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Mon Jul 22 10:46:14 2013 UTC (11 years, 1 month ago) by
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1.8.7
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: trees.c,v 1.1.1.2 2013/07/22 10:46:14 misho Exp $ */
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, ct_data *ltree,
150: 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:
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: */
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:
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: */
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: */
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: */
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: */
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: */
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: */
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: */
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: */
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: */
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: */
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: */
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: */
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: */
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: */
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, (ct_data *)static_ltree, (ct_data *)static_dtree);
976: #ifdef DEBUG
977: s->compressed_len += 3 + s->static_len;
978: #endif
979: } else {
980: send_bits(s, (DYN_TREES<<1)+last, 3);
981: send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
982: max_blindex+1);
983: compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree);
984: #ifdef DEBUG
985: s->compressed_len += 3 + s->opt_len;
986: #endif
987: }
988: Assert (s->compressed_len == s->bits_sent, "bad compressed size");
989: /* The above check is made mod 2^32, for files larger than 512 MB
990: * and uLong implemented on 32 bits.
991: */
992: init_block(s);
993:
994: if (last) {
995: bi_windup(s);
996: #ifdef DEBUG
997: s->compressed_len += 7; /* align on byte boundary */
998: #endif
999: }
1000: Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
1001: s->compressed_len-7*last));
1002: }
1003:
1004: /* ===========================================================================
1005: * Save the match info and tally the frequency counts. Return true if
1006: * the current block must be flushed.
1007: */
1008: int ZLIB_INTERNAL _tr_tally (s, dist, lc)
1009: deflate_state *s;
1010: unsigned dist; /* distance of matched string */
1011: unsigned lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */
1012: {
1013: s->d_buf[s->last_lit] = (ush)dist;
1014: s->l_buf[s->last_lit++] = (uch)lc;
1015: if (dist == 0) {
1016: /* lc is the unmatched char */
1017: s->dyn_ltree[lc].Freq++;
1018: } else {
1019: s->matches++;
1020: /* Here, lc is the match length - MIN_MATCH */
1021: dist--; /* dist = match distance - 1 */
1022: Assert((ush)dist < (ush)MAX_DIST(s) &&
1023: (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
1024: (ush)d_code(dist) < (ush)D_CODES, "_tr_tally: bad match");
1025:
1026: s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
1027: s->dyn_dtree[d_code(dist)].Freq++;
1028: }
1029:
1030: #ifdef TRUNCATE_BLOCK
1031: /* Try to guess if it is profitable to stop the current block here */
1032: if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
1033: /* Compute an upper bound for the compressed length */
1034: ulg out_length = (ulg)s->last_lit*8L;
1035: ulg in_length = (ulg)((long)s->strstart - s->block_start);
1036: int dcode;
1037: for (dcode = 0; dcode < D_CODES; dcode++) {
1038: out_length += (ulg)s->dyn_dtree[dcode].Freq *
1039: (5L+extra_dbits[dcode]);
1040: }
1041: out_length >>= 3;
1042: Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
1043: s->last_lit, in_length, out_length,
1044: 100L - out_length*100L/in_length));
1045: if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
1046: }
1047: #endif
1048: return (s->last_lit == s->lit_bufsize-1);
1049: /* We avoid equality with lit_bufsize because of wraparound at 64K
1050: * on 16 bit machines and because stored blocks are restricted to
1051: * 64K-1 bytes.
1052: */
1053: }
1054:
1055: /* ===========================================================================
1056: * Send the block data compressed using the given Huffman trees
1057: */
1058: local void compress_block(s, ltree, dtree)
1059: deflate_state *s;
1060: ct_data *ltree; /* literal tree */
1061: ct_data *dtree; /* distance tree */
1062: {
1063: unsigned dist; /* distance of matched string */
1064: int lc; /* match length or unmatched char (if dist == 0) */
1065: unsigned lx = 0; /* running index in l_buf */
1066: unsigned code; /* the code to send */
1067: int extra; /* number of extra bits to send */
1068:
1069: if (s->last_lit != 0) do {
1070: dist = s->d_buf[lx];
1071: lc = s->l_buf[lx++];
1072: if (dist == 0) {
1073: send_code(s, lc, ltree); /* send a literal byte */
1074: Tracecv(isgraph(lc), (stderr," '%c' ", lc));
1075: } else {
1076: /* Here, lc is the match length - MIN_MATCH */
1077: code = _length_code[lc];
1078: send_code(s, code+LITERALS+1, ltree); /* send the length code */
1079: extra = extra_lbits[code];
1080: if (extra != 0) {
1081: lc -= base_length[code];
1082: send_bits(s, lc, extra); /* send the extra length bits */
1083: }
1084: dist--; /* dist is now the match distance - 1 */
1085: code = d_code(dist);
1086: Assert (code < D_CODES, "bad d_code");
1087:
1088: send_code(s, code, dtree); /* send the distance code */
1089: extra = extra_dbits[code];
1090: if (extra != 0) {
1091: dist -= base_dist[code];
1092: send_bits(s, dist, extra); /* send the extra distance bits */
1093: }
1094: } /* literal or match pair ? */
1095:
1096: /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
1097: Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx,
1098: "pendingBuf overflow");
1099:
1100: } while (lx < s->last_lit);
1101:
1102: send_code(s, END_BLOCK, ltree);
1103: }
1104:
1105: /* ===========================================================================
1106: * Check if the data type is TEXT or BINARY, using the following algorithm:
1107: * - TEXT if the two conditions below are satisfied:
1108: * a) There are no non-portable control characters belonging to the
1109: * "black list" (0..6, 14..25, 28..31).
1110: * b) There is at least one printable character belonging to the
1111: * "white list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255).
1112: * - BINARY otherwise.
1113: * - The following partially-portable control characters form a
1114: * "gray list" that is ignored in this detection algorithm:
1115: * (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}).
1116: * IN assertion: the fields Freq of dyn_ltree are set.
1117: */
1118: local int detect_data_type(s)
1119: deflate_state *s;
1120: {
1121: /* black_mask is the bit mask of black-listed bytes
1122: * set bits 0..6, 14..25, and 28..31
1123: * 0xf3ffc07f = binary 11110011111111111100000001111111
1124: */
1125: unsigned long black_mask = 0xf3ffc07fUL;
1126: int n;
1127:
1128: /* Check for non-textual ("black-listed") bytes. */
1129: for (n = 0; n <= 31; n++, black_mask >>= 1)
1130: if ((black_mask & 1) && (s->dyn_ltree[n].Freq != 0))
1131: return Z_BINARY;
1132:
1133: /* Check for textual ("white-listed") bytes. */
1134: if (s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0
1135: || s->dyn_ltree[13].Freq != 0)
1136: return Z_TEXT;
1137: for (n = 32; n < LITERALS; n++)
1138: if (s->dyn_ltree[n].Freq != 0)
1139: return Z_TEXT;
1140:
1141: /* There are no "black-listed" or "white-listed" bytes:
1142: * this stream either is empty or has tolerated ("gray-listed") bytes only.
1143: */
1144: return Z_BINARY;
1145: }
1146:
1147: /* ===========================================================================
1148: * Reverse the first len bits of a code, using straightforward code (a faster
1149: * method would use a table)
1150: * IN assertion: 1 <= len <= 15
1151: */
1152: local unsigned bi_reverse(code, len)
1153: unsigned code; /* the value to invert */
1154: int len; /* its bit length */
1155: {
1156: register unsigned res = 0;
1157: do {
1158: res |= code & 1;
1159: code >>= 1, res <<= 1;
1160: } while (--len > 0);
1161: return res >> 1;
1162: }
1163:
1164: /* ===========================================================================
1165: * Flush the bit buffer, keeping at most 7 bits in it.
1166: */
1167: local void bi_flush(s)
1168: deflate_state *s;
1169: {
1170: if (s->bi_valid == 16) {
1171: put_short(s, s->bi_buf);
1172: s->bi_buf = 0;
1173: s->bi_valid = 0;
1174: } else if (s->bi_valid >= 8) {
1175: put_byte(s, (Byte)s->bi_buf);
1176: s->bi_buf >>= 8;
1177: s->bi_valid -= 8;
1178: }
1179: }
1180:
1181: /* ===========================================================================
1182: * Flush the bit buffer and align the output on a byte boundary
1183: */
1184: local void bi_windup(s)
1185: deflate_state *s;
1186: {
1187: if (s->bi_valid > 8) {
1188: put_short(s, s->bi_buf);
1189: } else if (s->bi_valid > 0) {
1190: put_byte(s, (Byte)s->bi_buf);
1191: }
1192: s->bi_buf = 0;
1193: s->bi_valid = 0;
1194: #ifdef DEBUG
1195: s->bits_sent = (s->bits_sent+7) & ~7;
1196: #endif
1197: }
1198:
1199: /* ===========================================================================
1200: * Copy a stored block, storing first the length and its
1201: * one's complement if requested.
1202: */
1203: local void copy_block(s, buf, len, header)
1204: deflate_state *s;
1205: charf *buf; /* the input data */
1206: unsigned len; /* its length */
1207: int header; /* true if block header must be written */
1208: {
1209: bi_windup(s); /* align on byte boundary */
1210:
1211: if (header) {
1212: put_short(s, (ush)len);
1213: put_short(s, (ush)~len);
1214: #ifdef DEBUG
1215: s->bits_sent += 2*16;
1216: #endif
1217: }
1218: #ifdef DEBUG
1219: s->bits_sent += (ulg)len<<3;
1220: #endif
1221: while (len--) {
1222: put_byte(s, *buf++);
1223: }
1224: }
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