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c801d85f 1/* trees.c -- output deflated data using Huffman coding
41faf807 2 * Copyright (C) 1995-2005 Jean-loup Gailly
e6ebb514 3 * For conditions of distribution and use, see copyright notice in zlib.h
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4 */
5
6/*
7 * ALGORITHM
8 *
9 * The "deflation" process uses several Huffman trees. The more
10 * common source values are represented by shorter bit sequences.
11 *
12 * Each code tree is stored in a compressed form which is itself
13 * a Huffman encoding of the lengths of all the code strings (in
14 * ascending order by source values). The actual code strings are
15 * reconstructed from the lengths in the inflate process, as described
16 * in the deflate specification.
17 *
18 * REFERENCES
19 *
20 * Deutsch, L.P.,"'Deflate' Compressed Data Format Specification".
21 * Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc
22 *
23 * Storer, James A.
24 * Data Compression: Methods and Theory, pp. 49-50.
25 * Computer Science Press, 1988. ISBN 0-7167-8156-5.
26 *
27 * Sedgewick, R.
28 * Algorithms, p290.
29 * Addison-Wesley, 1983. ISBN 0-201-06672-6.
30 */
31
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32
33/* #define GEN_TREES_H */
34
35#include "deflate.h"
36
51dbdf87 37#ifdef DEBUG
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38# include <ctype.h>
39#endif
40
41/* ===========================================================================
42 * Constants
43 */
44
45#define MAX_BL_BITS 7
46/* Bit length codes must not exceed MAX_BL_BITS bits */
47
48#define END_BLOCK 256
49/* end of block literal code */
50
51#define REP_3_6 16
52/* repeat previous bit length 3-6 times (2 bits of repeat count) */
53
54#define REPZ_3_10 17
55/* repeat a zero length 3-10 times (3 bits of repeat count) */
56
57#define REPZ_11_138 18
58/* repeat a zero length 11-138 times (7 bits of repeat count) */
59
60local const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */
61 = {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};
62
63local const int extra_dbits[D_CODES] /* extra bits for each distance code */
64 = {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};
65
66local const int extra_blbits[BL_CODES]/* extra bits for each bit length code */
67 = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};
68
69local const uch bl_order[BL_CODES]
70 = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};
71/* The lengths of the bit length codes are sent in order of decreasing
72 * probability, to avoid transmitting the lengths for unused bit length codes.
73 */
74
75#define Buf_size (8 * 2*sizeof(char))
76/* Number of bits used within bi_buf. (bi_buf might be implemented on
77 * more than 16 bits on some systems.)
78 */
79
80/* ===========================================================================
81 * Local data. These are initialized only once.
82 */
83
84#define DIST_CODE_LEN 512 /* see definition of array dist_code below */
85
86#if defined(GEN_TREES_H) || !defined(STDC)
87/* non ANSI compilers may not accept trees.h */
88
89local ct_data static_ltree[L_CODES+2];
90/* The static literal tree. Since the bit lengths are imposed, there is no
91 * need for the L_CODES extra codes used during heap construction. However
92 * The codes 286 and 287 are needed to build a canonical tree (see _tr_init
93 * below).
94 */
95
96local ct_data static_dtree[D_CODES];
97/* The static distance tree. (Actually a trivial tree since all codes use
98 * 5 bits.)
99 */
100
101uch _dist_code[DIST_CODE_LEN];
102/* Distance codes. The first 256 values correspond to the distances
103 * 3 .. 258, the last 256 values correspond to the top 8 bits of
104 * the 15 bit distances.
105 */
106
107uch _length_code[MAX_MATCH-MIN_MATCH+1];
108/* length code for each normalized match length (0 == MIN_MATCH) */
109
110local int base_length[LENGTH_CODES];
111/* First normalized length for each code (0 = MIN_MATCH) */
112
113local int base_dist[D_CODES];
114/* First normalized distance for each code (0 = distance of 1) */
115
116#else
117# include "trees.h"
118#endif /* GEN_TREES_H */
119
120struct static_tree_desc_s {
121 const ct_data *static_tree; /* static tree or NULL */
122 const intf *extra_bits; /* extra bits for each code or NULL */
123 int extra_base; /* base index for extra_bits */
124 int elems; /* max number of elements in the tree */
125 int max_length; /* max bit length for the codes */
126};
127
128local static_tree_desc static_l_desc =
129{static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};
130
131local static_tree_desc static_d_desc =
132{static_dtree, extra_dbits, 0, D_CODES, MAX_BITS};
133
134local static_tree_desc static_bl_desc =
135{(const ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS};
136
137/* ===========================================================================
138 * Local (static) routines in this file.
139 */
140
141local void tr_static_init OF((void));
142local void init_block OF((deflate_state *s));
143local void pqdownheap OF((deflate_state *s, ct_data *tree, int k));
144local void gen_bitlen OF((deflate_state *s, tree_desc *desc));
145local void gen_codes OF((ct_data *tree, int max_code, ushf *bl_count));
146local void build_tree OF((deflate_state *s, tree_desc *desc));
147local void scan_tree OF((deflate_state *s, ct_data *tree, int max_code));
148local void send_tree OF((deflate_state *s, ct_data *tree, int max_code));
149local int build_bl_tree OF((deflate_state *s));
150local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes,
151 int blcodes));
152local void compress_block OF((deflate_state *s, ct_data *ltree,
153 ct_data *dtree));
154local void set_data_type OF((deflate_state *s));
155local unsigned bi_reverse OF((unsigned value, int length));
156local void bi_windup OF((deflate_state *s));
157local void bi_flush OF((deflate_state *s));
158local void copy_block OF((deflate_state *s, charf *buf, unsigned len,
159 int header));
160
161#ifdef GEN_TREES_H
162local void gen_trees_header OF((void));
163#endif
164
51dbdf87 165#ifndef DEBUG
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166# define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
167 /* Send a code of the given tree. c and tree must not have side effects */
168
51dbdf87 169#else /* DEBUG */
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170# define send_code(s, c, tree) \
171 { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
172 send_bits(s, tree[c].Code, tree[c].Len); }
173#endif
174
175/* ===========================================================================
176 * Output a short LSB first on the stream.
177 * IN assertion: there is enough room in pendingBuf.
178 */
179#define put_short(s, w) { \
180 put_byte(s, (uch)((w) & 0xff)); \
181 put_byte(s, (uch)((ush)(w) >> 8)); \
182}
183
184/* ===========================================================================
185 * Send a value on a given number of bits.
186 * IN assertion: length <= 16 and value fits in length bits.
187 */
51dbdf87 188#ifdef DEBUG
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189local void send_bits OF((deflate_state *s, int value, int length));
190
191local void send_bits(s, value, length)
192 deflate_state *s;
193 int value; /* value to send */
194 int length; /* number of bits */
195{
196 Tracevv((stderr," l %2d v %4x ", length, value));
197 Assert(length > 0 && length <= 15, "invalid length");
198 s->bits_sent += (ulg)length;
199
200 /* If not enough room in bi_buf, use (valid) bits from bi_buf and
201 * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
202 * unused bits in value.
203 */
204 if (s->bi_valid > (int)Buf_size - length) {
205 s->bi_buf |= (value << s->bi_valid);
206 put_short(s, s->bi_buf);
207 s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);
208 s->bi_valid += length - Buf_size;
209 } else {
210 s->bi_buf |= value << s->bi_valid;
211 s->bi_valid += length;
212 }
213}
51dbdf87 214#else /* !DEBUG */
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215
216#define send_bits(s, value, length) \
217{ int len = length;\
218 if (s->bi_valid > (int)Buf_size - len) {\
219 int val = value;\
220 s->bi_buf |= (val << s->bi_valid);\
221 put_short(s, s->bi_buf);\
222 s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
223 s->bi_valid += len - Buf_size;\
224 } else {\
225 s->bi_buf |= (value) << s->bi_valid;\
226 s->bi_valid += len;\
227 }\
228}
51dbdf87 229#endif /* DEBUG */
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230
231
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232/* the arguments must not have side effects */
233
234/* ===========================================================================
235 * Initialize the various 'constant' tables.
236 */
237local void tr_static_init()
238{
239#if defined(GEN_TREES_H) || !defined(STDC)
240 static int static_init_done = 0;
241 int n; /* iterates over tree elements */
242 int bits; /* bit counter */
243 int length; /* length value */
244 int code; /* code value */
245 int dist; /* distance index */
246 ush bl_count[MAX_BITS+1];
247 /* number of codes at each bit length for an optimal tree */
248
249 if (static_init_done) return;
250
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251 /* For some embedded targets, global variables are not initialized: */
252 static_l_desc.static_tree = static_ltree;
253 static_l_desc.extra_bits = extra_lbits;
254 static_d_desc.static_tree = static_dtree;
255 static_d_desc.extra_bits = extra_dbits;
256 static_bl_desc.extra_bits = extra_blbits;
257
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258 /* Initialize the mapping length (0..255) -> length code (0..28) */
259 length = 0;
260 for (code = 0; code < LENGTH_CODES-1; code++) {
261 base_length[code] = length;
262 for (n = 0; n < (1<<extra_lbits[code]); n++) {
263 _length_code[length++] = (uch)code;
264 }
265 }
266 Assert (length == 256, "tr_static_init: length != 256");
267 /* Note that the length 255 (match length 258) can be represented
268 * in two different ways: code 284 + 5 bits or code 285, so we
269 * overwrite length_code[255] to use the best encoding:
270 */
271 _length_code[length-1] = (uch)code;
272
273 /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
274 dist = 0;
275 for (code = 0 ; code < 16; code++) {
276 base_dist[code] = dist;
277 for (n = 0; n < (1<<extra_dbits[code]); n++) {
278 _dist_code[dist++] = (uch)code;
279 }
280 }
281 Assert (dist == 256, "tr_static_init: dist != 256");
282 dist >>= 7; /* from now on, all distances are divided by 128 */
283 for ( ; code < D_CODES; code++) {
284 base_dist[code] = dist << 7;
285 for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
286 _dist_code[256 + dist++] = (uch)code;
287 }
288 }
289 Assert (dist == 256, "tr_static_init: 256+dist != 512");
290
291 /* Construct the codes of the static literal tree */
292 for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
293 n = 0;
294 while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
295 while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
296 while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
297 while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
298 /* Codes 286 and 287 do not exist, but we must include them in the
299 * tree construction to get a canonical Huffman tree (longest code
300 * all ones)
301 */
302 gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);
303
304 /* The static distance tree is trivial: */
305 for (n = 0; n < D_CODES; n++) {
306 static_dtree[n].Len = 5;
307 static_dtree[n].Code = bi_reverse((unsigned)n, 5);
308 }
309 static_init_done = 1;
310
311# ifdef GEN_TREES_H
312 gen_trees_header();
313# endif
314#endif /* defined(GEN_TREES_H) || !defined(STDC) */
315}
316
317/* ===========================================================================
318 * Genererate the file trees.h describing the static trees.
319 */
320#ifdef GEN_TREES_H
51dbdf87 321# ifndef DEBUG
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322# include <stdio.h>
323# endif
324
325# define SEPARATOR(i, last, width) \
326 ((i) == (last)? "\n};\n\n" : \
327 ((i) % (width) == (width)-1 ? ",\n" : ", "))
328
329void gen_trees_header()
330{
331 FILE *header = fopen("trees.h", "w");
332 int i;
333
334 Assert (header != NULL, "Can't open trees.h");
335 fprintf(header,
51dbdf87 336 "/* header created automatically with -DGEN_TREES_H */\n\n");
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337
338 fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n");
339 for (i = 0; i < L_CODES+2; i++) {
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340 fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code,
341 static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5));
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342 }
343
344 fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n");
345 for (i = 0; i < D_CODES; i++) {
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346 fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code,
347 static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5));
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348 }
349
350 fprintf(header, "const uch _dist_code[DIST_CODE_LEN] = {\n");
351 for (i = 0; i < DIST_CODE_LEN; i++) {
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352 fprintf(header, "%2u%s", _dist_code[i],
353 SEPARATOR(i, DIST_CODE_LEN-1, 20));
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354 }
355
356 fprintf(header, "const uch _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");
357 for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) {
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358 fprintf(header, "%2u%s", _length_code[i],
359 SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));
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360 }
361
362 fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");
363 for (i = 0; i < LENGTH_CODES; i++) {
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364 fprintf(header, "%1u%s", base_length[i],
365 SEPARATOR(i, LENGTH_CODES-1, 20));
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366 }
367
368 fprintf(header, "local const int base_dist[D_CODES] = {\n");
369 for (i = 0; i < D_CODES; i++) {
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370 fprintf(header, "%5u%s", base_dist[i],
371 SEPARATOR(i, D_CODES-1, 10));
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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 */
381void _tr_init(s)
382 deflate_state *s;
383{
384 tr_static_init();
385
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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 s->last_eob_len = 8; /* enough lookahead for inflate */
51dbdf87 398#ifdef DEBUG
a4019ec2 399 s->compressed_len = 0L;
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400 s->bits_sent = 0L;
401#endif
402
403 /* Initialize the first block of the first file: */
404 init_block(s);
405}
406
407/* ===========================================================================
408 * Initialize a new block.
409 */
410local void init_block(s)
411 deflate_state *s;
412{
413 int n; /* iterates over tree elements */
414
415 /* Initialize the trees. */
416 for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0;
417 for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0;
418 for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;
419
420 s->dyn_ltree[END_BLOCK].Freq = 1;
421 s->opt_len = s->static_len = 0L;
422 s->last_lit = s->matches = 0;
423}
424
425#define SMALLEST 1
426/* Index within the heap array of least frequent node in the Huffman tree */
427
428
429/* ===========================================================================
430 * Remove the smallest element from the heap and recreate the heap with
431 * one less element. Updates heap and heap_len.
432 */
433#define pqremove(s, tree, top) \
434{\
435 top = s->heap[SMALLEST]; \
436 s->heap[SMALLEST] = s->heap[s->heap_len--]; \
437 pqdownheap(s, tree, SMALLEST); \
438}
439
440/* ===========================================================================
441 * Compares to subtrees, using the tree depth as tie breaker when
442 * the subtrees have equal frequency. This minimizes the worst case length.
443 */
444#define smaller(tree, n, m, depth) \
445 (tree[n].Freq < tree[m].Freq || \
446 (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
447
448/* ===========================================================================
449 * Restore the heap property by moving down the tree starting at node k,
450 * exchanging a node with the smallest of its two sons if necessary, stopping
451 * when the heap property is re-established (each father smaller than its
452 * two sons).
453 */
454local void pqdownheap(s, tree, k)
455 deflate_state *s;
456 ct_data *tree; /* the tree to restore */
457 int k; /* node to move down */
458{
459 int v = s->heap[k];
460 int j = k << 1; /* left son of k */
461 while (j <= s->heap_len) {
462 /* Set j to the smallest of the two sons: */
463 if (j < s->heap_len &&
464 smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
465 j++;
466 }
467 /* Exit if v is smaller than both sons */
468 if (smaller(tree, v, s->heap[j], s->depth)) break;
469
470 /* Exchange v with the smallest son */
471 s->heap[k] = s->heap[j]; k = j;
472
473 /* And continue down the tree, setting j to the left son of k */
474 j <<= 1;
475 }
476 s->heap[k] = v;
477}
478
479/* ===========================================================================
480 * Compute the optimal bit lengths for a tree and update the total bit length
481 * for the current block.
482 * IN assertion: the fields freq and dad are set, heap[heap_max] and
483 * above are the tree nodes sorted by increasing frequency.
484 * OUT assertions: the field len is set to the optimal bit length, the
485 * array bl_count contains the frequencies for each bit length.
486 * The length opt_len is updated; static_len is also updated if stree is
487 * not null.
488 */
489local void gen_bitlen(s, desc)
490 deflate_state *s;
491 tree_desc *desc; /* the tree descriptor */
492{
493 ct_data *tree = desc->dyn_tree;
494 int max_code = desc->max_code;
495 const ct_data *stree = desc->stat_desc->static_tree;
496 const intf *extra = desc->stat_desc->extra_bits;
497 int base = desc->stat_desc->extra_base;
498 int max_length = desc->stat_desc->max_length;
499 int h; /* heap index */
500 int n, m; /* iterate over the tree elements */
501 int bits; /* bit length */
502 int xbits; /* extra bits */
503 ush f; /* frequency */
504 int overflow = 0; /* number of elements with bit length too large */
505
506 for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
507
508 /* In a first pass, compute the optimal bit lengths (which may
509 * overflow in the case of the bit length tree).
510 */
511 tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
512
513 for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
514 n = s->heap[h];
515 bits = tree[tree[n].Dad].Len + 1;
516 if (bits > max_length) bits = max_length, overflow++;
517 tree[n].Len = (ush)bits;
518 /* We overwrite tree[n].Dad which is no longer needed */
519
520 if (n > max_code) continue; /* not a leaf node */
521
522 s->bl_count[bits]++;
523 xbits = 0;
524 if (n >= base) xbits = extra[n-base];
525 f = tree[n].Freq;
526 s->opt_len += (ulg)f * (bits + xbits);
527 if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits);
528 }
529 if (overflow == 0) return;
530
531 Trace((stderr,"\nbit length overflow\n"));
532 /* This happens for example on obj2 and pic of the Calgary corpus */
533
534 /* Find the first bit length which could increase: */
535 do {
536 bits = max_length-1;
537 while (s->bl_count[bits] == 0) bits--;
538 s->bl_count[bits]--; /* move one leaf down the tree */
539 s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
540 s->bl_count[max_length]--;
541 /* The brother of the overflow item also moves one step up,
542 * but this does not affect bl_count[max_length]
543 */
544 overflow -= 2;
545 } while (overflow > 0);
546
547 /* Now recompute all bit lengths, scanning in increasing frequency.
548 * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
549 * lengths instead of fixing only the wrong ones. This idea is taken
550 * from 'ar' written by Haruhiko Okumura.)
551 */
552 for (bits = max_length; bits != 0; bits--) {
553 n = s->bl_count[bits];
554 while (n != 0) {
555 m = s->heap[--h];
556 if (m > max_code) continue;
41faf807 557 if ((unsigned) tree[m].Len != (unsigned) bits) {
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558 Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
559 s->opt_len += ((long)bits - (long)tree[m].Len)
560 *(long)tree[m].Freq;
561 tree[m].Len = (ush)bits;
562 }
563 n--;
564 }
565 }
566}
567
568/* ===========================================================================
569 * Generate the codes for a given tree and bit counts (which need not be
570 * optimal).
571 * IN assertion: the array bl_count contains the bit length statistics for
572 * the given tree and the field len is set for all tree elements.
573 * OUT assertion: the field code is set for all tree elements of non
574 * zero code length.
575 */
576local void gen_codes (tree, max_code, bl_count)
577 ct_data *tree; /* the tree to decorate */
578 int max_code; /* largest code with non zero frequency */
579 ushf *bl_count; /* number of codes at each bit length */
580{
581 ush next_code[MAX_BITS+1]; /* next code value for each bit length */
582 ush code = 0; /* running code value */
583 int bits; /* bit index */
584 int n; /* code index */
585
586 /* The distribution counts are first used to generate the code values
587 * without bit reversal.
588 */
589 for (bits = 1; bits <= MAX_BITS; bits++) {
590 next_code[bits] = code = (code + bl_count[bits-1]) << 1;
591 }
592 /* Check that the bit counts in bl_count are consistent. The last code
593 * must be all ones.
594 */
a4019ec2 595 Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
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596 "inconsistent bit counts");
597 Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
598
599 for (n = 0; n <= max_code; n++) {
600 int len = tree[n].Len;
601 if (len == 0) continue;
602 /* Now reverse the bits */
603 tree[n].Code = bi_reverse(next_code[len]++, len);
604
605 Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
606 n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
607 }
608}
609
610/* ===========================================================================
611 * Construct one Huffman tree and assigns the code bit strings and lengths.
612 * Update the total bit length for the current block.
613 * IN assertion: the field freq is set for all tree elements.
614 * OUT assertions: the fields len and code are set to the optimal bit length
615 * and corresponding code. The length opt_len is updated; static_len is
616 * also updated if stree is not null. The field max_code is set.
617 */
618local void build_tree(s, desc)
619 deflate_state *s;
620 tree_desc *desc; /* the tree descriptor */
621{
622 ct_data *tree = desc->dyn_tree;
623 const ct_data *stree = desc->stat_desc->static_tree;
624 int elems = desc->stat_desc->elems;
625 int n, m; /* iterate over heap elements */
626 int max_code = -1; /* largest code with non zero frequency */
627 int node; /* new node being created */
628
629 /* Construct the initial heap, with least frequent element in
630 * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
631 * heap[0] is not used.
632 */
633 s->heap_len = 0, s->heap_max = HEAP_SIZE;
634
635 for (n = 0; n < elems; n++) {
636 if (tree[n].Freq != 0) {
637 s->heap[++(s->heap_len)] = max_code = n;
638 s->depth[n] = 0;
639 } else {
640 tree[n].Len = 0;
641 }
642 }
643
644 /* The pkzip format requires that at least one distance code exists,
645 * and that at least one bit should be sent even if there is only one
646 * possible code. So to avoid special checks later on we force at least
647 * two codes of non zero frequency.
648 */
649 while (s->heap_len < 2) {
650 node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
651 tree[node].Freq = 1;
652 s->depth[node] = 0;
653 s->opt_len--; if (stree) s->static_len -= stree[node].Len;
654 /* node is 0 or 1 so it does not have extra bits */
655 }
656 desc->max_code = max_code;
657
658 /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
659 * establish sub-heaps of increasing lengths:
660 */
661 for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
662
663 /* Construct the Huffman tree by repeatedly combining the least two
664 * frequent nodes.
665 */
666 node = elems; /* next internal node of the tree */
667 do {
668 pqremove(s, tree, n); /* n = node of least frequency */
669 m = s->heap[SMALLEST]; /* m = node of next least frequency */
670
671 s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
672 s->heap[--(s->heap_max)] = m;
673
674 /* Create a new node father of n and m */
675 tree[node].Freq = tree[n].Freq + tree[m].Freq;
51dbdf87
VS
676 s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?
677 s->depth[n] : s->depth[m]) + 1);
c801d85f
KB
678 tree[n].Dad = tree[m].Dad = (ush)node;
679#ifdef DUMP_BL_TREE
680 if (tree == s->bl_tree) {
681 fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
682 node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
683 }
684#endif
685 /* and insert the new node in the heap */
686 s->heap[SMALLEST] = node++;
687 pqdownheap(s, tree, SMALLEST);
688
689 } while (s->heap_len >= 2);
690
691 s->heap[--(s->heap_max)] = s->heap[SMALLEST];
692
693 /* At this point, the fields freq and dad are set. We can now
694 * generate the bit lengths.
695 */
696 gen_bitlen(s, (tree_desc *)desc);
697
698 /* The field len is now set, we can generate the bit codes */
699 gen_codes ((ct_data *)tree, max_code, s->bl_count);
700}
701
702/* ===========================================================================
703 * Scan a literal or distance tree to determine the frequencies of the codes
704 * in the bit length tree.
705 */
706local void scan_tree (s, tree, max_code)
707 deflate_state *s;
708 ct_data *tree; /* the tree to be scanned */
709 int max_code; /* and its largest code of non zero frequency */
710{
711 int n; /* iterates over all tree elements */
712 int prevlen = -1; /* last emitted length */
713 int curlen; /* length of current code */
714 int nextlen = tree[0].Len; /* length of next code */
715 int count = 0; /* repeat count of the current code */
716 int max_count = 7; /* max repeat count */
717 int min_count = 4; /* min repeat count */
718
719 if (nextlen == 0) max_count = 138, min_count = 3;
720 tree[max_code+1].Len = (ush)0xffff; /* guard */
721
722 for (n = 0; n <= max_code; n++) {
723 curlen = nextlen; nextlen = tree[n+1].Len;
724 if (++count < max_count && curlen == nextlen) {
725 continue;
726 } else if (count < min_count) {
727 s->bl_tree[curlen].Freq += count;
728 } else if (curlen != 0) {
729 if (curlen != prevlen) s->bl_tree[curlen].Freq++;
730 s->bl_tree[REP_3_6].Freq++;
731 } else if (count <= 10) {
732 s->bl_tree[REPZ_3_10].Freq++;
733 } else {
734 s->bl_tree[REPZ_11_138].Freq++;
735 }
736 count = 0; prevlen = curlen;
737 if (nextlen == 0) {
738 max_count = 138, min_count = 3;
739 } else if (curlen == nextlen) {
740 max_count = 6, min_count = 3;
741 } else {
742 max_count = 7, min_count = 4;
743 }
744 }
745}
746
747/* ===========================================================================
748 * Send a literal or distance tree in compressed form, using the codes in
749 * bl_tree.
750 */
751local void send_tree (s, tree, max_code)
752 deflate_state *s;
753 ct_data *tree; /* the tree to be scanned */
754 int max_code; /* and its largest code of non zero frequency */
755{
756 int n; /* iterates over all tree elements */
757 int prevlen = -1; /* last emitted length */
758 int curlen; /* length of current code */
759 int nextlen = tree[0].Len; /* length of next code */
760 int count = 0; /* repeat count of the current code */
761 int max_count = 7; /* max repeat count */
762 int min_count = 4; /* min repeat count */
763
764 /* tree[max_code+1].Len = -1; */ /* guard already set */
765 if (nextlen == 0) max_count = 138, min_count = 3;
766
767 for (n = 0; n <= max_code; n++) {
768 curlen = nextlen; nextlen = tree[n+1].Len;
769 if (++count < max_count && curlen == nextlen) {
770 continue;
771 } else if (count < min_count) {
772 do { send_code(s, curlen, s->bl_tree); } while (--count != 0);
773
774 } else if (curlen != 0) {
775 if (curlen != prevlen) {
776 send_code(s, curlen, s->bl_tree); count--;
777 }
778 Assert(count >= 3 && count <= 6, " 3_6?");
779 send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);
780
781 } else if (count <= 10) {
782 send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);
783
784 } else {
785 send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
786 }
787 count = 0; prevlen = curlen;
788 if (nextlen == 0) {
789 max_count = 138, min_count = 3;
790 } else if (curlen == nextlen) {
791 max_count = 6, min_count = 3;
792 } else {
793 max_count = 7, min_count = 4;
794 }
795 }
796}
797
798/* ===========================================================================
799 * Construct the Huffman tree for the bit lengths and return the index in
800 * bl_order of the last bit length code to send.
801 */
802local int build_bl_tree(s)
803 deflate_state *s;
804{
805 int max_blindex; /* index of last bit length code of non zero freq */
806
807 /* Determine the bit length frequencies for literal and distance trees */
808 scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
809 scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);
810
811 /* Build the bit length tree: */
812 build_tree(s, (tree_desc *)(&(s->bl_desc)));
813 /* opt_len now includes the length of the tree representations, except
814 * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
815 */
816
817 /* Determine the number of bit length codes to send. The pkzip format
818 * requires that at least 4 bit length codes be sent. (appnote.txt says
819 * 3 but the actual value used is 4.)
820 */
821 for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
822 if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
823 }
824 /* Update opt_len to include the bit length tree and counts */
825 s->opt_len += 3*(max_blindex+1) + 5+5+4;
826 Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
827 s->opt_len, s->static_len));
828
829 return max_blindex;
830}
831
832/* ===========================================================================
833 * Send the header for a block using dynamic Huffman trees: the counts, the
834 * lengths of the bit length codes, the literal tree and the distance tree.
835 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
836 */
837local void send_all_trees(s, lcodes, dcodes, blcodes)
838 deflate_state *s;
839 int lcodes, dcodes, blcodes; /* number of codes for each tree */
840{
841 int rank; /* index in bl_order */
842
843 Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
844 Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
845 "too many codes");
846 Tracev((stderr, "\nbl counts: "));
847 send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
848 send_bits(s, dcodes-1, 5);
849 send_bits(s, blcodes-4, 4); /* not -3 as stated in appnote.txt */
850 for (rank = 0; rank < blcodes; rank++) {
851 Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
852 send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
853 }
854 Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));
855
856 send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
857 Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));
858
859 send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
860 Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
861}
862
863/* ===========================================================================
864 * Send a stored block
865 */
866void _tr_stored_block(s, buf, stored_len, eof)
867 deflate_state *s;
868 charf *buf; /* input block */
869 ulg stored_len; /* length of input block */
870 int eof; /* true if this is the last block for a file */
871{
872 send_bits(s, (STORED_BLOCK<<1)+eof, 3); /* send block type */
51dbdf87 873#ifdef DEBUG
c801d85f
KB
874 s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
875 s->compressed_len += (stored_len + 4) << 3;
a4019ec2 876#endif
c801d85f
KB
877 copy_block(s, buf, (unsigned)stored_len, 1); /* with header */
878}
879
880/* ===========================================================================
881 * Send one empty static block to give enough lookahead for inflate.
882 * This takes 10 bits, of which 7 may remain in the bit buffer.
883 * The current inflate code requires 9 bits of lookahead. If the
884 * last two codes for the previous block (real code plus EOB) were coded
885 * on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode
886 * the last real code. In this case we send two empty static blocks instead
887 * of one. (There are no problems if the previous block is stored or fixed.)
888 * To simplify the code, we assume the worst case of last real code encoded
889 * on one bit only.
890 */
891void _tr_align(s)
892 deflate_state *s;
893{
894 send_bits(s, STATIC_TREES<<1, 3);
895 send_code(s, END_BLOCK, static_ltree);
51dbdf87 896#ifdef DEBUG
c801d85f 897 s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
a4019ec2 898#endif
c801d85f
KB
899 bi_flush(s);
900 /* Of the 10 bits for the empty block, we have already sent
901 * (10 - bi_valid) bits. The lookahead for the last real code (before
902 * the EOB of the previous block) was thus at least one plus the length
903 * of the EOB plus what we have just sent of the empty static block.
904 */
905 if (1 + s->last_eob_len + 10 - s->bi_valid < 9) {
906 send_bits(s, STATIC_TREES<<1, 3);
907 send_code(s, END_BLOCK, static_ltree);
51dbdf87 908#ifdef DEBUG
c801d85f 909 s->compressed_len += 10L;
a4019ec2 910#endif
c801d85f
KB
911 bi_flush(s);
912 }
913 s->last_eob_len = 7;
914}
915
916/* ===========================================================================
917 * Determine the best encoding for the current block: dynamic trees, static
a4019ec2 918 * trees or store, and output the encoded block to the zip file.
c801d85f 919 */
a4019ec2 920void _tr_flush_block(s, buf, stored_len, eof)
c801d85f
KB
921 deflate_state *s;
922 charf *buf; /* input block, or NULL if too old */
923 ulg stored_len; /* length of input block */
924 int eof; /* true if this is the last block for a file */
925{
926 ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
927 int max_blindex = 0; /* index of last bit length code of non zero freq */
928
929 /* Build the Huffman trees unless a stored block is forced */
930 if (s->level > 0) {
931
41faf807
MW
932 /* Check if the file is binary or text */
933 if (stored_len > 0 && s->strm->data_type == Z_UNKNOWN)
934 set_data_type(s);
c801d85f 935
51dbdf87
VS
936 /* Construct the literal and distance trees */
937 build_tree(s, (tree_desc *)(&(s->l_desc)));
938 Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
939 s->static_len));
c801d85f 940
51dbdf87
VS
941 build_tree(s, (tree_desc *)(&(s->d_desc)));
942 Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
943 s->static_len));
944 /* At this point, opt_len and static_len are the total bit lengths of
945 * the compressed block data, excluding the tree representations.
946 */
c801d85f 947
51dbdf87
VS
948 /* Build the bit length tree for the above two trees, and get the index
949 * in bl_order of the last bit length code to send.
950 */
951 max_blindex = build_bl_tree(s);
c801d85f 952
51dbdf87
VS
953 /* Determine the best encoding. Compute the block lengths in bytes. */
954 opt_lenb = (s->opt_len+3+7)>>3;
955 static_lenb = (s->static_len+3+7)>>3;
c801d85f 956
51dbdf87
VS
957 Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
958 opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
959 s->last_lit));
c801d85f 960
51dbdf87 961 if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
c801d85f
KB
962
963 } else {
964 Assert(buf != (char*)0, "lost buf");
51dbdf87 965 opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
c801d85f
KB
966 }
967
c801d85f
KB
968#ifdef FORCE_STORED
969 if (buf != (char*)0) { /* force stored block */
970#else
971 if (stored_len+4 <= opt_lenb && buf != (char*)0) {
972 /* 4: two words for the lengths */
973#endif
974 /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
975 * Otherwise we can't have processed more than WSIZE input bytes since
976 * the last block flush, because compression would have been
977 * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
978 * transform a block into a stored block.
979 */
980 _tr_stored_block(s, buf, stored_len, eof);
981
982#ifdef FORCE_STATIC
983 } else if (static_lenb >= 0) { /* force static trees */
984#else
41faf807 985 } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) {
c801d85f
KB
986#endif
987 send_bits(s, (STATIC_TREES<<1)+eof, 3);
988 compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree);
51dbdf87 989#ifdef DEBUG
c801d85f 990 s->compressed_len += 3 + s->static_len;
a4019ec2 991#endif
c801d85f
KB
992 } else {
993 send_bits(s, (DYN_TREES<<1)+eof, 3);
994 send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
995 max_blindex+1);
996 compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree);
51dbdf87 997#ifdef DEBUG
c801d85f 998 s->compressed_len += 3 + s->opt_len;
a4019ec2 999#endif
c801d85f
KB
1000 }
1001 Assert (s->compressed_len == s->bits_sent, "bad compressed size");
a4019ec2
SC
1002 /* The above check is made mod 2^32, for files larger than 512 MB
1003 * and uLong implemented on 32 bits.
1004 */
c801d85f
KB
1005 init_block(s);
1006
1007 if (eof) {
1008 bi_windup(s);
51dbdf87 1009#ifdef DEBUG
c801d85f 1010 s->compressed_len += 7; /* align on byte boundary */
a4019ec2 1011#endif
c801d85f
KB
1012 }
1013 Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
1014 s->compressed_len-7*eof));
c801d85f
KB
1015}
1016
1017/* ===========================================================================
1018 * Save the match info and tally the frequency counts. Return true if
1019 * the current block must be flushed.
1020 */
1021int _tr_tally (s, dist, lc)
1022 deflate_state *s;
1023 unsigned dist; /* distance of matched string */
1024 unsigned lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */
1025{
1026 s->d_buf[s->last_lit] = (ush)dist;
1027 s->l_buf[s->last_lit++] = (uch)lc;
1028 if (dist == 0) {
1029 /* lc is the unmatched char */
1030 s->dyn_ltree[lc].Freq++;
1031 } else {
1032 s->matches++;
1033 /* Here, lc is the match length - MIN_MATCH */
1034 dist--; /* dist = match distance - 1 */
1035 Assert((ush)dist < (ush)MAX_DIST(s) &&
1036 (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
1037 (ush)d_code(dist) < (ush)D_CODES, "_tr_tally: bad match");
1038
1039 s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
1040 s->dyn_dtree[d_code(dist)].Freq++;
1041 }
1042
1043#ifdef TRUNCATE_BLOCK
1044 /* Try to guess if it is profitable to stop the current block here */
1045 if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
1046 /* Compute an upper bound for the compressed length */
1047 ulg out_length = (ulg)s->last_lit*8L;
1048 ulg in_length = (ulg)((long)s->strstart - s->block_start);
1049 int dcode;
1050 for (dcode = 0; dcode < D_CODES; dcode++) {
1051 out_length += (ulg)s->dyn_dtree[dcode].Freq *
1052 (5L+extra_dbits[dcode]);
1053 }
1054 out_length >>= 3;
1055 Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
1056 s->last_lit, in_length, out_length,
1057 100L - out_length*100L/in_length));
1058 if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
1059 }
1060#endif
1061 return (s->last_lit == s->lit_bufsize-1);
1062 /* We avoid equality with lit_bufsize because of wraparound at 64K
1063 * on 16 bit machines and because stored blocks are restricted to
1064 * 64K-1 bytes.
1065 */
1066}
1067
1068/* ===========================================================================
1069 * Send the block data compressed using the given Huffman trees
1070 */
1071local void compress_block(s, ltree, dtree)
1072 deflate_state *s;
1073 ct_data *ltree; /* literal tree */
1074 ct_data *dtree; /* distance tree */
1075{
1076 unsigned dist; /* distance of matched string */
1077 int lc; /* match length or unmatched char (if dist == 0) */
1078 unsigned lx = 0; /* running index in l_buf */
1079 unsigned code; /* the code to send */
1080 int extra; /* number of extra bits to send */
1081
1082 if (s->last_lit != 0) do {
1083 dist = s->d_buf[lx];
1084 lc = s->l_buf[lx++];
1085 if (dist == 0) {
1086 send_code(s, lc, ltree); /* send a literal byte */
1087 Tracecv(isgraph(lc), (stderr," '%c' ", lc));
1088 } else {
1089 /* Here, lc is the match length - MIN_MATCH */
1090 code = _length_code[lc];
1091 send_code(s, code+LITERALS+1, ltree); /* send the length code */
1092 extra = extra_lbits[code];
1093 if (extra != 0) {
1094 lc -= base_length[code];
1095 send_bits(s, lc, extra); /* send the extra length bits */
1096 }
1097 dist--; /* dist is now the match distance - 1 */
1098 code = d_code(dist);
1099 Assert (code < D_CODES, "bad d_code");
1100
1101 send_code(s, code, dtree); /* send the distance code */
1102 extra = extra_dbits[code];
1103 if (extra != 0) {
1104 dist -= base_dist[code];
1105 send_bits(s, dist, extra); /* send the extra distance bits */
1106 }
1107 } /* literal or match pair ? */
1108
1109 /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
51dbdf87
VS
1110 Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx,
1111 "pendingBuf overflow");
c801d85f
KB
1112
1113 } while (lx < s->last_lit);
1114
1115 send_code(s, END_BLOCK, ltree);
1116 s->last_eob_len = ltree[END_BLOCK].Len;
1117}
1118
1119/* ===========================================================================
41faf807
MW
1120 * Set the data type to BINARY or TEXT, using a crude approximation:
1121 * set it to Z_TEXT if all symbols are either printable characters (33 to 255)
1122 * or white spaces (9 to 13, or 32); or set it to Z_BINARY otherwise.
1123 * IN assertion: the fields Freq of dyn_ltree are set.
c801d85f
KB
1124 */
1125local void set_data_type(s)
1126 deflate_state *s;
1127{
41faf807
MW
1128 int n;
1129
1130 for (n = 0; n < 9; n++)
1131 if (s->dyn_ltree[n].Freq != 0)
1132 break;
1133 if (n == 9)
1134 for (n = 14; n < 32; n++)
1135 if (s->dyn_ltree[n].Freq != 0)
1136 break;
1137 s->strm->data_type = (n == 32) ? Z_TEXT : Z_BINARY;
c801d85f
KB
1138}
1139
1140/* ===========================================================================
1141 * Reverse the first len bits of a code, using straightforward code (a faster
1142 * method would use a table)
1143 * IN assertion: 1 <= len <= 15
1144 */
1145local unsigned bi_reverse(code, len)
1146 unsigned code; /* the value to invert */
1147 int len; /* its bit length */
1148{
1149 register unsigned res = 0;
1150 do {
1151 res |= code & 1;
1152 code >>= 1, res <<= 1;
1153 } while (--len > 0);
1154 return res >> 1;
1155}
1156
1157/* ===========================================================================
1158 * Flush the bit buffer, keeping at most 7 bits in it.
1159 */
1160local void bi_flush(s)
1161 deflate_state *s;
1162{
1163 if (s->bi_valid == 16) {
1164 put_short(s, s->bi_buf);
1165 s->bi_buf = 0;
1166 s->bi_valid = 0;
1167 } else if (s->bi_valid >= 8) {
1168 put_byte(s, (Byte)s->bi_buf);
1169 s->bi_buf >>= 8;
1170 s->bi_valid -= 8;
1171 }
1172}
1173
1174/* ===========================================================================
1175 * Flush the bit buffer and align the output on a byte boundary
1176 */
1177local void bi_windup(s)
1178 deflate_state *s;
1179{
1180 if (s->bi_valid > 8) {
1181 put_short(s, s->bi_buf);
1182 } else if (s->bi_valid > 0) {
1183 put_byte(s, (Byte)s->bi_buf);
1184 }
1185 s->bi_buf = 0;
1186 s->bi_valid = 0;
51dbdf87 1187#ifdef DEBUG
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1188 s->bits_sent = (s->bits_sent+7) & ~7;
1189#endif
1190}
1191
1192/* ===========================================================================
1193 * Copy a stored block, storing first the length and its
1194 * one's complement if requested.
1195 */
1196local void copy_block(s, buf, len, header)
1197 deflate_state *s;
1198 charf *buf; /* the input data */
1199 unsigned len; /* its length */
1200 int header; /* true if block header must be written */
1201{
1202 bi_windup(s); /* align on byte boundary */
1203 s->last_eob_len = 8; /* enough lookahead for inflate */
1204
1205 if (header) {
e6ebb514 1206 put_short(s, (ush)len);
c801d85f 1207 put_short(s, (ush)~len);
51dbdf87 1208#ifdef DEBUG
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1209 s->bits_sent += 2*16;
1210#endif
1211 }
51dbdf87 1212#ifdef DEBUG
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1213 s->bits_sent += (ulg)len<<3;
1214#endif
1215 while (len--) {
1216 put_byte(s, *buf++);
1217 }
1218}