varnish-cache/lib/libvgz/trees.c
1
/* trees.c -- output deflated data using Huffman coding
2
 * Copyright (C) 1995-2017 Jean-loup Gailly
3
 * detect_data_type() function provided freely by Cosmin Truta, 2006
4
 * For conditions of distribution and use, see copyright notice in zlib.h
5
 */
6
7
/*
8
 *  ALGORITHM
9
 *
10
 *      The "deflation" process uses several Huffman trees. The more
11
 *      common source values are represented by shorter bit sequences.
12
 *
13
 *      Each code tree is stored in a compressed form which is itself
14
 * a Huffman encoding of the lengths of all the code strings (in
15
 * ascending order by source values).  The actual code strings are
16
 * reconstructed from the lengths in the inflate process, as described
17
 * in the deflate specification.
18
 *
19
 *  REFERENCES
20
 *
21
 *      Deutsch, L.P.,"'Deflate' Compressed Data Format Specification".
22
 *      Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc
23
 *
24
 *      Storer, James A.
25
 *          Data Compression:  Methods and Theory, pp. 49-50.
26
 *          Computer Science Press, 1988.  ISBN 0-7167-8156-5.
27
 *
28
 *      Sedgewick, R.
29
 *          Algorithms, p290.
30
 *          Addison-Wesley, 1983. ISBN 0-201-06672-6.
31
 */
32
33
/* @(#) $Id$ */
34
35
/* #define GEN_TREES_H */
36
37
#include "deflate.h"
38
39
#ifdef ZLIB_DEBUG
40
#  include <ctype.h>
41
#endif
42
43
/* ===========================================================================
44
 * Constants
45
 */
46
47
#define MAX_BL_BITS 7
48
/* Bit length codes must not exceed MAX_BL_BITS bits */
49
50
#define END_BLOCK 256
51
/* end of block literal code */
52
53
#define REP_3_6      16
54
/* repeat previous bit length 3-6 times (2 bits of repeat count) */
55
56
#define REPZ_3_10    17
57
/* repeat a zero length 3-10 times  (3 bits of repeat count) */
58
59
#define REPZ_11_138  18
60
/* repeat a zero length 11-138 times  (7 bits of repeat count) */
61
62
local const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */
63
   = {0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5,0};
64
65
local const int extra_dbits[D_CODES] /* extra bits for each distance code */
66
   = {0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13};
67
68
local const int extra_blbits[BL_CODES]/* extra bits for each bit length code */
69
   = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};
70
71
local const uch bl_order[BL_CODES]
72
   = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};
73
/* The lengths of the bit length codes are sent in order of decreasing
74
 * probability, to avoid transmitting the lengths for unused bit length codes.
75
 */
76
77
/* ===========================================================================
78
 * Local data. These are initialized only once.
79
 */
80
81
#define DIST_CODE_LEN  512 /* see definition of array dist_code below */
82
83
#if defined(GEN_TREES_H) || !defined(STDC)
84
/* non ANSI compilers may not accept trees.h */
85
86
local ct_data static_ltree[L_CODES+2];
87
/* The static literal tree. Since the bit lengths are imposed, there is no
88
 * need for the L_CODES extra codes used during heap construction. However
89
 * The codes 286 and 287 are needed to build a canonical tree (see _tr_init
90
 * below).
91
 */
92
93
local ct_data static_dtree[D_CODES];
94
/* The static distance tree. (Actually a trivial tree since all codes use
95
 * 5 bits.)
96
 */
97
98
uch _dist_code[DIST_CODE_LEN];
99
/* Distance codes. The first 256 values correspond to the distances
100
 * 3 .. 258, the last 256 values correspond to the top 8 bits of
101
 * the 15 bit distances.
102
 */
103
104
uch _length_code[MAX_MATCH-MIN_MATCH+1];
105
/* length code for each normalized match length (0 == MIN_MATCH) */
106
107
local int base_length[LENGTH_CODES];
108
/* First normalized length for each code (0 = MIN_MATCH) */
109
110
local int base_dist[D_CODES];
111
/* First normalized distance for each code (0 = distance of 1) */
112
113
#else
114
#  include "trees.h"
115
#endif /* GEN_TREES_H */
116
117
struct static_tree_desc_s {
118
    const ct_data *static_tree;  /* static tree or NULL */
119
    const intf *extra_bits;      /* extra bits for each code or NULL */
120
    int     extra_base;          /* base index for extra_bits */
121
    int     elems;               /* max number of elements in the tree */
122
    int     max_length;          /* max bit length for the codes */
123
};
124
125
local const static_tree_desc  static_l_desc =
126
{static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};
127
128
local const static_tree_desc  static_d_desc =
129
{static_dtree, extra_dbits, 0,          D_CODES, MAX_BITS};
130
131
local const static_tree_desc  static_bl_desc =
132
{(const ct_data *)0, extra_blbits, 0,   BL_CODES, MAX_BL_BITS};
133
134
/* ===========================================================================
135
 * Local (static) routines in this file.
136
 */
137
138
local void tr_static_init OF((void));
139
local void init_block     OF((deflate_state *s));
140
local void pqdownheap     OF((deflate_state *s, ct_data *tree, int k));
141
local void gen_bitlen     OF((deflate_state *s, tree_desc *desc));
142
local void gen_codes      OF((ct_data *tree, int max_code, ushf *bl_count));
143
local void build_tree     OF((deflate_state *s, tree_desc *desc));
144
local void scan_tree      OF((deflate_state *s, ct_data *tree, int max_code));
145
local void send_tree      OF((deflate_state *s, ct_data *tree, int max_code));
146
local int  build_bl_tree  OF((deflate_state *s));
147
local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes,
148
                              int blcodes));
149
local void compress_block OF((deflate_state *s, const ct_data *ltree,
150
                              const ct_data *dtree));
151
local int  detect_data_type OF((deflate_state *s));
152
local unsigned bi_reverse OF((unsigned value, int length));
153
local void bi_windup      OF((deflate_state *s));
154
local void bi_flush       OF((deflate_state *s));
155
156
#ifdef GEN_TREES_H
157
local void gen_trees_header OF((void));
158
#endif
159
160
#ifndef ZLIB_DEBUG
161
#  define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
162
   /* Send a code of the given tree. c and tree must not have side effects */
163
164
#else /* !ZLIB_DEBUG */
165
#  define send_code(s, c, tree) \
166
     { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
167
       send_bits(s, tree[c].Code, tree[c].Len); }
168
#endif
169
170
/* ===========================================================================
171
 * Output a short LSB first on the stream.
172
 * IN assertion: there is enough room in pendingBuf.
173
 */
174
#define put_short(s, w) { \
175
    put_byte(s, (uch)((w) & 0xff)); \
176
    put_byte(s, (uch)((ush)(w) >> 8)); \
177
}
178
179
/* ===========================================================================
180
 * Send a value on a given number of bits.
181
 * IN assertion: length <= 16 and value fits in length bits.
182
 */
183
#ifdef ZLIB_DEBUG
184
local void send_bits      OF((deflate_state *s, int value, int length));
185
186
local void send_bits(s, value, length)
187
    deflate_state *s;
188
    int value;  /* value to send */
189
    int length; /* number of bits */
190
{
191
    Tracevv((stderr," l %2d v %4x ", length, value));
192
    Assert(length > 0 && length <= 15, "invalid length");
193
    s->bits_sent += (ulg)length;
194
195
    /* If not enough room in bi_buf, use (valid) bits from bi_buf and
196
     * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
197
     * unused bits in value.
198
     */
199
    if (s->bi_valid > (int)Buf_size - length) {
200
        s->bi_buf |= (ush)value << s->bi_valid;
201
        put_short(s, s->bi_buf);
202
        s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);
203
        s->bi_valid += length - Buf_size;
204
    } else {
205
        s->bi_buf |= (ush)value << s->bi_valid;
206
        s->bi_valid += length;
207
    }
208
}
209
#else /* !ZLIB_DEBUG */
210
211
#define send_bits(s, value, length) \
212
{ int len = length;\
213
  if (s->bi_valid > (int)Buf_size - len) {\
214
    int val = (int)value;\
215
    s->bi_buf |= (ush)val << s->bi_valid;\
216
    put_short(s, s->bi_buf);\
217
    s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
218
    s->bi_valid += len - Buf_size;\
219
  } else {\
220
    s->bi_buf |= (ush)(value) << s->bi_valid;\
221
    s->bi_valid += len;\
222
  }\
223
}
224
#endif /* ZLIB_DEBUG */
225
226
227
/* the arguments must not have side effects */
228
229
/* ===========================================================================
230
 * Initialize the various 'constant' tables.
231
 */
232 97
local void tr_static_init()
233
{
234
#if defined(GEN_TREES_H) || !defined(STDC)
235
    static int static_init_done = 0;
236
    int n;        /* iterates over tree elements */
237
    int bits;     /* bit counter */
238
    int length;   /* length value */
239
    int code;     /* code value */
240
    int dist;     /* distance index */
241
    ush bl_count[MAX_BITS+1];
242
    /* number of codes at each bit length for an optimal tree */
243
244
    if (static_init_done) return;
245
246
    /* For some embedded targets, global variables are not initialized: */
247
#ifdef NO_INIT_GLOBAL_POINTERS
248
    static_l_desc.static_tree = static_ltree;
249
    static_l_desc.extra_bits = extra_lbits;
250
    static_d_desc.static_tree = static_dtree;
251
    static_d_desc.extra_bits = extra_dbits;
252
    static_bl_desc.extra_bits = extra_blbits;
253
#endif
254
255
    /* Initialize the mapping length (0..255) -> length code (0..28) */
256
    length = 0;
257
    for (code = 0; code < LENGTH_CODES-1; code++) {
258
        base_length[code] = length;
259
        for (n = 0; n < (1<<extra_lbits[code]); n++) {
260
            _length_code[length++] = (uch)code;
261
        }
262
    }
263
    Assert (length == 256, "tr_static_init: length != 256");
264
    /* Note that the length 255 (match length 258) can be represented
265
     * in two different ways: code 284 + 5 bits or code 285, so we
266
     * overwrite length_code[255] to use the best encoding:
267
     */
268
    _length_code[length-1] = (uch)code;
269
270
    /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
271
    dist = 0;
272
    for (code = 0 ; code < 16; code++) {
273
        base_dist[code] = dist;
274
        for (n = 0; n < (1<<extra_dbits[code]); n++) {
275
            _dist_code[dist++] = (uch)code;
276
        }
277
    }
278
    Assert (dist == 256, "tr_static_init: dist != 256");
279
    dist >>= 7; /* from now on, all distances are divided by 128 */
280
    for ( ; code < D_CODES; code++) {
281
        base_dist[code] = dist << 7;
282
        for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
283
            _dist_code[256 + dist++] = (uch)code;
284
        }
285
    }
286
    Assert (dist == 256, "tr_static_init: 256+dist != 512");
287
288
    /* Construct the codes of the static literal tree */
289
    for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
290
    n = 0;
291
    while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
292
    while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
293
    while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
294
    while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
295
    /* Codes 286 and 287 do not exist, but we must include them in the
296
     * tree construction to get a canonical Huffman tree (longest code
297
     * all ones)
298
     */
299
    gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);
300
301
    /* The static distance tree is trivial: */
302
    for (n = 0; n < D_CODES; n++) {
303
        static_dtree[n].Len = 5;
304
        static_dtree[n].Code = bi_reverse((unsigned)n, 5);
305
    }
306
    static_init_done = 1;
307
308
#  ifdef GEN_TREES_H
309
    gen_trees_header();
310
#  endif
311
#endif /* defined(GEN_TREES_H) || !defined(STDC) */
312 97
}
313
314
/* ===========================================================================
315
 * Genererate the file trees.h describing the static trees.
316
 */
317
#ifdef GEN_TREES_H
318
#  ifndef ZLIB_DEBUG
319
#    include <stdio.h>
320
#  endif
321
322
#  define SEPARATOR(i, last, width) \
323
      ((i) == (last)? "\n};\n\n" :    \
324
       ((i) % (width) == (width)-1 ? ",\n" : ", "))
325
326
void gen_trees_header()
327
{
328
    FILE *header = fopen("trees.h", "w");
329
    int i;
330
331
    Assert (header != NULL, "Can't open trees.h");
332
    fprintf(header,
333
            "/* header created automatically with -DGEN_TREES_H */\n\n");
334
335
    fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n");
336
    for (i = 0; i < L_CODES+2; i++) {
337
        fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code,
338
                static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5));
339
    }
340
341
    fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n");
342
    for (i = 0; i < D_CODES; i++) {
343
        fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code,
344
                static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5));
345
    }
346
347
    fprintf(header, "const uch ZLIB_INTERNAL _dist_code[DIST_CODE_LEN] = {\n");
348
    for (i = 0; i < DIST_CODE_LEN; i++) {
349
        fprintf(header, "%2u%s", _dist_code[i],
350
                SEPARATOR(i, DIST_CODE_LEN-1, 20));
351
    }
352
353
    fprintf(header,
354
        "const uch ZLIB_INTERNAL _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");
355
    for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) {
356
        fprintf(header, "%2u%s", _length_code[i],
357
                SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));
358
    }
359
360
    fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");
361
    for (i = 0; i < LENGTH_CODES; i++) {
362
        fprintf(header, "%1u%s", base_length[i],
363
                SEPARATOR(i, LENGTH_CODES-1, 20));
364
    }
365
366
    fprintf(header, "local const int base_dist[D_CODES] = {\n");
367
    for (i = 0; i < D_CODES; i++) {
368
        fprintf(header, "%5u%s", base_dist[i],
369
                SEPARATOR(i, D_CODES-1, 10));
370
    }
371
372
    fclose(header);
373
}
374
#endif /* GEN_TREES_H */
375
376
/* ===========================================================================
377
 * Initialize the tree data structures for a new zlib stream.
378
 */
379 97
void ZLIB_INTERNAL _tr_init(s)
380
    deflate_state *s;
381
{
382 97
    tr_static_init();
383
384 97
    s->l_desc.dyn_tree = s->dyn_ltree;
385 97
    s->l_desc.stat_desc = &static_l_desc;
386
387 97
    s->d_desc.dyn_tree = s->dyn_dtree;
388 97
    s->d_desc.stat_desc = &static_d_desc;
389
390 97
    s->bl_desc.dyn_tree = s->bl_tree;
391 97
    s->bl_desc.stat_desc = &static_bl_desc;
392
393 97
    s->bi_buf = 0;
394 97
    s->bi_valid = 0;
395
#ifdef ZLIB_DEBUG
396
    s->compressed_len = 0L;
397
    s->bits_sent = 0L;
398
#endif
399
400
    /* Initialize the first block of the first file: */
401 97
    init_block(s);
402 97
}
403
404
/* ===========================================================================
405
 * Initialize a new block.
406
 */
407 263
local void init_block(s)
408
    deflate_state *s;
409
{
410
    int n; /* iterates over tree elements */
411
412
    /* Initialize the trees. */
413 263
    for (n = 0; n < L_CODES;  n++) s->dyn_ltree[n].Freq = 0;
414 263
    for (n = 0; n < D_CODES;  n++) s->dyn_dtree[n].Freq = 0;
415 263
    for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;
416
417 263
    s->dyn_ltree[END_BLOCK].Freq = 1;
418 263
    s->opt_len = s->static_len = 0L;
419 263
    s->last_lit = s->matches = 0;
420 263
}
421
422
#define SMALLEST 1
423
/* Index within the heap array of least frequent node in the Huffman tree */
424
425
426
/* ===========================================================================
427
 * Remove the smallest element from the heap and recreate the heap with
428
 * one less element. Updates heap and heap_len.
429
 */
430
#define pqremove(s, tree, top) \
431
{\
432
    top = s->heap[SMALLEST]; \
433
    s->heap[SMALLEST] = s->heap[s->heap_len--]; \
434
    pqdownheap(s, tree, SMALLEST); \
435
}
436
437
/* ===========================================================================
438
 * Compares to subtrees, using the tree depth as tie breaker when
439
 * the subtrees have equal frequency. This minimizes the worst case length.
440
 */
441
#define smaller(tree, n, m, depth) \
442
   (tree[n].Freq < tree[m].Freq || \
443
   (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
444
445
/* ===========================================================================
446
 * Restore the heap property by moving down the tree starting at node k,
447
 * exchanging a node with the smallest of its two sons if necessary, stopping
448
 * when the heap property is re-established (each father smaller than its
449
 * two sons).
450
 */
451 11482
local void pqdownheap(s, tree, k)
452
    deflate_state *s;
453
    ct_data *tree;  /* the tree to restore */
454
    int k;               /* node to move down */
455
{
456 11482
    int v = s->heap[k];
457 11482
    int j = k << 1;  /* left son of k */
458 46289
    while (j <= s->heap_len) {
459
        /* Set j to the smallest of the two sons: */
460 52113
        if (j < s->heap_len &&
461 47876
            smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
462 13312
            j++;
463
        }
464
        /* Exit if v is smaller than both sons */
465 26987
        if (smaller(tree, v, s->heap[j], s->depth)) break;
466
467
        /* Exchange v with the smallest son */
468 23325
        s->heap[k] = s->heap[j];  k = j;
469
470
        /* And continue down the tree, setting j to the left son of k */
471 23325
        j <<= 1;
472
    }
473 11482
    s->heap[k] = v;
474 11482
}
475
476
/* ===========================================================================
477
 * Compute the optimal bit lengths for a tree and update the total bit length
478
 * for the current block.
479
 * IN assertion: the fields freq and dad are set, heap[heap_max] and
480
 *    above are the tree nodes sorted by increasing frequency.
481
 * OUT assertions: the field len is set to the optimal bit length, the
482
 *     array bl_count contains the frequencies for each bit length.
483
 *     The length opt_len is updated; static_len is also updated if stree is
484
 *     not null.
485
 */
486 498
local void gen_bitlen(s, desc)
487
    deflate_state *s;
488
    tree_desc *desc;    /* the tree descriptor */
489
{
490 498
    ct_data *tree        = desc->dyn_tree;
491 498
    int max_code         = desc->max_code;
492 498
    const ct_data *stree = desc->stat_desc->static_tree;
493 498
    const intf *extra    = desc->stat_desc->extra_bits;
494 498
    int base             = desc->stat_desc->extra_base;
495 498
    int max_length       = desc->stat_desc->max_length;
496
    int h;              /* heap index */
497
    int n, m;           /* iterate over the tree elements */
498
    int bits;           /* bit length */
499
    int xbits;          /* extra bits */
500
    ush f;              /* frequency */
501 498
    int overflow = 0;   /* number of elements with bit length too large */
502
503 498
    for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
504
505
    /* In a first pass, compute the optimal bit lengths (which may
506
     * overflow in the case of the bit length tree).
507
     */
508 498
    tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
509
510 9540
    for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
511 9042
        n = s->heap[h];
512 9042
        bits = tree[tree[n].Dad].Len + 1;
513 9042
        if (bits > max_length) bits = max_length, overflow++;
514 9042
        tree[n].Len = (ush)bits;
515
        /* We overwrite tree[n].Dad which is no longer needed */
516
517 9042
        if (n > max_code) continue; /* not a leaf node */
518
519 5019
        s->bl_count[bits]++;
520 5019
        xbits = 0;
521 5019
        if (n >= base) xbits = extra[n-base];
522 5019
        f = tree[n].Freq;
523 5019
        s->opt_len += (ulg)f * (unsigned)(bits + xbits);
524 5019
        if (stree) s->static_len += (ulg)f * (unsigned)(stree[n].Len + xbits);
525
    }
526 996
    if (overflow == 0) return;
527
528
    Tracev((stderr,"\nbit length overflow\n"));
529
    /* This happens for example on obj2 and pic of the Calgary corpus */
530
531
    /* Find the first bit length which could increase: */
532
    do {
533 0
        bits = max_length-1;
534 0
        while (s->bl_count[bits] == 0) bits--;
535 0
        s->bl_count[bits]--;      /* move one leaf down the tree */
536 0
        s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
537 0
        s->bl_count[max_length]--;
538
        /* The brother of the overflow item also moves one step up,
539
         * but this does not affect bl_count[max_length]
540
         */
541 0
        overflow -= 2;
542 0
    } while (overflow > 0);
543
544
    /* Now recompute all bit lengths, scanning in increasing frequency.
545
     * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
546
     * lengths instead of fixing only the wrong ones. This idea is taken
547
     * from 'ar' written by Haruhiko Okumura.)
548
     */
549 0
    for (bits = max_length; bits != 0; bits--) {
550 0
        n = s->bl_count[bits];
551 0
        while (n != 0) {
552 0
            m = s->heap[--h];
553 0
            if (m > max_code) continue;
554 0
            if ((unsigned) tree[m].Len != (unsigned) bits) {
555
                Tracev((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
556 0
                s->opt_len += ((ulg)bits - tree[m].Len) * tree[m].Freq;
557 0
                tree[m].Len = (ush)bits;
558
            }
559 0
            n--;
560
        }
561
    }
562
}
563
564
/* ===========================================================================
565
 * Generate the codes for a given tree and bit counts (which need not be
566
 * optimal).
567
 * IN assertion: the array bl_count contains the bit length statistics for
568
 * the given tree and the field len is set for all tree elements.
569
 * OUT assertion: the field code is set for all tree elements of non
570
 *     zero code length.
571
 */
572 498
local void gen_codes (tree, max_code, bl_count)
573
    ct_data *tree;             /* the tree to decorate */
574
    int max_code;              /* largest code with non zero frequency */
575
    ushf *bl_count;            /* number of codes at each bit length */
576
{
577
    ush next_code[MAX_BITS+1]; /* next code value for each bit length */
578 498
    unsigned code = 0;         /* running code value */
579
    int bits;                  /* bit index */
580
    int n;                     /* code index */
581
582
    /* The distribution counts are first used to generate the code values
583
     * without bit reversal.
584
     */
585 7968
    for (bits = 1; bits <= MAX_BITS; bits++) {
586 7470
        code = (code + bl_count[bits-1]) << 1;
587 7470
        next_code[bits] = (ush)code;
588
    }
589
    /* Check that the bit counts in bl_count are consistent. The last code
590
     * must be all ones.
591
     */
592
    Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
593
            "inconsistent bit counts");
594
    Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
595
596 47162
    for (n = 0;  n <= max_code; n++) {
597 46664
        int len = tree[n].Len;
598 46664
        if (len == 0) continue;
599
        /* Now reverse the bits */
600 5019
        tree[n].Code = (ush)bi_reverse(next_code[len]++, len);
601
602
        Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
603
             n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
604
    }
605 498
}
606
607
/* ===========================================================================
608
 * Construct one Huffman tree and assigns the code bit strings and lengths.
609
 * Update the total bit length for the current block.
610
 * IN assertion: the field freq is set for all tree elements.
611
 * OUT assertions: the fields len and code are set to the optimal bit length
612
 *     and corresponding code. The length opt_len is updated; static_len is
613
 *     also updated if stree is not null. The field max_code is set.
614
 */
615 498
local void build_tree(s, desc)
616
    deflate_state *s;
617
    tree_desc *desc; /* the tree descriptor */
618
{
619 498
    ct_data *tree         = desc->dyn_tree;
620 498
    const ct_data *stree  = desc->stat_desc->static_tree;
621 498
    int elems             = desc->stat_desc->elems;
622
    int n, m;          /* iterate over heap elements */
623 498
    int max_code = -1; /* largest code with non zero frequency */
624
    int node;          /* new node being created */
625
626
    /* Construct the initial heap, with least frequent element in
627
     * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
628
     * heap[0] is not used.
629
     */
630 498
    s->heap_len = 0, s->heap_max = HEAP_SIZE;
631
632 56108
    for (n = 0; n < elems; n++) {
633 55610
        if (tree[n].Freq != 0) {
634 4713
            s->heap[++(s->heap_len)] = max_code = n;
635 4713
            s->depth[n] = 0;
636
        } else {
637 50897
            tree[n].Len = 0;
638
        }
639
    }
640
641
    /* The pkzip format requires that at least one distance code exists,
642
     * and that at least one bit should be sent even if there is only one
643
     * possible code. So to avoid special checks later on we force at least
644
     * two codes of non zero frequency.
645
     */
646 1302
    while (s->heap_len < 2) {
647 306
        node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
648 306
        tree[node].Freq = 1;
649 306
        s->depth[node] = 0;
650 306
        s->opt_len--; if (stree) s->static_len -= stree[node].Len;
651
        /* node is 0 or 1 so it does not have extra bits */
652
    }
653 498
    desc->max_code = max_code;
654
655
    /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
656
     * establish sub-heaps of increasing lengths:
657
     */
658 498
    for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
659
660
    /* Construct the Huffman tree by repeatedly combining the least two
661
     * frequent nodes.
662
     */
663 498
    node = elems;              /* next internal node of the tree */
664
    do {
665 4521
        pqremove(s, tree, n);  /* n = node of least frequency */
666 4521
        m = s->heap[SMALLEST]; /* m = node of next least frequency */
667
668 4521
        s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
669 4521
        s->heap[--(s->heap_max)] = m;
670
671
        /* Create a new node father of n and m */
672 4521
        tree[node].Freq = tree[n].Freq + tree[m].Freq;
673 9042
        s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?
674 4521
                                s->depth[n] : s->depth[m]) + 1);
675 4521
        tree[n].Dad = tree[m].Dad = (ush)node;
676
#ifdef DUMP_BL_TREE
677
        if (tree == s->bl_tree) {
678
            fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
679
                    node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
680
        }
681
#endif
682
        /* and insert the new node in the heap */
683 4521
        s->heap[SMALLEST] = node++;
684 4521
        pqdownheap(s, tree, SMALLEST);
685
686 4521
    } while (s->heap_len >= 2);
687
688 498
    s->heap[--(s->heap_max)] = s->heap[SMALLEST];
689
690
    /* At this point, the fields freq and dad are set. We can now
691
     * generate the bit lengths.
692
     */
693 498
    gen_bitlen(s, (tree_desc *)desc);
694
695
    /* The field len is now set, we can generate the bit codes */
696 498
    gen_codes ((ct_data *)tree, max_code, s->bl_count);
697 498
}
698
699
/* ===========================================================================
700
 * Scan a literal or distance tree to determine the frequencies of the codes
701
 * in the bit length tree.
702
 */
703 332
local void scan_tree (s, tree, max_code)
704
    deflate_state *s;
705
    ct_data *tree;   /* the tree to be scanned */
706
    int max_code;    /* and its largest code of non zero frequency */
707
{
708
    int n;                     /* iterates over all tree elements */
709 332
    int prevlen = -1;          /* last emitted length */
710
    int curlen;                /* length of current code */
711 332
    int nextlen = tree[0].Len; /* length of next code */
712 332
    int count = 0;             /* repeat count of the current code */
713 332
    int max_count = 7;         /* max repeat count */
714 332
    int min_count = 4;         /* min repeat count */
715
716 332
    if (nextlen == 0) max_count = 138, min_count = 3;
717 332
    tree[max_code+1].Len = (ush)0xffff; /* guard */
718
719 43842
    for (n = 0; n <= max_code; n++) {
720 43510
        curlen = nextlen; nextlen = tree[n+1].Len;
721 43510
        if (++count < max_count && curlen == nextlen) {
722 38699
            continue;
723 4811
        } else if (count < min_count) {
724 3936
            s->bl_tree[curlen].Freq += count;
725 875
        } else if (curlen != 0) {
726 47
            if (curlen != prevlen) s->bl_tree[curlen].Freq++;
727 47
            s->bl_tree[REP_3_6].Freq++;
728 828
        } else if (count <= 10) {
729 315
            s->bl_tree[REPZ_3_10].Freq++;
730
        } else {
731 513
            s->bl_tree[REPZ_11_138].Freq++;
732
        }
733 4811
        count = 0; prevlen = curlen;
734 4811
        if (nextlen == 0) {
735 1571
            max_count = 138, min_count = 3;
736 3240
        } else if (curlen == nextlen) {
737 0
            max_count = 6, min_count = 3;
738
        } else {
739 3240
            max_count = 7, min_count = 4;
740
        }
741
    }
742 332
}
743
744
/* ===========================================================================
745
 * Send a literal or distance tree in compressed form, using the codes in
746
 * bl_tree.
747
 */
748 4
local void send_tree (s, tree, max_code)
749
    deflate_state *s;
750
    ct_data *tree; /* the tree to be scanned */
751
    int max_code;       /* and its largest code of non zero frequency */
752
{
753
    int n;                     /* iterates over all tree elements */
754 4
    int prevlen = -1;          /* last emitted length */
755
    int curlen;                /* length of current code */
756 4
    int nextlen = tree[0].Len; /* length of next code */
757 4
    int count = 0;             /* repeat count of the current code */
758 4
    int max_count = 7;         /* max repeat count */
759 4
    int min_count = 4;         /* min repeat count */
760
761
    /* tree[max_code+1].Len = -1; */  /* guard already set */
762 4
    if (nextlen == 0) max_count = 138, min_count = 3;
763
764 550
    for (n = 0; n <= max_code; n++) {
765 546
        curlen = nextlen; nextlen = tree[n+1].Len;
766 546
        if (++count < max_count && curlen == nextlen) {
767 461
            continue;
768 85
        } else if (count < min_count) {
769 78
            do { send_code(s, curlen, s->bl_tree); } while (--count != 0);
770
771 20
        } else if (curlen != 0) {
772 1
            if (curlen != prevlen) {
773 1
                send_code(s, curlen, s->bl_tree); count--;
774
            }
775
            Assert(count >= 3 && count <= 6, " 3_6?");
776 1
            send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);
777
778 19
        } else if (count <= 10) {
779 8
            send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);
780
781
        } else {
782 11
            send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
783
        }
784 85
        count = 0; prevlen = curlen;
785 85
        if (nextlen == 0) {
786 28
            max_count = 138, min_count = 3;
787 57
        } else if (curlen == nextlen) {
788 0
            max_count = 6, min_count = 3;
789
        } else {
790 57
            max_count = 7, min_count = 4;
791
        }
792
    }
793 4
}
794
795
/* ===========================================================================
796
 * Construct the Huffman tree for the bit lengths and return the index in
797
 * bl_order of the last bit length code to send.
798
 */
799 166
local int build_bl_tree(s)
800
    deflate_state *s;
801
{
802
    int max_blindex;  /* index of last bit length code of non zero freq */
803
804
    /* Determine the bit length frequencies for literal and distance trees */
805 166
    scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
806 166
    scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);
807
808
    /* Build the bit length tree: */
809 166
    build_tree(s, (tree_desc *)(&(s->bl_desc)));
810
    /* opt_len now includes the length of the tree representations, except
811
     * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
812
     */
813
814
    /* Determine the number of bit length codes to send. The pkzip format
815
     * requires that at least 4 bit length codes be sent. (appnote.txt says
816
     * 3 but the actual value used is 4.)
817
     */
818 340
    for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
819 340
        if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
820
    }
821
    /* Update opt_len to include the bit length tree and counts */
822 166
    s->opt_len += 3*((ulg)max_blindex+1) + 5+5+4;
823
    Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
824
            s->opt_len, s->static_len));
825
826 166
    return max_blindex;
827
}
828
829
/* ===========================================================================
830
 * Send the header for a block using dynamic Huffman trees: the counts, the
831
 * lengths of the bit length codes, the literal tree and the distance tree.
832
 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
833
 */
834 2
local void send_all_trees(s, lcodes, dcodes, blcodes)
835
    deflate_state *s;
836
    int lcodes, dcodes, blcodes; /* number of codes for each tree */
837
{
838
    int rank;                    /* index in bl_order */
839
840
    Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
841
    Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
842
            "too many codes");
843
    Tracev((stderr, "\nbl counts: "));
844 2
    send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
845 2
    send_bits(s, dcodes-1,   5);
846 2
    send_bits(s, blcodes-4,  4); /* not -3 as stated in appnote.txt */
847 36
    for (rank = 0; rank < blcodes; rank++) {
848
        Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
849 34
        send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
850
    }
851
    Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));
852
853 2
    send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
854
    Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));
855
856 2
    send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
857
    Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
858 2
}
859
860
/* ===========================================================================
861
 * Send a stored block
862
 */
863 253
void ZLIB_INTERNAL _tr_stored_block(s, buf, stored_len, last)
864
    deflate_state *s;
865
    charf *buf;       /* input block */
866
    ulg stored_len;   /* length of input block */
867
    int last;         /* one if this is the last block for a file */
868
{
869 253
    if (last)
870 92
        s->strm->last_bit =
871 46
           (s->strm->total_out + s->pending) * 8 + s->bi_valid;
872
873 253
    send_bits(s, (STORED_BLOCK<<1)+last, 3);    /* send block type */
874 253
    bi_windup(s);        /* align on byte boundary */
875 253
    put_short(s, (ush)stored_len);
876 253
    put_short(s, (ush)~stored_len);
877 253
    if (stored_len)
878 40
        zmemcpy(s->pending_buf + s->pending, (Bytef *)buf, stored_len);
879 253
    s->pending += stored_len;
880
#ifdef ZLIB_DEBUG
881
    s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
882
    s->compressed_len += (stored_len + 4) << 3;
883
    s->bits_sent += 2*16;
884
    s->bits_sent += stored_len<<3;
885
#endif
886 253
    if (last)
887 92
        s->strm->stop_bit =
888 46
           (s->strm->total_out + s->pending) * 8 + s->bi_valid;
889 253
}
890
891
/* ===========================================================================
892
 * Flush the bits in the bit buffer to pending output (leaves at most 7 bits)
893
 */
894 704
void ZLIB_INTERNAL _tr_flush_bits(s)
895
    deflate_state *s;
896
{
897 704
    bi_flush(s);
898 704
}
899
900
/* ===========================================================================
901
 * Send one empty static block to give enough lookahead for inflate.
902
 * This takes 10 bits, of which 7 may remain in the bit buffer.
903
 */
904 0
void ZLIB_INTERNAL _tr_align(s)
905
    deflate_state *s;
906
{
907 0
    send_bits(s, STATIC_TREES<<1, 3);
908 0
    send_code(s, END_BLOCK, static_ltree);
909
#ifdef ZLIB_DEBUG
910
    s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
911
#endif
912 0
    bi_flush(s);
913 0
}
914
915
/* ===========================================================================
916
 * Determine the best encoding for the current block: dynamic trees, static
917
 * trees or store, and write out the encoded block.
918
 */
919 166
void ZLIB_INTERNAL _tr_flush_block(s, buf, stored_len, last)
920
    deflate_state *s;
921
    charf *buf;       /* input block, or NULL if too old */
922
    ulg stored_len;   /* length of input block */
923
    int last;         /* one if this is the last block for a file */
924
{
925
    ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
926 166
    int max_blindex = 0;  /* index of last bit length code of non zero freq */
927
928 166
    if (last)
929 96
        s->strm->last_bit =
930 48
           (s->strm->total_out + s->pending) * 8 + s->bi_valid;
931
932
    /* Build the Huffman trees unless a stored block is forced */
933 166
    if (s->level > 0) {
934
935
        /* Check if the file is binary or text */
936 166
        if (s->strm->data_type == Z_UNKNOWN)
937 48
            s->strm->data_type = detect_data_type(s);
938
939
        /* Construct the literal and distance trees */
940 166
        build_tree(s, (tree_desc *)(&(s->l_desc)));
941
        Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
942
                s->static_len));
943
944 166
        build_tree(s, (tree_desc *)(&(s->d_desc)));
945
        Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
946
                s->static_len));
947
        /* At this point, opt_len and static_len are the total bit lengths of
948
         * the compressed block data, excluding the tree representations.
949
         */
950
951
        /* Build the bit length tree for the above two trees, and get the index
952
         * in bl_order of the last bit length code to send.
953
         */
954 166
        max_blindex = build_bl_tree(s);
955
956
        /* Determine the best encoding. Compute the block lengths in bytes. */
957 166
        opt_lenb = (s->opt_len+3+7)>>3;
958 166
        static_lenb = (s->static_len+3+7)>>3;
959
960
        Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
961
                opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
962
                s->last_lit));
963
964 166
        if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
965
966
    } else {
967
        Assert(buf != (char*)0, "lost buf");
968 0
        opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
969
    }
970
971
#ifdef FORCE_STORED
972
    if (buf != (char*)0) { /* force stored block */
973
#else
974 166
    if (stored_len+4 <= opt_lenb && buf != (char*)0) {
975
                       /* 4: two words for the lengths */
976
#endif
977
        /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
978
         * Otherwise we can't have processed more than WSIZE input bytes since
979
         * the last block flush, because compression would have been
980
         * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
981
         * transform a block into a stored block.
982
         */
983 0
        _tr_stored_block(s, buf, stored_len, last);
984
985
#ifdef FORCE_STATIC
986
    } else if (static_lenb >= 0) { /* force static trees */
987
#else
988 166
    } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) {
989
#endif
990 164
        send_bits(s, (STATIC_TREES<<1)+last, 3);
991 164
        compress_block(s, (const ct_data *)static_ltree,
992
                       (const ct_data *)static_dtree);
993
#ifdef ZLIB_DEBUG
994
        s->compressed_len += 3 + s->static_len;
995
#endif
996
    } else {
997 2
        send_bits(s, (DYN_TREES<<1)+last, 3);
998 2
        send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
999
                       max_blindex+1);
1000 2
        compress_block(s, (const ct_data *)s->dyn_ltree,
1001 2
                       (const ct_data *)s->dyn_dtree);
1002
#ifdef ZLIB_DEBUG
1003
        s->compressed_len += 3 + s->opt_len;
1004
#endif
1005
    }
1006
    Assert (s->compressed_len == s->bits_sent, "bad compressed size");
1007
    /* The above check is made mod 2^32, for files larger than 512 MB
1008
     * and uLong implemented on 32 bits.
1009
     */
1010 166
    init_block(s);
1011
1012 166
    if (last) {
1013 96
        s->strm->stop_bit =
1014 48
           (s->strm->total_out + s->pending) * 8 + s->bi_valid;
1015 48
        bi_windup(s);
1016
#ifdef ZLIB_DEBUG
1017
        s->compressed_len += 7;  /* align on byte boundary */
1018
#endif
1019
    }
1020
    Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
1021
           s->compressed_len-7*last));
1022 166
}
1023
1024
/* ===========================================================================
1025
 * Save the match info and tally the frequency counts. Return true if
1026
 * the current block must be flushed.
1027
 */
1028 0
int ZLIB_INTERNAL _tr_tally (s, dist, lc)
1029
    deflate_state *s;
1030
    unsigned dist;  /* distance of matched string */
1031
    unsigned lc;    /* match length-MIN_MATCH or unmatched char (if dist==0) */
1032
{
1033 0
    s->d_buf[s->last_lit] = (ush)dist;
1034 0
    s->l_buf[s->last_lit++] = (uch)lc;
1035 0
    if (dist == 0) {
1036
        /* lc is the unmatched char */
1037 0
        s->dyn_ltree[lc].Freq++;
1038
    } else {
1039 0
        s->matches++;
1040
        /* Here, lc is the match length - MIN_MATCH */
1041 0
        dist--;             /* dist = match distance - 1 */
1042
        Assert((ush)dist < (ush)MAX_DIST(s) &&
1043
               (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
1044
               (ush)d_code(dist) < (ush)D_CODES,  "_tr_tally: bad match");
1045
1046 0
        s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
1047 0
        s->dyn_dtree[d_code(dist)].Freq++;
1048
    }
1049
1050
#ifdef TRUNCATE_BLOCK
1051
    /* Try to guess if it is profitable to stop the current block here */
1052
    if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
1053
        /* Compute an upper bound for the compressed length */
1054
        ulg out_length = (ulg)s->last_lit*8L;
1055
        ulg in_length = (ulg)((long)s->strstart - s->block_start);
1056
        int dcode;
1057
        for (dcode = 0; dcode < D_CODES; dcode++) {
1058
            out_length += (ulg)s->dyn_dtree[dcode].Freq *
1059
                (5L+extra_dbits[dcode]);
1060
        }
1061
        out_length >>= 3;
1062
        Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
1063
               s->last_lit, in_length, out_length,
1064
               100L - out_length*100L/in_length));
1065
        if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
1066
    }
1067
#endif
1068 0
    return (s->last_lit == s->lit_bufsize-1);
1069
    /* We avoid equality with lit_bufsize because of wraparound at 64K
1070
     * on 16 bit machines and because stored blocks are restricted to
1071
     * 64K-1 bytes.
1072
     */
1073
}
1074
1075
/* ===========================================================================
1076
 * Send the block data compressed using the given Huffman trees
1077
 */
1078 166
local void compress_block(s, ltree, dtree)
1079
    deflate_state *s;
1080
    const ct_data *ltree; /* literal tree */
1081
    const ct_data *dtree; /* distance tree */
1082
{
1083
    unsigned dist;      /* distance of matched string */
1084
    int lc;             /* match length or unmatched char (if dist == 0) */
1085 166
    unsigned lx = 0;    /* running index in l_buf */
1086
    unsigned code;      /* the code to send */
1087
    int extra;          /* number of extra bits to send */
1088
1089 166
    if (s->last_lit != 0) do {
1090 6032
        dist = s->d_buf[lx];
1091 6032
        lc = s->l_buf[lx++];
1092 6032
        if (dist == 0) {
1093 5949
            send_code(s, lc, ltree); /* send a literal byte */
1094
            Tracecv(isgraph(lc), (stderr," '%c' ", lc));
1095
        } else {
1096
            /* Here, lc is the match length - MIN_MATCH */
1097 83
            code = _length_code[lc];
1098 83
            send_code(s, code+LITERALS+1, ltree); /* send the length code */
1099 83
            extra = extra_lbits[code];
1100 83
            if (extra != 0) {
1101 5
                lc -= base_length[code];
1102 5
                send_bits(s, lc, extra);       /* send the extra length bits */
1103
            }
1104 83
            dist--; /* dist is now the match distance - 1 */
1105 83
            code = d_code(dist);
1106
            Assert (code < D_CODES, "bad d_code");
1107
1108 83
            send_code(s, code, dtree);       /* send the distance code */
1109 83
            extra = extra_dbits[code];
1110 83
            if (extra != 0) {
1111 67
                dist -= (unsigned)base_dist[code];
1112 67
                send_bits(s, dist, extra);   /* send the extra distance bits */
1113
            }
1114
        } /* literal or match pair ? */
1115
1116
        /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
1117
        Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx,
1118
               "pendingBuf overflow");
1119
1120 6032
    } while (lx < s->last_lit);
1121
1122 166
    send_code(s, END_BLOCK, ltree);
1123 166
}
1124
1125
/* ===========================================================================
1126
 * Check if the data type is TEXT or BINARY, using the following algorithm:
1127
 * - TEXT if the two conditions below are satisfied:
1128
 *    a) There are no non-portable control characters belonging to the
1129
 *       "black list" (0..6, 14..25, 28..31).
1130
 *    b) There is at least one printable character belonging to the
1131
 *       "white list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255).
1132
 * - BINARY otherwise.
1133
 * - The following partially-portable control characters form a
1134
 *   "gray list" that is ignored in this detection algorithm:
1135
 *   (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}).
1136
 * IN assertion: the fields Freq of dyn_ltree are set.
1137
 */
1138 48
local int detect_data_type(s)
1139
    deflate_state *s;
1140
{
1141
    /* black_mask is the bit mask of black-listed bytes
1142
     * set bits 0..6, 14..25, and 28..31
1143
     * 0xf3ffc07f = binary 11110011111111111100000001111111
1144
     */
1145 48
    unsigned long black_mask = 0xf3ffc07fUL;
1146
    int n;
1147
1148
    /* Check for non-textual ("black-listed") bytes. */
1149 1584
    for (n = 0; n <= 31; n++, black_mask >>= 1)
1150 1536
        if ((black_mask & 1) && (s->dyn_ltree[n].Freq != 0))
1151 0
            return Z_BINARY;
1152
1153
    /* Check for textual ("white-listed") bytes. */
1154 48
    if (s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0
1155 38
            || s->dyn_ltree[13].Freq != 0)
1156 10
        return Z_TEXT;
1157 1115
    for (n = 32; n < LITERALS; n++)
1158 1114
        if (s->dyn_ltree[n].Freq != 0)
1159 37
            return Z_TEXT;
1160
1161
    /* There are no "black-listed" or "white-listed" bytes:
1162
     * this stream either is empty or has tolerated ("gray-listed") bytes only.
1163
     */
1164 1
    return Z_BINARY;
1165
}
1166
1167
/* ===========================================================================
1168
 * Reverse the first len bits of a code, using straightforward code (a faster
1169
 * method would use a table)
1170
 * IN assertion: 1 <= len <= 15
1171
 */
1172 5019
local unsigned bi_reverse(code, len)
1173
    unsigned code; /* the value to invert */
1174
    int len;       /* its bit length */
1175
{
1176 5019
    register unsigned res = 0;
1177
    do {
1178 23646
        res |= code & 1;
1179 23646
        code >>= 1, res <<= 1;
1180 23646
    } while (--len > 0);
1181 5019
    return res >> 1;
1182
}
1183
1184
/* ===========================================================================
1185
 * Flush the bit buffer, keeping at most 7 bits in it.
1186
 */
1187 704
local void bi_flush(s)
1188
    deflate_state *s;
1189
{
1190 704
    if (s->bi_valid == 16) {
1191 2
        put_short(s, s->bi_buf);
1192 2
        s->bi_buf = 0;
1193 2
        s->bi_valid = 0;
1194 702
    } else if (s->bi_valid >= 8) {
1195 40
        put_byte(s, (Byte)s->bi_buf);
1196 40
        s->bi_buf >>= 8;
1197 40
        s->bi_valid -= 8;
1198
    }
1199 704
}
1200
1201
/* ===========================================================================
1202
 * Flush the bit buffer and align the output on a byte boundary
1203
 */
1204 301
local void bi_windup(s)
1205
    deflate_state *s;
1206
{
1207 301
    if (s->bi_valid > 8) {
1208 43
        put_short(s, s->bi_buf);
1209 258
    } else if (s->bi_valid > 0) {
1210 258
        put_byte(s, (Byte)s->bi_buf);
1211
    }
1212 301
    s->bi_buf = 0;
1213 301
    s->bi_valid = 0;
1214
#ifdef ZLIB_DEBUG
1215
    s->bits_sent = (s->bits_sent+7) & ~7;
1216
#endif
1217 301
}