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1 745 jeremybenn
/* trees.c -- output deflated data using Huffman coding
2
 * Copyright (C) 1995-2005 Jean-loup Gailly
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: trees.c,v 1.1.1.2 2002/03/11 21:53:27 tromey Exp $ */
33
 
34
/* #define GEN_TREES_H */
35
 
36
#include "deflate.h"
37
 
38
#ifdef 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
#define Buf_size (8 * 2*sizeof(char))
77
/* Number of bits used within bi_buf. (bi_buf might be implemented on
78
 * more than 16 bits on some systems.)
79
 */
80
 
81
/* ===========================================================================
82
 * Local data. These are initialized only once.
83
 */
84
 
85
#define DIST_CODE_LEN  512 /* see definition of array dist_code below */
86
 
87
#if defined(GEN_TREES_H) || !defined(STDC)
88
/* non ANSI compilers may not accept trees.h */
89
 
90
local ct_data static_ltree[L_CODES+2];
91
/* The static literal tree. Since the bit lengths are imposed, there is no
92
 * need for the L_CODES extra codes used during heap construction. However
93
 * The codes 286 and 287 are needed to build a canonical tree (see _tr_init
94
 * below).
95
 */
96
 
97
local ct_data static_dtree[D_CODES];
98
/* The static distance tree. (Actually a trivial tree since all codes use
99
 * 5 bits.)
100
 */
101
 
102
uch _dist_code[DIST_CODE_LEN];
103
/* Distance codes. The first 256 values correspond to the distances
104
 * 3 .. 258, the last 256 values correspond to the top 8 bits of
105
 * the 15 bit distances.
106
 */
107
 
108
uch _length_code[MAX_MATCH-MIN_MATCH+1];
109
/* length code for each normalized match length (0 == MIN_MATCH) */
110
 
111
local int base_length[LENGTH_CODES];
112
/* First normalized length for each code (0 = MIN_MATCH) */
113
 
114
local int base_dist[D_CODES];
115
/* First normalized distance for each code (0 = distance of 1) */
116
 
117
#else
118
#  include "trees.h"
119
#endif /* GEN_TREES_H */
120
 
121
struct static_tree_desc_s {
122
    const ct_data *static_tree;  /* static tree or NULL */
123
    const intf *extra_bits;      /* extra bits for each code or NULL */
124
    int     extra_base;          /* base index for extra_bits */
125
    int     elems;               /* max number of elements in the tree */
126
    int     max_length;          /* max bit length for the codes */
127
};
128
 
129
local static_tree_desc  static_l_desc =
130
{static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};
131
 
132
local static_tree_desc  static_d_desc =
133
{static_dtree, extra_dbits, 0,          D_CODES, MAX_BITS};
134
 
135
local static_tree_desc  static_bl_desc =
136
{(const ct_data *)0, extra_blbits, 0,   BL_CODES, MAX_BL_BITS};
137
 
138
/* ===========================================================================
139
 * Local (static) routines in this file.
140
 */
141
 
142
local void tr_static_init OF((void));
143
local void init_block     OF((deflate_state *s));
144
local void pqdownheap     OF((deflate_state *s, ct_data *tree, int k));
145
local void gen_bitlen     OF((deflate_state *s, tree_desc *desc));
146
local void gen_codes      OF((ct_data *tree, int max_code, ushf *bl_count));
147
local void build_tree     OF((deflate_state *s, tree_desc *desc));
148
local void scan_tree      OF((deflate_state *s, ct_data *tree, int max_code));
149
local void send_tree      OF((deflate_state *s, ct_data *tree, int max_code));
150
local int  build_bl_tree  OF((deflate_state *s));
151
local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes,
152
                              int blcodes));
153
local void compress_block OF((deflate_state *s, ct_data *ltree,
154
                              ct_data *dtree));
155
local void set_data_type  OF((deflate_state *s));
156
local unsigned bi_reverse OF((unsigned value, int length));
157
local void bi_windup      OF((deflate_state *s));
158
local void bi_flush       OF((deflate_state *s));
159
local void copy_block     OF((deflate_state *s, charf *buf, unsigned len,
160
                              int header));
161
 
162
#ifdef GEN_TREES_H
163
local void gen_trees_header OF((void));
164
#endif
165
 
166
#ifndef DEBUG
167
#  define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
168
   /* Send a code of the given tree. c and tree must not have side effects */
169
 
170
#else /* DEBUG */
171
#  define send_code(s, c, tree) \
172
     { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
173
       send_bits(s, tree[c].Code, tree[c].Len); }
174
#endif
175
 
176
/* ===========================================================================
177
 * Output a short LSB first on the stream.
178
 * IN assertion: there is enough room in pendingBuf.
179
 */
180
#define put_short(s, w) { \
181
    put_byte(s, (uch)((w) & 0xff)); \
182
    put_byte(s, (uch)((ush)(w) >> 8)); \
183
}
184
 
185
/* ===========================================================================
186
 * Send a value on a given number of bits.
187
 * IN assertion: length <= 16 and value fits in length bits.
188
 */
189
#ifdef DEBUG
190
local void send_bits      OF((deflate_state *s, int value, int length));
191
 
192
local void send_bits(s, value, length)
193
    deflate_state *s;
194
    int value;  /* value to send */
195
    int length; /* number of bits */
196
{
197
    Tracevv((stderr," l %2d v %4x ", length, value));
198
    Assert(length > 0 && length <= 15, "invalid length");
199
    s->bits_sent += (ulg)length;
200
 
201
    /* If not enough room in bi_buf, use (valid) bits from bi_buf and
202
     * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
203
     * unused bits in value.
204
     */
205
    if (s->bi_valid > (int)Buf_size - length) {
206
        s->bi_buf |= (value << s->bi_valid);
207
        put_short(s, s->bi_buf);
208
        s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);
209
        s->bi_valid += length - Buf_size;
210
    } else {
211
        s->bi_buf |= value << s->bi_valid;
212
        s->bi_valid += length;
213
    }
214
}
215
#else /* !DEBUG */
216
 
217
#define send_bits(s, value, length) \
218
{ int len = length;\
219
  if (s->bi_valid > (int)Buf_size - len) {\
220
    int val = value;\
221
    s->bi_buf |= (val << s->bi_valid);\
222
    put_short(s, s->bi_buf);\
223
    s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
224
    s->bi_valid += len - Buf_size;\
225
  } else {\
226
    s->bi_buf |= (value) << s->bi_valid;\
227
    s->bi_valid += len;\
228
  }\
229
}
230
#endif /* DEBUG */
231
 
232
 
233
/* the arguments must not have side effects */
234
 
235
/* ===========================================================================
236
 * Initialize the various 'constant' tables.
237
 */
238
local void tr_static_init()
239
{
240
#if defined(GEN_TREES_H) || !defined(STDC)
241
    static int static_init_done = 0;
242
    int n;        /* iterates over tree elements */
243
    int bits;     /* bit counter */
244
    int length;   /* length value */
245
    int code;     /* code value */
246
    int dist;     /* distance index */
247
    ush bl_count[MAX_BITS+1];
248
    /* number of codes at each bit length for an optimal tree */
249
 
250
    if (static_init_done) return;
251
 
252
    /* For some embedded targets, global variables are not initialized: */
253
    static_l_desc.static_tree = static_ltree;
254
    static_l_desc.extra_bits = extra_lbits;
255
    static_d_desc.static_tree = static_dtree;
256
    static_d_desc.extra_bits = extra_dbits;
257
    static_bl_desc.extra_bits = extra_blbits;
258
 
259
    /* Initialize the mapping length (0..255) -> length code (0..28) */
260
    length = 0;
261
    for (code = 0; code < LENGTH_CODES-1; code++) {
262
        base_length[code] = length;
263
        for (n = 0; n < (1<<extra_lbits[code]); n++) {
264
            _length_code[length++] = (uch)code;
265
        }
266
    }
267
    Assert (length == 256, "tr_static_init: length != 256");
268
    /* Note that the length 255 (match length 258) can be represented
269
     * in two different ways: code 284 + 5 bits or code 285, so we
270
     * overwrite length_code[255] to use the best encoding:
271
     */
272
    _length_code[length-1] = (uch)code;
273
 
274
    /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
275
    dist = 0;
276
    for (code = 0 ; code < 16; code++) {
277
        base_dist[code] = dist;
278
        for (n = 0; n < (1<<extra_dbits[code]); n++) {
279
            _dist_code[dist++] = (uch)code;
280
        }
281
    }
282
    Assert (dist == 256, "tr_static_init: dist != 256");
283
    dist >>= 7; /* from now on, all distances are divided by 128 */
284
    for ( ; code < D_CODES; code++) {
285
        base_dist[code] = dist << 7;
286
        for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
287
            _dist_code[256 + dist++] = (uch)code;
288
        }
289
    }
290
    Assert (dist == 256, "tr_static_init: 256+dist != 512");
291
 
292
    /* Construct the codes of the static literal tree */
293
    for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
294
    n = 0;
295
    while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
296
    while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
297
    while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
298
    while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
299
    /* Codes 286 and 287 do not exist, but we must include them in the
300
     * tree construction to get a canonical Huffman tree (longest code
301
     * all ones)
302
     */
303
    gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);
304
 
305
    /* The static distance tree is trivial: */
306
    for (n = 0; n < D_CODES; n++) {
307
        static_dtree[n].Len = 5;
308
        static_dtree[n].Code = bi_reverse((unsigned)n, 5);
309
    }
310
    static_init_done = 1;
311
 
312
#  ifdef GEN_TREES_H
313
    gen_trees_header();
314
#  endif
315
#endif /* defined(GEN_TREES_H) || !defined(STDC) */
316
}
317
 
318
/* ===========================================================================
319
 * Genererate the file trees.h describing the static trees.
320
 */
321
#ifdef GEN_TREES_H
322
#  ifndef DEBUG
323
#    include <stdio.h>
324
#  endif
325
 
326
#  define SEPARATOR(i, last, width) \
327
      ((i) == (last)? "\n};\n\n" :    \
328
       ((i) % (width) == (width)-1 ? ",\n" : ", "))
329
 
330
void gen_trees_header()
331
{
332
    FILE *header = fopen("trees.h", "w");
333
    int i;
334
 
335
    Assert (header != NULL, "Can't open trees.h");
336
    fprintf(header,
337
            "/* header created automatically with -DGEN_TREES_H */\n\n");
338
 
339
    fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n");
340
    for (i = 0; i < L_CODES+2; i++) {
341
        fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code,
342
                static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5));
343
    }
344
 
345
    fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n");
346
    for (i = 0; i < D_CODES; i++) {
347
        fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code,
348
                static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5));
349
    }
350
 
351
    fprintf(header, "const uch _dist_code[DIST_CODE_LEN] = {\n");
352
    for (i = 0; i < DIST_CODE_LEN; i++) {
353
        fprintf(header, "%2u%s", _dist_code[i],
354
                SEPARATOR(i, DIST_CODE_LEN-1, 20));
355
    }
356
 
357
    fprintf(header, "const uch _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");
358
    for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) {
359
        fprintf(header, "%2u%s", _length_code[i],
360
                SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));
361
    }
362
 
363
    fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");
364
    for (i = 0; i < LENGTH_CODES; i++) {
365
        fprintf(header, "%1u%s", base_length[i],
366
                SEPARATOR(i, LENGTH_CODES-1, 20));
367
    }
368
 
369
    fprintf(header, "local const int base_dist[D_CODES] = {\n");
370
    for (i = 0; i < D_CODES; i++) {
371
        fprintf(header, "%5u%s", base_dist[i],
372
                SEPARATOR(i, D_CODES-1, 10));
373
    }
374
 
375
    fclose(header);
376
}
377
#endif /* GEN_TREES_H */
378
 
379
/* ===========================================================================
380
 * Initialize the tree data structures for a new zlib stream.
381
 */
382
void _tr_init(s)
383
    deflate_state *s;
384
{
385
    tr_static_init();
386
 
387
    s->l_desc.dyn_tree = s->dyn_ltree;
388
    s->l_desc.stat_desc = &static_l_desc;
389
 
390
    s->d_desc.dyn_tree = s->dyn_dtree;
391
    s->d_desc.stat_desc = &static_d_desc;
392
 
393
    s->bl_desc.dyn_tree = s->bl_tree;
394
    s->bl_desc.stat_desc = &static_bl_desc;
395
 
396
    s->bi_buf = 0;
397
    s->bi_valid = 0;
398
    s->last_eob_len = 8; /* enough lookahead for inflate */
399
#ifdef DEBUG
400
    s->compressed_len = 0L;
401
    s->bits_sent = 0L;
402
#endif
403
 
404
    /* Initialize the first block of the first file: */
405
    init_block(s);
406
}
407
 
408
/* ===========================================================================
409
 * Initialize a new block.
410
 */
411
local void init_block(s)
412
    deflate_state *s;
413
{
414
    int n; /* iterates over tree elements */
415
 
416
    /* Initialize the trees. */
417
    for (n = 0; n < L_CODES;  n++) s->dyn_ltree[n].Freq = 0;
418
    for (n = 0; n < D_CODES;  n++) s->dyn_dtree[n].Freq = 0;
419
    for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;
420
 
421
    s->dyn_ltree[END_BLOCK].Freq = 1;
422
    s->opt_len = s->static_len = 0L;
423
    s->last_lit = s->matches = 0;
424
}
425
 
426
#define SMALLEST 1
427
/* Index within the heap array of least frequent node in the Huffman tree */
428
 
429
 
430
/* ===========================================================================
431
 * Remove the smallest element from the heap and recreate the heap with
432
 * one less element. Updates heap and heap_len.
433
 */
434
#define pqremove(s, tree, top) \
435
{\
436
    top = s->heap[SMALLEST]; \
437
    s->heap[SMALLEST] = s->heap[s->heap_len--]; \
438
    pqdownheap(s, tree, SMALLEST); \
439
}
440
 
441
/* ===========================================================================
442
 * Compares to subtrees, using the tree depth as tie breaker when
443
 * the subtrees have equal frequency. This minimizes the worst case length.
444
 */
445
#define smaller(tree, n, m, depth) \
446
   (tree[n].Freq < tree[m].Freq || \
447
   (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
448
 
449
/* ===========================================================================
450
 * Restore the heap property by moving down the tree starting at node k,
451
 * exchanging a node with the smallest of its two sons if necessary, stopping
452
 * when the heap property is re-established (each father smaller than its
453
 * two sons).
454
 */
455
local void pqdownheap(s, tree, k)
456
    deflate_state *s;
457
    ct_data *tree;  /* the tree to restore */
458
    int k;               /* node to move down */
459
{
460
    int v = s->heap[k];
461
    int j = k << 1;  /* left son of k */
462
    while (j <= s->heap_len) {
463
        /* Set j to the smallest of the two sons: */
464
        if (j < s->heap_len &&
465
            smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
466
            j++;
467
        }
468
        /* Exit if v is smaller than both sons */
469
        if (smaller(tree, v, s->heap[j], s->depth)) break;
470
 
471
        /* Exchange v with the smallest son */
472
        s->heap[k] = s->heap[j];  k = j;
473
 
474
        /* And continue down the tree, setting j to the left son of k */
475
        j <<= 1;
476
    }
477
    s->heap[k] = v;
478
}
479
 
480
/* ===========================================================================
481
 * Compute the optimal bit lengths for a tree and update the total bit length
482
 * for the current block.
483
 * IN assertion: the fields freq and dad are set, heap[heap_max] and
484
 *    above are the tree nodes sorted by increasing frequency.
485
 * OUT assertions: the field len is set to the optimal bit length, the
486
 *     array bl_count contains the frequencies for each bit length.
487
 *     The length opt_len is updated; static_len is also updated if stree is
488
 *     not null.
489
 */
490
local void gen_bitlen(s, desc)
491
    deflate_state *s;
492
    tree_desc *desc;    /* the tree descriptor */
493
{
494
    ct_data *tree        = desc->dyn_tree;
495
    int max_code         = desc->max_code;
496
    const ct_data *stree = desc->stat_desc->static_tree;
497
    const intf *extra    = desc->stat_desc->extra_bits;
498
    int base             = desc->stat_desc->extra_base;
499
    int max_length       = desc->stat_desc->max_length;
500
    int h;              /* heap index */
501
    int n, m;           /* iterate over the tree elements */
502
    int bits;           /* bit length */
503
    int xbits;          /* extra bits */
504
    ush f;              /* frequency */
505
    int overflow = 0;   /* number of elements with bit length too large */
506
 
507
    for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
508
 
509
    /* In a first pass, compute the optimal bit lengths (which may
510
     * overflow in the case of the bit length tree).
511
     */
512
    tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
513
 
514
    for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
515
        n = s->heap[h];
516
        bits = tree[tree[n].Dad].Len + 1;
517
        if (bits > max_length) bits = max_length, overflow++;
518
        tree[n].Len = (ush)bits;
519
        /* We overwrite tree[n].Dad which is no longer needed */
520
 
521
        if (n > max_code) continue; /* not a leaf node */
522
 
523
        s->bl_count[bits]++;
524
        xbits = 0;
525
        if (n >= base) xbits = extra[n-base];
526
        f = tree[n].Freq;
527
        s->opt_len += (ulg)f * (bits + xbits);
528
        if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits);
529
    }
530
    if (overflow == 0) return;
531
 
532
    Trace((stderr,"\nbit length overflow\n"));
533
    /* This happens for example on obj2 and pic of the Calgary corpus */
534
 
535
    /* Find the first bit length which could increase: */
536
    do {
537
        bits = max_length-1;
538
        while (s->bl_count[bits] == 0) bits--;
539
        s->bl_count[bits]--;      /* move one leaf down the tree */
540
        s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
541
        s->bl_count[max_length]--;
542
        /* The brother of the overflow item also moves one step up,
543
         * but this does not affect bl_count[max_length]
544
         */
545
        overflow -= 2;
546
    } while (overflow > 0);
547
 
548
    /* Now recompute all bit lengths, scanning in increasing frequency.
549
     * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
550
     * lengths instead of fixing only the wrong ones. This idea is taken
551
     * from 'ar' written by Haruhiko Okumura.)
552
     */
553
    for (bits = max_length; bits != 0; bits--) {
554
        n = s->bl_count[bits];
555
        while (n != 0) {
556
            m = s->heap[--h];
557
            if (m > max_code) continue;
558
            if ((unsigned) tree[m].Len != (unsigned) bits) {
559
                Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
560
                s->opt_len += ((long)bits - (long)tree[m].Len)
561
                              *(long)tree[m].Freq;
562
                tree[m].Len = (ush)bits;
563
            }
564
            n--;
565
        }
566
    }
567
}
568
 
569
/* ===========================================================================
570
 * Generate the codes for a given tree and bit counts (which need not be
571
 * optimal).
572
 * IN assertion: the array bl_count contains the bit length statistics for
573
 * the given tree and the field len is set for all tree elements.
574
 * OUT assertion: the field code is set for all tree elements of non
575
 *     zero code length.
576
 */
577
local void gen_codes (tree, max_code, bl_count)
578
    ct_data *tree;             /* the tree to decorate */
579
    int max_code;              /* largest code with non zero frequency */
580
    ushf *bl_count;            /* number of codes at each bit length */
581
{
582
    ush next_code[MAX_BITS+1]; /* next code value for each bit length */
583
    ush code = 0;              /* running code value */
584
    int bits;                  /* bit index */
585
    int n;                     /* code index */
586
 
587
    /* The distribution counts are first used to generate the code values
588
     * without bit reversal.
589
     */
590
    for (bits = 1; bits <= MAX_BITS; bits++) {
591
        next_code[bits] = code = (code + bl_count[bits-1]) << 1;
592
    }
593
    /* Check that the bit counts in bl_count are consistent. The last code
594
     * must be all ones.
595
     */
596
    Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
597
            "inconsistent bit counts");
598
    Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
599
 
600
    for (n = 0;  n <= max_code; n++) {
601
        int len = tree[n].Len;
602
        if (len == 0) continue;
603
        /* Now reverse the bits */
604
        tree[n].Code = bi_reverse(next_code[len]++, len);
605
 
606
        Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
607
             n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
608
    }
609
}
610
 
611
/* ===========================================================================
612
 * Construct one Huffman tree and assigns the code bit strings and lengths.
613
 * Update the total bit length for the current block.
614
 * IN assertion: the field freq is set for all tree elements.
615
 * OUT assertions: the fields len and code are set to the optimal bit length
616
 *     and corresponding code. The length opt_len is updated; static_len is
617
 *     also updated if stree is not null. The field max_code is set.
618
 */
619
local void build_tree(s, desc)
620
    deflate_state *s;
621
    tree_desc *desc; /* the tree descriptor */
622
{
623
    ct_data *tree         = desc->dyn_tree;
624
    const ct_data *stree  = desc->stat_desc->static_tree;
625
    int elems             = desc->stat_desc->elems;
626
    int n, m;          /* iterate over heap elements */
627
    int max_code = -1; /* largest code with non zero frequency */
628
    int node;          /* new node being created */
629
 
630
    /* Construct the initial heap, with least frequent element in
631
     * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
632
     * heap[0] is not used.
633
     */
634
    s->heap_len = 0, s->heap_max = HEAP_SIZE;
635
 
636
    for (n = 0; n < elems; n++) {
637
        if (tree[n].Freq != 0) {
638
            s->heap[++(s->heap_len)] = max_code = n;
639
            s->depth[n] = 0;
640
        } else {
641
            tree[n].Len = 0;
642
        }
643
    }
644
 
645
    /* The pkzip format requires that at least one distance code exists,
646
     * and that at least one bit should be sent even if there is only one
647
     * possible code. So to avoid special checks later on we force at least
648
     * two codes of non zero frequency.
649
     */
650
    while (s->heap_len < 2) {
651
        node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
652
        tree[node].Freq = 1;
653
        s->depth[node] = 0;
654
        s->opt_len--; if (stree) s->static_len -= stree[node].Len;
655
        /* node is 0 or 1 so it does not have extra bits */
656
    }
657
    desc->max_code = max_code;
658
 
659
    /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
660
     * establish sub-heaps of increasing lengths:
661
     */
662
    for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
663
 
664
    /* Construct the Huffman tree by repeatedly combining the least two
665
     * frequent nodes.
666
     */
667
    node = elems;              /* next internal node of the tree */
668
    do {
669
        pqremove(s, tree, n);  /* n = node of least frequency */
670
        m = s->heap[SMALLEST]; /* m = node of next least frequency */
671
 
672
        s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
673
        s->heap[--(s->heap_max)] = m;
674
 
675
        /* Create a new node father of n and m */
676
        tree[node].Freq = tree[n].Freq + tree[m].Freq;
677
        s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?
678
                                s->depth[n] : s->depth[m]) + 1);
679
        tree[n].Dad = tree[m].Dad = (ush)node;
680
#ifdef DUMP_BL_TREE
681
        if (tree == s->bl_tree) {
682
            fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
683
                    node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
684
        }
685
#endif
686
        /* and insert the new node in the heap */
687
        s->heap[SMALLEST] = node++;
688
        pqdownheap(s, tree, SMALLEST);
689
 
690
    } while (s->heap_len >= 2);
691
 
692
    s->heap[--(s->heap_max)] = s->heap[SMALLEST];
693
 
694
    /* At this point, the fields freq and dad are set. We can now
695
     * generate the bit lengths.
696
     */
697
    gen_bitlen(s, (tree_desc *)desc);
698
 
699
    /* The field len is now set, we can generate the bit codes */
700
    gen_codes ((ct_data *)tree, max_code, s->bl_count);
701
}
702
 
703
/* ===========================================================================
704
 * Scan a literal or distance tree to determine the frequencies of the codes
705
 * in the bit length tree.
706
 */
707
local void scan_tree (s, tree, max_code)
708
    deflate_state *s;
709
    ct_data *tree;   /* the tree to be scanned */
710
    int max_code;    /* and its largest code of non zero frequency */
711
{
712
    int n;                     /* iterates over all tree elements */
713
    int prevlen = -1;          /* last emitted length */
714
    int curlen;                /* length of current code */
715
    int nextlen = tree[0].Len; /* length of next code */
716
    int count = 0;             /* repeat count of the current code */
717
    int max_count = 7;         /* max repeat count */
718
    int min_count = 4;         /* min repeat count */
719
 
720
    if (nextlen == 0) max_count = 138, min_count = 3;
721
    tree[max_code+1].Len = (ush)0xffff; /* guard */
722
 
723
    for (n = 0; n <= max_code; n++) {
724
        curlen = nextlen; nextlen = tree[n+1].Len;
725
        if (++count < max_count && curlen == nextlen) {
726
            continue;
727
        } else if (count < min_count) {
728
            s->bl_tree[curlen].Freq += count;
729
        } else if (curlen != 0) {
730
            if (curlen != prevlen) s->bl_tree[curlen].Freq++;
731
            s->bl_tree[REP_3_6].Freq++;
732
        } else if (count <= 10) {
733
            s->bl_tree[REPZ_3_10].Freq++;
734
        } else {
735
            s->bl_tree[REPZ_11_138].Freq++;
736
        }
737
        count = 0; prevlen = curlen;
738
        if (nextlen == 0) {
739
            max_count = 138, min_count = 3;
740
        } else if (curlen == nextlen) {
741
            max_count = 6, min_count = 3;
742
        } else {
743
            max_count = 7, min_count = 4;
744
        }
745
    }
746
}
747
 
748
/* ===========================================================================
749
 * Send a literal or distance tree in compressed form, using the codes in
750
 * bl_tree.
751
 */
752
local void send_tree (s, tree, max_code)
753
    deflate_state *s;
754
    ct_data *tree; /* the tree to be scanned */
755
    int max_code;       /* and its largest code of non zero frequency */
756
{
757
    int n;                     /* iterates over all tree elements */
758
    int prevlen = -1;          /* last emitted length */
759
    int curlen;                /* length of current code */
760
    int nextlen = tree[0].Len; /* length of next code */
761
    int count = 0;             /* repeat count of the current code */
762
    int max_count = 7;         /* max repeat count */
763
    int min_count = 4;         /* min repeat count */
764
 
765
    /* tree[max_code+1].Len = -1; */  /* guard already set */
766
    if (nextlen == 0) max_count = 138, min_count = 3;
767
 
768
    for (n = 0; n <= max_code; n++) {
769
        curlen = nextlen; nextlen = tree[n+1].Len;
770
        if (++count < max_count && curlen == nextlen) {
771
            continue;
772
        } else if (count < min_count) {
773
            do { send_code(s, curlen, s->bl_tree); } while (--count != 0);
774
 
775
        } else if (curlen != 0) {
776
            if (curlen != prevlen) {
777
                send_code(s, curlen, s->bl_tree); count--;
778
            }
779
            Assert(count >= 3 && count <= 6, " 3_6?");
780
            send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);
781
 
782
        } else if (count <= 10) {
783
            send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);
784
 
785
        } else {
786
            send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
787
        }
788
        count = 0; prevlen = curlen;
789
        if (nextlen == 0) {
790
            max_count = 138, min_count = 3;
791
        } else if (curlen == nextlen) {
792
            max_count = 6, min_count = 3;
793
        } else {
794
            max_count = 7, min_count = 4;
795
        }
796
    }
797
}
798
 
799
/* ===========================================================================
800
 * Construct the Huffman tree for the bit lengths and return the index in
801
 * bl_order of the last bit length code to send.
802
 */
803
local int build_bl_tree(s)
804
    deflate_state *s;
805
{
806
    int max_blindex;  /* index of last bit length code of non zero freq */
807
 
808
    /* Determine the bit length frequencies for literal and distance trees */
809
    scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
810
    scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);
811
 
812
    /* Build the bit length tree: */
813
    build_tree(s, (tree_desc *)(&(s->bl_desc)));
814
    /* opt_len now includes the length of the tree representations, except
815
     * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
816
     */
817
 
818
    /* Determine the number of bit length codes to send. The pkzip format
819
     * requires that at least 4 bit length codes be sent. (appnote.txt says
820
     * 3 but the actual value used is 4.)
821
     */
822
    for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
823
        if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
824
    }
825
    /* Update opt_len to include the bit length tree and counts */
826
    s->opt_len += 3*(max_blindex+1) + 5+5+4;
827
    Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
828
            s->opt_len, s->static_len));
829
 
830
    return max_blindex;
831
}
832
 
833
/* ===========================================================================
834
 * Send the header for a block using dynamic Huffman trees: the counts, the
835
 * lengths of the bit length codes, the literal tree and the distance tree.
836
 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
837
 */
838
local void send_all_trees(s, lcodes, dcodes, blcodes)
839
    deflate_state *s;
840
    int lcodes, dcodes, blcodes; /* number of codes for each tree */
841
{
842
    int rank;                    /* index in bl_order */
843
 
844
    Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
845
    Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
846
            "too many codes");
847
    Tracev((stderr, "\nbl counts: "));
848
    send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
849
    send_bits(s, dcodes-1,   5);
850
    send_bits(s, blcodes-4,  4); /* not -3 as stated in appnote.txt */
851
    for (rank = 0; rank < blcodes; rank++) {
852
        Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
853
        send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
854
    }
855
    Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));
856
 
857
    send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
858
    Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));
859
 
860
    send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
861
    Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
862
}
863
 
864
/* ===========================================================================
865
 * Send a stored block
866
 */
867
void _tr_stored_block(s, buf, stored_len, eof)
868
    deflate_state *s;
869
    charf *buf;       /* input block */
870
    ulg stored_len;   /* length of input block */
871
    int eof;          /* true if this is the last block for a file */
872
{
873
    send_bits(s, (STORED_BLOCK<<1)+eof, 3);  /* send block type */
874
#ifdef DEBUG
875
    s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
876
    s->compressed_len += (stored_len + 4) << 3;
877
#endif
878
    copy_block(s, buf, (unsigned)stored_len, 1); /* with header */
879
}
880
 
881
/* ===========================================================================
882
 * Send one empty static block to give enough lookahead for inflate.
883
 * This takes 10 bits, of which 7 may remain in the bit buffer.
884
 * The current inflate code requires 9 bits of lookahead. If the
885
 * last two codes for the previous block (real code plus EOB) were coded
886
 * on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode
887
 * the last real code. In this case we send two empty static blocks instead
888
 * of one. (There are no problems if the previous block is stored or fixed.)
889
 * To simplify the code, we assume the worst case of last real code encoded
890
 * on one bit only.
891
 */
892
void _tr_align(s)
893
    deflate_state *s;
894
{
895
    send_bits(s, STATIC_TREES<<1, 3);
896
    send_code(s, END_BLOCK, static_ltree);
897
#ifdef DEBUG
898
    s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
899
#endif
900
    bi_flush(s);
901
    /* Of the 10 bits for the empty block, we have already sent
902
     * (10 - bi_valid) bits. The lookahead for the last real code (before
903
     * the EOB of the previous block) was thus at least one plus the length
904
     * of the EOB plus what we have just sent of the empty static block.
905
     */
906
    if (1 + s->last_eob_len + 10 - s->bi_valid < 9) {
907
        send_bits(s, STATIC_TREES<<1, 3);
908
        send_code(s, END_BLOCK, static_ltree);
909
#ifdef DEBUG
910
        s->compressed_len += 10L;
911
#endif
912
        bi_flush(s);
913
    }
914
    s->last_eob_len = 7;
915
}
916
 
917
/* ===========================================================================
918
 * Determine the best encoding for the current block: dynamic trees, static
919
 * trees or store, and output the encoded block to the zip file.
920
 */
921
void _tr_flush_block(s, buf, stored_len, eof)
922
    deflate_state *s;
923
    charf *buf;       /* input block, or NULL if too old */
924
    ulg stored_len;   /* length of input block */
925
    int eof;          /* true if this is the last block for a file */
926
{
927
    ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
928
    int max_blindex = 0;  /* index of last bit length code of non zero freq */
929
 
930
    /* Build the Huffman trees unless a stored block is forced */
931
    if (s->level > 0) {
932
 
933
        /* Check if the file is binary or text */
934
        if (stored_len > 0 && s->strm->data_type == Z_UNKNOWN)
935
            set_data_type(s);
936
 
937
        /* Construct the literal and distance trees */
938
        build_tree(s, (tree_desc *)(&(s->l_desc)));
939
        Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
940
                s->static_len));
941
 
942
        build_tree(s, (tree_desc *)(&(s->d_desc)));
943
        Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
944
                s->static_len));
945
        /* At this point, opt_len and static_len are the total bit lengths of
946
         * the compressed block data, excluding the tree representations.
947
         */
948
 
949
        /* Build the bit length tree for the above two trees, and get the index
950
         * in bl_order of the last bit length code to send.
951
         */
952
        max_blindex = build_bl_tree(s);
953
 
954
        /* Determine the best encoding. Compute the block lengths in bytes. */
955
        opt_lenb = (s->opt_len+3+7)>>3;
956
        static_lenb = (s->static_len+3+7)>>3;
957
 
958
        Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
959
                opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
960
                s->last_lit));
961
 
962
        if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
963
 
964
    } else {
965
        Assert(buf != (char*)0, "lost buf");
966
        opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
967
    }
968
 
969
#ifdef FORCE_STORED
970
    if (buf != (char*)0) { /* force stored block */
971
#else
972
    if (stored_len+4 <= opt_lenb && buf != (char*)0) {
973
                       /* 4: two words for the lengths */
974
#endif
975
        /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
976
         * Otherwise we can't have processed more than WSIZE input bytes since
977
         * the last block flush, because compression would have been
978
         * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
979
         * transform a block into a stored block.
980
         */
981
        _tr_stored_block(s, buf, stored_len, eof);
982
 
983
#ifdef FORCE_STATIC
984
    } else if (static_lenb >= 0) { /* force static trees */
985
#else
986
    } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) {
987
#endif
988
        send_bits(s, (STATIC_TREES<<1)+eof, 3);
989
        compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree);
990
#ifdef DEBUG
991
        s->compressed_len += 3 + s->static_len;
992
#endif
993
    } else {
994
        send_bits(s, (DYN_TREES<<1)+eof, 3);
995
        send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
996
                       max_blindex+1);
997
        compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree);
998
#ifdef DEBUG
999
        s->compressed_len += 3 + s->opt_len;
1000
#endif
1001
    }
1002
    Assert (s->compressed_len == s->bits_sent, "bad compressed size");
1003
    /* The above check is made mod 2^32, for files larger than 512 MB
1004
     * and uLong implemented on 32 bits.
1005
     */
1006
    init_block(s);
1007
 
1008
    if (eof) {
1009
        bi_windup(s);
1010
#ifdef DEBUG
1011
        s->compressed_len += 7;  /* align on byte boundary */
1012
#endif
1013
    }
1014
    Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
1015
           s->compressed_len-7*eof));
1016
}
1017
 
1018
/* ===========================================================================
1019
 * Save the match info and tally the frequency counts. Return true if
1020
 * the current block must be flushed.
1021
 */
1022
int _tr_tally (s, dist, lc)
1023
    deflate_state *s;
1024
    unsigned dist;  /* distance of matched string */
1025
    unsigned lc;    /* match length-MIN_MATCH or unmatched char (if dist==0) */
1026
{
1027
    s->d_buf[s->last_lit] = (ush)dist;
1028
    s->l_buf[s->last_lit++] = (uch)lc;
1029
    if (dist == 0) {
1030
        /* lc is the unmatched char */
1031
        s->dyn_ltree[lc].Freq++;
1032
    } else {
1033
        s->matches++;
1034
        /* Here, lc is the match length - MIN_MATCH */
1035
        dist--;             /* dist = match distance - 1 */
1036
        Assert((ush)dist < (ush)MAX_DIST(s) &&
1037
               (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
1038
               (ush)d_code(dist) < (ush)D_CODES,  "_tr_tally: bad match");
1039
 
1040
        s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
1041
        s->dyn_dtree[d_code(dist)].Freq++;
1042
    }
1043
 
1044
#ifdef TRUNCATE_BLOCK
1045
    /* Try to guess if it is profitable to stop the current block here */
1046
    if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
1047
        /* Compute an upper bound for the compressed length */
1048
        ulg out_length = (ulg)s->last_lit*8L;
1049
        ulg in_length = (ulg)((long)s->strstart - s->block_start);
1050
        int dcode;
1051
        for (dcode = 0; dcode < D_CODES; dcode++) {
1052
            out_length += (ulg)s->dyn_dtree[dcode].Freq *
1053
                (5L+extra_dbits[dcode]);
1054
        }
1055
        out_length >>= 3;
1056
        Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
1057
               s->last_lit, in_length, out_length,
1058
               100L - out_length*100L/in_length));
1059
        if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
1060
    }
1061
#endif
1062
    return (s->last_lit == s->lit_bufsize-1);
1063
    /* We avoid equality with lit_bufsize because of wraparound at 64K
1064
     * on 16 bit machines and because stored blocks are restricted to
1065
     * 64K-1 bytes.
1066
     */
1067
}
1068
 
1069
/* ===========================================================================
1070
 * Send the block data compressed using the given Huffman trees
1071
 */
1072
local void compress_block(s, ltree, dtree)
1073
    deflate_state *s;
1074
    ct_data *ltree; /* literal tree */
1075
    ct_data *dtree; /* distance tree */
1076
{
1077
    unsigned dist;      /* distance of matched string */
1078
    int lc;             /* match length or unmatched char (if dist == 0) */
1079
    unsigned lx = 0;    /* running index in l_buf */
1080
    unsigned code;      /* the code to send */
1081
    int extra;          /* number of extra bits to send */
1082
 
1083
    if (s->last_lit != 0) do {
1084
        dist = s->d_buf[lx];
1085
        lc = s->l_buf[lx++];
1086
        if (dist == 0) {
1087
            send_code(s, lc, ltree); /* send a literal byte */
1088
            Tracecv(isgraph(lc), (stderr," '%c' ", lc));
1089
        } else {
1090
            /* Here, lc is the match length - MIN_MATCH */
1091
            code = _length_code[lc];
1092
            send_code(s, code+LITERALS+1, ltree); /* send the length code */
1093
            extra = extra_lbits[code];
1094
            if (extra != 0) {
1095
                lc -= base_length[code];
1096
                send_bits(s, lc, extra);       /* send the extra length bits */
1097
            }
1098
            dist--; /* dist is now the match distance - 1 */
1099
            code = d_code(dist);
1100
            Assert (code < D_CODES, "bad d_code");
1101
 
1102
            send_code(s, code, dtree);       /* send the distance code */
1103
            extra = extra_dbits[code];
1104
            if (extra != 0) {
1105
                dist -= base_dist[code];
1106
                send_bits(s, dist, extra);   /* send the extra distance bits */
1107
            }
1108
        } /* literal or match pair ? */
1109
 
1110
        /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
1111
        Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx,
1112
               "pendingBuf overflow");
1113
 
1114
    } while (lx < s->last_lit);
1115
 
1116
    send_code(s, END_BLOCK, ltree);
1117
    s->last_eob_len = ltree[END_BLOCK].Len;
1118
}
1119
 
1120
/* ===========================================================================
1121
 * Set the data type to BINARY or TEXT, using a crude approximation:
1122
 * set it to Z_TEXT if all symbols are either printable characters (33 to 255)
1123
 * or white spaces (9 to 13, or 32); or set it to Z_BINARY otherwise.
1124
 * IN assertion: the fields Freq of dyn_ltree are set.
1125
 */
1126
local void set_data_type(s)
1127
    deflate_state *s;
1128
{
1129
    int n;
1130
 
1131
    for (n = 0; n < 9; n++)
1132
        if (s->dyn_ltree[n].Freq != 0)
1133
            break;
1134
    if (n == 9)
1135
        for (n = 14; n < 32; n++)
1136
            if (s->dyn_ltree[n].Freq != 0)
1137
                break;
1138
    s->strm->data_type = (n == 32) ? Z_TEXT : Z_BINARY;
1139
}
1140
 
1141
/* ===========================================================================
1142
 * Reverse the first len bits of a code, using straightforward code (a faster
1143
 * method would use a table)
1144
 * IN assertion: 1 <= len <= 15
1145
 */
1146
local unsigned bi_reverse(code, len)
1147
    unsigned code; /* the value to invert */
1148
    int len;       /* its bit length */
1149
{
1150
    register unsigned res = 0;
1151
    do {
1152
        res |= code & 1;
1153
        code >>= 1, res <<= 1;
1154
    } while (--len > 0);
1155
    return res >> 1;
1156
}
1157
 
1158
/* ===========================================================================
1159
 * Flush the bit buffer, keeping at most 7 bits in it.
1160
 */
1161
local void bi_flush(s)
1162
    deflate_state *s;
1163
{
1164
    if (s->bi_valid == 16) {
1165
        put_short(s, s->bi_buf);
1166
        s->bi_buf = 0;
1167
        s->bi_valid = 0;
1168
    } else if (s->bi_valid >= 8) {
1169
        put_byte(s, (Byte)s->bi_buf);
1170
        s->bi_buf >>= 8;
1171
        s->bi_valid -= 8;
1172
    }
1173
}
1174
 
1175
/* ===========================================================================
1176
 * Flush the bit buffer and align the output on a byte boundary
1177
 */
1178
local void bi_windup(s)
1179
    deflate_state *s;
1180
{
1181
    if (s->bi_valid > 8) {
1182
        put_short(s, s->bi_buf);
1183
    } else if (s->bi_valid > 0) {
1184
        put_byte(s, (Byte)s->bi_buf);
1185
    }
1186
    s->bi_buf = 0;
1187
    s->bi_valid = 0;
1188
#ifdef DEBUG
1189
    s->bits_sent = (s->bits_sent+7) & ~7;
1190
#endif
1191
}
1192
 
1193
/* ===========================================================================
1194
 * Copy a stored block, storing first the length and its
1195
 * one's complement if requested.
1196
 */
1197
local void copy_block(s, buf, len, header)
1198
    deflate_state *s;
1199
    charf    *buf;    /* the input data */
1200
    unsigned len;     /* its length */
1201
    int      header;  /* true if block header must be written */
1202
{
1203
    bi_windup(s);        /* align on byte boundary */
1204
    s->last_eob_len = 8; /* enough lookahead for inflate */
1205
 
1206
    if (header) {
1207
        put_short(s, (ush)len);
1208
        put_short(s, (ush)~len);
1209
#ifdef DEBUG
1210
        s->bits_sent += 2*16;
1211
#endif
1212
    }
1213
#ifdef DEBUG
1214
    s->bits_sent += (ulg)len<<3;
1215
#endif
1216
    while (len--) {
1217
        put_byte(s, *buf++);
1218
    }
1219
}

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