trees.c 42.7 KB
Newer Older
M
Mark Adler 已提交
1
/* trees.c -- output deflated data using Huffman coding
2
 * Copyright (C) 1995-2017 Jean-loup Gailly
M
Mark Adler 已提交
3
 * detect_data_type() function provided freely by Cosmin Truta, 2006
M
Mark Adler 已提交
4
 * For conditions of distribution and use, see copyright notice in zlib.h
M
Mark Adler 已提交
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
 */

/*
 *  ALGORITHM
 *
 *      The "deflation" process uses several Huffman trees. The more
 *      common source values are represented by shorter bit sequences.
 *
 *      Each code tree is stored in a compressed form which is itself
 * a Huffman encoding of the lengths of all the code strings (in
 * ascending order by source values).  The actual code strings are
 * reconstructed from the lengths in the inflate process, as described
 * in the deflate specification.
 *
 *  REFERENCES
 *
 *      Deutsch, L.P.,"'Deflate' Compressed Data Format Specification".
 *      Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc
 *
 *      Storer, James A.
 *          Data Compression:  Methods and Theory, pp. 49-50.
 *          Computer Science Press, 1988.  ISBN 0-7167-8156-5.
 *
 *      Sedgewick, R.
 *          Algorithms, p290.
 *          Addison-Wesley, 1983. ISBN 0-201-06672-6.
 */

M
Mark Adler 已提交
33
/* @(#) $Id$ */
M
Mark Adler 已提交
34

M
Mark Adler 已提交
35 36
/* #define GEN_TREES_H */

M
Mark Adler 已提交
37 38
#include "deflate.h"

39
#ifdef ZLIB_DEBUG
M
Mark Adler 已提交
40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61
#  include <ctype.h>
#endif

/* ===========================================================================
 * Constants
 */

#define MAX_BL_BITS 7
/* Bit length codes must not exceed MAX_BL_BITS bits */

#define END_BLOCK 256
/* end of block literal code */

#define REP_3_6      16
/* repeat previous bit length 3-6 times (2 bits of repeat count) */

#define REPZ_3_10    17
/* repeat a zero length 3-10 times  (3 bits of repeat count) */

#define REPZ_11_138  18
/* repeat a zero length 11-138 times  (7 bits of repeat count) */

M
Mark Adler 已提交
62
local const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */
M
Mark Adler 已提交
63 64
   = {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};

M
Mark Adler 已提交
65
local const int extra_dbits[D_CODES] /* extra bits for each distance code */
M
Mark Adler 已提交
66 67
   = {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};

M
Mark Adler 已提交
68
local const int extra_blbits[BL_CODES]/* extra bits for each bit length code */
M
Mark Adler 已提交
69 70
   = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};

M
Mark Adler 已提交
71
local const uch bl_order[BL_CODES]
M
Mark Adler 已提交
72 73 74 75 76 77 78 79 80
   = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};
/* The lengths of the bit length codes are sent in order of decreasing
 * probability, to avoid transmitting the lengths for unused bit length codes.
 */

/* ===========================================================================
 * Local data. These are initialized only once.
 */

M
Mark Adler 已提交
81 82 83 84 85
#define DIST_CODE_LEN  512 /* see definition of array dist_code below */

#if defined(GEN_TREES_H) || !defined(STDC)
/* non ANSI compilers may not accept trees.h */

M
Mark Adler 已提交
86 87 88
local ct_data static_ltree[L_CODES+2];
/* The static literal tree. Since the bit lengths are imposed, there is no
 * need for the L_CODES extra codes used during heap construction. However
M
Mark Adler 已提交
89
 * The codes 286 and 287 are needed to build a canonical tree (see _tr_init
M
Mark Adler 已提交
90 91 92 93 94 95 96 97
 * below).
 */

local ct_data static_dtree[D_CODES];
/* The static distance tree. (Actually a trivial tree since all codes use
 * 5 bits.)
 */

M
Mark Adler 已提交
98
uch _dist_code[DIST_CODE_LEN];
M
Mark Adler 已提交
99
/* Distance codes. The first 256 values correspond to the distances
M
Mark Adler 已提交
100 101 102 103
 * 3 .. 258, the last 256 values correspond to the top 8 bits of
 * the 15 bit distances.
 */

M
Mark Adler 已提交
104
uch _length_code[MAX_MATCH-MIN_MATCH+1];
M
Mark Adler 已提交
105 106 107 108 109 110 111 112
/* length code for each normalized match length (0 == MIN_MATCH) */

local int base_length[LENGTH_CODES];
/* First normalized length for each code (0 = MIN_MATCH) */

local int base_dist[D_CODES];
/* First normalized distance for each code (0 = distance of 1) */

M
Mark Adler 已提交
113 114 115 116
#else
#  include "trees.h"
#endif /* GEN_TREES_H */

M
Mark Adler 已提交
117
struct static_tree_desc_s {
M
Mark Adler 已提交
118
    const ct_data *static_tree;  /* static tree or NULL */
M
Mark Adler 已提交
119
    const intf *extra_bits;      /* extra bits for each code or NULL */
M
Mark Adler 已提交
120 121 122 123 124
    int     extra_base;          /* base index for extra_bits */
    int     elems;               /* max number of elements in the tree */
    int     max_length;          /* max bit length for the codes */
};

125
local const static_tree_desc  static_l_desc =
M
Mark Adler 已提交
126 127
{static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};

128
local const static_tree_desc  static_d_desc =
M
Mark Adler 已提交
129 130
{static_dtree, extra_dbits, 0,          D_CODES, MAX_BITS};

131
local const static_tree_desc  static_bl_desc =
M
Mark Adler 已提交
132
{(const ct_data *)0, extra_blbits, 0,   BL_CODES, MAX_BL_BITS};
M
Mark Adler 已提交
133 134 135 136 137

/* ===========================================================================
 * Local (static) routines in this file.
 */

M
Mark Adler 已提交
138
local void tr_static_init OF((void));
M
Mark Adler 已提交
139 140 141 142 143 144 145 146 147
local void init_block     OF((deflate_state *s));
local void pqdownheap     OF((deflate_state *s, ct_data *tree, int k));
local void gen_bitlen     OF((deflate_state *s, tree_desc *desc));
local void gen_codes      OF((ct_data *tree, int max_code, ushf *bl_count));
local void build_tree     OF((deflate_state *s, tree_desc *desc));
local void scan_tree      OF((deflate_state *s, ct_data *tree, int max_code));
local void send_tree      OF((deflate_state *s, ct_data *tree, int max_code));
local int  build_bl_tree  OF((deflate_state *s));
local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes,
M
Mark Adler 已提交
148
                              int blcodes));
149 150
local void compress_block OF((deflate_state *s, const ct_data *ltree,
                              const ct_data *dtree));
M
Mark Adler 已提交
151
local int  detect_data_type OF((deflate_state *s));
M
Mark Adler 已提交
152 153
local unsigned bi_reverse OF((unsigned value, int length));
local void bi_windup      OF((deflate_state *s));
M
Mark Adler 已提交
154
local void bi_flush       OF((deflate_state *s));
M
Mark Adler 已提交
155

M
Mark Adler 已提交
156 157 158 159
#ifdef GEN_TREES_H
local void gen_trees_header OF((void));
#endif

160
#ifndef ZLIB_DEBUG
M
Mark Adler 已提交
161 162 163
#  define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
   /* Send a code of the given tree. c and tree must not have side effects */

164
#else /* !ZLIB_DEBUG */
M
Mark Adler 已提交
165
#  define send_code(s, c, tree) \
M
Mark Adler 已提交
166
     { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
M
Mark Adler 已提交
167 168 169
       send_bits(s, tree[c].Code, tree[c].Len); }
#endif

M
Mark Adler 已提交
170 171 172 173 174 175 176 177 178 179 180 181 182
/* ===========================================================================
 * Output a short LSB first on the stream.
 * IN assertion: there is enough room in pendingBuf.
 */
#define put_short(s, w) { \
    put_byte(s, (uch)((w) & 0xff)); \
    put_byte(s, (uch)((ush)(w) >> 8)); \
}

/* ===========================================================================
 * Send a value on a given number of bits.
 * IN assertion: length <= 16 and value fits in length bits.
 */
183
#ifdef ZLIB_DEBUG
M
Mark Adler 已提交
184 185 186 187 188 189 190
local void send_bits      OF((deflate_state *s, int value, int length));

local void send_bits(s, value, length)
    deflate_state *s;
    int value;  /* value to send */
    int length; /* number of bits */
{
M
Mark Adler 已提交
191
    Tracevv((stderr," l %2d v %4x ", length, value));
M
Mark Adler 已提交
192 193 194 195 196 197 198 199
    Assert(length > 0 && length <= 15, "invalid length");
    s->bits_sent += (ulg)length;

    /* If not enough room in bi_buf, use (valid) bits from bi_buf and
     * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
     * unused bits in value.
     */
    if (s->bi_valid > (int)Buf_size - length) {
M
Mark Adler 已提交
200
        s->bi_buf |= (ush)value << s->bi_valid;
M
Mark Adler 已提交
201 202 203 204
        put_short(s, s->bi_buf);
        s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);
        s->bi_valid += length - Buf_size;
    } else {
M
Mark Adler 已提交
205
        s->bi_buf |= (ush)value << s->bi_valid;
M
Mark Adler 已提交
206 207 208
        s->bi_valid += length;
    }
}
209
#else /* !ZLIB_DEBUG */
M
Mark Adler 已提交
210 211 212 213

#define send_bits(s, value, length) \
{ int len = length;\
  if (s->bi_valid > (int)Buf_size - len) {\
M
Mark Adler 已提交
214
    int val = (int)value;\
M
Mark Adler 已提交
215
    s->bi_buf |= (ush)val << s->bi_valid;\
M
Mark Adler 已提交
216 217 218 219
    put_short(s, s->bi_buf);\
    s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
    s->bi_valid += len - Buf_size;\
  } else {\
M
Mark Adler 已提交
220
    s->bi_buf |= (ush)(value) << s->bi_valid;\
M
Mark Adler 已提交
221 222 223
    s->bi_valid += len;\
  }\
}
224
#endif /* ZLIB_DEBUG */
M
Mark Adler 已提交
225 226


M
Mark Adler 已提交
227 228 229
/* the arguments must not have side effects */

/* ===========================================================================
M
Mark Adler 已提交
230
 * Initialize the various 'constant' tables.
M
Mark Adler 已提交
231
 */
M
Mark Adler 已提交
232
local void tr_static_init()
M
Mark Adler 已提交
233
{
M
Mark Adler 已提交
234
#if defined(GEN_TREES_H) || !defined(STDC)
M
Mark Adler 已提交
235
    static int static_init_done = 0;
M
Mark Adler 已提交
236 237 238 239 240 241 242 243
    int n;        /* iterates over tree elements */
    int bits;     /* bit counter */
    int length;   /* length value */
    int code;     /* code value */
    int dist;     /* distance index */
    ush bl_count[MAX_BITS+1];
    /* number of codes at each bit length for an optimal tree */

M
Mark Adler 已提交
244 245
    if (static_init_done) return;

M
Mark Adler 已提交
246
    /* For some embedded targets, global variables are not initialized: */
M
Mark Adler 已提交
247
#ifdef NO_INIT_GLOBAL_POINTERS
M
Mark Adler 已提交
248 249 250 251 252
    static_l_desc.static_tree = static_ltree;
    static_l_desc.extra_bits = extra_lbits;
    static_d_desc.static_tree = static_dtree;
    static_d_desc.extra_bits = extra_dbits;
    static_bl_desc.extra_bits = extra_blbits;
M
Mark Adler 已提交
253
#endif
M
Mark Adler 已提交
254

M
Mark Adler 已提交
255 256 257 258 259
    /* Initialize the mapping length (0..255) -> length code (0..28) */
    length = 0;
    for (code = 0; code < LENGTH_CODES-1; code++) {
        base_length[code] = length;
        for (n = 0; n < (1<<extra_lbits[code]); n++) {
M
Mark Adler 已提交
260
            _length_code[length++] = (uch)code;
M
Mark Adler 已提交
261 262
        }
    }
M
Mark Adler 已提交
263
    Assert (length == 256, "tr_static_init: length != 256");
M
Mark Adler 已提交
264 265 266 267
    /* Note that the length 255 (match length 258) can be represented
     * in two different ways: code 284 + 5 bits or code 285, so we
     * overwrite length_code[255] to use the best encoding:
     */
M
Mark Adler 已提交
268
    _length_code[length-1] = (uch)code;
M
Mark Adler 已提交
269 270 271 272 273 274

    /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
    dist = 0;
    for (code = 0 ; code < 16; code++) {
        base_dist[code] = dist;
        for (n = 0; n < (1<<extra_dbits[code]); n++) {
M
Mark Adler 已提交
275
            _dist_code[dist++] = (uch)code;
M
Mark Adler 已提交
276 277
        }
    }
M
Mark Adler 已提交
278
    Assert (dist == 256, "tr_static_init: dist != 256");
M
Mark Adler 已提交
279 280 281 282
    dist >>= 7; /* from now on, all distances are divided by 128 */
    for ( ; code < D_CODES; code++) {
        base_dist[code] = dist << 7;
        for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
M
Mark Adler 已提交
283
            _dist_code[256 + dist++] = (uch)code;
M
Mark Adler 已提交
284 285
        }
    }
M
Mark Adler 已提交
286
    Assert (dist == 256, "tr_static_init: 256+dist != 512");
M
Mark Adler 已提交
287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303

    /* Construct the codes of the static literal tree */
    for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
    n = 0;
    while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
    while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
    while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
    while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
    /* Codes 286 and 287 do not exist, but we must include them in the
     * tree construction to get a canonical Huffman tree (longest code
     * all ones)
     */
    gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);

    /* The static distance tree is trivial: */
    for (n = 0; n < D_CODES; n++) {
        static_dtree[n].Len = 5;
M
Mark Adler 已提交
304
        static_dtree[n].Code = bi_reverse((unsigned)n, 5);
M
Mark Adler 已提交
305
    }
M
Mark Adler 已提交
306
    static_init_done = 1;
M
Mark Adler 已提交
307 308 309 310 311 312 313 314 315 316 317

#  ifdef GEN_TREES_H
    gen_trees_header();
#  endif
#endif /* defined(GEN_TREES_H) || !defined(STDC) */
}

/* ===========================================================================
 * Genererate the file trees.h describing the static trees.
 */
#ifdef GEN_TREES_H
318
#  ifndef ZLIB_DEBUG
M
Mark Adler 已提交
319 320 321 322 323 324 325 326 327 328 329 330 331 332
#    include <stdio.h>
#  endif

#  define SEPARATOR(i, last, width) \
      ((i) == (last)? "\n};\n\n" :    \
       ((i) % (width) == (width)-1 ? ",\n" : ", "))

void gen_trees_header()
{
    FILE *header = fopen("trees.h", "w");
    int i;

    Assert (header != NULL, "Can't open trees.h");
    fprintf(header,
M
Mark Adler 已提交
333
            "/* header created automatically with -DGEN_TREES_H */\n\n");
M
Mark Adler 已提交
334 335 336

    fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n");
    for (i = 0; i < L_CODES+2; i++) {
M
Mark Adler 已提交
337 338
        fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code,
                static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5));
M
Mark Adler 已提交
339 340 341 342
    }

    fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n");
    for (i = 0; i < D_CODES; i++) {
M
Mark Adler 已提交
343 344
        fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code,
                static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5));
M
Mark Adler 已提交
345 346
    }

M
Mark Adler 已提交
347
    fprintf(header, "const uch ZLIB_INTERNAL _dist_code[DIST_CODE_LEN] = {\n");
M
Mark Adler 已提交
348
    for (i = 0; i < DIST_CODE_LEN; i++) {
M
Mark Adler 已提交
349 350
        fprintf(header, "%2u%s", _dist_code[i],
                SEPARATOR(i, DIST_CODE_LEN-1, 20));
M
Mark Adler 已提交
351 352
    }

M
Mark Adler 已提交
353 354
    fprintf(header,
        "const uch ZLIB_INTERNAL _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");
M
Mark Adler 已提交
355
    for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) {
M
Mark Adler 已提交
356 357
        fprintf(header, "%2u%s", _length_code[i],
                SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));
M
Mark Adler 已提交
358 359 360 361
    }

    fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");
    for (i = 0; i < LENGTH_CODES; i++) {
M
Mark Adler 已提交
362 363
        fprintf(header, "%1u%s", base_length[i],
                SEPARATOR(i, LENGTH_CODES-1, 20));
M
Mark Adler 已提交
364 365 366 367
    }

    fprintf(header, "local const int base_dist[D_CODES] = {\n");
    for (i = 0; i < D_CODES; i++) {
M
Mark Adler 已提交
368 369
        fprintf(header, "%5u%s", base_dist[i],
                SEPARATOR(i, D_CODES-1, 10));
M
Mark Adler 已提交
370 371 372
    }

    fclose(header);
M
Mark Adler 已提交
373
}
M
Mark Adler 已提交
374
#endif /* GEN_TREES_H */
M
Mark Adler 已提交
375 376 377 378

/* ===========================================================================
 * Initialize the tree data structures for a new zlib stream.
 */
M
Mark Adler 已提交
379
void ZLIB_INTERNAL _tr_init(s)
M
Mark Adler 已提交
380 381
    deflate_state *s;
{
M
Mark Adler 已提交
382
    tr_static_init();
M
Mark Adler 已提交
383 384 385 386 387 388 389 390 391 392 393 394

    s->l_desc.dyn_tree = s->dyn_ltree;
    s->l_desc.stat_desc = &static_l_desc;

    s->d_desc.dyn_tree = s->dyn_dtree;
    s->d_desc.stat_desc = &static_d_desc;

    s->bl_desc.dyn_tree = s->bl_tree;
    s->bl_desc.stat_desc = &static_bl_desc;

    s->bi_buf = 0;
    s->bi_valid = 0;
395
#ifdef ZLIB_DEBUG
M
Mark Adler 已提交
396
    s->compressed_len = 0L;
M
Mark Adler 已提交
397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460
    s->bits_sent = 0L;
#endif

    /* Initialize the first block of the first file: */
    init_block(s);
}

/* ===========================================================================
 * Initialize a new block.
 */
local void init_block(s)
    deflate_state *s;
{
    int n; /* iterates over tree elements */

    /* Initialize the trees. */
    for (n = 0; n < L_CODES;  n++) s->dyn_ltree[n].Freq = 0;
    for (n = 0; n < D_CODES;  n++) s->dyn_dtree[n].Freq = 0;
    for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;

    s->dyn_ltree[END_BLOCK].Freq = 1;
    s->opt_len = s->static_len = 0L;
    s->last_lit = s->matches = 0;
}

#define SMALLEST 1
/* Index within the heap array of least frequent node in the Huffman tree */


/* ===========================================================================
 * Remove the smallest element from the heap and recreate the heap with
 * one less element. Updates heap and heap_len.
 */
#define pqremove(s, tree, top) \
{\
    top = s->heap[SMALLEST]; \
    s->heap[SMALLEST] = s->heap[s->heap_len--]; \
    pqdownheap(s, tree, SMALLEST); \
}

/* ===========================================================================
 * Compares to subtrees, using the tree depth as tie breaker when
 * the subtrees have equal frequency. This minimizes the worst case length.
 */
#define smaller(tree, n, m, depth) \
   (tree[n].Freq < tree[m].Freq || \
   (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))

/* ===========================================================================
 * Restore the heap property by moving down the tree starting at node k,
 * exchanging a node with the smallest of its two sons if necessary, stopping
 * when the heap property is re-established (each father smaller than its
 * two sons).
 */
local void pqdownheap(s, tree, k)
    deflate_state *s;
    ct_data *tree;  /* the tree to restore */
    int k;               /* node to move down */
{
    int v = s->heap[k];
    int j = k << 1;  /* left son of k */
    while (j <= s->heap_len) {
        /* Set j to the smallest of the two sons: */
        if (j < s->heap_len &&
M
Mark Adler 已提交
461 462 463
            smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
            j++;
        }
M
Mark Adler 已提交
464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489
        /* Exit if v is smaller than both sons */
        if (smaller(tree, v, s->heap[j], s->depth)) break;

        /* Exchange v with the smallest son */
        s->heap[k] = s->heap[j];  k = j;

        /* And continue down the tree, setting j to the left son of k */
        j <<= 1;
    }
    s->heap[k] = v;
}

/* ===========================================================================
 * Compute the optimal bit lengths for a tree and update the total bit length
 * for the current block.
 * IN assertion: the fields freq and dad are set, heap[heap_max] and
 *    above are the tree nodes sorted by increasing frequency.
 * OUT assertions: the field len is set to the optimal bit length, the
 *     array bl_count contains the frequencies for each bit length.
 *     The length opt_len is updated; static_len is also updated if stree is
 *     not null.
 */
local void gen_bitlen(s, desc)
    deflate_state *s;
    tree_desc *desc;    /* the tree descriptor */
{
M
Mark Adler 已提交
490 491 492 493 494 495
    ct_data *tree        = desc->dyn_tree;
    int max_code         = desc->max_code;
    const ct_data *stree = desc->stat_desc->static_tree;
    const intf *extra    = desc->stat_desc->extra_bits;
    int base             = desc->stat_desc->extra_base;
    int max_length       = desc->stat_desc->max_length;
M
Mark Adler 已提交
496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522
    int h;              /* heap index */
    int n, m;           /* iterate over the tree elements */
    int bits;           /* bit length */
    int xbits;          /* extra bits */
    ush f;              /* frequency */
    int overflow = 0;   /* number of elements with bit length too large */

    for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;

    /* In a first pass, compute the optimal bit lengths (which may
     * overflow in the case of the bit length tree).
     */
    tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */

    for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
        n = s->heap[h];
        bits = tree[tree[n].Dad].Len + 1;
        if (bits > max_length) bits = max_length, overflow++;
        tree[n].Len = (ush)bits;
        /* We overwrite tree[n].Dad which is no longer needed */

        if (n > max_code) continue; /* not a leaf node */

        s->bl_count[bits]++;
        xbits = 0;
        if (n >= base) xbits = extra[n-base];
        f = tree[n].Freq;
M
Mark Adler 已提交
523 524
        s->opt_len += (ulg)f * (unsigned)(bits + xbits);
        if (stree) s->static_len += (ulg)f * (unsigned)(stree[n].Len + xbits);
M
Mark Adler 已提交
525 526 527
    }
    if (overflow == 0) return;

528
    Tracev((stderr,"\nbit length overflow\n"));
M
Mark Adler 已提交
529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553
    /* This happens for example on obj2 and pic of the Calgary corpus */

    /* Find the first bit length which could increase: */
    do {
        bits = max_length-1;
        while (s->bl_count[bits] == 0) bits--;
        s->bl_count[bits]--;      /* move one leaf down the tree */
        s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
        s->bl_count[max_length]--;
        /* The brother of the overflow item also moves one step up,
         * but this does not affect bl_count[max_length]
         */
        overflow -= 2;
    } while (overflow > 0);

    /* Now recompute all bit lengths, scanning in increasing frequency.
     * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
     * lengths instead of fixing only the wrong ones. This idea is taken
     * from 'ar' written by Haruhiko Okumura.)
     */
    for (bits = max_length; bits != 0; bits--) {
        n = s->bl_count[bits];
        while (n != 0) {
            m = s->heap[--h];
            if (m > max_code) continue;
M
Mark Adler 已提交
554
            if ((unsigned) tree[m].Len != (unsigned) bits) {
555
                Tracev((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
M
Mark Adler 已提交
556
                s->opt_len += ((ulg)bits - tree[m].Len) * tree[m].Freq;
M
Mark Adler 已提交
557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574
                tree[m].Len = (ush)bits;
            }
            n--;
        }
    }
}

/* ===========================================================================
 * Generate the codes for a given tree and bit counts (which need not be
 * optimal).
 * IN assertion: the array bl_count contains the bit length statistics for
 * the given tree and the field len is set for all tree elements.
 * OUT assertion: the field code is set for all tree elements of non
 *     zero code length.
 */
local void gen_codes (tree, max_code, bl_count)
    ct_data *tree;             /* the tree to decorate */
    int max_code;              /* largest code with non zero frequency */
M
Mark Adler 已提交
575
    ushf *bl_count;            /* number of codes at each bit length */
M
Mark Adler 已提交
576 577
{
    ush next_code[MAX_BITS+1]; /* next code value for each bit length */
M
Mark Adler 已提交
578
    unsigned code = 0;         /* running code value */
M
Mark Adler 已提交
579 580 581 582 583 584 585
    int bits;                  /* bit index */
    int n;                     /* code index */

    /* The distribution counts are first used to generate the code values
     * without bit reversal.
     */
    for (bits = 1; bits <= MAX_BITS; bits++) {
M
Mark Adler 已提交
586 587
        code = (code + bl_count[bits-1]) << 1;
        next_code[bits] = (ush)code;
M
Mark Adler 已提交
588 589 590 591 592 593 594 595 596 597 598 599
    }
    /* Check that the bit counts in bl_count are consistent. The last code
     * must be all ones.
     */
    Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
            "inconsistent bit counts");
    Tracev((stderr,"\ngen_codes: max_code %d ", max_code));

    for (n = 0;  n <= max_code; n++) {
        int len = tree[n].Len;
        if (len == 0) continue;
        /* Now reverse the bits */
M
Mark Adler 已提交
600
        tree[n].Code = (ush)bi_reverse(next_code[len]++, len);
M
Mark Adler 已提交
601

M
Mark Adler 已提交
602
        Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
M
Mark Adler 已提交
603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618
             n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
    }
}

/* ===========================================================================
 * Construct one Huffman tree and assigns the code bit strings and lengths.
 * Update the total bit length for the current block.
 * IN assertion: the field freq is set for all tree elements.
 * OUT assertions: the fields len and code are set to the optimal bit length
 *     and corresponding code. The length opt_len is updated; static_len is
 *     also updated if stree is not null. The field max_code is set.
 */
local void build_tree(s, desc)
    deflate_state *s;
    tree_desc *desc; /* the tree descriptor */
{
M
Mark Adler 已提交
619 620 621
    ct_data *tree         = desc->dyn_tree;
    const ct_data *stree  = desc->stat_desc->static_tree;
    int elems             = desc->stat_desc->elems;
M
Mark Adler 已提交
622 623
    int n, m;          /* iterate over heap elements */
    int max_code = -1; /* largest code with non zero frequency */
M
Mark Adler 已提交
624
    int node;          /* new node being created */
M
Mark Adler 已提交
625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646

    /* Construct the initial heap, with least frequent element in
     * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
     * heap[0] is not used.
     */
    s->heap_len = 0, s->heap_max = HEAP_SIZE;

    for (n = 0; n < elems; n++) {
        if (tree[n].Freq != 0) {
            s->heap[++(s->heap_len)] = max_code = n;
            s->depth[n] = 0;
        } else {
            tree[n].Len = 0;
        }
    }

    /* The pkzip format requires that at least one distance code exists,
     * and that at least one bit should be sent even if there is only one
     * possible code. So to avoid special checks later on we force at least
     * two codes of non zero frequency.
     */
    while (s->heap_len < 2) {
M
Mark Adler 已提交
647 648 649 650 651
        node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
        tree[node].Freq = 1;
        s->depth[node] = 0;
        s->opt_len--; if (stree) s->static_len -= stree[node].Len;
        /* node is 0 or 1 so it does not have extra bits */
M
Mark Adler 已提交
652 653 654 655 656 657 658 659 660 661 662
    }
    desc->max_code = max_code;

    /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
     * establish sub-heaps of increasing lengths:
     */
    for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);

    /* Construct the Huffman tree by repeatedly combining the least two
     * frequent nodes.
     */
M
Mark Adler 已提交
663
    node = elems;              /* next internal node of the tree */
M
Mark Adler 已提交
664 665 666 667 668 669 670 671 672
    do {
        pqremove(s, tree, n);  /* n = node of least frequency */
        m = s->heap[SMALLEST]; /* m = node of next least frequency */

        s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
        s->heap[--(s->heap_max)] = m;

        /* Create a new node father of n and m */
        tree[node].Freq = tree[n].Freq + tree[m].Freq;
M
Mark Adler 已提交
673 674
        s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?
                                s->depth[n] : s->depth[m]) + 1);
M
Mark Adler 已提交
675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821
        tree[n].Dad = tree[m].Dad = (ush)node;
#ifdef DUMP_BL_TREE
        if (tree == s->bl_tree) {
            fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
                    node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
        }
#endif
        /* and insert the new node in the heap */
        s->heap[SMALLEST] = node++;
        pqdownheap(s, tree, SMALLEST);

    } while (s->heap_len >= 2);

    s->heap[--(s->heap_max)] = s->heap[SMALLEST];

    /* At this point, the fields freq and dad are set. We can now
     * generate the bit lengths.
     */
    gen_bitlen(s, (tree_desc *)desc);

    /* The field len is now set, we can generate the bit codes */
    gen_codes ((ct_data *)tree, max_code, s->bl_count);
}

/* ===========================================================================
 * Scan a literal or distance tree to determine the frequencies of the codes
 * in the bit length tree.
 */
local void scan_tree (s, tree, max_code)
    deflate_state *s;
    ct_data *tree;   /* the tree to be scanned */
    int max_code;    /* and its largest code of non zero frequency */
{
    int n;                     /* iterates over all tree elements */
    int prevlen = -1;          /* last emitted length */
    int curlen;                /* length of current code */
    int nextlen = tree[0].Len; /* length of next code */
    int count = 0;             /* repeat count of the current code */
    int max_count = 7;         /* max repeat count */
    int min_count = 4;         /* min repeat count */

    if (nextlen == 0) max_count = 138, min_count = 3;
    tree[max_code+1].Len = (ush)0xffff; /* guard */

    for (n = 0; n <= max_code; n++) {
        curlen = nextlen; nextlen = tree[n+1].Len;
        if (++count < max_count && curlen == nextlen) {
            continue;
        } else if (count < min_count) {
            s->bl_tree[curlen].Freq += count;
        } else if (curlen != 0) {
            if (curlen != prevlen) s->bl_tree[curlen].Freq++;
            s->bl_tree[REP_3_6].Freq++;
        } else if (count <= 10) {
            s->bl_tree[REPZ_3_10].Freq++;
        } else {
            s->bl_tree[REPZ_11_138].Freq++;
        }
        count = 0; prevlen = curlen;
        if (nextlen == 0) {
            max_count = 138, min_count = 3;
        } else if (curlen == nextlen) {
            max_count = 6, min_count = 3;
        } else {
            max_count = 7, min_count = 4;
        }
    }
}

/* ===========================================================================
 * Send a literal or distance tree in compressed form, using the codes in
 * bl_tree.
 */
local void send_tree (s, tree, max_code)
    deflate_state *s;
    ct_data *tree; /* the tree to be scanned */
    int max_code;       /* and its largest code of non zero frequency */
{
    int n;                     /* iterates over all tree elements */
    int prevlen = -1;          /* last emitted length */
    int curlen;                /* length of current code */
    int nextlen = tree[0].Len; /* length of next code */
    int count = 0;             /* repeat count of the current code */
    int max_count = 7;         /* max repeat count */
    int min_count = 4;         /* min repeat count */

    /* tree[max_code+1].Len = -1; */  /* guard already set */
    if (nextlen == 0) max_count = 138, min_count = 3;

    for (n = 0; n <= max_code; n++) {
        curlen = nextlen; nextlen = tree[n+1].Len;
        if (++count < max_count && curlen == nextlen) {
            continue;
        } else if (count < min_count) {
            do { send_code(s, curlen, s->bl_tree); } while (--count != 0);

        } else if (curlen != 0) {
            if (curlen != prevlen) {
                send_code(s, curlen, s->bl_tree); count--;
            }
            Assert(count >= 3 && count <= 6, " 3_6?");
            send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);

        } else if (count <= 10) {
            send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);

        } else {
            send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
        }
        count = 0; prevlen = curlen;
        if (nextlen == 0) {
            max_count = 138, min_count = 3;
        } else if (curlen == nextlen) {
            max_count = 6, min_count = 3;
        } else {
            max_count = 7, min_count = 4;
        }
    }
}

/* ===========================================================================
 * Construct the Huffman tree for the bit lengths and return the index in
 * bl_order of the last bit length code to send.
 */
local int build_bl_tree(s)
    deflate_state *s;
{
    int max_blindex;  /* index of last bit length code of non zero freq */

    /* Determine the bit length frequencies for literal and distance trees */
    scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
    scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);

    /* Build the bit length tree: */
    build_tree(s, (tree_desc *)(&(s->bl_desc)));
    /* opt_len now includes the length of the tree representations, except
     * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
     */

    /* Determine the number of bit length codes to send. The pkzip format
     * requires that at least 4 bit length codes be sent. (appnote.txt says
     * 3 but the actual value used is 4.)
     */
    for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
        if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
    }
    /* Update opt_len to include the bit length tree and counts */
M
Mark Adler 已提交
822
    s->opt_len += 3*((ulg)max_blindex+1) + 5+5+4;
M
Mark Adler 已提交
823
    Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
M
Mark Adler 已提交
824
            s->opt_len, s->static_len));
M
Mark Adler 已提交
825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859

    return max_blindex;
}

/* ===========================================================================
 * Send the header for a block using dynamic Huffman trees: the counts, the
 * lengths of the bit length codes, the literal tree and the distance tree.
 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
 */
local void send_all_trees(s, lcodes, dcodes, blcodes)
    deflate_state *s;
    int lcodes, dcodes, blcodes; /* number of codes for each tree */
{
    int rank;                    /* index in bl_order */

    Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
    Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
            "too many codes");
    Tracev((stderr, "\nbl counts: "));
    send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
    send_bits(s, dcodes-1,   5);
    send_bits(s, blcodes-4,  4); /* not -3 as stated in appnote.txt */
    for (rank = 0; rank < blcodes; rank++) {
        Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
        send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
    }
    Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));

    send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
    Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));

    send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
    Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
}

M
Mark Adler 已提交
860 861 862
/* ===========================================================================
 * Send a stored block
 */
M
Mark Adler 已提交
863
void ZLIB_INTERNAL _tr_stored_block(s, buf, stored_len, last)
M
Mark Adler 已提交
864
    deflate_state *s;
M
Mark Adler 已提交
865
    charf *buf;       /* input block */
M
Mark Adler 已提交
866
    ulg stored_len;   /* length of input block */
M
Mark Adler 已提交
867
    int last;         /* one if this is the last block for a file */
M
Mark Adler 已提交
868
{
M
Mark Adler 已提交
869
    send_bits(s, (STORED_BLOCK<<1)+last, 3);    /* send block type */
M
Mark Adler 已提交
870 871 872
    bi_windup(s);        /* align on byte boundary */
    put_short(s, (ush)stored_len);
    put_short(s, (ush)~stored_len);
873
    zmemcpy(s->pending_buf + s->pending, (Bytef *)buf, stored_len);
M
Mark Adler 已提交
874
    s->pending += stored_len;
875
#ifdef ZLIB_DEBUG
M
Mark Adler 已提交
876
    s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
M
Mark Adler 已提交
877
    s->compressed_len += (stored_len + 4) << 3;
M
Mark Adler 已提交
878 879
    s->bits_sent += 2*16;
    s->bits_sent += stored_len<<3;
M
Mark Adler 已提交
880
#endif
M
Mark Adler 已提交
881 882
}

883 884 885 886 887 888 889 890 891
/* ===========================================================================
 * Flush the bits in the bit buffer to pending output (leaves at most 7 bits)
 */
void ZLIB_INTERNAL _tr_flush_bits(s)
    deflate_state *s;
{
    bi_flush(s);
}

M
Mark Adler 已提交
892
/* ===========================================================================
M
Mark Adler 已提交
893 894
 * Send one empty static block to give enough lookahead for inflate.
 * This takes 10 bits, of which 7 may remain in the bit buffer.
M
Mark Adler 已提交
895
 */
M
Mark Adler 已提交
896
void ZLIB_INTERNAL _tr_align(s)
M
Mark Adler 已提交
897 898 899 900
    deflate_state *s;
{
    send_bits(s, STATIC_TREES<<1, 3);
    send_code(s, END_BLOCK, static_ltree);
901
#ifdef ZLIB_DEBUG
M
Mark Adler 已提交
902
    s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
M
Mark Adler 已提交
903
#endif
M
Mark Adler 已提交
904
    bi_flush(s);
M
Mark Adler 已提交
905 906
}

M
Mark Adler 已提交
907 908
/* ===========================================================================
 * Determine the best encoding for the current block: dynamic trees, static
909
 * trees or store, and write out the encoded block.
M
Mark Adler 已提交
910
 */
M
Mark Adler 已提交
911
void ZLIB_INTERNAL _tr_flush_block(s, buf, stored_len, last)
M
Mark Adler 已提交
912
    deflate_state *s;
M
Mark Adler 已提交
913
    charf *buf;       /* input block, or NULL if too old */
M
Mark Adler 已提交
914
    ulg stored_len;   /* length of input block */
M
Mark Adler 已提交
915
    int last;         /* one if this is the last block for a file */
M
Mark Adler 已提交
916 917
{
    ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
M
Mark Adler 已提交
918
    int max_blindex = 0;  /* index of last bit length code of non zero freq */
M
Mark Adler 已提交
919

M
Mark Adler 已提交
920 921
    /* Build the Huffman trees unless a stored block is forced */
    if (s->level > 0) {
M
Mark Adler 已提交
922

M
Mark Adler 已提交
923
        /* Check if the file is binary or text */
M
Mark Adler 已提交
924 925
        if (s->strm->data_type == Z_UNKNOWN)
            s->strm->data_type = detect_data_type(s);
M
Mark Adler 已提交
926

M
Mark Adler 已提交
927 928 929 930
        /* Construct the literal and distance trees */
        build_tree(s, (tree_desc *)(&(s->l_desc)));
        Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
                s->static_len));
M
Mark Adler 已提交
931

M
Mark Adler 已提交
932 933 934 935 936 937
        build_tree(s, (tree_desc *)(&(s->d_desc)));
        Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
                s->static_len));
        /* At this point, opt_len and static_len are the total bit lengths of
         * the compressed block data, excluding the tree representations.
         */
M
Mark Adler 已提交
938

M
Mark Adler 已提交
939 940 941 942
        /* Build the bit length tree for the above two trees, and get the index
         * in bl_order of the last bit length code to send.
         */
        max_blindex = build_bl_tree(s);
M
Mark Adler 已提交
943

M
Mark Adler 已提交
944
        /* Determine the best encoding. Compute the block lengths in bytes. */
M
Mark Adler 已提交
945 946
        opt_lenb = (s->opt_len+3+7)>>3;
        static_lenb = (s->static_len+3+7)>>3;
M
Mark Adler 已提交
947

M
Mark Adler 已提交
948 949 950
        Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
                opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
                s->last_lit));
M
Mark Adler 已提交
951

M
Mark Adler 已提交
952
        if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
M
Mark Adler 已提交
953 954 955

    } else {
        Assert(buf != (char*)0, "lost buf");
M
Mark Adler 已提交
956
        opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
M
Mark Adler 已提交
957
    }
M
Mark Adler 已提交
958

M
Mark Adler 已提交
959 960
#ifdef FORCE_STORED
    if (buf != (char*)0) { /* force stored block */
M
Mark Adler 已提交
961 962 963 964 965 966 967 968 969 970
#else
    if (stored_len+4 <= opt_lenb && buf != (char*)0) {
                       /* 4: two words for the lengths */
#endif
        /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
         * Otherwise we can't have processed more than WSIZE input bytes since
         * the last block flush, because compression would have been
         * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
         * transform a block into a stored block.
         */
M
Mark Adler 已提交
971
        _tr_stored_block(s, buf, stored_len, last);
M
Mark Adler 已提交
972

M
Mark Adler 已提交
973 974
#ifdef FORCE_STATIC
    } else if (static_lenb >= 0) { /* force static trees */
M
Mark Adler 已提交
975
#else
M
Mark Adler 已提交
976
    } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) {
M
Mark Adler 已提交
977
#endif
M
Mark Adler 已提交
978
        send_bits(s, (STATIC_TREES<<1)+last, 3);
979 980
        compress_block(s, (const ct_data *)static_ltree,
                       (const ct_data *)static_dtree);
981
#ifdef ZLIB_DEBUG
M
Mark Adler 已提交
982
        s->compressed_len += 3 + s->static_len;
M
Mark Adler 已提交
983
#endif
M
Mark Adler 已提交
984
    } else {
M
Mark Adler 已提交
985
        send_bits(s, (DYN_TREES<<1)+last, 3);
M
Mark Adler 已提交
986
        send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
M
Mark Adler 已提交
987
                       max_blindex+1);
988 989
        compress_block(s, (const ct_data *)s->dyn_ltree,
                       (const ct_data *)s->dyn_dtree);
990
#ifdef ZLIB_DEBUG
M
Mark Adler 已提交
991
        s->compressed_len += 3 + s->opt_len;
M
Mark Adler 已提交
992
#endif
M
Mark Adler 已提交
993 994
    }
    Assert (s->compressed_len == s->bits_sent, "bad compressed size");
M
Mark Adler 已提交
995 996 997
    /* The above check is made mod 2^32, for files larger than 512 MB
     * and uLong implemented on 32 bits.
     */
M
Mark Adler 已提交
998 999
    init_block(s);

M
Mark Adler 已提交
1000
    if (last) {
M
Mark Adler 已提交
1001
        bi_windup(s);
1002
#ifdef ZLIB_DEBUG
M
Mark Adler 已提交
1003
        s->compressed_len += 7;  /* align on byte boundary */
M
Mark Adler 已提交
1004
#endif
M
Mark Adler 已提交
1005 1006
    }
    Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
M
Mark Adler 已提交
1007
           s->compressed_len-7*last));
M
Mark Adler 已提交
1008 1009 1010 1011 1012 1013
}

/* ===========================================================================
 * Save the match info and tally the frequency counts. Return true if
 * the current block must be flushed.
 */
M
Mark Adler 已提交
1014
int ZLIB_INTERNAL _tr_tally (s, dist, lc)
M
Mark Adler 已提交
1015
    deflate_state *s;
M
Mark Adler 已提交
1016 1017
    unsigned dist;  /* distance of matched string */
    unsigned lc;    /* match length-MIN_MATCH or unmatched char (if dist==0) */
M
Mark Adler 已提交
1018 1019 1020 1021 1022 1023 1024
{
    s->d_buf[s->last_lit] = (ush)dist;
    s->l_buf[s->last_lit++] = (uch)lc;
    if (dist == 0) {
        /* lc is the unmatched char */
        s->dyn_ltree[lc].Freq++;
    } else {
M
Mark Adler 已提交
1025
        s->matches++;
M
Mark Adler 已提交
1026 1027 1028 1029
        /* Here, lc is the match length - MIN_MATCH */
        dist--;             /* dist = match distance - 1 */
        Assert((ush)dist < (ush)MAX_DIST(s) &&
               (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
M
Mark Adler 已提交
1030
               (ush)d_code(dist) < (ush)D_CODES,  "_tr_tally: bad match");
M
Mark Adler 已提交
1031

M
Mark Adler 已提交
1032
        s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
M
Mark Adler 已提交
1033 1034 1035
        s->dyn_dtree[d_code(dist)].Freq++;
    }

M
Mark Adler 已提交
1036
#ifdef TRUNCATE_BLOCK
M
Mark Adler 已提交
1037
    /* Try to guess if it is profitable to stop the current block here */
M
Mark Adler 已提交
1038
    if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
M
Mark Adler 已提交
1039 1040
        /* Compute an upper bound for the compressed length */
        ulg out_length = (ulg)s->last_lit*8L;
M
Mark Adler 已提交
1041
        ulg in_length = (ulg)((long)s->strstart - s->block_start);
M
Mark Adler 已提交
1042 1043 1044
        int dcode;
        for (dcode = 0; dcode < D_CODES; dcode++) {
            out_length += (ulg)s->dyn_dtree[dcode].Freq *
M
Mark Adler 已提交
1045
                (5L+extra_dbits[dcode]);
M
Mark Adler 已提交
1046 1047 1048 1049 1050 1051 1052
        }
        out_length >>= 3;
        Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
               s->last_lit, in_length, out_length,
               100L - out_length*100L/in_length));
        if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
    }
M
Mark Adler 已提交
1053
#endif
M
Mark Adler 已提交
1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065
    return (s->last_lit == s->lit_bufsize-1);
    /* We avoid equality with lit_bufsize because of wraparound at 64K
     * on 16 bit machines and because stored blocks are restricted to
     * 64K-1 bytes.
     */
}

/* ===========================================================================
 * Send the block data compressed using the given Huffman trees
 */
local void compress_block(s, ltree, dtree)
    deflate_state *s;
1066 1067
    const ct_data *ltree; /* literal tree */
    const ct_data *dtree; /* distance tree */
M
Mark Adler 已提交
1068 1069 1070 1071 1072 1073 1074 1075
{
    unsigned dist;      /* distance of matched string */
    int lc;             /* match length or unmatched char (if dist == 0) */
    unsigned lx = 0;    /* running index in l_buf */
    unsigned code;      /* the code to send */
    int extra;          /* number of extra bits to send */

    if (s->last_lit != 0) do {
M
Mark Adler 已提交
1076
        dist = s->d_buf[lx];
M
Mark Adler 已提交
1077 1078 1079 1080 1081 1082
        lc = s->l_buf[lx++];
        if (dist == 0) {
            send_code(s, lc, ltree); /* send a literal byte */
            Tracecv(isgraph(lc), (stderr," '%c' ", lc));
        } else {
            /* Here, lc is the match length - MIN_MATCH */
M
Mark Adler 已提交
1083
            code = _length_code[lc];
M
Mark Adler 已提交
1084 1085 1086 1087 1088 1089
            send_code(s, code+LITERALS+1, ltree); /* send the length code */
            extra = extra_lbits[code];
            if (extra != 0) {
                lc -= base_length[code];
                send_bits(s, lc, extra);       /* send the extra length bits */
            }
M
Mark Adler 已提交
1090
            dist--; /* dist is now the match distance - 1 */
M
Mark Adler 已提交
1091 1092 1093 1094 1095 1096
            code = d_code(dist);
            Assert (code < D_CODES, "bad d_code");

            send_code(s, code, dtree);       /* send the distance code */
            extra = extra_dbits[code];
            if (extra != 0) {
M
Mark Adler 已提交
1097
                dist -= (unsigned)base_dist[code];
M
Mark Adler 已提交
1098 1099 1100 1101
                send_bits(s, dist, extra);   /* send the extra distance bits */
            }
        } /* literal or match pair ? */

M
Mark Adler 已提交
1102
        /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
M
Mark Adler 已提交
1103 1104
        Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx,
               "pendingBuf overflow");
M
Mark Adler 已提交
1105 1106 1107 1108 1109 1110 1111

    } while (lx < s->last_lit);

    send_code(s, END_BLOCK, ltree);
}

/* ===========================================================================
M
Mark Adler 已提交
1112 1113 1114 1115 1116 1117 1118 1119 1120 1121
 * Check if the data type is TEXT or BINARY, using the following algorithm:
 * - TEXT if the two conditions below are satisfied:
 *    a) There are no non-portable control characters belonging to the
 *       "black list" (0..6, 14..25, 28..31).
 *    b) There is at least one printable character belonging to the
 *       "white list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255).
 * - BINARY otherwise.
 * - The following partially-portable control characters form a
 *   "gray list" that is ignored in this detection algorithm:
 *   (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}).
M
Mark Adler 已提交
1122
 * IN assertion: the fields Freq of dyn_ltree are set.
M
Mark Adler 已提交
1123
 */
M
Mark Adler 已提交
1124
local int detect_data_type(s)
M
Mark Adler 已提交
1125 1126
    deflate_state *s;
{
M
Mark Adler 已提交
1127 1128 1129 1130 1131
    /* black_mask is the bit mask of black-listed bytes
     * set bits 0..6, 14..25, and 28..31
     * 0xf3ffc07f = binary 11110011111111111100000001111111
     */
    unsigned long black_mask = 0xf3ffc07fUL;
M
Mark Adler 已提交
1132 1133
    int n;

M
Mark Adler 已提交
1134 1135 1136 1137 1138 1139 1140 1141 1142 1143
    /* Check for non-textual ("black-listed") bytes. */
    for (n = 0; n <= 31; n++, black_mask >>= 1)
        if ((black_mask & 1) && (s->dyn_ltree[n].Freq != 0))
            return Z_BINARY;

    /* Check for textual ("white-listed") bytes. */
    if (s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0
            || s->dyn_ltree[13].Freq != 0)
        return Z_TEXT;
    for (n = 32; n < LITERALS; n++)
M
Mark Adler 已提交
1144
        if (s->dyn_ltree[n].Freq != 0)
M
Mark Adler 已提交
1145 1146 1147 1148 1149 1150
            return Z_TEXT;

    /* There are no "black-listed" or "white-listed" bytes:
     * this stream either is empty or has tolerated ("gray-listed") bytes only.
     */
    return Z_BINARY;
M
Mark Adler 已提交
1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170
}

/* ===========================================================================
 * Reverse the first len bits of a code, using straightforward code (a faster
 * method would use a table)
 * IN assertion: 1 <= len <= 15
 */
local unsigned bi_reverse(code, len)
    unsigned code; /* the value to invert */
    int len;       /* its bit length */
{
    register unsigned res = 0;
    do {
        res |= code & 1;
        code >>= 1, res <<= 1;
    } while (--len > 0);
    return res >> 1;
}

/* ===========================================================================
M
Mark Adler 已提交
1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188
 * Flush the bit buffer, keeping at most 7 bits in it.
 */
local void bi_flush(s)
    deflate_state *s;
{
    if (s->bi_valid == 16) {
        put_short(s, s->bi_buf);
        s->bi_buf = 0;
        s->bi_valid = 0;
    } else if (s->bi_valid >= 8) {
        put_byte(s, (Byte)s->bi_buf);
        s->bi_buf >>= 8;
        s->bi_valid -= 8;
    }
}

/* ===========================================================================
 * Flush the bit buffer and align the output on a byte boundary
M
Mark Adler 已提交
1189 1190 1191 1192 1193 1194 1195
 */
local void bi_windup(s)
    deflate_state *s;
{
    if (s->bi_valid > 8) {
        put_short(s, s->bi_buf);
    } else if (s->bi_valid > 0) {
M
Mark Adler 已提交
1196
        put_byte(s, (Byte)s->bi_buf);
M
Mark Adler 已提交
1197 1198 1199
    }
    s->bi_buf = 0;
    s->bi_valid = 0;
1200
#ifdef ZLIB_DEBUG
M
Mark Adler 已提交
1201 1202 1203
    s->bits_sent = (s->bits_sent+7) & ~7;
#endif
}