1: /* trees.c -- output deflated data using Huffman coding
2: * Copyright (C) 1995-2010 Jean-loup Gailly
3: * detect_data_type() function provided freely by Cosmin Truta, 2006
4: * For conditions of distribution and use, see copyright notice in zlib.h
5: */
6:
7: /*
8: * ALGORITHM
9: *
10: * The "deflation" process uses several Huffman trees. The more
11: * common source values are represented by shorter bit sequences.
12: *
13: * Each code tree is stored in a compressed form which is itself
14: * a Huffman encoding of the lengths of all the code strings (in
15: * ascending order by source values). The actual code strings are
16: * reconstructed from the lengths in the inflate process, as described
17: * in the deflate specification.
18: *
19: * REFERENCES
20: *
21: * Deutsch, L.P.,"'Deflate' Compressed Data Format Specification".
22: * Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc
23: *
24: * Storer, James A.
25: * Data Compression: Methods and Theory, pp. 49-50.
26: * Computer Science Press, 1988. ISBN 0-7167-8156-5.
27: *
28: * Sedgewick, R.
29: * Algorithms, p290.
30: * Addison-Wesley, 1983. ISBN 0-201-06672-6.
31: */
32:
33: /* @(#) $Id: trees.c,v 1.1.1.1 2012/02/21 16:23:02 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: #define Buf_size (8 * 2*sizeof(char))
78: /* Number of bits used within bi_buf. (bi_buf might be implemented on
79: * more than 16 bits on some systems.)
80: */
81:
82: /* ===========================================================================
83: * Local data. These are initialized only once.
84: */
85:
86: #define DIST_CODE_LEN 512 /* see definition of array dist_code below */
87:
88: #if defined(GEN_TREES_H) || !defined(STDC)
89: /* non ANSI compilers may not accept trees.h */
90:
91: local ct_data static_ltree[L_CODES+2];
92: /* The static literal tree. Since the bit lengths are imposed, there is no
93: * need for the L_CODES extra codes used during heap construction. However
94: * The codes 286 and 287 are needed to build a canonical tree (see _tr_init
95: * below).
96: */
97:
98: local ct_data static_dtree[D_CODES];
99: /* The static distance tree. (Actually a trivial tree since all codes use
100: * 5 bits.)
101: */
102:
103: uch _dist_code[DIST_CODE_LEN];
104: /* Distance codes. The first 256 values correspond to the distances
105: * 3 .. 258, the last 256 values correspond to the top 8 bits of
106: * the 15 bit distances.
107: */
108:
109: uch _length_code[MAX_MATCH-MIN_MATCH+1];
110: /* length code for each normalized match length (0 == MIN_MATCH) */
111:
112: local int base_length[LENGTH_CODES];
113: /* First normalized length for each code (0 = MIN_MATCH) */
114:
115: local int base_dist[D_CODES];
116: /* First normalized distance for each code (0 = distance of 1) */
117:
118: #else
119: # include "trees.h"
120: #endif /* GEN_TREES_H */
121:
122: struct static_tree_desc_s {
123: const ct_data *static_tree; /* static tree or NULL */
124: const intf *extra_bits; /* extra bits for each code or NULL */
125: int extra_base; /* base index for extra_bits */
126: int elems; /* max number of elements in the tree */
127: int max_length; /* max bit length for the codes */
128: };
129:
130: local static_tree_desc static_l_desc =
131: {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};
132:
133: local static_tree_desc static_d_desc =
134: {static_dtree, extra_dbits, 0, D_CODES, MAX_BITS};
135:
136: local static_tree_desc static_bl_desc =
137: {(const ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS};
138:
139: /* ===========================================================================
140: * Local (static) routines in this file.
141: */
142:
143: local void tr_static_init OF((void));
144: local void init_block OF((deflate_state *s));
145: local void pqdownheap OF((deflate_state *s, ct_data *tree, int k));
146: local void gen_bitlen OF((deflate_state *s, tree_desc *desc));
147: local void gen_codes OF((ct_data *tree, int max_code, ushf *bl_count));
148: local void build_tree OF((deflate_state *s, tree_desc *desc));
149: local void scan_tree OF((deflate_state *s, ct_data *tree, int max_code));
150: local void send_tree OF((deflate_state *s, ct_data *tree, int max_code));
151: local int build_bl_tree OF((deflate_state *s));
152: local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes,
153: int blcodes));
154: local void compress_block OF((deflate_state *s, ct_data *ltree,
155: ct_data *dtree));
156: local int detect_data_type OF((deflate_state *s));
157: local unsigned bi_reverse OF((unsigned value, int length));
158: local void bi_windup OF((deflate_state *s));
159: local void bi_flush OF((deflate_state *s));
160: local void copy_block OF((deflate_state *s, charf *buf, unsigned len,
161: int header));
162:
163: #ifdef GEN_TREES_H
164: local void gen_trees_header OF((void));
165: #endif
166:
167: #ifndef DEBUG
168: # define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
169: /* Send a code of the given tree. c and tree must not have side effects */
170:
171: #else /* DEBUG */
172: # define send_code(s, c, tree) \
173: { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
174: send_bits(s, tree[c].Code, tree[c].Len); }
175: #endif
176:
177: /* ===========================================================================
178: * Output a short LSB first on the stream.
179: * IN assertion: there is enough room in pendingBuf.
180: */
181: #define put_short(s, w) { \
182: put_byte(s, (uch)((w) & 0xff)); \
183: put_byte(s, (uch)((ush)(w) >> 8)); \
184: }
185:
186: /* ===========================================================================
187: * Send a value on a given number of bits.
188: * IN assertion: length <= 16 and value fits in length bits.
189: */
190: #ifdef DEBUG
191: local void send_bits OF((deflate_state *s, int value, int length));
192:
193: local void send_bits(s, value, length)
194: deflate_state *s;
195: int value; /* value to send */
196: int length; /* number of bits */
197: {
198: Tracevv((stderr," l %2d v %4x ", length, value));
199: Assert(length > 0 && length <= 15, "invalid length");
200: s->bits_sent += (ulg)length;
201:
202: /* If not enough room in bi_buf, use (valid) bits from bi_buf and
203: * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
204: * unused bits in value.
205: */
206: if (s->bi_valid > (int)Buf_size - length) {
207: s->bi_buf |= (ush)value << s->bi_valid;
208: put_short(s, s->bi_buf);
209: s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);
210: s->bi_valid += length - Buf_size;
211: } else {
212: s->bi_buf |= (ush)value << s->bi_valid;
213: s->bi_valid += length;
214: }
215: }
216: #else /* !DEBUG */
217:
218: #define send_bits(s, value, length) \
219: { int len = length;\
220: if (s->bi_valid > (int)Buf_size - len) {\
221: int val = value;\
222: s->bi_buf |= (ush)val << s->bi_valid;\
223: put_short(s, s->bi_buf);\
224: s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
225: s->bi_valid += len - Buf_size;\
226: } else {\
227: s->bi_buf |= (ush)(value) << s->bi_valid;\
228: s->bi_valid += len;\
229: }\
230: }
231: #endif /* DEBUG */
232:
233:
234: /* the arguments must not have side effects */
235:
236: /* ===========================================================================
237: * Initialize the various 'constant' tables.
238: */
239: local void tr_static_init()
240: {
241: #if defined(GEN_TREES_H) || !defined(STDC)
242: static int static_init_done = 0;
243: int n; /* iterates over tree elements */
244: int bits; /* bit counter */
245: int length; /* length value */
246: int code; /* code value */
247: int dist; /* distance index */
248: ush bl_count[MAX_BITS+1];
249: /* number of codes at each bit length for an optimal tree */
250:
251: if (static_init_done) return;
252:
253: /* For some embedded targets, global variables are not initialized: */
254: #ifdef NO_INIT_GLOBAL_POINTERS
255: static_l_desc.static_tree = static_ltree;
256: static_l_desc.extra_bits = extra_lbits;
257: static_d_desc.static_tree = static_dtree;
258: static_d_desc.extra_bits = extra_dbits;
259: static_bl_desc.extra_bits = extra_blbits;
260: #endif
261:
262: /* Initialize the mapping length (0..255) -> length code (0..28) */
263: length = 0;
264: for (code = 0; code < LENGTH_CODES-1; code++) {
265: base_length[code] = length;
266: for (n = 0; n < (1<<extra_lbits[code]); n++) {
267: _length_code[length++] = (uch)code;
268: }
269: }
270: Assert (length == 256, "tr_static_init: length != 256");
271: /* Note that the length 255 (match length 258) can be represented
272: * in two different ways: code 284 + 5 bits or code 285, so we
273: * overwrite length_code[255] to use the best encoding:
274: */
275: _length_code[length-1] = (uch)code;
276:
277: /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
278: dist = 0;
279: for (code = 0 ; code < 16; code++) {
280: base_dist[code] = dist;
281: for (n = 0; n < (1<<extra_dbits[code]); n++) {
282: _dist_code[dist++] = (uch)code;
283: }
284: }
285: Assert (dist == 256, "tr_static_init: dist != 256");
286: dist >>= 7; /* from now on, all distances are divided by 128 */
287: for ( ; code < D_CODES; code++) {
288: base_dist[code] = dist << 7;
289: for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
290: _dist_code[256 + dist++] = (uch)code;
291: }
292: }
293: Assert (dist == 256, "tr_static_init: 256+dist != 512");
294:
295: /* Construct the codes of the static literal tree */
296: for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
297: n = 0;
298: while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
299: while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
300: while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
301: while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
302: /* Codes 286 and 287 do not exist, but we must include them in the
303: * tree construction to get a canonical Huffman tree (longest code
304: * all ones)
305: */
306: gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);
307:
308: /* The static distance tree is trivial: */
309: for (n = 0; n < D_CODES; n++) {
310: static_dtree[n].Len = 5;
311: static_dtree[n].Code = bi_reverse((unsigned)n, 5);
312: }
313: static_init_done = 1;
314:
315: # ifdef GEN_TREES_H
316: gen_trees_header();
317: # endif
318: #endif /* defined(GEN_TREES_H) || !defined(STDC) */
319: }
320:
321: /* ===========================================================================
322: * Genererate the file trees.h describing the static trees.
323: */
324: #ifdef GEN_TREES_H
325: # ifndef DEBUG
326: # include <stdio.h>
327: # endif
328:
329: # define SEPARATOR(i, last, width) \
330: ((i) == (last)? "\n};\n\n" : \
331: ((i) % (width) == (width)-1 ? ",\n" : ", "))
332:
333: void gen_trees_header()
334: {
335: FILE *header = fopen("trees.h", "w");
336: int i;
337:
338: Assert (header != NULL, "Can't open trees.h");
339: fprintf(header,
340: "/* header created automatically with -DGEN_TREES_H */\n\n");
341:
342: fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n");
343: for (i = 0; i < L_CODES+2; i++) {
344: fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code,
345: static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5));
346: }
347:
348: fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n");
349: for (i = 0; i < D_CODES; i++) {
350: fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code,
351: static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5));
352: }
353:
354: fprintf(header, "const uch ZLIB_INTERNAL _dist_code[DIST_CODE_LEN] = {\n");
355: for (i = 0; i < DIST_CODE_LEN; i++) {
356: fprintf(header, "%2u%s", _dist_code[i],
357: SEPARATOR(i, DIST_CODE_LEN-1, 20));
358: }
359:
360: fprintf(header,
361: "const uch ZLIB_INTERNAL _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");
362: for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) {
363: fprintf(header, "%2u%s", _length_code[i],
364: SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));
365: }
366:
367: fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");
368: for (i = 0; i < LENGTH_CODES; i++) {
369: fprintf(header, "%1u%s", base_length[i],
370: SEPARATOR(i, LENGTH_CODES-1, 20));
371: }
372:
373: fprintf(header, "local const int base_dist[D_CODES] = {\n");
374: for (i = 0; i < D_CODES; i++) {
375: fprintf(header, "%5u%s", base_dist[i],
376: SEPARATOR(i, D_CODES-1, 10));
377: }
378:
379: fclose(header);
380: }
381: #endif /* GEN_TREES_H */
382:
383: /* ===========================================================================
384: * Initialize the tree data structures for a new zlib stream.
385: */
386: void ZLIB_INTERNAL _tr_init(s)
387: deflate_state *s;
388: {
389: tr_static_init();
390:
391: s->l_desc.dyn_tree = s->dyn_ltree;
392: s->l_desc.stat_desc = &static_l_desc;
393:
394: s->d_desc.dyn_tree = s->dyn_dtree;
395: s->d_desc.stat_desc = &static_d_desc;
396:
397: s->bl_desc.dyn_tree = s->bl_tree;
398: s->bl_desc.stat_desc = &static_bl_desc;
399:
400: s->bi_buf = 0;
401: s->bi_valid = 0;
402: s->last_eob_len = 8; /* enough lookahead for inflate */
403: #ifdef DEBUG
404: s->compressed_len = 0L;
405: s->bits_sent = 0L;
406: #endif
407:
408: /* Initialize the first block of the first file: */
409: init_block(s);
410: }
411:
412: /* ===========================================================================
413: * Initialize a new block.
414: */
415: local void init_block(s)
416: deflate_state *s;
417: {
418: int n; /* iterates over tree elements */
419:
420: /* Initialize the trees. */
421: for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0;
422: for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0;
423: for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;
424:
425: s->dyn_ltree[END_BLOCK].Freq = 1;
426: s->opt_len = s->static_len = 0L;
427: s->last_lit = s->matches = 0;
428: }
429:
430: #define SMALLEST 1
431: /* Index within the heap array of least frequent node in the Huffman tree */
432:
433:
434: /* ===========================================================================
435: * Remove the smallest element from the heap and recreate the heap with
436: * one less element. Updates heap and heap_len.
437: */
438: #define pqremove(s, tree, top) \
439: {\
440: top = s->heap[SMALLEST]; \
441: s->heap[SMALLEST] = s->heap[s->heap_len--]; \
442: pqdownheap(s, tree, SMALLEST); \
443: }
444:
445: /* ===========================================================================
446: * Compares to subtrees, using the tree depth as tie breaker when
447: * the subtrees have equal frequency. This minimizes the worst case length.
448: */
449: #define smaller(tree, n, m, depth) \
450: (tree[n].Freq < tree[m].Freq || \
451: (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
452:
453: /* ===========================================================================
454: * Restore the heap property by moving down the tree starting at node k,
455: * exchanging a node with the smallest of its two sons if necessary, stopping
456: * when the heap property is re-established (each father smaller than its
457: * two sons).
458: */
459: local void pqdownheap(s, tree, k)
460: deflate_state *s;
461: ct_data *tree; /* the tree to restore */
462: int k; /* node to move down */
463: {
464: int v = s->heap[k];
465: int j = k << 1; /* left son of k */
466: while (j <= s->heap_len) {
467: /* Set j to the smallest of the two sons: */
468: if (j < s->heap_len &&
469: smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
470: j++;
471: }
472: /* Exit if v is smaller than both sons */
473: if (smaller(tree, v, s->heap[j], s->depth)) break;
474:
475: /* Exchange v with the smallest son */
476: s->heap[k] = s->heap[j]; k = j;
477:
478: /* And continue down the tree, setting j to the left son of k */
479: j <<= 1;
480: }
481: s->heap[k] = v;
482: }
483:
484: /* ===========================================================================
485: * Compute the optimal bit lengths for a tree and update the total bit length
486: * for the current block.
487: * IN assertion: the fields freq and dad are set, heap[heap_max] and
488: * above are the tree nodes sorted by increasing frequency.
489: * OUT assertions: the field len is set to the optimal bit length, the
490: * array bl_count contains the frequencies for each bit length.
491: * The length opt_len is updated; static_len is also updated if stree is
492: * not null.
493: */
494: local void gen_bitlen(s, desc)
495: deflate_state *s;
496: tree_desc *desc; /* the tree descriptor */
497: {
498: ct_data *tree = desc->dyn_tree;
499: int max_code = desc->max_code;
500: const ct_data *stree = desc->stat_desc->static_tree;
501: const intf *extra = desc->stat_desc->extra_bits;
502: int base = desc->stat_desc->extra_base;
503: int max_length = desc->stat_desc->max_length;
504: int h; /* heap index */
505: int n, m; /* iterate over the tree elements */
506: int bits; /* bit length */
507: int xbits; /* extra bits */
508: ush f; /* frequency */
509: int overflow = 0; /* number of elements with bit length too large */
510:
511: for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
512:
513: /* In a first pass, compute the optimal bit lengths (which may
514: * overflow in the case of the bit length tree).
515: */
516: tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
517:
518: for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
519: n = s->heap[h];
520: bits = tree[tree[n].Dad].Len + 1;
521: if (bits > max_length) bits = max_length, overflow++;
522: tree[n].Len = (ush)bits;
523: /* We overwrite tree[n].Dad which is no longer needed */
524:
525: if (n > max_code) continue; /* not a leaf node */
526:
527: s->bl_count[bits]++;
528: xbits = 0;
529: if (n >= base) xbits = extra[n-base];
530: f = tree[n].Freq;
531: s->opt_len += (ulg)f * (bits + xbits);
532: if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits);
533: }
534: if (overflow == 0) return;
535:
536: Trace((stderr,"\nbit length overflow\n"));
537: /* This happens for example on obj2 and pic of the Calgary corpus */
538:
539: /* Find the first bit length which could increase: */
540: do {
541: bits = max_length-1;
542: while (s->bl_count[bits] == 0) bits--;
543: s->bl_count[bits]--; /* move one leaf down the tree */
544: s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
545: s->bl_count[max_length]--;
546: /* The brother of the overflow item also moves one step up,
547: * but this does not affect bl_count[max_length]
548: */
549: overflow -= 2;
550: } while (overflow > 0);
551:
552: /* Now recompute all bit lengths, scanning in increasing frequency.
553: * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
554: * lengths instead of fixing only the wrong ones. This idea is taken
555: * from 'ar' written by Haruhiko Okumura.)
556: */
557: for (bits = max_length; bits != 0; bits--) {
558: n = s->bl_count[bits];
559: while (n != 0) {
560: m = s->heap[--h];
561: if (m > max_code) continue;
562: if ((unsigned) tree[m].Len != (unsigned) bits) {
563: Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
564: s->opt_len += ((long)bits - (long)tree[m].Len)
565: *(long)tree[m].Freq;
566: tree[m].Len = (ush)bits;
567: }
568: n--;
569: }
570: }
571: }
572:
573: /* ===========================================================================
574: * Generate the codes for a given tree and bit counts (which need not be
575: * optimal).
576: * IN assertion: the array bl_count contains the bit length statistics for
577: * the given tree and the field len is set for all tree elements.
578: * OUT assertion: the field code is set for all tree elements of non
579: * zero code length.
580: */
581: local void gen_codes (tree, max_code, bl_count)
582: ct_data *tree; /* the tree to decorate */
583: int max_code; /* largest code with non zero frequency */
584: ushf *bl_count; /* number of codes at each bit length */
585: {
586: ush next_code[MAX_BITS+1]; /* next code value for each bit length */
587: ush code = 0; /* running code value */
588: int bits; /* bit index */
589: int n; /* code index */
590:
591: /* The distribution counts are first used to generate the code values
592: * without bit reversal.
593: */
594: for (bits = 1; bits <= MAX_BITS; bits++) {
595: next_code[bits] = code = (code + bl_count[bits-1]) << 1;
596: }
597: /* Check that the bit counts in bl_count are consistent. The last code
598: * must be all ones.
599: */
600: Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
601: "inconsistent bit counts");
602: Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
603:
604: for (n = 0; n <= max_code; n++) {
605: int len = tree[n].Len;
606: if (len == 0) continue;
607: /* Now reverse the bits */
608: tree[n].Code = bi_reverse(next_code[len]++, len);
609:
610: Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
611: n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
612: }
613: }
614:
615: /* ===========================================================================
616: * Construct one Huffman tree and assigns the code bit strings and lengths.
617: * Update the total bit length for the current block.
618: * IN assertion: the field freq is set for all tree elements.
619: * OUT assertions: the fields len and code are set to the optimal bit length
620: * and corresponding code. The length opt_len is updated; static_len is
621: * also updated if stree is not null. The field max_code is set.
622: */
623: local void build_tree(s, desc)
624: deflate_state *s;
625: tree_desc *desc; /* the tree descriptor */
626: {
627: ct_data *tree = desc->dyn_tree;
628: const ct_data *stree = desc->stat_desc->static_tree;
629: int elems = desc->stat_desc->elems;
630: int n, m; /* iterate over heap elements */
631: int max_code = -1; /* largest code with non zero frequency */
632: int node; /* new node being created */
633:
634: /* Construct the initial heap, with least frequent element in
635: * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
636: * heap[0] is not used.
637: */
638: s->heap_len = 0, s->heap_max = HEAP_SIZE;
639:
640: for (n = 0; n < elems; n++) {
641: if (tree[n].Freq != 0) {
642: s->heap[++(s->heap_len)] = max_code = n;
643: s->depth[n] = 0;
644: } else {
645: tree[n].Len = 0;
646: }
647: }
648:
649: /* The pkzip format requires that at least one distance code exists,
650: * and that at least one bit should be sent even if there is only one
651: * possible code. So to avoid special checks later on we force at least
652: * two codes of non zero frequency.
653: */
654: while (s->heap_len < 2) {
655: node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
656: tree[node].Freq = 1;
657: s->depth[node] = 0;
658: s->opt_len--; if (stree) s->static_len -= stree[node].Len;
659: /* node is 0 or 1 so it does not have extra bits */
660: }
661: desc->max_code = max_code;
662:
663: /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
664: * establish sub-heaps of increasing lengths:
665: */
666: for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
667:
668: /* Construct the Huffman tree by repeatedly combining the least two
669: * frequent nodes.
670: */
671: node = elems; /* next internal node of the tree */
672: do {
673: pqremove(s, tree, n); /* n = node of least frequency */
674: m = s->heap[SMALLEST]; /* m = node of next least frequency */
675:
676: s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
677: s->heap[--(s->heap_max)] = m;
678:
679: /* Create a new node father of n and m */
680: tree[node].Freq = tree[n].Freq + tree[m].Freq;
681: s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?
682: s->depth[n] : s->depth[m]) + 1);
683: tree[n].Dad = tree[m].Dad = (ush)node;
684: #ifdef DUMP_BL_TREE
685: if (tree == s->bl_tree) {
686: fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
687: node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
688: }
689: #endif
690: /* and insert the new node in the heap */
691: s->heap[SMALLEST] = node++;
692: pqdownheap(s, tree, SMALLEST);
693:
694: } while (s->heap_len >= 2);
695:
696: s->heap[--(s->heap_max)] = s->heap[SMALLEST];
697:
698: /* At this point, the fields freq and dad are set. We can now
699: * generate the bit lengths.
700: */
701: gen_bitlen(s, (tree_desc *)desc);
702:
703: /* The field len is now set, we can generate the bit codes */
704: gen_codes ((ct_data *)tree, max_code, s->bl_count);
705: }
706:
707: /* ===========================================================================
708: * Scan a literal or distance tree to determine the frequencies of the codes
709: * in the bit length tree.
710: */
711: local void scan_tree (s, tree, max_code)
712: deflate_state *s;
713: ct_data *tree; /* the tree to be scanned */
714: int max_code; /* and its largest code of non zero frequency */
715: {
716: int n; /* iterates over all tree elements */
717: int prevlen = -1; /* last emitted length */
718: int curlen; /* length of current code */
719: int nextlen = tree[0].Len; /* length of next code */
720: int count = 0; /* repeat count of the current code */
721: int max_count = 7; /* max repeat count */
722: int min_count = 4; /* min repeat count */
723:
724: if (nextlen == 0) max_count = 138, min_count = 3;
725: tree[max_code+1].Len = (ush)0xffff; /* guard */
726:
727: for (n = 0; n <= max_code; n++) {
728: curlen = nextlen; nextlen = tree[n+1].Len;
729: if (++count < max_count && curlen == nextlen) {
730: continue;
731: } else if (count < min_count) {
732: s->bl_tree[curlen].Freq += count;
733: } else if (curlen != 0) {
734: if (curlen != prevlen) s->bl_tree[curlen].Freq++;
735: s->bl_tree[REP_3_6].Freq++;
736: } else if (count <= 10) {
737: s->bl_tree[REPZ_3_10].Freq++;
738: } else {
739: s->bl_tree[REPZ_11_138].Freq++;
740: }
741: count = 0; prevlen = curlen;
742: if (nextlen == 0) {
743: max_count = 138, min_count = 3;
744: } else if (curlen == nextlen) {
745: max_count = 6, min_count = 3;
746: } else {
747: max_count = 7, min_count = 4;
748: }
749: }
750: }
751:
752: /* ===========================================================================
753: * Send a literal or distance tree in compressed form, using the codes in
754: * bl_tree.
755: */
756: local void send_tree (s, tree, max_code)
757: deflate_state *s;
758: ct_data *tree; /* the tree to be scanned */
759: int max_code; /* and its largest code of non zero frequency */
760: {
761: int n; /* iterates over all tree elements */
762: int prevlen = -1; /* last emitted length */
763: int curlen; /* length of current code */
764: int nextlen = tree[0].Len; /* length of next code */
765: int count = 0; /* repeat count of the current code */
766: int max_count = 7; /* max repeat count */
767: int min_count = 4; /* min repeat count */
768:
769: /* tree[max_code+1].Len = -1; */ /* guard already set */
770: if (nextlen == 0) max_count = 138, min_count = 3;
771:
772: for (n = 0; n <= max_code; n++) {
773: curlen = nextlen; nextlen = tree[n+1].Len;
774: if (++count < max_count && curlen == nextlen) {
775: continue;
776: } else if (count < min_count) {
777: do { send_code(s, curlen, s->bl_tree); } while (--count != 0);
778:
779: } else if (curlen != 0) {
780: if (curlen != prevlen) {
781: send_code(s, curlen, s->bl_tree); count--;
782: }
783: Assert(count >= 3 && count <= 6, " 3_6?");
784: send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);
785:
786: } else if (count <= 10) {
787: send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);
788:
789: } else {
790: send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
791: }
792: count = 0; prevlen = curlen;
793: if (nextlen == 0) {
794: max_count = 138, min_count = 3;
795: } else if (curlen == nextlen) {
796: max_count = 6, min_count = 3;
797: } else {
798: max_count = 7, min_count = 4;
799: }
800: }
801: }
802:
803: /* ===========================================================================
804: * Construct the Huffman tree for the bit lengths and return the index in
805: * bl_order of the last bit length code to send.
806: */
807: local int build_bl_tree(s)
808: deflate_state *s;
809: {
810: int max_blindex; /* index of last bit length code of non zero freq */
811:
812: /* Determine the bit length frequencies for literal and distance trees */
813: scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
814: scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);
815:
816: /* Build the bit length tree: */
817: build_tree(s, (tree_desc *)(&(s->bl_desc)));
818: /* opt_len now includes the length of the tree representations, except
819: * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
820: */
821:
822: /* Determine the number of bit length codes to send. The pkzip format
823: * requires that at least 4 bit length codes be sent. (appnote.txt says
824: * 3 but the actual value used is 4.)
825: */
826: for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
827: if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
828: }
829: /* Update opt_len to include the bit length tree and counts */
830: s->opt_len += 3*(max_blindex+1) + 5+5+4;
831: Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
832: s->opt_len, s->static_len));
833:
834: return max_blindex;
835: }
836:
837: /* ===========================================================================
838: * Send the header for a block using dynamic Huffman trees: the counts, the
839: * lengths of the bit length codes, the literal tree and the distance tree.
840: * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
841: */
842: local void send_all_trees(s, lcodes, dcodes, blcodes)
843: deflate_state *s;
844: int lcodes, dcodes, blcodes; /* number of codes for each tree */
845: {
846: int rank; /* index in bl_order */
847:
848: Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
849: Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
850: "too many codes");
851: Tracev((stderr, "\nbl counts: "));
852: send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
853: send_bits(s, dcodes-1, 5);
854: send_bits(s, blcodes-4, 4); /* not -3 as stated in appnote.txt */
855: for (rank = 0; rank < blcodes; rank++) {
856: Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
857: send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
858: }
859: Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));
860:
861: send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
862: Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));
863:
864: send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
865: Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
866: }
867:
868: /* ===========================================================================
869: * Send a stored block
870: */
871: void ZLIB_INTERNAL _tr_stored_block(s, buf, stored_len, last)
872: deflate_state *s;
873: charf *buf; /* input block */
874: ulg stored_len; /* length of input block */
875: int last; /* one if this is the last block for a file */
876: {
877: send_bits(s, (STORED_BLOCK<<1)+last, 3); /* send block type */
878: #ifdef DEBUG
879: s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
880: s->compressed_len += (stored_len + 4) << 3;
881: #endif
882: copy_block(s, buf, (unsigned)stored_len, 1); /* with header */
883: }
884:
885: /* ===========================================================================
886: * Send one empty static block to give enough lookahead for inflate.
887: * This takes 10 bits, of which 7 may remain in the bit buffer.
888: * The current inflate code requires 9 bits of lookahead. If the
889: * last two codes for the previous block (real code plus EOB) were coded
890: * on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode
891: * the last real code. In this case we send two empty static blocks instead
892: * of one. (There are no problems if the previous block is stored or fixed.)
893: * To simplify the code, we assume the worst case of last real code encoded
894: * on one bit only.
895: */
896: void ZLIB_INTERNAL _tr_align(s)
897: deflate_state *s;
898: {
899: send_bits(s, STATIC_TREES<<1, 3);
900: send_code(s, END_BLOCK, static_ltree);
901: #ifdef DEBUG
902: s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
903: #endif
904: bi_flush(s);
905: /* Of the 10 bits for the empty block, we have already sent
906: * (10 - bi_valid) bits. The lookahead for the last real code (before
907: * the EOB of the previous block) was thus at least one plus the length
908: * of the EOB plus what we have just sent of the empty static block.
909: */
910: if (1 + s->last_eob_len + 10 - s->bi_valid < 9) {
911: send_bits(s, STATIC_TREES<<1, 3);
912: send_code(s, END_BLOCK, static_ltree);
913: #ifdef DEBUG
914: s->compressed_len += 10L;
915: #endif
916: bi_flush(s);
917: }
918: s->last_eob_len = 7;
919: }
920:
921: /* ===========================================================================
922: * Determine the best encoding for the current block: dynamic trees, static
923: * trees or store, and output the encoded block to the zip file.
924: */
925: void ZLIB_INTERNAL _tr_flush_block(s, buf, stored_len, last)
926: deflate_state *s;
927: charf *buf; /* input block, or NULL if too old */
928: ulg stored_len; /* length of input block */
929: int last; /* one if this is the last block for a file */
930: {
931: ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
932: int max_blindex = 0; /* index of last bit length code of non zero freq */
933:
934: /* Build the Huffman trees unless a stored block is forced */
935: if (s->level > 0) {
936:
937: /* Check if the file is binary or text */
938: if (s->strm->data_type == Z_UNKNOWN)
939: s->strm->data_type = detect_data_type(s);
940:
941: /* Construct the literal and distance trees */
942: build_tree(s, (tree_desc *)(&(s->l_desc)));
943: Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
944: s->static_len));
945:
946: build_tree(s, (tree_desc *)(&(s->d_desc)));
947: Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
948: s->static_len));
949: /* At this point, opt_len and static_len are the total bit lengths of
950: * the compressed block data, excluding the tree representations.
951: */
952:
953: /* Build the bit length tree for the above two trees, and get the index
954: * in bl_order of the last bit length code to send.
955: */
956: max_blindex = build_bl_tree(s);
957:
958: /* Determine the best encoding. Compute the block lengths in bytes. */
959: opt_lenb = (s->opt_len+3+7)>>3;
960: static_lenb = (s->static_len+3+7)>>3;
961:
962: Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
963: opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
964: s->last_lit));
965:
966: if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
967:
968: } else {
969: Assert(buf != (char*)0, "lost buf");
970: opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
971: }
972:
973: #ifdef FORCE_STORED
974: if (buf != (char*)0) { /* force stored block */
975: #else
976: if (stored_len+4 <= opt_lenb && buf != (char*)0) {
977: /* 4: two words for the lengths */
978: #endif
979: /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
980: * Otherwise we can't have processed more than WSIZE input bytes since
981: * the last block flush, because compression would have been
982: * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
983: * transform a block into a stored block.
984: */
985: _tr_stored_block(s, buf, stored_len, last);
986:
987: #ifdef FORCE_STATIC
988: } else if (static_lenb >= 0) { /* force static trees */
989: #else
990: } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) {
991: #endif
992: send_bits(s, (STATIC_TREES<<1)+last, 3);
993: compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree);
994: #ifdef DEBUG
995: s->compressed_len += 3 + s->static_len;
996: #endif
997: } else {
998: send_bits(s, (DYN_TREES<<1)+last, 3);
999: send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
1000: max_blindex+1);
1001: compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree);
1002: #ifdef DEBUG
1003: s->compressed_len += 3 + s->opt_len;
1004: #endif
1005: }
1006: Assert (s->compressed_len == s->bits_sent, "bad compressed size");
1007: /* The above check is made mod 2^32, for files larger than 512 MB
1008: * and uLong implemented on 32 bits.
1009: */
1010: init_block(s);
1011:
1012: if (last) {
1013: bi_windup(s);
1014: #ifdef DEBUG
1015: s->compressed_len += 7; /* align on byte boundary */
1016: #endif
1017: }
1018: Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
1019: s->compressed_len-7*last));
1020: }
1021:
1022: /* ===========================================================================
1023: * Save the match info and tally the frequency counts. Return true if
1024: * the current block must be flushed.
1025: */
1026: int ZLIB_INTERNAL _tr_tally (s, dist, lc)
1027: deflate_state *s;
1028: unsigned dist; /* distance of matched string */
1029: unsigned lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */
1030: {
1031: s->d_buf[s->last_lit] = (ush)dist;
1032: s->l_buf[s->last_lit++] = (uch)lc;
1033: if (dist == 0) {
1034: /* lc is the unmatched char */
1035: s->dyn_ltree[lc].Freq++;
1036: } else {
1037: s->matches++;
1038: /* Here, lc is the match length - MIN_MATCH */
1039: dist--; /* dist = match distance - 1 */
1040: Assert((ush)dist < (ush)MAX_DIST(s) &&
1041: (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
1042: (ush)d_code(dist) < (ush)D_CODES, "_tr_tally: bad match");
1043:
1044: s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
1045: s->dyn_dtree[d_code(dist)].Freq++;
1046: }
1047:
1048: #ifdef TRUNCATE_BLOCK
1049: /* Try to guess if it is profitable to stop the current block here */
1050: if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
1051: /* Compute an upper bound for the compressed length */
1052: ulg out_length = (ulg)s->last_lit*8L;
1053: ulg in_length = (ulg)((long)s->strstart - s->block_start);
1054: int dcode;
1055: for (dcode = 0; dcode < D_CODES; dcode++) {
1056: out_length += (ulg)s->dyn_dtree[dcode].Freq *
1057: (5L+extra_dbits[dcode]);
1058: }
1059: out_length >>= 3;
1060: Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
1061: s->last_lit, in_length, out_length,
1062: 100L - out_length*100L/in_length));
1063: if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
1064: }
1065: #endif
1066: return (s->last_lit == s->lit_bufsize-1);
1067: /* We avoid equality with lit_bufsize because of wraparound at 64K
1068: * on 16 bit machines and because stored blocks are restricted to
1069: * 64K-1 bytes.
1070: */
1071: }
1072:
1073: /* ===========================================================================
1074: * Send the block data compressed using the given Huffman trees
1075: */
1076: local void compress_block(s, ltree, dtree)
1077: deflate_state *s;
1078: ct_data *ltree; /* literal tree */
1079: ct_data *dtree; /* distance tree */
1080: {
1081: unsigned dist; /* distance of matched string */
1082: int lc; /* match length or unmatched char (if dist == 0) */
1083: unsigned lx = 0; /* running index in l_buf */
1084: unsigned code; /* the code to send */
1085: int extra; /* number of extra bits to send */
1086:
1087: if (s->last_lit != 0) do {
1088: dist = s->d_buf[lx];
1089: lc = s->l_buf[lx++];
1090: if (dist == 0) {
1091: send_code(s, lc, ltree); /* send a literal byte */
1092: Tracecv(isgraph(lc), (stderr," '%c' ", lc));
1093: } else {
1094: /* Here, lc is the match length - MIN_MATCH */
1095: code = _length_code[lc];
1096: send_code(s, code+LITERALS+1, ltree); /* send the length code */
1097: extra = extra_lbits[code];
1098: if (extra != 0) {
1099: lc -= base_length[code];
1100: send_bits(s, lc, extra); /* send the extra length bits */
1101: }
1102: dist--; /* dist is now the match distance - 1 */
1103: code = d_code(dist);
1104: Assert (code < D_CODES, "bad d_code");
1105:
1106: send_code(s, code, dtree); /* send the distance code */
1107: extra = extra_dbits[code];
1108: if (extra != 0) {
1109: dist -= base_dist[code];
1110: send_bits(s, dist, extra); /* send the extra distance bits */
1111: }
1112: } /* literal or match pair ? */
1113:
1114: /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
1115: Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx,
1116: "pendingBuf overflow");
1117:
1118: } while (lx < s->last_lit);
1119:
1120: send_code(s, END_BLOCK, ltree);
1121: s->last_eob_len = ltree[END_BLOCK].Len;
1122: }
1123:
1124: /* ===========================================================================
1125: * Check if the data type is TEXT or BINARY, using the following algorithm:
1126: * - TEXT if the two conditions below are satisfied:
1127: * a) There are no non-portable control characters belonging to the
1128: * "black list" (0..6, 14..25, 28..31).
1129: * b) There is at least one printable character belonging to the
1130: * "white list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255).
1131: * - BINARY otherwise.
1132: * - The following partially-portable control characters form a
1133: * "gray list" that is ignored in this detection algorithm:
1134: * (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}).
1135: * IN assertion: the fields Freq of dyn_ltree are set.
1136: */
1137: local int detect_data_type(s)
1138: deflate_state *s;
1139: {
1140: /* black_mask is the bit mask of black-listed bytes
1141: * set bits 0..6, 14..25, and 28..31
1142: * 0xf3ffc07f = binary 11110011111111111100000001111111
1143: */
1144: unsigned long black_mask = 0xf3ffc07fUL;
1145: int n;
1146:
1147: /* Check for non-textual ("black-listed") bytes. */
1148: for (n = 0; n <= 31; n++, black_mask >>= 1)
1149: if ((black_mask & 1) && (s->dyn_ltree[n].Freq != 0))
1150: return Z_BINARY;
1151:
1152: /* Check for textual ("white-listed") bytes. */
1153: if (s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0
1154: || s->dyn_ltree[13].Freq != 0)
1155: return Z_TEXT;
1156: for (n = 32; n < LITERALS; n++)
1157: if (s->dyn_ltree[n].Freq != 0)
1158: return Z_TEXT;
1159:
1160: /* There are no "black-listed" or "white-listed" bytes:
1161: * this stream either is empty or has tolerated ("gray-listed") bytes only.
1162: */
1163: return Z_BINARY;
1164: }
1165:
1166: /* ===========================================================================
1167: * Reverse the first len bits of a code, using straightforward code (a faster
1168: * method would use a table)
1169: * IN assertion: 1 <= len <= 15
1170: */
1171: local unsigned bi_reverse(code, len)
1172: unsigned code; /* the value to invert */
1173: int len; /* its bit length */
1174: {
1175: register unsigned res = 0;
1176: do {
1177: res |= code & 1;
1178: code >>= 1, res <<= 1;
1179: } while (--len > 0);
1180: return res >> 1;
1181: }
1182:
1183: /* ===========================================================================
1184: * Flush the bit buffer, keeping at most 7 bits in it.
1185: */
1186: local void bi_flush(s)
1187: deflate_state *s;
1188: {
1189: if (s->bi_valid == 16) {
1190: put_short(s, s->bi_buf);
1191: s->bi_buf = 0;
1192: s->bi_valid = 0;
1193: } else if (s->bi_valid >= 8) {
1194: put_byte(s, (Byte)s->bi_buf);
1195: s->bi_buf >>= 8;
1196: s->bi_valid -= 8;
1197: }
1198: }
1199:
1200: /* ===========================================================================
1201: * Flush the bit buffer and align the output on a byte boundary
1202: */
1203: local void bi_windup(s)
1204: deflate_state *s;
1205: {
1206: if (s->bi_valid > 8) {
1207: put_short(s, s->bi_buf);
1208: } else if (s->bi_valid > 0) {
1209: put_byte(s, (Byte)s->bi_buf);
1210: }
1211: s->bi_buf = 0;
1212: s->bi_valid = 0;
1213: #ifdef DEBUG
1214: s->bits_sent = (s->bits_sent+7) & ~7;
1215: #endif
1216: }
1217:
1218: /* ===========================================================================
1219: * Copy a stored block, storing first the length and its
1220: * one's complement if requested.
1221: */
1222: local void copy_block(s, buf, len, header)
1223: deflate_state *s;
1224: charf *buf; /* the input data */
1225: unsigned len; /* its length */
1226: int header; /* true if block header must be written */
1227: {
1228: bi_windup(s); /* align on byte boundary */
1229: s->last_eob_len = 8; /* enough lookahead for inflate */
1230:
1231: if (header) {
1232: put_short(s, (ush)len);
1233: put_short(s, (ush)~len);
1234: #ifdef DEBUG
1235: s->bits_sent += 2*16;
1236: #endif
1237: }
1238: #ifdef DEBUG
1239: s->bits_sent += (ulg)len<<3;
1240: #endif
1241: while (len--) {
1242: put_byte(s, *buf++);
1243: }
1244: }
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