1 /* trees.c -- output deflated data using Huffman coding
2  * Copyright (C) 1995-2012 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 
62 local const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */
63    = {0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5,0};
64 
65 local const int extra_dbits[D_CODES] /* extra bits for each distance code */
66    = {0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13};
67 
68 local const int extra_blbits[BL_CODES]/* extra bits for each bit length code */
69    = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};
70 
71 local const uch bl_order[BL_CODES]
72    = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};
73 /* The lengths of the bit length codes are sent in order of decreasing
74  * probability, to avoid transmitting the lengths for unused bit length codes.
75  */
76 
77 /* ===========================================================================
78  * Local data. These are initialized only once.
79  */
80 
81 #define DIST_CODE_LEN  512 /* see definition of array dist_code below */
82 
83 #if defined(GEN_TREES_H) || !defined(STDC)
84 /* non ANSI compilers may not accept trees.h */
85 
86 local ct_data static_ltree[L_CODES+2];
87 /* The static literal tree. Since the bit lengths are imposed, there is no
88  * need for the L_CODES extra codes used during heap construction. However
89  * The codes 286 and 287 are needed to build a canonical tree (see _tr_init
90  * below).
91  */
92 
93 local ct_data static_dtree[D_CODES];
94 /* The static distance tree. (Actually a trivial tree since all codes use
95  * 5 bits.)
96  */
97 
98 uch _dist_code[DIST_CODE_LEN];
99 /* Distance codes. The first 256 values correspond to the distances
100  * 3 .. 258, the last 256 values correspond to the top 8 bits of
101  * the 15 bit distances.
102  */
103 
104 uch _length_code[MAX_MATCH-MIN_MATCH+1];
105 /* length code for each normalized match length (0 == MIN_MATCH) */
106 
107 local int base_length[LENGTH_CODES];
108 /* First normalized length for each code (0 = MIN_MATCH) */
109 
110 local int base_dist[D_CODES];
111 /* First normalized distance for each code (0 = distance of 1) */
112 
113 #else
114 #  include "trees.h"
115 #endif /* GEN_TREES_H */
116 
117 struct static_tree_desc_s {
118     const ct_data *static_tree;  /* static tree or NULL */
119     const intf *extra_bits;      /* extra bits for each code or NULL */
120     int     extra_base;          /* base index for extra_bits */
121     int     elems;               /* max number of elements in the tree */
122     int     max_length;          /* max bit length for the codes */
123 };
124 
125 local static_tree_desc  static_l_desc =
126 {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};
127 
128 local static_tree_desc  static_d_desc =
129 {static_dtree, extra_dbits, 0,          D_CODES, MAX_BITS};
130 
131 local static_tree_desc  static_bl_desc =
132 {(const ct_data *)0, extra_blbits, 0,   BL_CODES, MAX_BL_BITS};
133 
134 /* ===========================================================================
135  * Local (static) routines in this file.
136  */
137 
138 local void tr_static_init OF((void));
139 local void init_block     OF((deflate_state *s));
140 local void pqdownheap     OF((deflate_state *s, ct_data *tree, int k));
141 local void gen_bitlen     OF((deflate_state *s, tree_desc *desc));
142 local void gen_codes      OF((ct_data *tree, int max_code, ushf *bl_count));
143 local void build_tree     OF((deflate_state *s, tree_desc *desc));
144 local void scan_tree      OF((deflate_state *s, ct_data *tree, int max_code));
145 local void send_tree      OF((deflate_state *s, ct_data *tree, int max_code));
146 local int  build_bl_tree  OF((deflate_state *s));
147 local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes,
148                               int blcodes));
149 local void compress_block OF((deflate_state *s, const ct_data *ltree,
150                               const ct_data *dtree));
151 local int  detect_data_type OF((deflate_state *s));
152 local unsigned bi_reverse OF((unsigned value, int length));
153 local void bi_windup      OF((deflate_state *s));
154 local void bi_flush       OF((deflate_state *s));
155 local void copy_block     OF((deflate_state *s, charf *buf, unsigned len,
156                               int header));
157 
158 #ifdef GEN_TREES_H
159 local void gen_trees_header OF((void));
160 #endif
161 
162 #ifndef DEBUG
163 #  define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
164    /* Send a code of the given tree. c and tree must not have side effects */
165 
166 #else /* DEBUG */
167 #  define send_code(s, c, tree) \
168      { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
169        send_bits(s, tree[c].Code, tree[c].Len); }
170 #endif
171 
172 /* ===========================================================================
173  * Output a short LSB first on the stream.
174  * IN assertion: there is enough room in pendingBuf.
175  */
176 #define put_short(s, w) { \
177     put_byte(s, (uch)((w) & 0xff)); \
178     put_byte(s, (uch)((ush)(w) >> 8)); \
179 }
180 
181 /* ===========================================================================
182  * Send a value on a given number of bits.
183  * IN assertion: length <= 16 and value fits in length bits.
184  */
185 #ifdef DEBUG
186 local void send_bits      OF((deflate_state *s, int value, int length));
187 
send_bits(s,value,length)188 local void send_bits(s, value, length)
189     deflate_state *s;
190     int value;  /* value to send */
191     int length; /* number of bits */
192 {
193     Tracevv((stderr," l %2d v %4x ", length, value));
194     Assert(length > 0 && length <= 15, "invalid length");
195     s->bits_sent += (ulg)length;
196 
197     /* If not enough room in bi_buf, use (valid) bits from bi_buf and
198      * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
199      * unused bits in value.
200      */
201     if (s->bi_valid > (int)Buf_size - length) {
202         s->bi_buf |= (ush)value << s->bi_valid;
203         put_short(s, s->bi_buf);
204         s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);
205         s->bi_valid += length - Buf_size;
206     } else {
207         s->bi_buf |= (ush)value << s->bi_valid;
208         s->bi_valid += length;
209     }
210 }
211 #else /* !DEBUG */
212 
213 #define send_bits(s, value, length) \
214 { int len = length;\
215   if (s->bi_valid > (int)Buf_size - len) {\
216     int val = value;\
217     s->bi_buf |= (ush)val << s->bi_valid;\
218     put_short(s, s->bi_buf);\
219     s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
220     s->bi_valid += len - Buf_size;\
221   } else {\
222     s->bi_buf |= (ush)(value) << s->bi_valid;\
223     s->bi_valid += len;\
224   }\
225 }
226 #endif /* DEBUG */
227 
228 
229 /* the arguments must not have side effects */
230 
231 /* ===========================================================================
232  * Initialize the various 'constant' tables.
233  */
tr_static_init()234 local void tr_static_init()
235 {
236 #if defined(GEN_TREES_H) || !defined(STDC)
237     static int static_init_done = 0;
238     int n;        /* iterates over tree elements */
239     int bits;     /* bit counter */
240     int length;   /* length value */
241     int code;     /* code value */
242     int dist;     /* distance index */
243     ush bl_count[MAX_BITS+1];
244     /* number of codes at each bit length for an optimal tree */
245 
246     if (static_init_done) return;
247 
248     /* For some embedded targets, global variables are not initialized: */
249 #ifdef NO_INIT_GLOBAL_POINTERS
250     static_l_desc.static_tree = static_ltree;
251     static_l_desc.extra_bits = extra_lbits;
252     static_d_desc.static_tree = static_dtree;
253     static_d_desc.extra_bits = extra_dbits;
254     static_bl_desc.extra_bits = extra_blbits;
255 #endif
256 
257     /* Initialize the mapping length (0..255) -> length code (0..28) */
258     length = 0;
259     for (code = 0; code < LENGTH_CODES-1; code++) {
260         base_length[code] = length;
261         for (n = 0; n < (1<<extra_lbits[code]); n++) {
262             _length_code[length++] = (uch)code;
263         }
264     }
265     Assert (length == 256, "tr_static_init: length != 256");
266     /* Note that the length 255 (match length 258) can be represented
267      * in two different ways: code 284 + 5 bits or code 285, so we
268      * overwrite length_code[255] to use the best encoding:
269      */
270     _length_code[length-1] = (uch)code;
271 
272     /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
273     dist = 0;
274     for (code = 0 ; code < 16; code++) {
275         base_dist[code] = dist;
276         for (n = 0; n < (1<<extra_dbits[code]); n++) {
277             _dist_code[dist++] = (uch)code;
278         }
279     }
280     Assert (dist == 256, "tr_static_init: dist != 256");
281     dist >>= 7; /* from now on, all distances are divided by 128 */
282     for ( ; code < D_CODES; code++) {
283         base_dist[code] = dist << 7;
284         for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
285             _dist_code[256 + dist++] = (uch)code;
286         }
287     }
288     Assert (dist == 256, "tr_static_init: 256+dist != 512");
289 
290     /* Construct the codes of the static literal tree */
291     for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
292     n = 0;
293     while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
294     while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
295     while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
296     while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
297     /* Codes 286 and 287 do not exist, but we must include them in the
298      * tree construction to get a canonical Huffman tree (longest code
299      * all ones)
300      */
301     gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);
302 
303     /* The static distance tree is trivial: */
304     for (n = 0; n < D_CODES; n++) {
305         static_dtree[n].Len = 5;
306         static_dtree[n].Code = bi_reverse((unsigned)n, 5);
307     }
308     static_init_done = 1;
309 
310 #  ifdef GEN_TREES_H
311     gen_trees_header();
312 #  endif
313 #endif /* defined(GEN_TREES_H) || !defined(STDC) */
314 }
315 
316 /* ===========================================================================
317  * Genererate the file trees.h describing the static trees.
318  */
319 #ifdef GEN_TREES_H
320 #  ifndef DEBUG
321 #    include <stdio.h>
322 #  endif
323 
324 #  define SEPARATOR(i, last, width) \
325       ((i) == (last)? "\n};\n\n" :    \
326        ((i) % (width) == (width)-1 ? ",\n" : ", "))
327 
gen_trees_header()328 void gen_trees_header()
329 {
330     FILE *header = fopen("trees.h", "w");
331     int i;
332 
333     Assert (header != NULL, "Can't open trees.h");
334     fprintf(header,
335             "/* header created automatically with -DGEN_TREES_H */\n\n");
336 
337     fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n");
338     for (i = 0; i < L_CODES+2; i++) {
339         fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code,
340                 static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5));
341     }
342 
343     fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n");
344     for (i = 0; i < D_CODES; i++) {
345         fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code,
346                 static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5));
347     }
348 
349     fprintf(header, "const uch ZLIB_INTERNAL _dist_code[DIST_CODE_LEN] = {\n");
350     for (i = 0; i < DIST_CODE_LEN; i++) {
351         fprintf(header, "%2u%s", _dist_code[i],
352                 SEPARATOR(i, DIST_CODE_LEN-1, 20));
353     }
354 
355     fprintf(header,
356         "const uch ZLIB_INTERNAL _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");
357     for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) {
358         fprintf(header, "%2u%s", _length_code[i],
359                 SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));
360     }
361 
362     fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");
363     for (i = 0; i < LENGTH_CODES; i++) {
364         fprintf(header, "%1u%s", base_length[i],
365                 SEPARATOR(i, LENGTH_CODES-1, 20));
366     }
367 
368     fprintf(header, "local const int base_dist[D_CODES] = {\n");
369     for (i = 0; i < D_CODES; i++) {
370         fprintf(header, "%5u%s", base_dist[i],
371                 SEPARATOR(i, D_CODES-1, 10));
372     }
373 
374     fclose(header);
375 }
376 #endif /* GEN_TREES_H */
377 
378 /* ===========================================================================
379  * Initialize the tree data structures for a new zlib stream.
380  */
_tr_init(s)381 void ZLIB_INTERNAL _tr_init(s)
382     deflate_state *s;
383 {
384     tr_static_init();
385 
386     s->l_desc.dyn_tree = s->dyn_ltree;
387     s->l_desc.stat_desc = &static_l_desc;
388 
389     s->d_desc.dyn_tree = s->dyn_dtree;
390     s->d_desc.stat_desc = &static_d_desc;
391 
392     s->bl_desc.dyn_tree = s->bl_tree;
393     s->bl_desc.stat_desc = &static_bl_desc;
394 
395     s->bi_buf = 0;
396     s->bi_valid = 0;
397 #ifdef DEBUG
398     s->compressed_len = 0L;
399     s->bits_sent = 0L;
400 #endif
401 
402     /* Initialize the first block of the first file: */
403     init_block(s);
404 }
405 
406 /* ===========================================================================
407  * Initialize a new block.
408  */
init_block(s)409 local void init_block(s)
410     deflate_state *s;
411 {
412     int n; /* iterates over tree elements */
413 
414     /* Initialize the trees. */
415     for (n = 0; n < L_CODES;  n++) s->dyn_ltree[n].Freq = 0;
416     for (n = 0; n < D_CODES;  n++) s->dyn_dtree[n].Freq = 0;
417     for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;
418 
419     s->dyn_ltree[END_BLOCK].Freq = 1;
420     s->opt_len = s->static_len = 0L;
421     s->last_lit = s->matches = 0;
422 }
423 
424 #define SMALLEST 1
425 /* Index within the heap array of least frequent node in the Huffman tree */
426 
427 
428 /* ===========================================================================
429  * Remove the smallest element from the heap and recreate the heap with
430  * one less element. Updates heap and heap_len.
431  */
432 #define pqremove(s, tree, top) \
433 {\
434     top = s->heap[SMALLEST]; \
435     s->heap[SMALLEST] = s->heap[s->heap_len--]; \
436     pqdownheap(s, tree, SMALLEST); \
437 }
438 
439 /* ===========================================================================
440  * Compares to subtrees, using the tree depth as tie breaker when
441  * the subtrees have equal frequency. This minimizes the worst case length.
442  */
443 #define smaller(tree, n, m, depth) \
444    (tree[n].Freq < tree[m].Freq || \
445    (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
446 
447 /* ===========================================================================
448  * Restore the heap property by moving down the tree starting at node k,
449  * exchanging a node with the smallest of its two sons if necessary, stopping
450  * when the heap property is re-established (each father smaller than its
451  * two sons).
452  */
pqdownheap(s,tree,k)453 local void pqdownheap(s, tree, k)
454     deflate_state *s;
455     ct_data *tree;  /* the tree to restore */
456     int k;               /* node to move down */
457 {
458     int v = s->heap[k];
459     int j = k << 1;  /* left son of k */
460     while (j <= s->heap_len) {
461         /* Set j to the smallest of the two sons: */
462         if (j < s->heap_len &&
463             smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
464             j++;
465         }
466         /* Exit if v is smaller than both sons */
467         if (smaller(tree, v, s->heap[j], s->depth)) break;
468 
469         /* Exchange v with the smallest son */
470         s->heap[k] = s->heap[j];  k = j;
471 
472         /* And continue down the tree, setting j to the left son of k */
473         j <<= 1;
474     }
475     s->heap[k] = v;
476 }
477 
478 /* ===========================================================================
479  * Compute the optimal bit lengths for a tree and update the total bit length
480  * for the current block.
481  * IN assertion: the fields freq and dad are set, heap[heap_max] and
482  *    above are the tree nodes sorted by increasing frequency.
483  * OUT assertions: the field len is set to the optimal bit length, the
484  *     array bl_count contains the frequencies for each bit length.
485  *     The length opt_len is updated; static_len is also updated if stree is
486  *     not null.
487  */
gen_bitlen(s,desc)488 local void gen_bitlen(s, desc)
489     deflate_state *s;
490     tree_desc *desc;    /* the tree descriptor */
491 {
492     ct_data *tree        = desc->dyn_tree;
493     int max_code         = desc->max_code;
494     const ct_data *stree = desc->stat_desc->static_tree;
495     const intf *extra    = desc->stat_desc->extra_bits;
496     int base             = desc->stat_desc->extra_base;
497     int max_length       = desc->stat_desc->max_length;
498     int h;              /* heap index */
499     int n, m;           /* iterate over the tree elements */
500     int bits;           /* bit length */
501     int xbits;          /* extra bits */
502     ush f;              /* frequency */
503     int overflow = 0;   /* number of elements with bit length too large */
504 
505     for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
506 
507     /* In a first pass, compute the optimal bit lengths (which may
508      * overflow in the case of the bit length tree).
509      */
510     tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
511 
512     for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
513         n = s->heap[h];
514         bits = tree[tree[n].Dad].Len + 1;
515         if (bits > max_length) bits = max_length, overflow++;
516         tree[n].Len = (ush)bits;
517         /* We overwrite tree[n].Dad which is no longer needed */
518 
519         if (n > max_code) continue; /* not a leaf node */
520 
521         s->bl_count[bits]++;
522         xbits = 0;
523         if (n >= base) xbits = extra[n-base];
524         f = tree[n].Freq;
525         s->opt_len += (ulg)f * (bits + xbits);
526         if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits);
527     }
528     if (overflow == 0) return;
529 
530     Trace((stderr,"\nbit length overflow\n"));
531     /* This happens for example on obj2 and pic of the Calgary corpus */
532 
533     /* Find the first bit length which could increase: */
534     do {
535         bits = max_length-1;
536         while (s->bl_count[bits] == 0) bits--;
537         s->bl_count[bits]--;      /* move one leaf down the tree */
538         s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
539         s->bl_count[max_length]--;
540         /* The brother of the overflow item also moves one step up,
541          * but this does not affect bl_count[max_length]
542          */
543         overflow -= 2;
544     } while (overflow > 0);
545 
546     /* Now recompute all bit lengths, scanning in increasing frequency.
547      * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
548      * lengths instead of fixing only the wrong ones. This idea is taken
549      * from 'ar' written by Haruhiko Okumura.)
550      */
551     for (bits = max_length; bits != 0; bits--) {
552         n = s->bl_count[bits];
553         while (n != 0) {
554             m = s->heap[--h];
555             if (m > max_code) continue;
556             if ((unsigned) tree[m].Len != (unsigned) bits) {
557                 Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
558                 s->opt_len += ((long)bits - (long)tree[m].Len)
559                               *(long)tree[m].Freq;
560                 tree[m].Len = (ush)bits;
561             }
562             n--;
563         }
564     }
565 }
566 
567 /* ===========================================================================
568  * Generate the codes for a given tree and bit counts (which need not be
569  * optimal).
570  * IN assertion: the array bl_count contains the bit length statistics for
571  * the given tree and the field len is set for all tree elements.
572  * OUT assertion: the field code is set for all tree elements of non
573  *     zero code length.
574  */
gen_codes(tree,max_code,bl_count)575 local void gen_codes (tree, max_code, bl_count)
576     ct_data *tree;             /* the tree to decorate */
577     int max_code;              /* largest code with non zero frequency */
578     ushf *bl_count;            /* number of codes at each bit length */
579 {
580     ush next_code[MAX_BITS+1]; /* next code value for each bit length */
581     ush code = 0;              /* running code value */
582     int bits;                  /* bit index */
583     int n;                     /* code index */
584 
585     /* The distribution counts are first used to generate the code values
586      * without bit reversal.
587      */
588     for (bits = 1; bits <= MAX_BITS; bits++) {
589         next_code[bits] = code = (code + bl_count[bits-1]) << 1;
590     }
591     /* Check that the bit counts in bl_count are consistent. The last code
592      * must be all ones.
593      */
594     Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
595             "inconsistent bit counts");
596     Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
597 
598     for (n = 0;  n <= max_code; n++) {
599         int len = tree[n].Len;
600         if (len == 0) continue;
601         /* Now reverse the bits */
602         tree[n].Code = bi_reverse(next_code[len]++, len);
603 
604         Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
605              n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
606     }
607 }
608 
609 /* ===========================================================================
610  * Construct one Huffman tree and assigns the code bit strings and lengths.
611  * Update the total bit length for the current block.
612  * IN assertion: the field freq is set for all tree elements.
613  * OUT assertions: the fields len and code are set to the optimal bit length
614  *     and corresponding code. The length opt_len is updated; static_len is
615  *     also updated if stree is not null. The field max_code is set.
616  */
build_tree(s,desc)617 local void build_tree(s, desc)
618     deflate_state *s;
619     tree_desc *desc; /* the tree descriptor */
620 {
621     ct_data *tree         = desc->dyn_tree;
622     const ct_data *stree  = desc->stat_desc->static_tree;
623     int elems             = desc->stat_desc->elems;
624     int n, m;          /* iterate over heap elements */
625     int max_code = -1; /* largest code with non zero frequency */
626     int node;          /* new node being created */
627 
628     /* Construct the initial heap, with least frequent element in
629      * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
630      * heap[0] is not used.
631      */
632     s->heap_len = 0, s->heap_max = HEAP_SIZE;
633 
634     for (n = 0; n < elems; n++) {
635         if (tree[n].Freq != 0) {
636             s->heap[++(s->heap_len)] = max_code = n;
637             s->depth[n] = 0;
638         } else {
639             tree[n].Len = 0;
640         }
641     }
642 
643     /* The pkzip format requires that at least one distance code exists,
644      * and that at least one bit should be sent even if there is only one
645      * possible code. So to avoid special checks later on we force at least
646      * two codes of non zero frequency.
647      */
648     while (s->heap_len < 2) {
649         node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
650         tree[node].Freq = 1;
651         s->depth[node] = 0;
652         s->opt_len--; if (stree) s->static_len -= stree[node].Len;
653         /* node is 0 or 1 so it does not have extra bits */
654     }
655     desc->max_code = max_code;
656 
657     /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
658      * establish sub-heaps of increasing lengths:
659      */
660     for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
661 
662     /* Construct the Huffman tree by repeatedly combining the least two
663      * frequent nodes.
664      */
665     node = elems;              /* next internal node of the tree */
666     do {
667         pqremove(s, tree, n);  /* n = node of least frequency */
668         m = s->heap[SMALLEST]; /* m = node of next least frequency */
669 
670         s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
671         s->heap[--(s->heap_max)] = m;
672 
673         /* Create a new node father of n and m */
674         tree[node].Freq = tree[n].Freq + tree[m].Freq;
675         s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?
676                                 s->depth[n] : s->depth[m]) + 1);
677         tree[n].Dad = tree[m].Dad = (ush)node;
678 #ifdef DUMP_BL_TREE
679         if (tree == s->bl_tree) {
680             fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
681                     node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
682         }
683 #endif
684         /* and insert the new node in the heap */
685         s->heap[SMALLEST] = node++;
686         pqdownheap(s, tree, SMALLEST);
687 
688     } while (s->heap_len >= 2);
689 
690     s->heap[--(s->heap_max)] = s->heap[SMALLEST];
691 
692     /* At this point, the fields freq and dad are set. We can now
693      * generate the bit lengths.
694      */
695     gen_bitlen(s, (tree_desc *)desc);
696 
697     /* The field len is now set, we can generate the bit codes */
698     gen_codes ((ct_data *)tree, max_code, s->bl_count);
699 }
700 
701 /* ===========================================================================
702  * Scan a literal or distance tree to determine the frequencies of the codes
703  * in the bit length tree.
704  */
scan_tree(s,tree,max_code)705 local void scan_tree (s, tree, max_code)
706     deflate_state *s;
707     ct_data *tree;   /* the tree to be scanned */
708     int max_code;    /* and its largest code of non zero frequency */
709 {
710     int n;                     /* iterates over all tree elements */
711     int prevlen = -1;          /* last emitted length */
712     int curlen;                /* length of current code */
713     int nextlen = tree[0].Len; /* length of next code */
714     int count = 0;             /* repeat count of the current code */
715     int max_count = 7;         /* max repeat count */
716     int min_count = 4;         /* min repeat count */
717 
718     if (nextlen == 0) max_count = 138, min_count = 3;
719     tree[max_code+1].Len = (ush)0xffff; /* guard */
720 
721     for (n = 0; n <= max_code; n++) {
722         curlen = nextlen; nextlen = tree[n+1].Len;
723         if (++count < max_count && curlen == nextlen) {
724             continue;
725         } else if (count < min_count) {
726             s->bl_tree[curlen].Freq += count;
727         } else if (curlen != 0) {
728             if (curlen != prevlen) s->bl_tree[curlen].Freq++;
729             s->bl_tree[REP_3_6].Freq++;
730         } else if (count <= 10) {
731             s->bl_tree[REPZ_3_10].Freq++;
732         } else {
733             s->bl_tree[REPZ_11_138].Freq++;
734         }
735         count = 0; prevlen = curlen;
736         if (nextlen == 0) {
737             max_count = 138, min_count = 3;
738         } else if (curlen == nextlen) {
739             max_count = 6, min_count = 3;
740         } else {
741             max_count = 7, min_count = 4;
742         }
743     }
744 }
745 
746 /* ===========================================================================
747  * Send a literal or distance tree in compressed form, using the codes in
748  * bl_tree.
749  */
send_tree(s,tree,max_code)750 local void send_tree (s, tree, max_code)
751     deflate_state *s;
752     ct_data *tree; /* the tree to be scanned */
753     int max_code;       /* and its largest code of non zero frequency */
754 {
755     int n;                     /* iterates over all tree elements */
756     int prevlen = -1;          /* last emitted length */
757     int curlen;                /* length of current code */
758     int nextlen = tree[0].Len; /* length of next code */
759     int count = 0;             /* repeat count of the current code */
760     int max_count = 7;         /* max repeat count */
761     int min_count = 4;         /* min repeat count */
762 
763     /* tree[max_code+1].Len = -1; */  /* guard already set */
764     if (nextlen == 0) max_count = 138, min_count = 3;
765 
766     for (n = 0; n <= max_code; n++) {
767         curlen = nextlen; nextlen = tree[n+1].Len;
768         if (++count < max_count && curlen == nextlen) {
769             continue;
770         } else if (count < min_count) {
771             do { send_code(s, curlen, s->bl_tree); } while (--count != 0);
772 
773         } else if (curlen != 0) {
774             if (curlen != prevlen) {
775                 send_code(s, curlen, s->bl_tree); count--;
776             }
777             Assert(count >= 3 && count <= 6, " 3_6?");
778             send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);
779 
780         } else if (count <= 10) {
781             send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);
782 
783         } else {
784             send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
785         }
786         count = 0; prevlen = curlen;
787         if (nextlen == 0) {
788             max_count = 138, min_count = 3;
789         } else if (curlen == nextlen) {
790             max_count = 6, min_count = 3;
791         } else {
792             max_count = 7, min_count = 4;
793         }
794     }
795 }
796 
797 /* ===========================================================================
798  * Construct the Huffman tree for the bit lengths and return the index in
799  * bl_order of the last bit length code to send.
800  */
build_bl_tree(s)801 local int build_bl_tree(s)
802     deflate_state *s;
803 {
804     int max_blindex;  /* index of last bit length code of non zero freq */
805 
806     /* Determine the bit length frequencies for literal and distance trees */
807     scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
808     scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);
809 
810     /* Build the bit length tree: */
811     build_tree(s, (tree_desc *)(&(s->bl_desc)));
812     /* opt_len now includes the length of the tree representations, except
813      * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
814      */
815 
816     /* Determine the number of bit length codes to send. The pkzip format
817      * requires that at least 4 bit length codes be sent. (appnote.txt says
818      * 3 but the actual value used is 4.)
819      */
820     for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
821         if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
822     }
823     /* Update opt_len to include the bit length tree and counts */
824     s->opt_len += 3*(max_blindex+1) + 5+5+4;
825     Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
826             s->opt_len, s->static_len));
827 
828     return max_blindex;
829 }
830 
831 /* ===========================================================================
832  * Send the header for a block using dynamic Huffman trees: the counts, the
833  * lengths of the bit length codes, the literal tree and the distance tree.
834  * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
835  */
send_all_trees(s,lcodes,dcodes,blcodes)836 local void send_all_trees(s, lcodes, dcodes, blcodes)
837     deflate_state *s;
838     int lcodes, dcodes, blcodes; /* number of codes for each tree */
839 {
840     int rank;                    /* index in bl_order */
841 
842     Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
843     Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
844             "too many codes");
845     Tracev((stderr, "\nbl counts: "));
846     send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
847     send_bits(s, dcodes-1,   5);
848     send_bits(s, blcodes-4,  4); /* not -3 as stated in appnote.txt */
849     for (rank = 0; rank < blcodes; rank++) {
850         Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
851         send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
852     }
853     Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));
854 
855     send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
856     Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));
857 
858     send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
859     Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
860 }
861 
862 /* ===========================================================================
863  * Send a stored block
864  */
_tr_stored_block(s,buf,stored_len,last)865 void ZLIB_INTERNAL _tr_stored_block(s, buf, stored_len, last)
866     deflate_state *s;
867     charf *buf;       /* input block */
868     ulg stored_len;   /* length of input block */
869     int last;         /* one if this is the last block for a file */
870 {
871     send_bits(s, (STORED_BLOCK<<1)+last, 3);    /* send block type */
872 #ifdef DEBUG
873     s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
874     s->compressed_len += (stored_len + 4) << 3;
875 #endif
876     copy_block(s, buf, (unsigned)stored_len, 1); /* with header */
877 }
878 
879 /* ===========================================================================
880  * Flush the bits in the bit buffer to pending output (leaves at most 7 bits)
881  */
_tr_flush_bits(s)882 void ZLIB_INTERNAL _tr_flush_bits(s)
883     deflate_state *s;
884 {
885     bi_flush(s);
886 }
887 
888 /* ===========================================================================
889  * Send one empty static block to give enough lookahead for inflate.
890  * This takes 10 bits, of which 7 may remain in the bit buffer.
891  */
_tr_align(s)892 void ZLIB_INTERNAL _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 }
902 
903 /* ===========================================================================
904  * Determine the best encoding for the current block: dynamic trees, static
905  * trees or store, and output the encoded block to the zip file.
906  */
_tr_flush_block(s,buf,stored_len,last)907 void ZLIB_INTERNAL _tr_flush_block(s, buf, stored_len, last)
908     deflate_state *s;
909     charf *buf;       /* input block, or NULL if too old */
910     ulg stored_len;   /* length of input block */
911     int last;         /* one if this is the last block for a file */
912 {
913     ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
914     int max_blindex = 0;  /* index of last bit length code of non zero freq */
915 
916     /* Build the Huffman trees unless a stored block is forced */
917     if (s->level > 0) {
918 
919         /* Check if the file is binary or text */
920         if (s->strm->data_type == Z_UNKNOWN)
921             s->strm->data_type = detect_data_type(s);
922 
923         /* Construct the literal and distance trees */
924         build_tree(s, (tree_desc *)(&(s->l_desc)));
925         Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
926                 s->static_len));
927 
928         build_tree(s, (tree_desc *)(&(s->d_desc)));
929         Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
930                 s->static_len));
931         /* At this point, opt_len and static_len are the total bit lengths of
932          * the compressed block data, excluding the tree representations.
933          */
934 
935         /* Build the bit length tree for the above two trees, and get the index
936          * in bl_order of the last bit length code to send.
937          */
938         max_blindex = build_bl_tree(s);
939 
940         /* Determine the best encoding. Compute the block lengths in bytes. */
941         opt_lenb = (s->opt_len+3+7)>>3;
942         static_lenb = (s->static_len+3+7)>>3;
943 
944         Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
945                 opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
946                 s->last_lit));
947 
948         if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
949 
950     } else {
951         Assert(buf != (char*)0, "lost buf");
952         opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
953     }
954 
955 #ifdef FORCE_STORED
956     if (buf != (char*)0) { /* force stored block */
957 #else
958     if (stored_len+4 <= opt_lenb && buf != (char*)0) {
959                        /* 4: two words for the lengths */
960 #endif
961         /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
962          * Otherwise we can't have processed more than WSIZE input bytes since
963          * the last block flush, because compression would have been
964          * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
965          * transform a block into a stored block.
966          */
967         _tr_stored_block(s, buf, stored_len, last);
968 
969 #ifdef FORCE_STATIC
970     } else if (static_lenb >= 0) { /* force static trees */
971 #else
972     } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) {
973 #endif
974         send_bits(s, (STATIC_TREES<<1)+last, 3);
975         compress_block(s, (const ct_data *)static_ltree,
976                        (const ct_data *)static_dtree);
977 #ifdef DEBUG
978         s->compressed_len += 3 + s->static_len;
979 #endif
980     } else {
981         send_bits(s, (DYN_TREES<<1)+last, 3);
982         send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
983                        max_blindex+1);
984         compress_block(s, (const ct_data *)s->dyn_ltree,
985                        (const ct_data *)s->dyn_dtree);
986 #ifdef DEBUG
987         s->compressed_len += 3 + s->opt_len;
988 #endif
989     }
990     Assert (s->compressed_len == s->bits_sent, "bad compressed size");
991     /* The above check is made mod 2^32, for files larger than 512 MB
992      * and uLong implemented on 32 bits.
993      */
994     init_block(s);
995 
996     if (last) {
997         bi_windup(s);
998 #ifdef DEBUG
999         s->compressed_len += 7;  /* align on byte boundary */
1000 #endif
1001     }
1002     Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
1003            s->compressed_len-7*last));
1004 }
1005 
1006 /* ===========================================================================
1007  * Save the match info and tally the frequency counts. Return true if
1008  * the current block must be flushed.
1009  */
_tr_tally(s,dist,lc)1010 int ZLIB_INTERNAL _tr_tally (s, dist, lc)
1011     deflate_state *s;
1012     unsigned dist;  /* distance of matched string */
1013     unsigned lc;    /* match length-MIN_MATCH or unmatched char (if dist==0) */
1014 {
1015     s->d_buf[s->last_lit] = (ush)dist;
1016     s->l_buf[s->last_lit++] = (uch)lc;
1017     if (dist == 0) {
1018         /* lc is the unmatched char */
1019         s->dyn_ltree[lc].Freq++;
1020     } else {
1021         s->matches++;
1022         /* Here, lc is the match length - MIN_MATCH */
1023         dist--;             /* dist = match distance - 1 */
1024         Assert((ush)dist < (ush)MAX_DIST(s) &&
1025                (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
1026                (ush)d_code(dist) < (ush)D_CODES,  "_tr_tally: bad match");
1027 
1028         s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
1029         s->dyn_dtree[d_code(dist)].Freq++;
1030     }
1031 
1032 #ifdef TRUNCATE_BLOCK
1033     /* Try to guess if it is profitable to stop the current block here */
1034     if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
1035         /* Compute an upper bound for the compressed length */
1036         ulg out_length = (ulg)s->last_lit*8L;
1037         ulg in_length = (ulg)((long)s->strstart - s->block_start);
1038         int dcode;
1039         for (dcode = 0; dcode < D_CODES; dcode++) {
1040             out_length += (ulg)s->dyn_dtree[dcode].Freq *
1041                 (5L+extra_dbits[dcode]);
1042         }
1043         out_length >>= 3;
1044         Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
1045                s->last_lit, in_length, out_length,
1046                100L - out_length*100L/in_length));
1047         if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
1048     }
1049 #endif
1050     return (s->last_lit == s->lit_bufsize-1);
1051     /* We avoid equality with lit_bufsize because of wraparound at 64K
1052      * on 16 bit machines and because stored blocks are restricted to
1053      * 64K-1 bytes.
1054      */
1055 }
1056 
1057 /* ===========================================================================
1058  * Send the block data compressed using the given Huffman trees
1059  */
compress_block(s,ltree,dtree)1060 local void compress_block(s, ltree, dtree)
1061     deflate_state *s;
1062     const ct_data *ltree; /* literal tree */
1063     const ct_data *dtree; /* distance tree */
1064 {
1065     unsigned dist;      /* distance of matched string */
1066     int lc;             /* match length or unmatched char (if dist == 0) */
1067     unsigned lx = 0;    /* running index in l_buf */
1068     unsigned code;      /* the code to send */
1069     int extra;          /* number of extra bits to send */
1070 
1071     if (s->last_lit != 0) do {
1072         dist = s->d_buf[lx];
1073         lc = s->l_buf[lx++];
1074         if (dist == 0) {
1075             send_code(s, lc, ltree); /* send a literal byte */
1076             Tracecv(isgraph(lc), (stderr," '%c' ", lc));
1077         } else {
1078             /* Here, lc is the match length - MIN_MATCH */
1079             code = _length_code[lc];
1080             send_code(s, code+LITERALS+1, ltree); /* send the length code */
1081             extra = extra_lbits[code];
1082             if (extra != 0) {
1083                 lc -= base_length[code];
1084                 send_bits(s, lc, extra);       /* send the extra length bits */
1085             }
1086             dist--; /* dist is now the match distance - 1 */
1087             code = d_code(dist);
1088             Assert (code < D_CODES, "bad d_code");
1089 
1090             send_code(s, code, dtree);       /* send the distance code */
1091             extra = extra_dbits[code];
1092             if (extra != 0) {
1093                 dist -= base_dist[code];
1094                 send_bits(s, dist, extra);   /* send the extra distance bits */
1095             }
1096         } /* literal or match pair ? */
1097 
1098         /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
1099         Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx,
1100                "pendingBuf overflow");
1101 
1102     } while (lx < s->last_lit);
1103 
1104     send_code(s, END_BLOCK, ltree);
1105 }
1106 
1107 /* ===========================================================================
1108  * Check if the data type is TEXT or BINARY, using the following algorithm:
1109  * - TEXT if the two conditions below are satisfied:
1110  *    a) There are no non-portable control characters belonging to the
1111  *       "black list" (0..6, 14..25, 28..31).
1112  *    b) There is at least one printable character belonging to the
1113  *       "white list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255).
1114  * - BINARY otherwise.
1115  * - The following partially-portable control characters form a
1116  *   "gray list" that is ignored in this detection algorithm:
1117  *   (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}).
1118  * IN assertion: the fields Freq of dyn_ltree are set.
1119  */
detect_data_type(s)1120 local int detect_data_type(s)
1121     deflate_state *s;
1122 {
1123     /* black_mask is the bit mask of black-listed bytes
1124      * set bits 0..6, 14..25, and 28..31
1125      * 0xf3ffc07f = binary 11110011111111111100000001111111
1126      */
1127     unsigned long black_mask = 0xf3ffc07fUL;
1128     int n;
1129 
1130     /* Check for non-textual ("black-listed") bytes. */
1131     for (n = 0; n <= 31; n++, black_mask >>= 1)
1132         if ((black_mask & 1) && (s->dyn_ltree[n].Freq != 0))
1133             return Z_BINARY;
1134 
1135     /* Check for textual ("white-listed") bytes. */
1136     if (s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0
1137             || s->dyn_ltree[13].Freq != 0)
1138         return Z_TEXT;
1139     for (n = 32; n < LITERALS; n++)
1140         if (s->dyn_ltree[n].Freq != 0)
1141             return Z_TEXT;
1142 
1143     /* There are no "black-listed" or "white-listed" bytes:
1144      * this stream either is empty or has tolerated ("gray-listed") bytes only.
1145      */
1146     return Z_BINARY;
1147 }
1148 
1149 /* ===========================================================================
1150  * Reverse the first len bits of a code, using straightforward code (a faster
1151  * method would use a table)
1152  * IN assertion: 1 <= len <= 15
1153  */
bi_reverse(code,len)1154 local unsigned bi_reverse(code, len)
1155     unsigned code; /* the value to invert */
1156     int len;       /* its bit length */
1157 {
1158     register unsigned res = 0;
1159     do {
1160         res |= code & 1;
1161         code >>= 1, res <<= 1;
1162     } while (--len > 0);
1163     return res >> 1;
1164 }
1165 
1166 /* ===========================================================================
1167  * Flush the bit buffer, keeping at most 7 bits in it.
1168  */
bi_flush(s)1169 local void bi_flush(s)
1170     deflate_state *s;
1171 {
1172     if (s->bi_valid == 16) {
1173         put_short(s, s->bi_buf);
1174         s->bi_buf = 0;
1175         s->bi_valid = 0;
1176     } else if (s->bi_valid >= 8) {
1177         put_byte(s, (Byte)s->bi_buf);
1178         s->bi_buf >>= 8;
1179         s->bi_valid -= 8;
1180     }
1181 }
1182 
1183 /* ===========================================================================
1184  * Flush the bit buffer and align the output on a byte boundary
1185  */
bi_windup(s)1186 local void bi_windup(s)
1187     deflate_state *s;
1188 {
1189     if (s->bi_valid > 8) {
1190         put_short(s, s->bi_buf);
1191     } else if (s->bi_valid > 0) {
1192         put_byte(s, (Byte)s->bi_buf);
1193     }
1194     s->bi_buf = 0;
1195     s->bi_valid = 0;
1196 #ifdef DEBUG
1197     s->bits_sent = (s->bits_sent+7) & ~7;
1198 #endif
1199 }
1200 
1201 /* ===========================================================================
1202  * Copy a stored block, storing first the length and its
1203  * one's complement if requested.
1204  */
copy_block(s,buf,len,header)1205 local void copy_block(s, buf, len, header)
1206     deflate_state *s;
1207     charf    *buf;    /* the input data */
1208     unsigned len;     /* its length */
1209     int      header;  /* true if block header must be written */
1210 {
1211     bi_windup(s);        /* align on byte boundary */
1212 
1213     if (header) {
1214         put_short(s, (ush)len);
1215         put_short(s, (ush)~len);
1216 #ifdef DEBUG
1217         s->bits_sent += 2*16;
1218 #endif
1219     }
1220 #ifdef DEBUG
1221     s->bits_sent += (ulg)len<<3;
1222 #endif
1223     while (len--) {
1224         put_byte(s, *buf++);
1225     }
1226 }
1227