… jan.nijtmans 865 put_short(s, (ush)~stored_len);
adb9e8e… drh 866 if (stored_len)
adb9e8e… drh 867 zmemcpy(s->pending_buf + s->pending, (Bytef *)buf, stored_len);
e38d5e1… jan.nijtmans 868 s->pending += stored_len;
e38d5e1… jan.nijtmans 869 #ifdef ZLIB_DEBUG
7ef7284… drh 870 s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
7ef7284… drh 871 s->compressed_len += (stored_len + 4) << 3;
e38d5e1… jan.nijtmans 872 s->bits_sent += 2*16;
a9e589c… florian 873 s->bits_sent += stored_len << 3;
7ef7284… drh 874 #endif
7ef7284… drh 875 }
7ef7284… drh 876
7ef7284… drh 877 /* ===========================================================================
7ef7284… drh 878 * Flush the bits in the bit buffer to pending output (leaves at most 7 bits)
7ef7284… drh 879 */
f1f1d6c… drh 880 void ZLIB_INTERNAL _tr_flush_bits(deflate_state *s) {
7ef7284… drh 881 bi_flush(s);
7ef7284… drh 882 }
7ef7284… drh 883
7ef7284… drh 884 /* ===========================================================================
7ef7284… drh 885 * Send one empty static block to give enough lookahead for inflate.
7ef7284… drh 886 * This takes 10 bits, of which 7 may remain in the bit buffer.
7ef7284… drh 887 */
f1f1d6c… drh 888 void ZLIB_INTERNAL _tr_align(deflate_state *s) {
7ef7284… drh 889 send_bits(s, STATIC_TREES<<1, 3);
7ef7284… drh 890 send_code(s, END_BLOCK, static_ltree);
e38d5e1… jan.nijtmans 891 #ifdef ZLIB_DEBUG
7ef7284… drh 892 s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
7ef7284… drh 893 #endif
7ef7284… drh 894 bi_flush(s);
7ef7284… drh 895 }
7ef7284… drh 896
7ef7284… drh 897 /* ===========================================================================
f1f1d6c… drh 898 * Send the block data compressed using the given Huffman trees
f1f1d6c… drh 899 */
f1f1d6c… drh 900 local void compress_block(deflate_state *s, const ct_data *ltree,
f1f1d6c… drh 901 const ct_data *dtree) {
f1f1d6c… drh 902 unsigned dist; /* distance of matched string */
f1f1d6c… drh 903 int lc; /* match length or unmatched char (if dist == 0) */
64ce68d… drh 904 unsigned sx = 0; /* running index in symbol buffers */
f1f1d6c… drh 905 unsigned code; /* the code to send */
f1f1d6c… drh 906 int extra; /* number of extra bits to send */
f1f1d6c… drh 907
f1f1d6c… drh 908 if (s->sym_next != 0) do {
64ce68d… drh 909 #ifdef LIT_MEM
64ce68d… drh 910 dist = s->d_buf[sx];
64ce68d… drh 911 lc = s->l_buf[sx++];
64ce68d… drh 912 #else
f1f1d6c… drh 913 dist = s->sym_buf[sx++] & 0xff;
f1f1d6c… drh 914 dist += (unsigned)(s->sym_buf[sx++] & 0xff) << 8;
f1f1d6c… drh 915 lc = s->sym_buf[sx++];
64ce68d… drh 916 #endif
f1f1d6c… drh 917 if (dist == 0) {
f1f1d6c… drh 918 send_code(s, lc, ltree); /* send a literal byte */
f1f1d6c… drh 919 Tracecv(isgraph(lc), (stderr," '%c' ", lc));
f1f1d6c… drh 920 } else {
f1f1d6c… drh 921 /* Here, lc is the match length - MIN_MATCH */
f1f1d6c… drh 922 code = _length_code[lc];
f1f1d6c… drh 923 send_code(s, code + LITERALS + 1, ltree); /* send length code */
f1f1d6c… drh 924 extra = extra_lbits[code];
f1f1d6c… drh 925 if (extra != 0) {
f1f1d6c… drh 926 lc -= base_length[code];
f1f1d6c… drh 927 send_bits(s, lc, extra); /* send the extra length bits */
f1f1d6c… drh 928 }
f1f1d6c… drh 929 dist--; /* dist is now the match distance - 1 */
f1f1d6c… drh 930 code = d_code(dist);
f1f1d6c… drh 931 Assert (code < D_CODES, "bad d_code");
f1f1d6c… drh 932
f1f1d6c… drh 933 send_code(s, code, dtree); /* send the distance code */
f1f1d6c… drh 934 extra = extra_dbits[code];
f1f1d6c… drh 935 if (extra != 0) {
f1f1d6c… drh 936 dist -= (unsigned)base_dist[code];
6ea30fb… florian 937 send_bits(s, (int)dist, extra); /* send the extra bits */
f1f1d6c… drh 938 }
f1f1d6c… drh 939 } /* literal or match pair ? */
f1f1d6c… drh 940
64ce68d… drh 941 /* Check for no overlay of pending_buf on needed symbols */
64ce68d… drh 942 #ifdef LIT_MEM
64ce68d… drh 943 Assert(s->pending < 2 * (s->lit_bufsize + sx), "pendingBuf overflow");
64ce68d… drh 944 #else
f1f1d6c… drh 945 Assert(s->pending < s->lit_bufsize + sx, "pendingBuf overflow");
64ce68d… drh 946 #endif
f1f1d6c… drh 947
f1f1d6c… drh 948 } while (sx < s->sym_next);
f1f1d6c… drh 949
f1f1d6c… drh 950 send_code(s, END_BLOCK, ltree);
f1f1d6c… drh 951 }
f1f1d6c… drh 952
f1f1d6c… drh 953 /* ===========================================================================
f1f1d6c… drh 954 * Check if the data type is TEXT or BINARY, using the following algorithm:
f1f1d6c… drh 955 * - TEXT if the two conditions below are satisfied:
f1f1d6c… drh 956 * a) There are no non-portable control characters belonging to the
f1f1d6c… drh 957 * "block list" (0..6, 14..25, 28..31).
f1f1d6c… drh 958 * b) There is at least one printable character belonging to the
f1f1d6c… drh 959 * "allow list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255).
f1f1d6c… drh 960 * - BINARY otherwise.
f1f1d6c… drh 961 * - The following partially-portable control characters form a
f1f1d6c… drh 962 * "gray list" that is ignored in this detection algorithm:
f1f1d6c… drh 963 * (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}).
f1f1d6c… drh 964 * IN assertion: the fields Freq of dyn_ltree are set.
f1f1d6c… drh 965 */
f1f1d6c… drh 966 local int detect_data_type(deflate_state *s) {
f1f1d6c… drh 967 /* block_mask is the bit mask of block-listed bytes
f1f1d6c… drh 968 * set bits 0..6, 14..25, and 28..31
f1f1d6c… drh 969 * 0xf3ffc07f = binary 11110011111111111100000001111111
f1f1d6c… drh 970 */
f1f1d6c… drh 971 unsigned long block_mask = 0xf3ffc07fUL;
f1f1d6c… drh 972 int n;
f1f1d6c… drh 973
f1f1d6c… drh 974 /* Check for non-textual ("block-listed") bytes. */
f1f1d6c… drh 975 for (n = 0; n <= 31; n++, block_mask >>= 1)
f1f1d6c… drh 976 if ((block_mask & 1) && (s->dyn_ltree[n].Freq != 0))
f1f1d6c… drh 977 return Z_BINARY;
f1f1d6c… drh 978
f1f1d6c… drh 979 /* Check for textual ("allow-listed") bytes. */
f1f1d6c… drh 980 if (s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0
f1f1d6c… drh 981 || s->dyn_ltree[13].Freq != 0)
f1f1d6c… drh 982 return Z_TEXT;
f1f1d6c… drh 983 for (n = 32; n < LITERALS; n++)
f1f1d6c… drh 984 if (s->dyn_ltree[n].Freq != 0)
f1f1d6c… drh 985 return Z_TEXT;
f1f1d6c… drh 986
f1f1d6c… drh 987 /* There are no "block-listed" or "allow-listed" bytes:
f1f1d6c… drh 988 * this stream either is empty or has tolerated ("gray-listed") bytes only.
f1f1d6c… drh 989 */
f1f1d6c… drh 990 return Z_BINARY;
f1f1d6c… drh 991 }
f1f1d6c… drh 992
f1f1d6c… drh 993 /* ===========================================================================
a9e589c… florian 994 * Determine the best encoding for the current block: dynamic trees, static
a9e589c… florian 995 * trees or store, and write out the encoded block.
a9e589c… florian 996 */
f1f1d6c… drh 997 void ZLIB_INTERNAL _tr_flush_block(deflate_state *s, charf *buf,
f1f1d6c… drh 998 ulg stored_len, int last) {
a9e589c… florian 999 ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
a9e589c… florian 1000 int max_blindex = 0; /* index of last bit length code of non zero freq */
a9e589c… florian 1001
a9e589c… florian 1002 /* Build the Huffman trees unless a stored block is forced */
a9e589c… florian 1003 if (s->level > 0) {
a9e589c… florian 1004
a9e589c… florian 1005 /* Check if the file is binary or text */
a9e589c… florian 1006 if (s->strm->data_type == Z_UNKNOWN)
a9e589c… florian 1007 s->strm->data_type = detect_data_type(s);
a9e589c… florian 1008
a9e589c… florian 1009 /* Construct the literal and distance trees */
a9e589c… florian 1010 build_tree(s, (tree_desc *)(&(s->l_desc)));
6ea30fb… florian 1011 Tracev((stderr, "\nlit data: dyn %lu, stat %lu", s->opt_len,
a9e589c… florian 1012 s->static_len));
a9e589c… florian 1013
a9e589c… florian 1014 build_tree(s, (tree_desc *)(&(s->d_desc)));
6ea30fb… florian 1015 Tracev((stderr, "\ndist data: dyn %lu, stat %lu", s->opt_len,
a9e589c… florian 1016 s->static_len));
a9e589c… florian 1017 /* At this point, opt_len and static_len are the total bit lengths of
a9e589c… florian 1018 * the compressed block data, excluding the tree representations.
a9e589c… florian 1019 */
a9e589c… florian 1020
a9e589c… florian 1021 /* Build the bit length tree for the above two trees, and get the index
a9e589c… florian 1022 * in bl_order of the last bit length code to send.
a9e589c… florian 1023 */
a9e589c… florian 1024 max_blindex = build_bl_tree(s);
a9e589c… florian 1025
a9e589c… florian 1026 /* Determine the best encoding. Compute the block lengths in bytes. */
a9e589c… florian 1027 opt_lenb = (s->opt_len + 3 + 7) >> 3;
a9e589c… florian 1028 static_lenb = (s->static_len + 3 + 7) >> 3;
a9e589c… florian 1029
a9e589c… florian 1030 Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
a9e589c… florian 1031 opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
a9e589c… florian 1032 s->sym_next / 3));
a9e589c… florian 1033
a9e589c… florian 1034 #ifndef FORCE_STATIC
a9e589c… florian 1035 if (static_lenb <= opt_lenb || s->strategy == Z_FIXED)
a9e589c… florian 1036 #endif
a9e589c… florian 1037 opt_lenb = static_lenb;
a9e589c… florian 1038
a9e589c… florian 1039 } else {
a9e589c… florian 1040 Assert(buf != (char*)0, "lost buf");
a9e589c… florian 1041 opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
a9e589c… florian 1042 }
a9e589c… florian 1043
a9e589c… florian 1044 #ifdef FORCE_STORED
a9e589c… florian 1045 if (buf != (char*)0) { /* force stored block */
a9e589c… florian 1046 #else
a9e589c… florian 1047 if (stored_len + 4 <= opt_lenb && buf != (char*)0) {
a9e589c… florian 1048 /* 4: two words for the lengths */
a9e589c… florian 1049 #endif
a9e589c… florian 1050 /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
a9e589c… florian 1051 * Otherwise we can't have processed more than WSIZE input bytes since
a9e589c… florian 1052 * the last block flush, because compression would have been
a9e589c… florian 1053 * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
a9e589c… florian 1054 * transform a block into a stored block.
a9e589c… florian 1055 */
a9e589c… florian 1056 _tr_stored_block(s, buf, stored_len, last);
a9e589c… florian 1057
a9e589c… florian 1058 } else if (static_lenb == opt_lenb) {
a9e589c… florian 1059 send_bits(s, (STATIC_TREES<<1) + last, 3);
a9e589c… florian 1060 compress_block(s, (const ct_data *)static_ltree,
a9e589c… florian 1061 (const ct_data *)static_dtree);
a9e589c… florian 1062 #ifdef ZLIB_DEBUG
a9e589c… florian 1063 s->compressed_len += 3 + s->static_len;
a9e589c… florian 1064 #endif
a9e589c… florian 1065 } else {
a9e589c… florian 1066 send_bits(s, (DYN_TREES<<1) + last, 3);
a9e589c… florian 1067 send_all_trees(s, s->l_desc.max_code + 1, s->d_desc.max_code + 1,
a9e589c… florian 1068 max_blindex + 1);
a9e589c… florian 1069 compress_block(s, (const ct_data *)s->dyn_ltree,
a9e589c… florian 1070 (const ct_data *)s->dyn_dtree);
a9e589c… florian 1071 #ifdef ZLIB_DEBUG
a9e589c… florian 1072 s->compressed_len += 3 + s->opt_len;
a9e589c… florian 1073 #endif
a9e589c… florian 1074 }
a9e589c… florian 1075 Assert (s->compressed_len == s->bits_sent, "bad compressed size");
a9e589c… florian 1076 /* The above check is made mod 2^32, for files larger than 512 MB
a9e589c… florian 1077 * and uLong implemented on 32 bits.
a9e589c… florian 1078 */
a9e589c… florian 1079 init_block(s);
a9e589c… florian 1080
a9e589c… florian 1081 if (last) {
a9e589c… florian 1082 bi_windup(s);
a9e589c… florian 1083 #ifdef ZLIB_DEBUG
a9e589c… florian 1084 s->compressed_len += 7; /* align on byte boundary */
a9e589c… florian 1085 #endif
a9e589c… florian 1086 }
a9e589c… florian 1087 Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len >> 3,
6ea30fb… florian 1088 s->compressed_len - 7*(ulg)last));
a9e589c… florian 1089 }
a9e589c… florian 1090
a9e589c… florian 1091 /* ===========================================================================
a9e589c… florian 1092 * Save the match info and tally the frequency counts. Return true if
a9e589c… florian 1093 * the current block must be flushed.
a9e589c… florian 1094 */
f1f1d6c… drh 1095 int ZLIB_INTERNAL _tr_tally(deflate_state *s, unsigned dist, unsigned lc) {
64ce68d… drh 1096 #ifdef LIT_MEM
64ce68d… drh 1097 s->d_buf[s->sym_next] = (ush)dist;
64ce68d… drh 1098 s->l_buf[s->sym_next++] = (uch)lc;
64ce68d… drh 1099 #else
a9e589c… florian 1100 s->sym_buf[s->sym_next++] = (uch)dist;
a9e589c… florian 1101 s->sym_buf[s->sym_next++] = (uch)(dist >> 8);
a9e589c… florian 1102 s->sym_buf[s->sym_next++] = (uch)lc;
64ce68d… drh 1103 #endif
a9e589c… florian 1104 if (dist == 0) {
a9e589c… florian 1105 /* lc is the unmatched char */
a9e589c… florian 1106 s->dyn_ltree[lc].Freq++;
a9e589c… florian 1107 } else {
a9e589c… florian 1108 s->matches++;
a9e589c… florian 1109 /* Here, lc is the match length - MIN_MATCH */
a9e589c… florian 1110 dist--; /* dist = match distance - 1 */
a9e589c… florian 1111 Assert((ush)dist < (ush)MAX_DIST(s) &&
a9e589c… florian 1112 (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
a9e589c… florian 1113 (ush)d_code(dist) < (ush)D_CODES, "_tr_tally: bad match");
a9e589c… florian 1114
a9e589c… florian 1115 s->dyn_ltree[_length_code[lc] + LITERALS + 1].Freq++;
a9e589c… florian 1116 s->dyn_dtree[d_code(dist)].Freq++;
a9e589c… florian 1117 }
a9e589c… florian 1118 return (s->sym_next == s->sym_end);
7ef7284… drh 1119 }

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