COIN-OR::LEMON - Graph Library

source: lemon-project-template-glpk/deps/glpk/src/zlib/trees.c @ 10:5545663ca997

subpack-glpk
Last change on this file since 10:5545663ca997 was 9:33de93886c88, checked in by Alpar Juttner <alpar@…>, 13 years ago

Import GLPK 4.47

File size: 44.2 KB
Line 
1/* trees.c -- output deflated data using Huffman coding
2 * Copyright (C) 1995-2010 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 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
62local 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
65local 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
68local 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
71local 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#define Buf_size (8 * 2*sizeof(char))
78/* Number of bits used within bi_buf. (bi_buf might be implemented on
79 * more than 16 bits on some systems.)
80 */
81
82/* ===========================================================================
83 * Local data. These are initialized only once.
84 */
85
86#define DIST_CODE_LEN  512 /* see definition of array dist_code below */
87
88#if defined(GEN_TREES_H) || !defined(STDC)
89/* non ANSI compilers may not accept trees.h */
90
91local ct_data static_ltree[L_CODES+2];
92/* The static literal tree. Since the bit lengths are imposed, there is no
93 * need for the L_CODES extra codes used during heap construction. However
94 * The codes 286 and 287 are needed to build a canonical tree (see _tr_init
95 * below).
96 */
97
98local ct_data static_dtree[D_CODES];
99/* The static distance tree. (Actually a trivial tree since all codes use
100 * 5 bits.)
101 */
102
103uch _dist_code[DIST_CODE_LEN];
104/* Distance codes. The first 256 values correspond to the distances
105 * 3 .. 258, the last 256 values correspond to the top 8 bits of
106 * the 15 bit distances.
107 */
108
109uch _length_code[MAX_MATCH-MIN_MATCH+1];
110/* length code for each normalized match length (0 == MIN_MATCH) */
111
112local int base_length[LENGTH_CODES];
113/* First normalized length for each code (0 = MIN_MATCH) */
114
115local int base_dist[D_CODES];
116/* First normalized distance for each code (0 = distance of 1) */
117
118#else
119#  include "trees.h"
120#endif /* GEN_TREES_H */
121
122struct static_tree_desc_s {
123    const ct_data *static_tree;  /* static tree or NULL */
124    const intf *extra_bits;      /* extra bits for each code or NULL */
125    int     extra_base;          /* base index for extra_bits */
126    int     elems;               /* max number of elements in the tree */
127    int     max_length;          /* max bit length for the codes */
128};
129
130local static_tree_desc  static_l_desc =
131{static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};
132
133local static_tree_desc  static_d_desc =
134{static_dtree, extra_dbits, 0,          D_CODES, MAX_BITS};
135
136local static_tree_desc  static_bl_desc =
137{(const ct_data *)0, extra_blbits, 0,   BL_CODES, MAX_BL_BITS};
138
139/* ===========================================================================
140 * Local (static) routines in this file.
141 */
142
143local void tr_static_init OF((void));
144local void init_block     OF((deflate_state *s));
145local void pqdownheap     OF((deflate_state *s, ct_data *tree, int k));
146local void gen_bitlen     OF((deflate_state *s, tree_desc *desc));
147local void gen_codes      OF((ct_data *tree, int max_code, ushf *bl_count));
148local void build_tree     OF((deflate_state *s, tree_desc *desc));
149local void scan_tree      OF((deflate_state *s, ct_data *tree, int max_code));
150local void send_tree      OF((deflate_state *s, ct_data *tree, int max_code));
151local int  build_bl_tree  OF((deflate_state *s));
152local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes,
153                              int blcodes));
154local void compress_block OF((deflate_state *s, ct_data *ltree,
155                              ct_data *dtree));
156local int  detect_data_type OF((deflate_state *s));
157local unsigned bi_reverse OF((unsigned value, int length));
158local void bi_windup      OF((deflate_state *s));
159local void bi_flush       OF((deflate_state *s));
160local void copy_block     OF((deflate_state *s, charf *buf, unsigned len,
161                              int header));
162
163#ifdef GEN_TREES_H
164local void gen_trees_header OF((void));
165#endif
166
167#ifndef DEBUG
168#  define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
169   /* Send a code of the given tree. c and tree must not have side effects */
170
171#else /* DEBUG */
172#  define send_code(s, c, tree) \
173     { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
174       send_bits(s, tree[c].Code, tree[c].Len); }
175#endif
176
177/* ===========================================================================
178 * Output a short LSB first on the stream.
179 * IN assertion: there is enough room in pendingBuf.
180 */
181#define put_short(s, w) { \
182    put_byte(s, (uch)((w) & 0xff)); \
183    put_byte(s, (uch)((ush)(w) >> 8)); \
184}
185
186/* ===========================================================================
187 * Send a value on a given number of bits.
188 * IN assertion: length <= 16 and value fits in length bits.
189 */
190#ifdef DEBUG
191local void send_bits      OF((deflate_state *s, int value, int length));
192
193local void send_bits(s, value, length)
194    deflate_state *s;
195    int value;  /* value to send */
196    int length; /* number of bits */
197{
198    Tracevv((stderr," l %2d v %4x ", length, value));
199    Assert(length > 0 && length <= 15, "invalid length");
200    s->bits_sent += (ulg)length;
201
202    /* If not enough room in bi_buf, use (valid) bits from bi_buf and
203     * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
204     * unused bits in value.
205     */
206    if (s->bi_valid > (int)Buf_size - length) {
207        s->bi_buf |= (ush)value << s->bi_valid;
208        put_short(s, s->bi_buf);
209        s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);
210        s->bi_valid += length - Buf_size;
211    } else {
212        s->bi_buf |= (ush)value << s->bi_valid;
213        s->bi_valid += length;
214    }
215}
216#else /* !DEBUG */
217
218#define send_bits(s, value, length) \
219{ int len = length;\
220  if (s->bi_valid > (int)Buf_size - len) {\
221    int val = value;\
222    s->bi_buf |= (ush)val << s->bi_valid;\
223    put_short(s, s->bi_buf);\
224    s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
225    s->bi_valid += len - Buf_size;\
226  } else {\
227    s->bi_buf |= (ush)(value) << s->bi_valid;\
228    s->bi_valid += len;\
229  }\
230}
231#endif /* DEBUG */
232
233
234/* the arguments must not have side effects */
235
236/* ===========================================================================
237 * Initialize the various 'constant' tables.
238 */
239local void tr_static_init()
240{
241#if defined(GEN_TREES_H) || !defined(STDC)
242    static int static_init_done = 0;
243    int n;        /* iterates over tree elements */
244    int bits;     /* bit counter */
245    int length;   /* length value */
246    int code;     /* code value */
247    int dist;     /* distance index */
248    ush bl_count[MAX_BITS+1];
249    /* number of codes at each bit length for an optimal tree */
250
251    if (static_init_done) return;
252
253    /* For some embedded targets, global variables are not initialized: */
254#ifdef NO_INIT_GLOBAL_POINTERS
255    static_l_desc.static_tree = static_ltree;
256    static_l_desc.extra_bits = extra_lbits;
257    static_d_desc.static_tree = static_dtree;
258    static_d_desc.extra_bits = extra_dbits;
259    static_bl_desc.extra_bits = extra_blbits;
260#endif
261
262    /* Initialize the mapping length (0..255) -> length code (0..28) */
263    length = 0;
264    for (code = 0; code < LENGTH_CODES-1; code++) {
265        base_length[code] = length;
266        for (n = 0; n < (1<<extra_lbits[code]); n++) {
267            _length_code[length++] = (uch)code;
268        }
269    }
270    Assert (length == 256, "tr_static_init: length != 256");
271    /* Note that the length 255 (match length 258) can be represented
272     * in two different ways: code 284 + 5 bits or code 285, so we
273     * overwrite length_code[255] to use the best encoding:
274     */
275    _length_code[length-1] = (uch)code;
276
277    /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
278    dist = 0;
279    for (code = 0 ; code < 16; code++) {
280        base_dist[code] = dist;
281        for (n = 0; n < (1<<extra_dbits[code]); n++) {
282            _dist_code[dist++] = (uch)code;
283        }
284    }
285    Assert (dist == 256, "tr_static_init: dist != 256");
286    dist >>= 7; /* from now on, all distances are divided by 128 */
287    for ( ; code < D_CODES; code++) {
288        base_dist[code] = dist << 7;
289        for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
290            _dist_code[256 + dist++] = (uch)code;
291        }
292    }
293    Assert (dist == 256, "tr_static_init: 256+dist != 512");
294
295    /* Construct the codes of the static literal tree */
296    for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
297    n = 0;
298    while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
299    while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
300    while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
301    while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
302    /* Codes 286 and 287 do not exist, but we must include them in the
303     * tree construction to get a canonical Huffman tree (longest code
304     * all ones)
305     */
306    gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);
307
308    /* The static distance tree is trivial: */
309    for (n = 0; n < D_CODES; n++) {
310        static_dtree[n].Len = 5;
311        static_dtree[n].Code = bi_reverse((unsigned)n, 5);
312    }
313    static_init_done = 1;
314
315#  ifdef GEN_TREES_H
316    gen_trees_header();
317#  endif
318#endif /* defined(GEN_TREES_H) || !defined(STDC) */
319}
320
321/* ===========================================================================
322 * Genererate the file trees.h describing the static trees.
323 */
324#ifdef GEN_TREES_H
325#  ifndef DEBUG
326#    include <stdio.h>
327#  endif
328
329#  define SEPARATOR(i, last, width) \
330      ((i) == (last)? "\n};\n\n" :    \
331       ((i) % (width) == (width)-1 ? ",\n" : ", "))
332
333void gen_trees_header()
334{
335    FILE *header = fopen("trees.h", "w");
336    int i;
337
338    Assert (header != NULL, "Can't open trees.h");
339    fprintf(header,
340            "/* header created automatically with -DGEN_TREES_H */\n\n");
341
342    fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n");
343    for (i = 0; i < L_CODES+2; i++) {
344        fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code,
345                static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5));
346    }
347
348    fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n");
349    for (i = 0; i < D_CODES; i++) {
350        fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code,
351                static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5));
352    }
353
354    fprintf(header, "const uch ZLIB_INTERNAL _dist_code[DIST_CODE_LEN] = {\n");
355    for (i = 0; i < DIST_CODE_LEN; i++) {
356        fprintf(header, "%2u%s", _dist_code[i],
357                SEPARATOR(i, DIST_CODE_LEN-1, 20));
358    }
359
360    fprintf(header,
361        "const uch ZLIB_INTERNAL _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");
362    for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) {
363        fprintf(header, "%2u%s", _length_code[i],
364                SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));
365    }
366
367    fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");
368    for (i = 0; i < LENGTH_CODES; i++) {
369        fprintf(header, "%1u%s", base_length[i],
370                SEPARATOR(i, LENGTH_CODES-1, 20));
371    }
372
373    fprintf(header, "local const int base_dist[D_CODES] = {\n");
374    for (i = 0; i < D_CODES; i++) {
375        fprintf(header, "%5u%s", base_dist[i],
376                SEPARATOR(i, D_CODES-1, 10));
377    }
378
379    fclose(header);
380}
381#endif /* GEN_TREES_H */
382
383/* ===========================================================================
384 * Initialize the tree data structures for a new zlib stream.
385 */
386void ZLIB_INTERNAL _tr_init(s)
387    deflate_state *s;
388{
389    tr_static_init();
390
391    s->l_desc.dyn_tree = s->dyn_ltree;
392    s->l_desc.stat_desc = &static_l_desc;
393
394    s->d_desc.dyn_tree = s->dyn_dtree;
395    s->d_desc.stat_desc = &static_d_desc;
396
397    s->bl_desc.dyn_tree = s->bl_tree;
398    s->bl_desc.stat_desc = &static_bl_desc;
399
400    s->bi_buf = 0;
401    s->bi_valid = 0;
402    s->last_eob_len = 8; /* enough lookahead for inflate */
403#ifdef DEBUG
404    s->compressed_len = 0L;
405    s->bits_sent = 0L;
406#endif
407
408    /* Initialize the first block of the first file: */
409    init_block(s);
410}
411
412/* ===========================================================================
413 * Initialize a new block.
414 */
415local void init_block(s)
416    deflate_state *s;
417{
418    int n; /* iterates over tree elements */
419
420    /* Initialize the trees. */
421    for (n = 0; n < L_CODES;  n++) s->dyn_ltree[n].Freq = 0;
422    for (n = 0; n < D_CODES;  n++) s->dyn_dtree[n].Freq = 0;
423    for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;
424
425    s->dyn_ltree[END_BLOCK].Freq = 1;
426    s->opt_len = s->static_len = 0L;
427    s->last_lit = s->matches = 0;
428}
429
430#define SMALLEST 1
431/* Index within the heap array of least frequent node in the Huffman tree */
432
433
434/* ===========================================================================
435 * Remove the smallest element from the heap and recreate the heap with
436 * one less element. Updates heap and heap_len.
437 */
438#define pqremove(s, tree, top) \
439{\
440    top = s->heap[SMALLEST]; \
441    s->heap[SMALLEST] = s->heap[s->heap_len--]; \
442    pqdownheap(s, tree, SMALLEST); \
443}
444
445/* ===========================================================================
446 * Compares to subtrees, using the tree depth as tie breaker when
447 * the subtrees have equal frequency. This minimizes the worst case length.
448 */
449#define smaller(tree, n, m, depth) \
450   (tree[n].Freq < tree[m].Freq || \
451   (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
452
453/* ===========================================================================
454 * Restore the heap property by moving down the tree starting at node k,
455 * exchanging a node with the smallest of its two sons if necessary, stopping
456 * when the heap property is re-established (each father smaller than its
457 * two sons).
458 */
459local void pqdownheap(s, tree, k)
460    deflate_state *s;
461    ct_data *tree;  /* the tree to restore */
462    int k;               /* node to move down */
463{
464    int v = s->heap[k];
465    int j = k << 1;  /* left son of k */
466    while (j <= s->heap_len) {
467        /* Set j to the smallest of the two sons: */
468        if (j < s->heap_len &&
469            smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
470            j++;
471        }
472        /* Exit if v is smaller than both sons */
473        if (smaller(tree, v, s->heap[j], s->depth)) break;
474
475        /* Exchange v with the smallest son */
476        s->heap[k] = s->heap[j];  k = j;
477
478        /* And continue down the tree, setting j to the left son of k */
479        j <<= 1;
480    }
481    s->heap[k] = v;
482}
483
484/* ===========================================================================
485 * Compute the optimal bit lengths for a tree and update the total bit length
486 * for the current block.
487 * IN assertion: the fields freq and dad are set, heap[heap_max] and
488 *    above are the tree nodes sorted by increasing frequency.
489 * OUT assertions: the field len is set to the optimal bit length, the
490 *     array bl_count contains the frequencies for each bit length.
491 *     The length opt_len is updated; static_len is also updated if stree is
492 *     not null.
493 */
494local void gen_bitlen(s, desc)
495    deflate_state *s;
496    tree_desc *desc;    /* the tree descriptor */
497{
498    ct_data *tree        = desc->dyn_tree;
499    int max_code         = desc->max_code;
500    const ct_data *stree = desc->stat_desc->static_tree;
501    const intf *extra    = desc->stat_desc->extra_bits;
502    int base             = desc->stat_desc->extra_base;
503    int max_length       = desc->stat_desc->max_length;
504    int h;              /* heap index */
505    int n, m;           /* iterate over the tree elements */
506    int bits;           /* bit length */
507    int xbits;          /* extra bits */
508    ush f;              /* frequency */
509    int overflow = 0;   /* number of elements with bit length too large */
510
511    for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
512
513    /* In a first pass, compute the optimal bit lengths (which may
514     * overflow in the case of the bit length tree).
515     */
516    tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
517
518    for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
519        n = s->heap[h];
520        bits = tree[tree[n].Dad].Len + 1;
521        if (bits > max_length) bits = max_length, overflow++;
522        tree[n].Len = (ush)bits;
523        /* We overwrite tree[n].Dad which is no longer needed */
524
525        if (n > max_code) continue; /* not a leaf node */
526
527        s->bl_count[bits]++;
528        xbits = 0;
529        if (n >= base) xbits = extra[n-base];
530        f = tree[n].Freq;
531        s->opt_len += (ulg)f * (bits + xbits);
532        if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits);
533    }
534    if (overflow == 0) return;
535
536    Trace((stderr,"\nbit length overflow\n"));
537    /* This happens for example on obj2 and pic of the Calgary corpus */
538
539    /* Find the first bit length which could increase: */
540    do {
541        bits = max_length-1;
542        while (s->bl_count[bits] == 0) bits--;
543        s->bl_count[bits]--;      /* move one leaf down the tree */
544        s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
545        s->bl_count[max_length]--;
546        /* The brother of the overflow item also moves one step up,
547         * but this does not affect bl_count[max_length]
548         */
549        overflow -= 2;
550    } while (overflow > 0);
551
552    /* Now recompute all bit lengths, scanning in increasing frequency.
553     * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
554     * lengths instead of fixing only the wrong ones. This idea is taken
555     * from 'ar' written by Haruhiko Okumura.)
556     */
557    for (bits = max_length; bits != 0; bits--) {
558        n = s->bl_count[bits];
559        while (n != 0) {
560            m = s->heap[--h];
561            if (m > max_code) continue;
562            if ((unsigned) tree[m].Len != (unsigned) bits) {
563                Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
564                s->opt_len += ((long)bits - (long)tree[m].Len)
565                              *(long)tree[m].Freq;
566                tree[m].Len = (ush)bits;
567            }
568            n--;
569        }
570    }
571}
572
573/* ===========================================================================
574 * Generate the codes for a given tree and bit counts (which need not be
575 * optimal).
576 * IN assertion: the array bl_count contains the bit length statistics for
577 * the given tree and the field len is set for all tree elements.
578 * OUT assertion: the field code is set for all tree elements of non
579 *     zero code length.
580 */
581local void gen_codes (tree, max_code, bl_count)
582    ct_data *tree;             /* the tree to decorate */
583    int max_code;              /* largest code with non zero frequency */
584    ushf *bl_count;            /* number of codes at each bit length */
585{
586    ush next_code[MAX_BITS+1]; /* next code value for each bit length */
587    ush code = 0;              /* running code value */
588    int bits;                  /* bit index */
589    int n;                     /* code index */
590
591    /* The distribution counts are first used to generate the code values
592     * without bit reversal.
593     */
594    for (bits = 1; bits <= MAX_BITS; bits++) {
595        next_code[bits] = code = (code + bl_count[bits-1]) << 1;
596    }
597    /* Check that the bit counts in bl_count are consistent. The last code
598     * must be all ones.
599     */
600    Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
601            "inconsistent bit counts");
602    Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
603
604    for (n = 0;  n <= max_code; n++) {
605        int len = tree[n].Len;
606        if (len == 0) continue;
607        /* Now reverse the bits */
608        tree[n].Code = bi_reverse(next_code[len]++, len);
609
610        Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
611             n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
612    }
613}
614
615/* ===========================================================================
616 * Construct one Huffman tree and assigns the code bit strings and lengths.
617 * Update the total bit length for the current block.
618 * IN assertion: the field freq is set for all tree elements.
619 * OUT assertions: the fields len and code are set to the optimal bit length
620 *     and corresponding code. The length opt_len is updated; static_len is
621 *     also updated if stree is not null. The field max_code is set.
622 */
623local void build_tree(s, desc)
624    deflate_state *s;
625    tree_desc *desc; /* the tree descriptor */
626{
627    ct_data *tree         = desc->dyn_tree;
628    const ct_data *stree  = desc->stat_desc->static_tree;
629    int elems             = desc->stat_desc->elems;
630    int n, m;          /* iterate over heap elements */
631    int max_code = -1; /* largest code with non zero frequency */
632    int node;          /* new node being created */
633
634    /* Construct the initial heap, with least frequent element in
635     * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
636     * heap[0] is not used.
637     */
638    s->heap_len = 0, s->heap_max = HEAP_SIZE;
639
640    for (n = 0; n < elems; n++) {
641        if (tree[n].Freq != 0) {
642            s->heap[++(s->heap_len)] = max_code = n;
643            s->depth[n] = 0;
644        } else {
645            tree[n].Len = 0;
646        }
647    }
648
649    /* The pkzip format requires that at least one distance code exists,
650     * and that at least one bit should be sent even if there is only one
651     * possible code. So to avoid special checks later on we force at least
652     * two codes of non zero frequency.
653     */
654    while (s->heap_len < 2) {
655        node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
656        tree[node].Freq = 1;
657        s->depth[node] = 0;
658        s->opt_len--; if (stree) s->static_len -= stree[node].Len;
659        /* node is 0 or 1 so it does not have extra bits */
660    }
661    desc->max_code = max_code;
662
663    /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
664     * establish sub-heaps of increasing lengths:
665     */
666    for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
667
668    /* Construct the Huffman tree by repeatedly combining the least two
669     * frequent nodes.
670     */
671    node = elems;              /* next internal node of the tree */
672    do {
673        pqremove(s, tree, n);  /* n = node of least frequency */
674        m = s->heap[SMALLEST]; /* m = node of next least frequency */
675
676        s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
677        s->heap[--(s->heap_max)] = m;
678
679        /* Create a new node father of n and m */
680        tree[node].Freq = tree[n].Freq + tree[m].Freq;
681        s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?
682                                s->depth[n] : s->depth[m]) + 1);
683        tree[n].Dad = tree[m].Dad = (ush)node;
684#ifdef DUMP_BL_TREE
685        if (tree == s->bl_tree) {
686            fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
687                    node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
688        }
689#endif
690        /* and insert the new node in the heap */
691        s->heap[SMALLEST] = node++;
692        pqdownheap(s, tree, SMALLEST);
693
694    } while (s->heap_len >= 2);
695
696    s->heap[--(s->heap_max)] = s->heap[SMALLEST];
697
698    /* At this point, the fields freq and dad are set. We can now
699     * generate the bit lengths.
700     */
701    gen_bitlen(s, (tree_desc *)desc);
702
703    /* The field len is now set, we can generate the bit codes */
704    gen_codes ((ct_data *)tree, max_code, s->bl_count);
705}
706
707/* ===========================================================================
708 * Scan a literal or distance tree to determine the frequencies of the codes
709 * in the bit length tree.
710 */
711local void scan_tree (s, tree, max_code)
712    deflate_state *s;
713    ct_data *tree;   /* the tree to be scanned */
714    int max_code;    /* and its largest code of non zero frequency */
715{
716    int n;                     /* iterates over all tree elements */
717    int prevlen = -1;          /* last emitted length */
718    int curlen;                /* length of current code */
719    int nextlen = tree[0].Len; /* length of next code */
720    int count = 0;             /* repeat count of the current code */
721    int max_count = 7;         /* max repeat count */
722    int min_count = 4;         /* min repeat count */
723
724    if (nextlen == 0) max_count = 138, min_count = 3;
725    tree[max_code+1].Len = (ush)0xffff; /* guard */
726
727    for (n = 0; n <= max_code; n++) {
728        curlen = nextlen; nextlen = tree[n+1].Len;
729        if (++count < max_count && curlen == nextlen) {
730            continue;
731        } else if (count < min_count) {
732            s->bl_tree[curlen].Freq += count;
733        } else if (curlen != 0) {
734            if (curlen != prevlen) s->bl_tree[curlen].Freq++;
735            s->bl_tree[REP_3_6].Freq++;
736        } else if (count <= 10) {
737            s->bl_tree[REPZ_3_10].Freq++;
738        } else {
739            s->bl_tree[REPZ_11_138].Freq++;
740        }
741        count = 0; prevlen = curlen;
742        if (nextlen == 0) {
743            max_count = 138, min_count = 3;
744        } else if (curlen == nextlen) {
745            max_count = 6, min_count = 3;
746        } else {
747            max_count = 7, min_count = 4;
748        }
749    }
750}
751
752/* ===========================================================================
753 * Send a literal or distance tree in compressed form, using the codes in
754 * bl_tree.
755 */
756local void send_tree (s, tree, max_code)
757    deflate_state *s;
758    ct_data *tree; /* the tree to be scanned */
759    int max_code;       /* and its largest code of non zero frequency */
760{
761    int n;                     /* iterates over all tree elements */
762    int prevlen = -1;          /* last emitted length */
763    int curlen;                /* length of current code */
764    int nextlen = tree[0].Len; /* length of next code */
765    int count = 0;             /* repeat count of the current code */
766    int max_count = 7;         /* max repeat count */
767    int min_count = 4;         /* min repeat count */
768
769    /* tree[max_code+1].Len = -1; */  /* guard already set */
770    if (nextlen == 0) max_count = 138, min_count = 3;
771
772    for (n = 0; n <= max_code; n++) {
773        curlen = nextlen; nextlen = tree[n+1].Len;
774        if (++count < max_count && curlen == nextlen) {
775            continue;
776        } else if (count < min_count) {
777            do { send_code(s, curlen, s->bl_tree); } while (--count != 0);
778
779        } else if (curlen != 0) {
780            if (curlen != prevlen) {
781                send_code(s, curlen, s->bl_tree); count--;
782            }
783            Assert(count >= 3 && count <= 6, " 3_6?");
784            send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);
785
786        } else if (count <= 10) {
787            send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);
788
789        } else {
790            send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
791        }
792        count = 0; prevlen = curlen;
793        if (nextlen == 0) {
794            max_count = 138, min_count = 3;
795        } else if (curlen == nextlen) {
796            max_count = 6, min_count = 3;
797        } else {
798            max_count = 7, min_count = 4;
799        }
800    }
801}
802
803/* ===========================================================================
804 * Construct the Huffman tree for the bit lengths and return the index in
805 * bl_order of the last bit length code to send.
806 */
807local int build_bl_tree(s)
808    deflate_state *s;
809{
810    int max_blindex;  /* index of last bit length code of non zero freq */
811
812    /* Determine the bit length frequencies for literal and distance trees */
813    scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
814    scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);
815
816    /* Build the bit length tree: */
817    build_tree(s, (tree_desc *)(&(s->bl_desc)));
818    /* opt_len now includes the length of the tree representations, except
819     * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
820     */
821
822    /* Determine the number of bit length codes to send. The pkzip format
823     * requires that at least 4 bit length codes be sent. (appnote.txt says
824     * 3 but the actual value used is 4.)
825     */
826    for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
827        if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
828    }
829    /* Update opt_len to include the bit length tree and counts */
830    s->opt_len += 3*(max_blindex+1) + 5+5+4;
831    Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
832            s->opt_len, s->static_len));
833
834    return max_blindex;
835}
836
837/* ===========================================================================
838 * Send the header for a block using dynamic Huffman trees: the counts, the
839 * lengths of the bit length codes, the literal tree and the distance tree.
840 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
841 */
842local void send_all_trees(s, lcodes, dcodes, blcodes)
843    deflate_state *s;
844    int lcodes, dcodes, blcodes; /* number of codes for each tree */
845{
846    int rank;                    /* index in bl_order */
847
848    Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
849    Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
850            "too many codes");
851    Tracev((stderr, "\nbl counts: "));
852    send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
853    send_bits(s, dcodes-1,   5);
854    send_bits(s, blcodes-4,  4); /* not -3 as stated in appnote.txt */
855    for (rank = 0; rank < blcodes; rank++) {
856        Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
857        send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
858    }
859    Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));
860
861    send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
862    Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));
863
864    send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
865    Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
866}
867
868/* ===========================================================================
869 * Send a stored block
870 */
871void ZLIB_INTERNAL _tr_stored_block(s, buf, stored_len, last)
872    deflate_state *s;
873    charf *buf;       /* input block */
874    ulg stored_len;   /* length of input block */
875    int last;         /* one if this is the last block for a file */
876{
877    send_bits(s, (STORED_BLOCK<<1)+last, 3);    /* send block type */
878#ifdef DEBUG
879    s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
880    s->compressed_len += (stored_len + 4) << 3;
881#endif
882    copy_block(s, buf, (unsigned)stored_len, 1); /* with header */
883}
884
885/* ===========================================================================
886 * Send one empty static block to give enough lookahead for inflate.
887 * This takes 10 bits, of which 7 may remain in the bit buffer.
888 * The current inflate code requires 9 bits of lookahead. If the
889 * last two codes for the previous block (real code plus EOB) were coded
890 * on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode
891 * the last real code. In this case we send two empty static blocks instead
892 * of one. (There are no problems if the previous block is stored or fixed.)
893 * To simplify the code, we assume the worst case of last real code encoded
894 * on one bit only.
895 */
896void ZLIB_INTERNAL _tr_align(s)
897    deflate_state *s;
898{
899    send_bits(s, STATIC_TREES<<1, 3);
900    send_code(s, END_BLOCK, static_ltree);
901#ifdef DEBUG
902    s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
903#endif
904    bi_flush(s);
905    /* Of the 10 bits for the empty block, we have already sent
906     * (10 - bi_valid) bits. The lookahead for the last real code (before
907     * the EOB of the previous block) was thus at least one plus the length
908     * of the EOB plus what we have just sent of the empty static block.
909     */
910    if (1 + s->last_eob_len + 10 - s->bi_valid < 9) {
911        send_bits(s, STATIC_TREES<<1, 3);
912        send_code(s, END_BLOCK, static_ltree);
913#ifdef DEBUG
914        s->compressed_len += 10L;
915#endif
916        bi_flush(s);
917    }
918    s->last_eob_len = 7;
919}
920
921/* ===========================================================================
922 * Determine the best encoding for the current block: dynamic trees, static
923 * trees or store, and output the encoded block to the zip file.
924 */
925void ZLIB_INTERNAL _tr_flush_block(s, buf, stored_len, last)
926    deflate_state *s;
927    charf *buf;       /* input block, or NULL if too old */
928    ulg stored_len;   /* length of input block */
929    int last;         /* one if this is the last block for a file */
930{
931    ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
932    int max_blindex = 0;  /* index of last bit length code of non zero freq */
933
934    /* Build the Huffman trees unless a stored block is forced */
935    if (s->level > 0) {
936
937        /* Check if the file is binary or text */
938        if (s->strm->data_type == Z_UNKNOWN)
939            s->strm->data_type = detect_data_type(s);
940
941        /* Construct the literal and distance trees */
942        build_tree(s, (tree_desc *)(&(s->l_desc)));
943        Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
944                s->static_len));
945
946        build_tree(s, (tree_desc *)(&(s->d_desc)));
947        Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
948                s->static_len));
949        /* At this point, opt_len and static_len are the total bit lengths of
950         * the compressed block data, excluding the tree representations.
951         */
952
953        /* Build the bit length tree for the above two trees, and get the index
954         * in bl_order of the last bit length code to send.
955         */
956        max_blindex = build_bl_tree(s);
957
958        /* Determine the best encoding. Compute the block lengths in bytes. */
959        opt_lenb = (s->opt_len+3+7)>>3;
960        static_lenb = (s->static_len+3+7)>>3;
961
962        Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
963                opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
964                s->last_lit));
965
966        if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
967
968    } else {
969        Assert(buf != (char*)0, "lost buf");
970        opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
971    }
972
973#ifdef FORCE_STORED
974    if (buf != (char*)0) { /* force stored block */
975#else
976    if (stored_len+4 <= opt_lenb && buf != (char*)0) {
977                       /* 4: two words for the lengths */
978#endif
979        /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
980         * Otherwise we can't have processed more than WSIZE input bytes since
981         * the last block flush, because compression would have been
982         * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
983         * transform a block into a stored block.
984         */
985        _tr_stored_block(s, buf, stored_len, last);
986
987#ifdef FORCE_STATIC
988    } else if (static_lenb >= 0) { /* force static trees */
989#else
990    } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) {
991#endif
992        send_bits(s, (STATIC_TREES<<1)+last, 3);
993        compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree);
994#ifdef DEBUG
995        s->compressed_len += 3 + s->static_len;
996#endif
997    } else {
998        send_bits(s, (DYN_TREES<<1)+last, 3);
999        send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
1000                       max_blindex+1);
1001        compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree);
1002#ifdef 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    init_block(s);
1011
1012    if (last) {
1013        bi_windup(s);
1014#ifdef DEBUG
1015        s->compressed_len += 7;  /* align on byte boundary */
1016#endif
1017    }
1018    Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
1019           s->compressed_len-7*last));
1020}
1021
1022/* ===========================================================================
1023 * Save the match info and tally the frequency counts. Return true if
1024 * the current block must be flushed.
1025 */
1026int ZLIB_INTERNAL _tr_tally (s, dist, lc)
1027    deflate_state *s;
1028    unsigned dist;  /* distance of matched string */
1029    unsigned lc;    /* match length-MIN_MATCH or unmatched char (if dist==0) */
1030{
1031    s->d_buf[s->last_lit] = (ush)dist;
1032    s->l_buf[s->last_lit++] = (uch)lc;
1033    if (dist == 0) {
1034        /* lc is the unmatched char */
1035        s->dyn_ltree[lc].Freq++;
1036    } else {
1037        s->matches++;
1038        /* Here, lc is the match length - MIN_MATCH */
1039        dist--;             /* dist = match distance - 1 */
1040        Assert((ush)dist < (ush)MAX_DIST(s) &&
1041               (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
1042               (ush)d_code(dist) < (ush)D_CODES,  "_tr_tally: bad match");
1043
1044        s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
1045        s->dyn_dtree[d_code(dist)].Freq++;
1046    }
1047
1048#ifdef TRUNCATE_BLOCK
1049    /* Try to guess if it is profitable to stop the current block here */
1050    if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
1051        /* Compute an upper bound for the compressed length */
1052        ulg out_length = (ulg)s->last_lit*8L;
1053        ulg in_length = (ulg)((long)s->strstart - s->block_start);
1054        int dcode;
1055        for (dcode = 0; dcode < D_CODES; dcode++) {
1056            out_length += (ulg)s->dyn_dtree[dcode].Freq *
1057                (5L+extra_dbits[dcode]);
1058        }
1059        out_length >>= 3;
1060        Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
1061               s->last_lit, in_length, out_length,
1062               100L - out_length*100L/in_length));
1063        if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
1064    }
1065#endif
1066    return (s->last_lit == s->lit_bufsize-1);
1067    /* We avoid equality with lit_bufsize because of wraparound at 64K
1068     * on 16 bit machines and because stored blocks are restricted to
1069     * 64K-1 bytes.
1070     */
1071}
1072
1073/* ===========================================================================
1074 * Send the block data compressed using the given Huffman trees
1075 */
1076local void compress_block(s, ltree, dtree)
1077    deflate_state *s;
1078    ct_data *ltree; /* literal tree */
1079    ct_data *dtree; /* distance tree */
1080{
1081    unsigned dist;      /* distance of matched string */
1082    int lc;             /* match length or unmatched char (if dist == 0) */
1083    unsigned lx = 0;    /* running index in l_buf */
1084    unsigned code;      /* the code to send */
1085    int extra;          /* number of extra bits to send */
1086
1087    if (s->last_lit != 0) do {
1088        dist = s->d_buf[lx];
1089        lc = s->l_buf[lx++];
1090        if (dist == 0) {
1091            send_code(s, lc, ltree); /* send a literal byte */
1092            Tracecv(isgraph(lc), (stderr," '%c' ", lc));
1093        } else {
1094            /* Here, lc is the match length - MIN_MATCH */
1095            code = _length_code[lc];
1096            send_code(s, code+LITERALS+1, ltree); /* send the length code */
1097            extra = extra_lbits[code];
1098            if (extra != 0) {
1099                lc -= base_length[code];
1100                send_bits(s, lc, extra);       /* send the extra length bits */
1101            }
1102            dist--; /* dist is now the match distance - 1 */
1103            code = d_code(dist);
1104            Assert (code < D_CODES, "bad d_code");
1105
1106            send_code(s, code, dtree);       /* send the distance code */
1107            extra = extra_dbits[code];
1108            if (extra != 0) {
1109                dist -= base_dist[code];
1110                send_bits(s, dist, extra);   /* send the extra distance bits */
1111            }
1112        } /* literal or match pair ? */
1113
1114        /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
1115        Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx,
1116               "pendingBuf overflow");
1117
1118    } while (lx < s->last_lit);
1119
1120    send_code(s, END_BLOCK, ltree);
1121    s->last_eob_len = ltree[END_BLOCK].Len;
1122}
1123
1124/* ===========================================================================
1125 * Check if the data type is TEXT or BINARY, using the following algorithm:
1126 * - TEXT if the two conditions below are satisfied:
1127 *    a) There are no non-portable control characters belonging to the
1128 *       "black list" (0..6, 14..25, 28..31).
1129 *    b) There is at least one printable character belonging to the
1130 *       "white list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255).
1131 * - BINARY otherwise.
1132 * - The following partially-portable control characters form a
1133 *   "gray list" that is ignored in this detection algorithm:
1134 *   (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}).
1135 * IN assertion: the fields Freq of dyn_ltree are set.
1136 */
1137local int detect_data_type(s)
1138    deflate_state *s;
1139{
1140    /* black_mask is the bit mask of black-listed bytes
1141     * set bits 0..6, 14..25, and 28..31
1142     * 0xf3ffc07f = binary 11110011111111111100000001111111
1143     */
1144    unsigned long black_mask = 0xf3ffc07fUL;
1145    int n;
1146
1147    /* Check for non-textual ("black-listed") bytes. */
1148    for (n = 0; n <= 31; n++, black_mask >>= 1)
1149        if ((black_mask & 1) && (s->dyn_ltree[n].Freq != 0))
1150            return Z_BINARY;
1151
1152    /* Check for textual ("white-listed") bytes. */
1153    if (s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0
1154            || s->dyn_ltree[13].Freq != 0)
1155        return Z_TEXT;
1156    for (n = 32; n < LITERALS; n++)
1157        if (s->dyn_ltree[n].Freq != 0)
1158            return Z_TEXT;
1159
1160    /* There are no "black-listed" or "white-listed" bytes:
1161     * this stream either is empty or has tolerated ("gray-listed") bytes only.
1162     */
1163    return Z_BINARY;
1164}
1165
1166/* ===========================================================================
1167 * Reverse the first len bits of a code, using straightforward code (a faster
1168 * method would use a table)
1169 * IN assertion: 1 <= len <= 15
1170 */
1171local unsigned bi_reverse(code, len)
1172    unsigned code; /* the value to invert */
1173    int len;       /* its bit length */
1174{
1175    register unsigned res = 0;
1176    do {
1177        res |= code & 1;
1178        code >>= 1, res <<= 1;
1179    } while (--len > 0);
1180    return res >> 1;
1181}
1182
1183/* ===========================================================================
1184 * Flush the bit buffer, keeping at most 7 bits in it.
1185 */
1186local void bi_flush(s)
1187    deflate_state *s;
1188{
1189    if (s->bi_valid == 16) {
1190        put_short(s, s->bi_buf);
1191        s->bi_buf = 0;
1192        s->bi_valid = 0;
1193    } else if (s->bi_valid >= 8) {
1194        put_byte(s, (Byte)s->bi_buf);
1195        s->bi_buf >>= 8;
1196        s->bi_valid -= 8;
1197    }
1198}
1199
1200/* ===========================================================================
1201 * Flush the bit buffer and align the output on a byte boundary
1202 */
1203local void bi_windup(s)
1204    deflate_state *s;
1205{
1206    if (s->bi_valid > 8) {
1207        put_short(s, s->bi_buf);
1208    } else if (s->bi_valid > 0) {
1209        put_byte(s, (Byte)s->bi_buf);
1210    }
1211    s->bi_buf = 0;
1212    s->bi_valid = 0;
1213#ifdef DEBUG
1214    s->bits_sent = (s->bits_sent+7) & ~7;
1215#endif
1216}
1217
1218/* ===========================================================================
1219 * Copy a stored block, storing first the length and its
1220 * one's complement if requested.
1221 */
1222local void copy_block(s, buf, len, header)
1223    deflate_state *s;
1224    charf    *buf;    /* the input data */
1225    unsigned len;     /* its length */
1226    int      header;  /* true if block header must be written */
1227{
1228    bi_windup(s);        /* align on byte boundary */
1229    s->last_eob_len = 8; /* enough lookahead for inflate */
1230
1231    if (header) {
1232        put_short(s, (ush)len);
1233        put_short(s, (ush)~len);
1234#ifdef DEBUG
1235        s->bits_sent += 2*16;
1236#endif
1237    }
1238#ifdef DEBUG
1239    s->bits_sent += (ulg)len<<3;
1240#endif
1241    while (len--) {
1242        put_byte(s, *buf++);
1243    }
1244}
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