varnish-cache/lib/libvgz/trees.c
0
/* trees.c -- output deflated data using Huffman coding
1
 * Copyright (C) 1995-2021 Jean-loup Gailly
2
 * detect_data_type() function provided freely by Cosmin Truta, 2006
3
 * For conditions of distribution and use, see copyright notice in zlib.h
4
 */
5
6
/*
7
 *  ALGORITHM
8
 *
9
 *      The "deflation" process uses several Huffman trees. The more
10
 *      common source values are represented by shorter bit sequences.
11
 *
12
 *      Each code tree is stored in a compressed form which is itself
13
 * a Huffman encoding of the lengths of all the code strings (in
14
 * ascending order by source values).  The actual code strings are
15
 * reconstructed from the lengths in the inflate process, as described
16
 * in the deflate specification.
17
 *
18
 *  REFERENCES
19
 *
20
 *      Deutsch, L.P.,"'Deflate' Compressed Data Format Specification".
21
 *      Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc
22
 *
23
 *      Storer, James A.
24
 *          Data Compression:  Methods and Theory, pp. 49-50.
25
 *          Computer Science Press, 1988.  ISBN 0-7167-8156-5.
26
 *
27
 *      Sedgewick, R.
28
 *          Algorithms, p290.
29
 *          Addison-Wesley, 1983. ISBN 0-201-06672-6.
30
 */
31
32
/* @(#) $Id$ */
33
34
/* #define GEN_TREES_H */
35
36
#include "deflate.h"
37
38
#ifdef ZLIB_DEBUG
39
#  include <ctype.h>
40
#endif
41
42
/* ===========================================================================
43
 * Constants
44
 */
45
46
#define MAX_BL_BITS 7
47
/* Bit length codes must not exceed MAX_BL_BITS bits */
48
49
#define END_BLOCK 256
50
/* end of block literal code */
51
52
#define REP_3_6      16
53
/* repeat previous bit length 3-6 times (2 bits of repeat count) */
54
55
#define REPZ_3_10    17
56
/* repeat a zero length 3-10 times  (3 bits of repeat count) */
57
58
#define REPZ_11_138  18
59
/* repeat a zero length 11-138 times  (7 bits of repeat count) */
60
61
local const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */
62
   = {0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5,0};
63
64
local const int extra_dbits[D_CODES] /* extra bits for each distance code */
65
   = {0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13};
66
67
local const int extra_blbits[BL_CODES]/* extra bits for each bit length code */
68
   = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};
69
70
local const uch bl_order[BL_CODES]
71
   = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};
72
/* The lengths of the bit length codes are sent in order of decreasing
73
 * probability, to avoid transmitting the lengths for unused bit length codes.
74
 */
75
76
/* ===========================================================================
77
 * Local data. These are initialized only once.
78
 */
79
80
#define DIST_CODE_LEN  512 /* see definition of array dist_code below */
81
82
#if defined(GEN_TREES_H) || !defined(STDC)
83
/* non ANSI compilers may not accept trees.h */
84
85
local ct_data static_ltree[L_CODES+2];
86
/* The static literal tree. Since the bit lengths are imposed, there is no
87
 * need for the L_CODES extra codes used during heap construction. However
88
 * The codes 286 and 287 are needed to build a canonical tree (see _tr_init
89
 * below).
90
 */
91
92
local ct_data static_dtree[D_CODES];
93
/* The static distance tree. (Actually a trivial tree since all codes use
94
 * 5 bits.)
95
 */
96
97
uch _dist_code[DIST_CODE_LEN];
98
/* Distance codes. The first 256 values correspond to the distances
99
 * 3 .. 258, the last 256 values correspond to the top 8 bits of
100
 * the 15 bit distances.
101
 */
102
103
uch _length_code[MAX_MATCH-MIN_MATCH+1];
104
/* length code for each normalized match length (0 == MIN_MATCH) */
105
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local int base_length[LENGTH_CODES];
107
/* First normalized length for each code (0 = MIN_MATCH) */
108
109
local int base_dist[D_CODES];
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/* First normalized distance for each code (0 = distance of 1) */
111
112
#else
113
#  include "trees.h"
114
#endif /* GEN_TREES_H */
115
116
struct static_tree_desc_s {
117
    const ct_data *static_tree;  /* static tree or NULL */
118
    const intf *extra_bits;      /* extra bits for each code or NULL */
119
    int     extra_base;          /* base index for extra_bits */
120
    int     elems;               /* max number of elements in the tree */
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    int     max_length;          /* max bit length for the codes */
122
};
123
124
#ifdef NO_INIT_GLOBAL_POINTERS
125
#  define TCONST
126
#else
127
#  define TCONST const
128
#endif
129
130
local TCONST static_tree_desc  static_l_desc =
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{static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};
132
133
local TCONST static_tree_desc  static_d_desc =
134
{static_dtree, extra_dbits, 0,          D_CODES, MAX_BITS};
135
136
local TCONST static_tree_desc  static_bl_desc =
137
{(const ct_data *)0, extra_blbits, 0,   BL_CODES, MAX_BL_BITS};
138
139
/* ===========================================================================
140
 * Output a short LSB first on the stream.
141
 * IN assertion: there is enough room in pendingBuf.
142
 */
143
#define put_short(s, w) { \
144
    put_byte(s, (uch)((w) & 0xff)); \
145
    put_byte(s, (uch)((ush)(w) >> 8)); \
146
}
147
148
/* ===========================================================================
149
 * Reverse the first len bits of a code, using straightforward code (a faster
150
 * method would use a table)
151
 * IN assertion: 1 <= len <= 15
152
 */
153 258179
local unsigned bi_reverse(unsigned code, int len) {
154 258179
    register unsigned res = 0;
155 258179
    do {
156 1142671
        res |= code & 1;
157 1142671
        code >>= 1, res <<= 1;
158 1142671
    } while (--len > 0);
159 258179
    return res >> 1;
160
}
161
162
/* ===========================================================================
163
 * Flush the bit buffer, keeping at most 7 bits in it.
164
 */
165 53846
local void bi_flush(deflate_state *s) {
166 53846
    if (s->bi_valid == 16) {
167 226
        put_short(s, s->bi_buf);
168 226
        s->bi_buf = 0;
169 226
        s->bi_valid = 0;
170 53846
    } else if (s->bi_valid >= 8) {
171 2994
        put_byte(s, (Byte)s->bi_buf);
172 2994
        s->bi_buf >>= 8;
173 2994
        s->bi_valid -= 8;
174 2994
    }
175 53846
}
176
177
/* ===========================================================================
178
 * Flush the bit buffer and align the output on a byte boundary
179
 */
180 22610
local void bi_windup(deflate_state *s) {
181 22610
    if (s->bi_valid > 8) {
182 3313
        put_short(s, s->bi_buf);
183 22610
    } else if (s->bi_valid > 0) {
184 19297
        put_byte(s, (Byte)s->bi_buf);
185 19297
    }
186 22610
    s->bi_buf = 0;
187 22610
    s->bi_valid = 0;
188
#ifdef ZLIB_DEBUG
189
    s->bits_sent = (s->bits_sent+7) & ~7;
190
#endif
191 22610
}
192
193
/* ===========================================================================
194
 * Generate the codes for a given tree and bit counts (which need not be
195
 * optimal).
196
 * IN assertion: the array bl_count contains the bit length statistics for
197
 * the given tree and the field len is set for all tree elements.
198
 * OUT assertion: the field code is set for all tree elements of non
199
 *     zero code length.
200
 */
201 30210
local void gen_codes(ct_data *tree, int max_code, ushf *bl_count) {
202
    ush next_code[MAX_BITS+1]; /* next code value for each bit length */
203 30210
    unsigned code = 0;         /* running code value */
204
    int bits;                  /* bit index */
205
    int n;                     /* code index */
206
207
    /* The distribution counts are first used to generate the code values
208
     * without bit reversal.
209
     */
210 483360
    for (bits = 1; bits <= MAX_BITS; bits++) {
211 453150
        code = (code + bl_count[bits-1]) << 1;
212 453150
        next_code[bits] = (ush)code;
213 453150
    }
214
    /* Check that the bit counts in bl_count are consistent. The last code
215
     * must be all ones.
216
     */
217
    Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
218
            "inconsistent bit counts");
219
    Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
220
221 2864861
    for (n = 0;  n <= max_code; n++) {
222 2834651
        int len = tree[n].Len;
223 2834651
        if (len == 0) continue;
224
        /* Now reverse the bits */
225 258179
        tree[n].Code = (ush)bi_reverse(next_code[len]++, len);
226
227
        Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
228
             n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
229 258179
    }
230 30210
}
231
232
#ifdef GEN_TREES_H
233
local void gen_trees_header (void);
234
#endif
235
236
#ifndef ZLIB_DEBUG
237
#  define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
238
   /* Send a code of the given tree. c and tree must not have side effects */
239
240
#else /* !ZLIB_DEBUG */
241
#  define send_code(s, c, tree) \
242
     { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
243
       send_bits(s, tree[c].Code, tree[c].Len); }
244
#endif
245
246
/* ===========================================================================
247
 * Send a value on a given number of bits.
248
 * IN assertion: length <= 16 and value fits in length bits.
249
 */
250
#ifdef ZLIB_DEBUG
251
local void send_bits(deflate_state *s, int value, int length) {
252
    Tracevv((stderr," l %2d v %4x ", length, value));
253
    Assert(length > 0 && length <= 15, "invalid length");
254
    s->bits_sent += (ulg)length;
255
256
    /* If not enough room in bi_buf, use (valid) bits from bi_buf and
257
     * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
258
     * unused bits in value.
259
     */
260
    if (s->bi_valid > (int)Buf_size - length) {
261
        s->bi_buf |= (ush)value << s->bi_valid;
262
        put_short(s, s->bi_buf);
263
        s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);
264
        s->bi_valid += length - Buf_size;
265
    } else {
266
        s->bi_buf |= (ush)value << s->bi_valid;
267
        s->bi_valid += length;
268
    }
269
}
270
#else /* !ZLIB_DEBUG */
271
272
#define send_bits(s, value, length) \
273
{ int len = length;\
274
  if (s->bi_valid > (int)Buf_size - len) {\
275
    int val = (int)value;\
276
    s->bi_buf |= (ush)val << s->bi_valid;\
277
    put_short(s, s->bi_buf);\
278
    s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
279
    s->bi_valid += len - Buf_size;\
280
  } else {\
281
    s->bi_buf |= (ush)(value) << s->bi_valid;\
282
    s->bi_valid += len;\
283
  }\
284
}
285
#endif /* ZLIB_DEBUG */
286
287
288
/* the arguments must not have side effects */
289
290
/* ===========================================================================
291
 * Initialize the various 'constant' tables.
292
 */
293 9766
local void tr_static_init(void) {
294
#if defined(GEN_TREES_H) || !defined(STDC)
295
    static int static_init_done = 0;
296
    int n;        /* iterates over tree elements */
297
    int bits;     /* bit counter */
298
    int length;   /* length value */
299
    int code;     /* code value */
300
    int dist;     /* distance index */
301
    ush bl_count[MAX_BITS+1];
302
    /* number of codes at each bit length for an optimal tree */
303
304
    if (static_init_done) return;
305
306
    /* For some embedded targets, global variables are not initialized: */
307
#ifdef NO_INIT_GLOBAL_POINTERS
308
    static_l_desc.static_tree = static_ltree;
309
    static_l_desc.extra_bits = extra_lbits;
310
    static_d_desc.static_tree = static_dtree;
311
    static_d_desc.extra_bits = extra_dbits;
312
    static_bl_desc.extra_bits = extra_blbits;
313
#endif
314
315
    /* Initialize the mapping length (0..255) -> length code (0..28) */
316
    length = 0;
317
    for (code = 0; code < LENGTH_CODES-1; code++) {
318
        base_length[code] = length;
319
        for (n = 0; n < (1<<extra_lbits[code]); n++) {
320
            _length_code[length++] = (uch)code;
321
        }
322
    }
323
    Assert (length == 256, "tr_static_init: length != 256");
324
    /* Note that the length 255 (match length 258) can be represented
325
     * in two different ways: code 284 + 5 bits or code 285, so we
326
     * overwrite length_code[255] to use the best encoding:
327
     */
328
    _length_code[length-1] = (uch)code;
329
330
    /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
331
    dist = 0;
332
    for (code = 0 ; code < 16; code++) {
333
        base_dist[code] = dist;
334
        for (n = 0; n < (1<<extra_dbits[code]); n++) {
335
            _dist_code[dist++] = (uch)code;
336
        }
337
    }
338
    Assert (dist == 256, "tr_static_init: dist != 256");
339
    dist >>= 7; /* from now on, all distances are divided by 128 */
340
    for ( ; code < D_CODES; code++) {
341
        base_dist[code] = dist << 7;
342
        for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
343
            _dist_code[256 + dist++] = (uch)code;
344
        }
345
    }
346
    Assert (dist == 256, "tr_static_init: 256+dist != 512");
347
348
    /* Construct the codes of the static literal tree */
349
    for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
350
    n = 0;
351
    while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
352
    while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
353
    while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
354
    while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
355
    /* Codes 286 and 287 do not exist, but we must include them in the
356
     * tree construction to get a canonical Huffman tree (longest code
357
     * all ones)
358
     */
359
    gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);
360
361
    /* The static distance tree is trivial: */
362
    for (n = 0; n < D_CODES; n++) {
363
        static_dtree[n].Len = 5;
364
        static_dtree[n].Code = bi_reverse((unsigned)n, 5);
365
    }
366
    static_init_done = 1;
367
368
#  ifdef GEN_TREES_H
369
    gen_trees_header();
370
#  endif
371
#endif /* defined(GEN_TREES_H) || !defined(STDC) */
372 9766
}
373
374
/* ===========================================================================
375
 * Generate the file trees.h describing the static trees.
376
 */
377
#ifdef GEN_TREES_H
378
#  ifndef ZLIB_DEBUG
379
#    include <stdio.h>
380
#  endif
381
382
#  define SEPARATOR(i, last, width) \
383
      ((i) == (last)? "\n};\n\n" :    \
384
       ((i) % (width) == (width)-1 ? ",\n" : ", "))
385
386
void gen_trees_header(void) {
387
    FILE *header = fopen("trees.h", "w");
388
    int i;
389
390
    Assert (header != NULL, "Can't open trees.h");
391
    fprintf(header,
392
            "/* header created automatically with -DGEN_TREES_H */\n\n");
393
394
    fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n");
395
    for (i = 0; i < L_CODES+2; i++) {
396
        fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code,
397
                static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5));
398
    }
399
400
    fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n");
401
    for (i = 0; i < D_CODES; i++) {
402
        fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code,
403
                static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5));
404
    }
405
406
    fprintf(header, "const uch ZLIB_INTERNAL _dist_code[DIST_CODE_LEN] = {\n");
407
    for (i = 0; i < DIST_CODE_LEN; i++) {
408
        fprintf(header, "%2u%s", _dist_code[i],
409
                SEPARATOR(i, DIST_CODE_LEN-1, 20));
410
    }
411
412
    fprintf(header,
413
        "const uch ZLIB_INTERNAL _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");
414
    for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) {
415
        fprintf(header, "%2u%s", _length_code[i],
416
                SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));
417
    }
418
419
    fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");
420
    for (i = 0; i < LENGTH_CODES; i++) {
421
        fprintf(header, "%1u%s", base_length[i],
422
                SEPARATOR(i, LENGTH_CODES-1, 20));
423
    }
424
425
    fprintf(header, "local const int base_dist[D_CODES] = {\n");
426
    for (i = 0; i < D_CODES; i++) {
427
        fprintf(header, "%5u%s", base_dist[i],
428
                SEPARATOR(i, D_CODES-1, 10));
429
    }
430
431
    fclose(header);
432
}
433
#endif /* GEN_TREES_H */
434
435
/* ===========================================================================
436
 * Initialize a new block.
437
 */
438 19836
local void init_block(deflate_state *s) {
439
    int n; /* iterates over tree elements */
440
441
    /* Initialize the trees. */
442 5692932
    for (n = 0; n < L_CODES;  n++) s->dyn_ltree[n].Freq = 0;
443 614916
    for (n = 0; n < D_CODES;  n++) s->dyn_dtree[n].Freq = 0;
444 396720
    for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;
445
446 19836
    s->dyn_ltree[END_BLOCK].Freq = 1;
447 19836
    s->opt_len = s->static_len = 0L;
448 19836
    s->sym_next = s->matches = 0;
449 19836
}
450
451
/* ===========================================================================
452
 * Initialize the tree data structures for a new zlib stream.
453
 */
454 9766
void ZLIB_INTERNAL _tr_init(deflate_state *s) {
455 9766
    tr_static_init();
456
457 9766
    s->l_desc.dyn_tree = s->dyn_ltree;
458 9766
    s->l_desc.stat_desc = &static_l_desc;
459
460 9766
    s->d_desc.dyn_tree = s->dyn_dtree;
461 9766
    s->d_desc.stat_desc = &static_d_desc;
462
463 9766
    s->bl_desc.dyn_tree = s->bl_tree;
464 9766
    s->bl_desc.stat_desc = &static_bl_desc;
465
466 9766
    s->bi_buf = 0;
467 9766
    s->bi_valid = 0;
468
#ifdef ZLIB_DEBUG
469
    s->compressed_len = 0L;
470
    s->bits_sent = 0L;
471
#endif
472
473
    /* Initialize the first block of the first file: */
474 9766
    init_block(s);
475 9766
}
476
477
#define SMALLEST 1
478
/* Index within the heap array of least frequent node in the Huffman tree */
479
480
481
/* ===========================================================================
482
 * Remove the smallest element from the heap and recreate the heap with
483
 * one less element. Updates heap and heap_len.
484
 */
485
#define pqremove(s, tree, top) \
486
{\
487
    top = s->heap[SMALLEST]; \
488
    s->heap[SMALLEST] = s->heap[s->heap_len--]; \
489
    pqdownheap(s, tree, SMALLEST); \
490
}
491
492
/* ===========================================================================
493
 * Compares to subtrees, using the tree depth as tie breaker when
494
 * the subtrees have equal frequency. This minimizes the worst case length.
495
 */
496
#define smaller(tree, n, m, depth) \
497
   (tree[n].Freq < tree[m].Freq || \
498
   (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
499
500
/* ===========================================================================
501
 * Restore the heap property by moving down the tree starting at node k,
502
 * exchanging a node with the smallest of its two sons if necessary, stopping
503
 * when the heap property is re-established (each father smaller than its
504
 * two sons).
505
 */
506 581316
local void pqdownheap(deflate_state *s, ct_data *tree, int k) {
507 581316
    int v = s->heap[k];
508 581316
    int j = k << 1;  /* left son of k */
509 1652105
    while (j <= s->heap_len) {
510
        /* Set j to the smallest of the two sons: */
511 1903326
        if (j < s->heap_len &&
512 1165895
            smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
513 627792
            j++;
514 627792
        }
515
        /* Exit if v is smaller than both sons */
516 1267144
        if (smaller(tree, v, s->heap[j], s->depth)) break;
517
518
        /* Exchange v with the smallest son */
519 1070789
        s->heap[k] = s->heap[j];  k = j;
520
521
        /* And continue down the tree, setting j to the left son of k */
522 1070789
        j <<= 1;
523
    }
524 581316
    s->heap[k] = v;
525 581316
}
526
527
/* ===========================================================================
528
 * Compute the optimal bit lengths for a tree and update the total bit length
529
 * for the current block.
530
 * IN assertion: the fields freq and dad are set, heap[heap_max] and
531
 *    above are the tree nodes sorted by increasing frequency.
532
 * OUT assertions: the field len is set to the optimal bit length, the
533
 *     array bl_count contains the frequencies for each bit length.
534
 *     The length opt_len is updated; static_len is also updated if stree is
535
 *     not null.
536
 */
537 30210
local void gen_bitlen(deflate_state *s, tree_desc *desc) {
538 30210
    ct_data *tree        = desc->dyn_tree;
539 30210
    int max_code         = desc->max_code;
540 30210
    const ct_data *stree = desc->stat_desc->static_tree;
541 30210
    const intf *extra    = desc->stat_desc->extra_bits;
542 30210
    int base             = desc->stat_desc->extra_base;
543 30210
    int max_length       = desc->stat_desc->max_length;
544
    int h;              /* heap index */
545
    int n, m;           /* iterate over the tree elements */
546
    int bits;           /* bit length */
547
    int xbits;          /* extra bits */
548
    ush f;              /* frequency */
549 30210
    int overflow = 0;   /* number of elements with bit length too large */
550
551 513570
    for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
552
553
    /* In a first pass, compute the optimal bit lengths (which may
554
     * overflow in the case of the bit length tree).
555
     */
556 30210
    tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
557
558 486148
    for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
559 455938
        n = s->heap[h];
560 455938
        bits = tree[tree[n].Dad].Len + 1;
561 455938
        if (bits > max_length) bits = max_length, overflow++;
562 455938
        tree[n].Len = (ush)bits;
563
        /* We overwrite tree[n].Dad which is no longer needed */
564
565 455938
        if (n > max_code) continue; /* not a leaf node */
566
567 258179
        s->bl_count[bits]++;
568 258179
        xbits = 0;
569 258179
        if (n >= base) xbits = extra[n-base];
570 258179
        f = tree[n].Freq;
571 258179
        s->opt_len += (ulg)f * (unsigned)(bits + xbits);
572 258179
        if (stree) s->static_len += (ulg)f * (unsigned)(stree[n].Len + xbits);
573 258179
    }
574 30210
    if (overflow == 0) return;
575
576
    Tracev((stderr,"\nbit length overflow\n"));
577
    /* This happens for example on obj2 and pic of the Calgary corpus */
578
579
    /* Find the first bit length which could increase: */
580 0
    do {
581 0
        bits = max_length-1;
582 0
        while (s->bl_count[bits] == 0) bits--;
583 0
        s->bl_count[bits]--;      /* move one leaf down the tree */
584 0
        s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
585 0
        s->bl_count[max_length]--;
586
        /* The brother of the overflow item also moves one step up,
587
         * but this does not affect bl_count[max_length]
588
         */
589 0
        overflow -= 2;
590 0
    } while (overflow > 0);
591
592
    /* Now recompute all bit lengths, scanning in increasing frequency.
593
     * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
594
     * lengths instead of fixing only the wrong ones. This idea is taken
595
     * from 'ar' written by Haruhiko Okumura.)
596
     */
597 0
    for (bits = max_length; bits != 0; bits--) {
598 0
        n = s->bl_count[bits];
599 0
        while (n != 0) {
600 0
            m = s->heap[--h];
601 0
            if (m > max_code) continue;
602 0
            if ((unsigned) tree[m].Len != (unsigned) bits) {
603
                Tracev((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
604 0
                s->opt_len += ((ulg)bits - tree[m].Len) * tree[m].Freq;
605 0
                tree[m].Len = (ush)bits;
606 0
            }
607 0
            n--;
608
        }
609 0
    }
610 30210
}
611
612
#ifdef DUMP_BL_TREE
613
#  include <stdio.h>
614
#endif
615
616
/* ===========================================================================
617
 * Construct one Huffman tree and assigns the code bit strings and lengths.
618
 * Update the total bit length for the current block.
619
 * IN assertion: the field freq is set for all tree elements.
620
 * OUT assertions: the fields len and code are set to the optimal bit length
621
 *     and corresponding code. The length opt_len is updated; static_len is
622
 *     also updated if stree is not null. The field max_code is set.
623
 */
624 30210
local void build_tree(deflate_state *s, tree_desc *desc) {
625 30210
    ct_data *tree         = desc->dyn_tree;
626 30210
    const ct_data *stree  = desc->stat_desc->static_tree;
627 30210
    int elems             = desc->stat_desc->elems;
628
    int n, m;          /* iterate over heap elements */
629 30210
    int max_code = -1; /* largest code with non zero frequency */
630
    int node;          /* new node being created */
631
632
    /* Construct the initial heap, with least frequent element in
633
     * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
634
     * heap[0] is not used.
635
     */
636 30210
    s->heap_len = 0, s->heap_max = HEAP_SIZE;
637
638 3403660
    for (n = 0; n < elems; n++) {
639 3373450
        if (tree[n].Freq != 0) {
640 238634
            s->heap[++(s->heap_len)] = max_code = n;
641 238634
            s->depth[n] = 0;
642 238634
        } else {
643 3134816
            tree[n].Len = 0;
644
        }
645 3373450
    }
646
647
    /* The pkzip format requires that at least one distance code exists,
648
     * and that at least one bit should be sent even if there is only one
649
     * possible code. So to avoid special checks later on we force at least
650
     * two codes of non zero frequency.
651
     */
652 49755
    while (s->heap_len < 2) {
653 19545
        node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
654 19545
        tree[node].Freq = 1;
655 19545
        s->depth[node] = 0;
656 19545
        s->opt_len--; if (stree) s->static_len -= stree[node].Len;
657
        /* node is 0 or 1 so it does not have extra bits */
658
    }
659 30210
    desc->max_code = max_code;
660
661
    /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
662
     * establish sub-heaps of increasing lengths:
663
     */
664 155588
    for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
665
666
    /* Construct the Huffman tree by repeatedly combining the least two
667
     * frequent nodes.
668
     */
669 30210
    node = elems;              /* next internal node of the tree */
670 30210
    do {
671 227969
        pqremove(s, tree, n);  /* n = node of least frequency */
672 227969
        m = s->heap[SMALLEST]; /* m = node of next least frequency */
673
674 227969
        s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
675 227969
        s->heap[--(s->heap_max)] = m;
676
677
        /* Create a new node father of n and m */
678 227969
        tree[node].Freq = tree[n].Freq + tree[m].Freq;
679 227969
        s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?
680 227969
                                s->depth[n] : s->depth[m]) + 1);
681 227969
        tree[n].Dad = tree[m].Dad = (ush)node;
682
#ifdef DUMP_BL_TREE
683
        if (tree == s->bl_tree) {
684
            fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
685
                    node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
686
        }
687
#endif
688
        /* and insert the new node in the heap */
689 227969
        s->heap[SMALLEST] = node++;
690 227969
        pqdownheap(s, tree, SMALLEST);
691
692 227969
    } while (s->heap_len >= 2);
693
694 30210
    s->heap[--(s->heap_max)] = s->heap[SMALLEST];
695
696
    /* At this point, the fields freq and dad are set. We can now
697
     * generate the bit lengths.
698
     */
699 30210
    gen_bitlen(s, (tree_desc *)desc);
700
701
    /* The field len is now set, we can generate the bit codes */
702 30210
    gen_codes ((ct_data *)tree, max_code, s->bl_count);
703 30210
}
704
705
/* ===========================================================================
706
 * Scan a literal or distance tree to determine the frequencies of the codes
707
 * in the bit length tree.
708
 */
709 20140
local void scan_tree(deflate_state *s, ct_data *tree, int max_code) {
710
    int n;                     /* iterates over all tree elements */
711 20140
    int prevlen = -1;          /* last emitted length */
712
    int curlen;                /* length of current code */
713 20140
    int nextlen = tree[0].Len; /* length of next code */
714 20140
    int count = 0;             /* repeat count of the current code */
715 20140
    int max_count = 7;         /* max repeat count */
716 20140
    int min_count = 4;         /* min repeat count */
717
718 20140
    if (nextlen == 0) max_count = 138, min_count = 3;
719 20140
    tree[max_code+1].Len = (ush)0xffff; /* guard */
720
721 2663461
    for (n = 0; n <= max_code; n++) {
722 2643321
        curlen = nextlen; nextlen = tree[n+1].Len;
723 2643321
        if (++count < max_count && curlen == nextlen) {
724 2403527
            continue;
725 239794
        } else if (count < min_count) {
726 187420
            s->bl_tree[curlen].Freq += count;
727 239794
        } else if (curlen != 0) {
728 4066
            if (curlen != prevlen) s->bl_tree[curlen].Freq++;
729 4066
            s->bl_tree[REP_3_6].Freq++;
730 52374
        } else if (count <= 10) {
731 17954
            s->bl_tree[REPZ_3_10].Freq++;
732 17954
        } else {
733 30354
            s->bl_tree[REPZ_11_138].Freq++;
734
        }
735 239794
        count = 0; prevlen = curlen;
736 239794
        if (nextlen == 0) {
737 80608
            max_count = 138, min_count = 3;
738 239794
        } else if (curlen == nextlen) {
739 889
            max_count = 6, min_count = 3;
740 889
        } else {
741 158297
            max_count = 7, min_count = 4;
742
        }
743 239794
    }
744 20140
}
745
746
/* ===========================================================================
747
 * Send a literal or distance tree in compressed form, using the codes in
748
 * bl_tree.
749
 */
750 228
local void send_tree(deflate_state *s, ct_data *tree, int max_code) {
751
    int n;                     /* iterates over all tree elements */
752 228
    int prevlen = -1;          /* last emitted length */
753
    int curlen;                /* length of current code */
754 228
    int nextlen = tree[0].Len; /* length of next code */
755 228
    int count = 0;             /* repeat count of the current code */
756 228
    int max_count = 7;         /* max repeat count */
757 228
    int min_count = 4;         /* min repeat count */
758
759
    /* tree[max_code+1].Len = -1; */  /* guard already set */
760 228
    if (nextlen == 0) max_count = 138, min_count = 3;
761
762 31958
    for (n = 0; n <= max_code; n++) {
763 31730
        curlen = nextlen; nextlen = tree[n+1].Len;
764 31730
        if (++count < max_count && curlen == nextlen) {
765 26866
            continue;
766 4864
        } else if (count < min_count) {
767 4484
            do { send_code(s, curlen, s->bl_tree); } while (--count != 0);
768
769 4864
        } else if (curlen != 0) {
770 342
            if (curlen != prevlen) {
771 304
                send_code(s, curlen, s->bl_tree); count--;
772 304
            }
773
            Assert(count >= 3 && count <= 6, " 3_6?");
774 342
            send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);
775
776 1292
        } else if (count <= 10) {
777 418
            send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);
778
779 418
        } else {
780 532
            send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
781
        }
782 4864
        count = 0; prevlen = curlen;
783 4864
        if (nextlen == 0) {
784 1292
            max_count = 138, min_count = 3;
785 4864
        } else if (curlen == nextlen) {
786 76
            max_count = 6, min_count = 3;
787 76
        } else {
788 3496
            max_count = 7, min_count = 4;
789
        }
790 4864
    }
791 228
}
792
793
/* ===========================================================================
794
 * Construct the Huffman tree for the bit lengths and return the index in
795
 * bl_order of the last bit length code to send.
796
 */
797 10070
local int build_bl_tree(deflate_state *s) {
798
    int max_blindex;  /* index of last bit length code of non zero freq */
799
800
    /* Determine the bit length frequencies for literal and distance trees */
801 10070
    scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
802 10070
    scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);
803
804
    /* Build the bit length tree: */
805 10070
    build_tree(s, (tree_desc *)(&(s->bl_desc)));
806
    /* opt_len now includes the length of the tree representations, except the
807
     * lengths of the bit lengths codes and the 5 + 5 + 4 bits for the counts.
808
     */
809
810
    /* Determine the number of bit length codes to send. The pkzip format
811
     * requires that at least 4 bit length codes be sent. (appnote.txt says
812
     * 3 but the actual value used is 4.)
813
     */
814 20446
    for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
815 20446
        if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
816 10376
    }
817
    /* Update opt_len to include the bit length tree and counts */
818 10070
    s->opt_len += 3*((ulg)max_blindex+1) + 5+5+4;
819
    Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
820
            s->opt_len, s->static_len));
821
822 10070
    return max_blindex;
823
}
824
825
/* ===========================================================================
826
 * Send the header for a block using dynamic Huffman trees: the counts, the
827
 * lengths of the bit length codes, the literal tree and the distance tree.
828
 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
829
 */
830 114
local void send_all_trees(deflate_state *s, int lcodes, int dcodes,
831
                          int blcodes) {
832
    int rank;                    /* index in bl_order */
833
834
    Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
835
    Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
836
            "too many codes");
837
    Tracev((stderr, "\nbl counts: "));
838 114
    send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
839 114
    send_bits(s, dcodes-1,   5);
840 114
    send_bits(s, blcodes-4,  4); /* not -3 as stated in appnote.txt */
841 2090
    for (rank = 0; rank < blcodes; rank++) {
842
        Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
843 1976
        send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
844 1976
    }
845
    Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));
846
847 114
    send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
848
    Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));
849
850 114
    send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
851
    Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
852 114
}
853
854
/* ===========================================================================
855
 * Send a stored block
856
 */
857 19152
void ZLIB_INTERNAL _tr_stored_block(deflate_state *s, charf *buf,
858
                                    ulg stored_len, int last) {
859 19152
    if (last)
860 6118
        s->strm->last_bit =
861 6118
           (s->strm->total_out + s->pending) * 8 + s->bi_valid;
862
863 19152
    send_bits(s, (STORED_BLOCK<<1)+last, 3);    /* send block type */
864 19152
    bi_windup(s);        /* align on byte boundary */
865 19152
    put_short(s, (ush)stored_len);
866 19152
    put_short(s, (ush)~stored_len);
867 19152
    if (stored_len)
868 1520
        zmemcpy(s->pending_buf + s->pending, (Bytef *)buf, stored_len);
869 19152
    s->pending += stored_len;
870
#ifdef ZLIB_DEBUG
871
    s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
872
    s->compressed_len += (stored_len + 4) << 3;
873
    s->bits_sent += 2*16;
874
    s->bits_sent += stored_len<<3;
875
#endif
876 19152
    if (last)
877 6118
        s->strm->stop_bit =
878 6118
           (s->strm->total_out + s->pending) * 8 + s->bi_valid;
879 19152
}
880
881
/* ===========================================================================
882
 * Flush the bits in the bit buffer to pending output (leaves at most 7 bits)
883
 */
884 53846
void ZLIB_INTERNAL _tr_flush_bits(deflate_state *s) {
885 53846
    bi_flush(s);
886 53846
}
887
888
/* ===========================================================================
889
 * Send one empty static block to give enough lookahead for inflate.
890
 * This takes 10 bits, of which 7 may remain in the bit buffer.
891
 */
892 0
void ZLIB_INTERNAL _tr_align(deflate_state *s) {
893 0
    send_bits(s, STATIC_TREES<<1, 3);
894 0
    send_code(s, END_BLOCK, static_ltree);
895
#ifdef ZLIB_DEBUG
896
    s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
897
#endif
898 0
    bi_flush(s);
899 0
}
900
901
/* ===========================================================================
902
 * Send the block data compressed using the given Huffman trees
903
 */
904 10070
local void compress_block(deflate_state *s, const ct_data *ltree,
905
                          const ct_data *dtree) {
906
    unsigned dist;      /* distance of matched string */
907
    int lc;             /* match length or unmatched char (if dist == 0) */
908 10070
    unsigned sx = 0;    /* running index in sym_buf */
909
    unsigned code;      /* the code to send */
910
    int extra;          /* number of extra bits to send */
911
912 10070
    if (s->sym_next != 0) do {
913 274263
        dist = s->sym_buf[sx++] & 0xff;
914 274263
        dist += (unsigned)(s->sym_buf[sx++] & 0xff) << 8;
915 274263
        lc = s->sym_buf[sx++];
916 274263
        if (dist == 0) {
917 268859
            send_code(s, lc, ltree); /* send a literal byte */
918
            Tracecv(isgraph(lc), (stderr," '%c' ", lc));
919 268859
        } else {
920
            /* Here, lc is the match length - MIN_MATCH */
921 5404
            code = _length_code[lc];
922 5404
            send_code(s, code + LITERALS + 1, ltree);   /* send length code */
923 5404
            extra = extra_lbits[code];
924 5404
            if (extra != 0) {
925 1406
                lc -= base_length[code];
926 1406
                send_bits(s, lc, extra);       /* send the extra length bits */
927 1406
            }
928 5404
            dist--; /* dist is now the match distance - 1 */
929 5404
            code = d_code(dist);
930
            Assert (code < D_CODES, "bad d_code");
931
932 5404
            send_code(s, code, dtree);       /* send the distance code */
933 5404
            extra = extra_dbits[code];
934 5404
            if (extra != 0) {
935 4794
                dist -= (unsigned)base_dist[code];
936 4794
                send_bits(s, dist, extra);   /* send the extra distance bits */
937 4794
            }
938
        } /* literal or match pair ? */
939
940
        /* Check that the overlay between pending_buf and sym_buf is ok: */
941
        Assert(s->pending < s->lit_bufsize + sx, "pendingBuf overflow");
942
943 274263
    } while (sx < s->sym_next);
944
945 10070
    send_code(s, END_BLOCK, ltree);
946 10070
}
947
948
/* ===========================================================================
949
 * Check if the data type is TEXT or BINARY, using the following algorithm:
950
 * - TEXT if the two conditions below are satisfied:
951
 *    a) There are no non-portable control characters belonging to the
952
 *       "block list" (0..6, 14..25, 28..31).
953
 *    b) There is at least one printable character belonging to the
954
 *       "allow list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255).
955
 * - BINARY otherwise.
956
 * - The following partially-portable control characters form a
957
 *   "gray list" that is ignored in this detection algorithm:
958
 *   (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}).
959
 * IN assertion: the fields Freq of dyn_ltree are set.
960
 */
961 3458
local int detect_data_type(deflate_state *s) {
962
    /* block_mask is the bit mask of block-listed bytes
963
     * set bits 0..6, 14..25, and 28..31
964
     * 0xf3ffc07f = binary 11110011111111111100000001111111
965
     */
966 3458
    unsigned long block_mask = 0xf3ffc07fUL;
967
    int n;
968
969
    /* Check for non-textual ("block-listed") bytes. */
970 114114
    for (n = 0; n <= 31; n++, block_mask >>= 1)
971 110656
        if ((block_mask & 1) && (s->dyn_ltree[n].Freq != 0))
972 0
            return Z_BINARY;
973
974
    /* Check for textual ("allow-listed") bytes. */
975 3458
    if (s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0
976 3116
            || s->dyn_ltree[13].Freq != 0)
977 760
        return Z_TEXT;
978 68438
    for (n = 32; n < LITERALS; n++)
979 68438
        if (s->dyn_ltree[n].Freq != 0)
980 2698
            return Z_TEXT;
981
982
    /* There are no "block-listed" or "allow-listed" bytes:
983
     * this stream either is empty or has tolerated ("gray-listed") bytes only.
984
     */
985 0
    return Z_BINARY;
986 3458
}
987
988
/* ===========================================================================
989
 * Determine the best encoding for the current block: dynamic trees, static
990
 * trees or store, and write out the encoded block.
991
 */
992 10070
void ZLIB_INTERNAL _tr_flush_block(deflate_state *s, charf *buf,
993
                                   ulg stored_len, int last) {
994
    ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
995 10070
    int max_blindex = 0;  /* index of last bit length code of non zero freq */
996
997 10070
    if (last)
998 3458
        s->strm->last_bit =
999 3458
           (s->strm->total_out + s->pending) * 8 + s->bi_valid;
1000
1001
    /* Build the Huffman trees unless a stored block is forced */
1002 10070
    if (s->level > 0) {
1003
1004
        /* Check if the file is binary or text */
1005 10070
        if (s->strm->data_type == Z_UNKNOWN)
1006 3458
            s->strm->data_type = detect_data_type(s);
1007
1008
        /* Construct the literal and distance trees */
1009 10070
        build_tree(s, (tree_desc *)(&(s->l_desc)));
1010
        Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
1011
                s->static_len));
1012
1013 10070
        build_tree(s, (tree_desc *)(&(s->d_desc)));
1014
        Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
1015
                s->static_len));
1016
        /* At this point, opt_len and static_len are the total bit lengths of
1017
         * the compressed block data, excluding the tree representations.
1018
         */
1019
1020
        /* Build the bit length tree for the above two trees, and get the index
1021
         * in bl_order of the last bit length code to send.
1022
         */
1023 10070
        max_blindex = build_bl_tree(s);
1024
1025
        /* Determine the best encoding. Compute the block lengths in bytes. */
1026 10070
        opt_lenb = (s->opt_len+3+7)>>3;
1027 10070
        static_lenb = (s->static_len+3+7)>>3;
1028
1029
        Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
1030
                opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
1031
                s->sym_next / 3));
1032
1033
#ifndef FORCE_STATIC
1034 10070
        if (static_lenb <= opt_lenb || s->strategy == Z_FIXED)
1035
#endif
1036 9956
            opt_lenb = static_lenb;
1037
1038 10070
    } else {
1039
        Assert(buf != (char*)0, "lost buf");
1040 0
        opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
1041
    }
1042
1043
#ifdef FORCE_STORED
1044
    if (buf != (char*)0) { /* force stored block */
1045
#else
1046 10070
    if (stored_len+4 <= opt_lenb && buf != (char*)0) {
1047
                       /* 4: two words for the lengths */
1048
#endif
1049
        /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
1050
         * Otherwise we can't have processed more than WSIZE input bytes since
1051
         * the last block flush, because compression would have been
1052
         * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
1053
         * transform a block into a stored block.
1054
         */
1055 0
        _tr_stored_block(s, buf, stored_len, last);
1056
1057 10070
    } else if (static_lenb == opt_lenb) {
1058 9956
        send_bits(s, (STATIC_TREES<<1)+last, 3);
1059 9956
        compress_block(s, (const ct_data *)static_ltree,
1060
                       (const ct_data *)static_dtree);
1061
#ifdef ZLIB_DEBUG
1062
        s->compressed_len += 3 + s->static_len;
1063
#endif
1064 9956
    } else {
1065 114
        send_bits(s, (DYN_TREES<<1)+last, 3);
1066 228
        send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
1067 114
                       max_blindex+1);
1068 228
        compress_block(s, (const ct_data *)s->dyn_ltree,
1069 114
                       (const ct_data *)s->dyn_dtree);
1070
#ifdef ZLIB_DEBUG
1071
        s->compressed_len += 3 + s->opt_len;
1072
#endif
1073
    }
1074
    Assert (s->compressed_len == s->bits_sent, "bad compressed size");
1075
    /* The above check is made mod 2^32, for files larger than 512 MB
1076
     * and uLong implemented on 32 bits.
1077
     */
1078 10070
    init_block(s);
1079
1080 10070
    if (last) {
1081 3458
        s->strm->stop_bit =
1082 3458
           (s->strm->total_out + s->pending) * 8 + s->bi_valid;
1083 3458
        bi_windup(s);
1084
#ifdef ZLIB_DEBUG
1085
        s->compressed_len += 7;  /* align on byte boundary */
1086
#endif
1087 3458
    }
1088
    Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
1089
           s->compressed_len-7*last));
1090 10070
}
1091
1092
/* ===========================================================================
1093
 * Save the match info and tally the frequency counts. Return true if
1094
 * the current block must be flushed.
1095
 */
1096 0
int ZLIB_INTERNAL _tr_tally(deflate_state *s, unsigned dist, unsigned lc) {
1097 0
    s->sym_buf[s->sym_next++] = (uch)dist;
1098 0
    s->sym_buf[s->sym_next++] = (uch)(dist >> 8);
1099 0
    s->sym_buf[s->sym_next++] = (uch)lc;
1100 0
    if (dist == 0) {
1101
        /* lc is the unmatched char */
1102 0
        s->dyn_ltree[lc].Freq++;
1103 0
    } else {
1104 0
        s->matches++;
1105
        /* Here, lc is the match length - MIN_MATCH */
1106 0
        dist--;             /* dist = match distance - 1 */
1107
        Assert((ush)dist < (ush)MAX_DIST(s) &&
1108
               (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
1109
               (ush)d_code(dist) < (ush)D_CODES,  "_tr_tally: bad match");
1110
1111 0
        s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
1112 0
        s->dyn_dtree[d_code(dist)].Freq++;
1113
    }
1114 0
    return (s->sym_next == s->sym_end);
1115
}