Watt-32 tcp/ip  2.2 dev-rel.10
ztrees.c
1 /* trees.c -- output deflated data using Huffman coding
2  * Copyright (C) 1995-2003 Jean-loup Gailly
3  * For conditions of distribution and use, see copyright notice in zlib.h
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 
32 /* @(#) $Id$ */
33 
34 /* #define GEN_TREES_H */
35 
36 #include "wattcp.h"
37 #include "zdeflate.h"
38 
39 #if defined(USE_GZIP)
40 
41 #ifdef DEBUG
42 # include <ctype.h>
43 #endif
44 
45 /* ===========================================================================
46  * Constants
47  */
48 
49 #define MAX_BL_BITS 7
50 /* Bit length codes must not exceed MAX_BL_BITS bits */
51 
52 #define END_BLOCK 256
53 /* end of block literal code */
54 
55 #define REP_3_6 16
56 /* repeat previous bit length 3-6 times (2 bits of repeat count) */
57 
58 #define REPZ_3_10 17
59 /* repeat a zero length 3-10 times (3 bits of repeat count) */
60 
61 #define REPZ_11_138 18
62 /* repeat a zero length 11-138 times (7 bits of repeat count) */
63 
64 local const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */
65  = {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};
66 
67 local const int extra_dbits[D_CODES] /* extra bits for each distance code */
68  = {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};
69 
70 local const int extra_blbits[BL_CODES]/* extra bits for each bit length code */
71  = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};
72 
73 local const uch bl_order[BL_CODES]
74  = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};
75 /* The lengths of the bit length codes are sent in order of decreasing
76  * probability, to avoid transmitting the lengths for unused bit length codes.
77  */
78 
79 #define Buf_size (8 * 2*sizeof(char))
80 /* Number of bits used within bi_buf. (bi_buf might be implemented on
81  * more than 16 bits on some systems.)
82  */
83 
84 /* ===========================================================================
85  * Local data. These are initialized only once.
86  */
87 
88 #define DIST_CODE_LEN 512 /* see definition of array dist_code below */
89 
90 #if defined(GEN_TREES_H) || !defined(STDC)
91 /* non ANSI compilers may not accept ztrees.h */
92 
93 local ct_data static_ltree[L_CODES+2];
94 /* The static literal tree. Since the bit lengths are imposed, there is no
95  * need for the L_CODES extra codes used during heap construction. However
96  * The codes 286 and 287 are needed to build a canonical tree (see _tr_init
97  * below).
98  */
99 
100 local ct_data static_dtree[D_CODES];
101 /* The static distance tree. (Actually a trivial tree since all codes use
102  * 5 bits.)
103  */
104 
105 uch _dist_code[DIST_CODE_LEN];
106 /* Distance codes. The first 256 values correspond to the distances
107  * 3 .. 258, the last 256 values correspond to the top 8 bits of
108  * the 15 bit distances.
109  */
110 
111 uch _length_code[MAX_MATCH-MIN_MATCH+1];
112 /* length code for each normalized match length (0 == MIN_MATCH) */
113 
114 local int base_length[LENGTH_CODES];
115 /* First normalized length for each code (0 = MIN_MATCH) */
116 
117 local int base_dist[D_CODES];
118 /* First normalized distance for each code (0 = distance of 1) */
119 
120 #else
121 # include "ztrees.h"
122 #endif /* GEN_TREES_H */
123 
124 struct static_tree_desc_s {
125  const ct_data *static_tree; /* static tree or NULL */
126  const intf *extra_bits; /* extra bits for each code or NULL */
127  int extra_base; /* base index for extra_bits */
128  int elems; /* max number of elements in the tree */
129  int max_length; /* max bit length for the codes */
130 };
131 
132 local static_tree_desc static_l_desc =
133 {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};
134 
135 local static_tree_desc static_d_desc =
136 {static_dtree, extra_dbits, 0, D_CODES, MAX_BITS};
137 
138 local static_tree_desc static_bl_desc =
139 {(const ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS};
140 
141 /* ===========================================================================
142  * Local (static) routines in this file.
143  */
144 
145 local void tr_static_init OF((void));
146 local void init_block OF((deflate_state *s));
147 local void pqdownheap OF((deflate_state *s, ct_data *tree, int k));
148 local void gen_bitlen OF((deflate_state *s, tree_desc *desc));
149 local void gen_codes OF((ct_data *tree, int max_code, ushf *bl_count));
150 local void build_tree OF((deflate_state *s, tree_desc *desc));
151 local void scan_tree OF((deflate_state *s, ct_data *tree, int max_code));
152 local void send_tree OF((deflate_state *s, ct_data *tree, int max_code));
153 local int build_bl_tree OF((deflate_state *s));
154 local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes,
155  int blcodes));
156 local void compress_block OF((deflate_state *s, ct_data *ltree,
157  ct_data *dtree));
158 local void set_data_type OF((deflate_state *s));
159 local unsigned bi_reverse OF((unsigned value, int length));
160 local void bi_windup OF((deflate_state *s));
161 local void bi_flush OF((deflate_state *s));
162 local void copy_block OF((deflate_state *s, charf *buf, unsigned len,
163  int header));
164 
165 #ifdef GEN_TREES_H
166 local void gen_trees_header OF((void));
167 #endif
168 
169 #ifndef DEBUG
170 # define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
171  /* Send a code of the given tree. c and tree must not have side effects */
172 
173 #else /* DEBUG */
174 # define send_code(s, c, tree) \
175  { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
176  send_bits(s, tree[c].Code, tree[c].Len); }
177 #endif
178 
179 /* ===========================================================================
180  * Output a short LSB first on the stream.
181  * IN assertion: there is enough room in pendingBuf.
182  */
183 #define put_short(s, w) { \
184  put_byte(s, (uch)((w) & 0xff)); \
185  put_byte(s, (uch)((ush)(w) >> 8)); \
186 }
187 
188 /* ===========================================================================
189  * Send a value on a given number of bits.
190  * IN assertion: length <= 16 and value fits in length bits.
191  */
192 #ifdef DEBUG
193 local void send_bits OF((deflate_state *s, int value, int length));
194 
195 local void send_bits(s, value, length)
196  deflate_state *s;
197  int value; /* value to send */
198  int length; /* number of bits */
199 {
200  Tracevv((stderr," l %2d v %4x ", length, value));
201  Assert(length > 0 && length <= 15, "invalid length");
202  s->bits_sent += (ulg)length;
203 
204  /* If not enough room in bi_buf, use (valid) bits from bi_buf and
205  * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
206  * unused bits in value.
207  */
208  if (s->bi_valid > (int)Buf_size - length) {
209  s->bi_buf |= (value << s->bi_valid);
210  put_short(s, s->bi_buf);
211  s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);
212  s->bi_valid += length - Buf_size;
213  } else {
214  s->bi_buf |= value << s->bi_valid;
215  s->bi_valid += length;
216  }
217 }
218 #else /* !DEBUG */
219 
220 #define send_bits(s, value, length) \
221 { int len = length;\
222  if (s->bi_valid > (int)Buf_size - len) {\
223  int val = value;\
224  s->bi_buf |= (val << s->bi_valid);\
225  put_short(s, s->bi_buf);\
226  s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
227  s->bi_valid += len - Buf_size;\
228  } else {\
229  s->bi_buf |= (value) << s->bi_valid;\
230  s->bi_valid += len;\
231  }\
232 }
233 #endif /* DEBUG */
234 
235 
236 /* the arguments must not have side effects */
237 
238 /* ===========================================================================
239  * Initialize the various 'constant' tables.
240  */
241 local void tr_static_init()
242 {
243 #if defined(GEN_TREES_H) || !defined(STDC)
244  static int static_init_done = 0;
245  int n; /* iterates over tree elements */
246  int bits; /* bit counter */
247  int length; /* length value */
248  int code; /* code value */
249  int dist; /* distance index */
250  ush bl_count[MAX_BITS+1];
251  /* number of codes at each bit length for an optimal tree */
252 
253  if (static_init_done) return;
254 
255  /* For some embedded targets, global variables are not initialized: */
256  static_l_desc.static_tree = static_ltree;
257  static_l_desc.extra_bits = extra_lbits;
258  static_d_desc.static_tree = static_dtree;
259  static_d_desc.extra_bits = extra_dbits;
260  static_bl_desc.extra_bits = extra_blbits;
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("ztrees.h", "w");
336  int i;
337 
338  Assert (header != NULL, "Can't open ztrees.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 _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, "const uch _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");
361  for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) {
362  fprintf(header, "%2u%s", _length_code[i],
363  SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));
364  }
365 
366  fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");
367  for (i = 0; i < LENGTH_CODES; i++) {
368  fprintf(header, "%1u%s", base_length[i],
369  SEPARATOR(i, LENGTH_CODES-1, 20));
370  }
371 
372  fprintf(header, "local const int base_dist[D_CODES] = {\n");
373  for (i = 0; i < D_CODES; i++) {
374  fprintf(header, "%5u%s", base_dist[i],
375  SEPARATOR(i, D_CODES-1, 10));
376  }
377 
378  fclose(header);
379 }
380 #endif /* GEN_TREES_H */
381 
382 /* ===========================================================================
383  * Initialize the tree data structures for a new zlib stream.
384  */
385 void _tr_init(s)
386  deflate_state *s;
387 {
388  tr_static_init();
389 
390  s->l_desc.dyn_tree = s->dyn_ltree;
391  s->l_desc.stat_desc = &static_l_desc;
392 
393  s->d_desc.dyn_tree = s->dyn_dtree;
394  s->d_desc.stat_desc = &static_d_desc;
395 
396  s->bl_desc.dyn_tree = s->bl_tree;
397  s->bl_desc.stat_desc = &static_bl_desc;
398 
399  s->bi_buf = 0;
400  s->bi_valid = 0;
401  s->last_eob_len = 8; /* enough lookahead for inflate */
402 #ifdef DEBUG
403  s->compressed_len = 0L;
404  s->bits_sent = 0L;
405 #endif
406 
407  /* Initialize the first block of the first file: */
408  init_block(s);
409 }
410 
411 /* ===========================================================================
412  * Initialize a new block.
413  */
414 local void init_block(s)
415  deflate_state *s;
416 {
417  int n; /* iterates over tree elements */
418 
419  /* Initialize the trees. */
420  for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0;
421  for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0;
422  for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;
423 
424  s->dyn_ltree[END_BLOCK].Freq = 1;
425  s->opt_len = s->static_len = 0L;
426  s->last_lit = s->matches = 0;
427 }
428 
429 #define SMALLEST 1
430 /* Index within the heap array of least frequent node in the Huffman tree */
431 
432 
433 /* ===========================================================================
434  * Remove the smallest element from the heap and recreate the heap with
435  * one less element. Updates heap and heap_len.
436  */
437 #define pqremove(s, tree, top) \
438 {\
439  top = s->heap[SMALLEST]; \
440  s->heap[SMALLEST] = s->heap[s->heap_len--]; \
441  pqdownheap(s, tree, SMALLEST); \
442 }
443 
444 /* ===========================================================================
445  * Compares to subtrees, using the tree depth as tie breaker when
446  * the subtrees have equal frequency. This minimizes the worst case length.
447  */
448 #define smaller(tree, n, m, depth) \
449  (tree[n].Freq < tree[m].Freq || \
450  (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
451 
452 /* ===========================================================================
453  * Restore the heap property by moving down the tree starting at node k,
454  * exchanging a node with the smallest of its two sons if necessary, stopping
455  * when the heap property is re-established (each father smaller than its
456  * two sons).
457  */
458 local void pqdownheap(s, tree, k)
459  deflate_state *s;
460  ct_data *tree; /* the tree to restore */
461  int k; /* node to move down */
462 {
463  int v = s->heap[k];
464  int j = k << 1; /* left son of k */
465  while (j <= s->heap_len) {
466  /* Set j to the smallest of the two sons: */
467  if (j < s->heap_len &&
468  smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
469  j++;
470  }
471  /* Exit if v is smaller than both sons */
472  if (smaller(tree, v, s->heap[j], s->depth)) break;
473 
474  /* Exchange v with the smallest son */
475  s->heap[k] = s->heap[j]; k = j;
476 
477  /* And continue down the tree, setting j to the left son of k */
478  j <<= 1;
479  }
480  s->heap[k] = v;
481 }
482 
483 /* ===========================================================================
484  * Compute the optimal bit lengths for a tree and update the total bit length
485  * for the current block.
486  * IN assertion: the fields freq and dad are set, heap[heap_max] and
487  * above are the tree nodes sorted by increasing frequency.
488  * OUT assertions: the field len is set to the optimal bit length, the
489  * array bl_count contains the frequencies for each bit length.
490  * The length opt_len is updated; static_len is also updated if stree is
491  * not null.
492  */
493 local void gen_bitlen(s, desc)
494  deflate_state *s;
495  tree_desc *desc; /* the tree descriptor */
496 {
497  ct_data *tree = desc->dyn_tree;
498  int max_code = desc->max_code;
499  const ct_data *stree = desc->stat_desc->static_tree;
500  const intf *extra = desc->stat_desc->extra_bits;
501  int base = desc->stat_desc->extra_base;
502  int max_length = desc->stat_desc->max_length;
503  int h; /* heap index */
504  int n, m; /* iterate over the tree elements */
505  int bits; /* bit length */
506  int xbits; /* extra bits */
507  ush f; /* frequency */
508  int overflow = 0; /* number of elements with bit length too large */
509 
510  for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
511 
512  /* In a first pass, compute the optimal bit lengths (which may
513  * overflow in the case of the bit length tree).
514  */
515  tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
516 
517  for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
518  n = s->heap[h];
519  bits = tree[tree[n].Dad].Len + 1;
520  if (bits > max_length) bits = max_length, overflow++;
521  tree[n].Len = (ush)bits;
522  /* We overwrite tree[n].Dad which is no longer needed */
523 
524  if (n > max_code) continue; /* not a leaf node */
525 
526  s->bl_count[bits]++;
527  xbits = 0;
528  if (n >= base) xbits = extra[n-base];
529  f = tree[n].Freq;
530  s->opt_len += (ulg)f * (bits + xbits);
531  if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits);
532  }
533  if (overflow == 0) return;
534 
535  Trace((stderr,"\nbit length overflow\n"));
536  /* This happens for example on obj2 and pic of the Calgary corpus */
537 
538  /* Find the first bit length which could increase: */
539  do {
540  bits = max_length-1;
541  while (s->bl_count[bits] == 0) bits--;
542  s->bl_count[bits]--; /* move one leaf down the tree */
543  s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
544  s->bl_count[max_length]--;
545  /* The brother of the overflow item also moves one step up,
546  * but this does not affect bl_count[max_length]
547  */
548  overflow -= 2;
549  } while (overflow > 0);
550 
551  /* Now recompute all bit lengths, scanning in increasing frequency.
552  * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
553  * lengths instead of fixing only the wrong ones. This idea is taken
554  * from 'ar' written by Haruhiko Okumura.)
555  */
556  for (bits = max_length; bits != 0; bits--) {
557  n = s->bl_count[bits];
558  while (n != 0) {
559  m = s->heap[--h];
560  if (m > max_code) continue;
561  if (tree[m].Len != (unsigned) bits) {
562  Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
563  s->opt_len += ((long)bits - (long)tree[m].Len)
564  *(long)tree[m].Freq;
565  tree[m].Len = (ush)bits;
566  }
567  n--;
568  }
569  }
570 }
571 
572 /* ===========================================================================
573  * Generate the codes for a given tree and bit counts (which need not be
574  * optimal).
575  * IN assertion: the array bl_count contains the bit length statistics for
576  * the given tree and the field len is set for all tree elements.
577  * OUT assertion: the field code is set for all tree elements of non
578  * zero code length.
579  */
580 local void gen_codes (tree, max_code, bl_count)
581  ct_data *tree; /* the tree to decorate */
582  int max_code; /* largest code with non zero frequency */
583  ushf *bl_count; /* number of codes at each bit length */
584 {
585  ush next_code[MAX_BITS+1]; /* next code value for each bit length */
586  ush code = 0; /* running code value */
587  int bits; /* bit index */
588  int n; /* code index */
589 
590  /* The distribution counts are first used to generate the code values
591  * without bit reversal.
592  */
593  for (bits = 1; bits <= MAX_BITS; bits++) {
594  next_code[bits] = code = (code + bl_count[bits-1]) << 1;
595  }
596  /* Check that the bit counts in bl_count are consistent. The last code
597  * must be all ones.
598  */
599  Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
600  "inconsistent bit counts");
601  Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
602 
603  for (n = 0; n <= max_code; n++) {
604  int len = tree[n].Len;
605  if (len == 0) continue;
606  /* Now reverse the bits */
607  tree[n].Code = bi_reverse(next_code[len]++, len);
608 
609  Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
610  n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
611  }
612 }
613 
614 /* ===========================================================================
615  * Construct one Huffman tree and assigns the code bit strings and lengths.
616  * Update the total bit length for the current block.
617  * IN assertion: the field freq is set for all tree elements.
618  * OUT assertions: the fields len and code are set to the optimal bit length
619  * and corresponding code. The length opt_len is updated; static_len is
620  * also updated if stree is not null. The field max_code is set.
621  */
622 local void build_tree(s, desc)
623  deflate_state *s;
624  tree_desc *desc; /* the tree descriptor */
625 {
626  ct_data *tree = desc->dyn_tree;
627  const ct_data *stree = desc->stat_desc->static_tree;
628  int elems = desc->stat_desc->elems;
629  int n, m; /* iterate over heap elements */
630  int max_code = -1; /* largest code with non zero frequency */
631  int node; /* new node being created */
632 
633  /* Construct the initial heap, with least frequent element in
634  * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
635  * heap[0] is not used.
636  */
637  s->heap_len = 0, s->heap_max = HEAP_SIZE;
638 
639  for (n = 0; n < elems; n++) {
640  if (tree[n].Freq != 0) {
641  s->heap[++(s->heap_len)] = max_code = n;
642  s->depth[n] = 0;
643  } else {
644  tree[n].Len = 0;
645  }
646  }
647 
648  /* The pkzip format requires that at least one distance code exists,
649  * and that at least one bit should be sent even if there is only one
650  * possible code. So to avoid special checks later on we force at least
651  * two codes of non zero frequency.
652  */
653  while (s->heap_len < 2) {
654  node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
655  tree[node].Freq = 1;
656  s->depth[node] = 0;
657  s->opt_len--; if (stree) s->static_len -= stree[node].Len;
658  /* node is 0 or 1 so it does not have extra bits */
659  }
660  desc->max_code = max_code;
661 
662  /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
663  * establish sub-heaps of increasing lengths:
664  */
665  for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
666 
667  /* Construct the Huffman tree by repeatedly combining the least two
668  * frequent nodes.
669  */
670  node = elems; /* next internal node of the tree */
671  do {
672  pqremove(s, tree, n); /* n = node of least frequency */
673  m = s->heap[SMALLEST]; /* m = node of next least frequency */
674 
675  s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
676  s->heap[--(s->heap_max)] = m;
677 
678  /* Create a new node father of n and m */
679  tree[node].Freq = tree[n].Freq + tree[m].Freq;
680  s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?
681  s->depth[n] : s->depth[m]) + 1);
682  tree[n].Dad = tree[m].Dad = (ush)node;
683 #ifdef DUMP_BL_TREE
684  if (tree == s->bl_tree) {
685  fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
686  node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
687  }
688 #endif
689  /* and insert the new node in the heap */
690  s->heap[SMALLEST] = node++;
691  pqdownheap(s, tree, SMALLEST);
692 
693  } while (s->heap_len >= 2);
694 
695  s->heap[--(s->heap_max)] = s->heap[SMALLEST];
696 
697  /* At this point, the fields freq and dad are set. We can now
698  * generate the bit lengths.
699  */
700  gen_bitlen(s, (tree_desc *)desc);
701 
702  /* The field len is now set, we can generate the bit codes */
703  gen_codes ((ct_data *)tree, max_code, s->bl_count);
704 }
705 
706 /* ===========================================================================
707  * Scan a literal or distance tree to determine the frequencies of the codes
708  * in the bit length tree.
709  */
710 local void scan_tree (s, tree, max_code)
711  deflate_state *s;
712  ct_data *tree; /* the tree to be scanned */
713  int max_code; /* and its largest code of non zero frequency */
714 {
715  int n; /* iterates over all tree elements */
716  int prevlen = -1; /* last emitted length */
717  int curlen; /* length of current code */
718  int nextlen = tree[0].Len; /* length of next code */
719  int count = 0; /* repeat count of the current code */
720  int max_count = 7; /* max repeat count */
721  int min_count = 4; /* min repeat count */
722 
723  if (nextlen == 0) max_count = 138, min_count = 3;
724  tree[max_code+1].Len = (ush)0xffff; /* guard */
725 
726  for (n = 0; n <= max_code; n++) {
727  curlen = nextlen; nextlen = tree[n+1].Len;
728  if (++count < max_count && curlen == nextlen) {
729  continue;
730  } else if (count < min_count) {
731  s->bl_tree[curlen].Freq += count;
732  } else if (curlen != 0) {
733  if (curlen != prevlen) s->bl_tree[curlen].Freq++;
734  s->bl_tree[REP_3_6].Freq++;
735  } else if (count <= 10) {
736  s->bl_tree[REPZ_3_10].Freq++;
737  } else {
738  s->bl_tree[REPZ_11_138].Freq++;
739  }
740  count = 0; prevlen = curlen;
741  if (nextlen == 0) {
742  max_count = 138, min_count = 3;
743  } else if (curlen == nextlen) {
744  max_count = 6, min_count = 3;
745  } else {
746  max_count = 7, min_count = 4;
747  }
748  }
749 }
750 
751 /* ===========================================================================
752  * Send a literal or distance tree in compressed form, using the codes in
753  * bl_tree.
754  */
755 local void send_tree (s, tree, max_code)
756  deflate_state *s;
757  ct_data *tree; /* the tree to be scanned */
758  int max_code; /* and its largest code of non zero frequency */
759 {
760  int n; /* iterates over all tree elements */
761  int prevlen = -1; /* last emitted length */
762  int curlen; /* length of current code */
763  int nextlen = tree[0].Len; /* length of next code */
764  int count = 0; /* repeat count of the current code */
765  int max_count = 7; /* max repeat count */
766  int min_count = 4; /* min repeat count */
767 
768  /* tree[max_code+1].Len = -1; */ /* guard already set */
769  if (nextlen == 0) max_count = 138, min_count = 3;
770 
771  for (n = 0; n <= max_code; n++) {
772  curlen = nextlen; nextlen = tree[n+1].Len;
773  if (++count < max_count && curlen == nextlen) {
774  continue;
775  } else if (count < min_count) {
776  do { send_code(s, curlen, s->bl_tree); } while (--count != 0);
777 
778  } else if (curlen != 0) {
779  if (curlen != prevlen) {
780  send_code(s, curlen, s->bl_tree); count--;
781  }
782  Assert(count >= 3 && count <= 6, " 3_6?");
783  send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);
784 
785  } else if (count <= 10) {
786  send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);
787 
788  } else {
789  send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
790  }
791  count = 0; prevlen = curlen;
792  if (nextlen == 0) {
793  max_count = 138, min_count = 3;
794  } else if (curlen == nextlen) {
795  max_count = 6, min_count = 3;
796  } else {
797  max_count = 7, min_count = 4;
798  }
799  }
800 }
801 
802 /* ===========================================================================
803  * Construct the Huffman tree for the bit lengths and return the index in
804  * bl_order of the last bit length code to send.
805  */
806 local int build_bl_tree(s)
807  deflate_state *s;
808 {
809  int max_blindex; /* index of last bit length code of non zero freq */
810 
811  /* Determine the bit length frequencies for literal and distance trees */
812  scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
813  scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);
814 
815  /* Build the bit length tree: */
816  build_tree(s, (tree_desc *)(&(s->bl_desc)));
817  /* opt_len now includes the length of the tree representations, except
818  * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
819  */
820 
821  /* Determine the number of bit length codes to send. The pkzip format
822  * requires that at least 4 bit length codes be sent. (appnote.txt says
823  * 3 but the actual value used is 4.)
824  */
825  for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
826  if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
827  }
828  /* Update opt_len to include the bit length tree and counts */
829  s->opt_len += 3*(max_blindex+1) + 5+5+4;
830  Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
831  s->opt_len, s->static_len));
832 
833  return max_blindex;
834 }
835 
836 /* ===========================================================================
837  * Send the header for a block using dynamic Huffman trees: the counts, the
838  * lengths of the bit length codes, the literal tree and the distance tree.
839  * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
840  */
841 local void send_all_trees(s, lcodes, dcodes, blcodes)
842  deflate_state *s;
843  int lcodes, dcodes, blcodes; /* number of codes for each tree */
844 {
845  int rank; /* index in bl_order */
846 
847  Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
848  Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
849  "too many codes");
850  Tracev((stderr, "\nbl counts: "));
851  send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
852  send_bits(s, dcodes-1, 5);
853  send_bits(s, blcodes-4, 4); /* not -3 as stated in appnote.txt */
854  for (rank = 0; rank < blcodes; rank++) {
855  Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
856  send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
857  }
858  Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));
859 
860  send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
861  Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));
862 
863  send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
864  Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
865 }
866 
867 /* ===========================================================================
868  * Send a stored block
869  */
870 void _tr_stored_block(s, buf, stored_len, eof)
871  deflate_state *s;
872  charf *buf; /* input block */
873  ulg stored_len; /* length of input block */
874  int eof; /* true if this is the last block for a file */
875 {
876  send_bits(s, (STORED_BLOCK<<1)+eof, 3); /* send block type */
877 #ifdef DEBUG
878  s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
879  s->compressed_len += (stored_len + 4) << 3;
880 #endif
881  copy_block(s, buf, (unsigned)stored_len, 1); /* with header */
882 }
883 
884 /* ===========================================================================
885  * Send one empty static block to give enough lookahead for inflate.
886  * This takes 10 bits, of which 7 may remain in the bit buffer.
887  * The current inflate code requires 9 bits of lookahead. If the
888  * last two codes for the previous block (real code plus EOB) were coded
889  * on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode
890  * the last real code. In this case we send two empty static blocks instead
891  * of one. (There are no problems if the previous block is stored or fixed.)
892  * To simplify the code, we assume the worst case of last real code encoded
893  * on one bit only.
894  */
895 void _tr_align(s)
896  deflate_state *s;
897 {
898  send_bits(s, STATIC_TREES<<1, 3);
899  send_code(s, END_BLOCK, static_ltree);
900 #ifdef DEBUG
901  s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
902 #endif
903  bi_flush(s);
904  /* Of the 10 bits for the empty block, we have already sent
905  * (10 - bi_valid) bits. The lookahead for the last real code (before
906  * the EOB of the previous block) was thus at least one plus the length
907  * of the EOB plus what we have just sent of the empty static block.
908  */
909  if (1 + s->last_eob_len + 10 - s->bi_valid < 9) {
910  send_bits(s, STATIC_TREES<<1, 3);
911  send_code(s, END_BLOCK, static_ltree);
912 #ifdef DEBUG
913  s->compressed_len += 10L;
914 #endif
915  bi_flush(s);
916  }
917  s->last_eob_len = 7;
918 }
919 
920 /* ===========================================================================
921  * Determine the best encoding for the current block: dynamic trees, static
922  * trees or store, and output the encoded block to the zip file.
923  */
924 void _tr_flush_block(s, buf, stored_len, eof)
925  deflate_state *s;
926  charf *buf; /* input block, or NULL if too old */
927  ulg stored_len; /* length of input block */
928  int eof; /* true if this is the last block for a file */
929 {
930  ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
931  int max_blindex = 0; /* index of last bit length code of non zero freq */
932 
933  /* Build the Huffman trees unless a stored block is forced */
934  if (s->level > 0) {
935 
936  /* Check if the file is ascii or binary */
937  if (s->data_type == Z_UNKNOWN) set_data_type(s);
938 
939  /* Construct the literal and distance trees */
940  build_tree(s, (tree_desc *)(&(s->l_desc)));
941  Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
942  s->static_len));
943 
944  build_tree(s, (tree_desc *)(&(s->d_desc)));
945  Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
946  s->static_len));
947  /* At this point, opt_len and static_len are the total bit lengths of
948  * the compressed block data, excluding the tree representations.
949  */
950 
951  /* Build the bit length tree for the above two trees, and get the index
952  * in bl_order of the last bit length code to send.
953  */
954  max_blindex = build_bl_tree(s);
955 
956  /* Determine the best encoding. Compute the block lengths in bytes. */
957  opt_lenb = (s->opt_len+3+7)>>3;
958  static_lenb = (s->static_len+3+7)>>3;
959 
960  Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
961  opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
962  s->last_lit));
963 
964  if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
965 
966  } else {
967  Assert(buf != (char*)0, "lost buf");
968  opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
969  }
970 
971 #ifdef FORCE_STORED
972  if (buf != (char*)0) { /* force stored block */
973 #else
974  if (stored_len+4 <= opt_lenb && buf != (char*)0) {
975  /* 4: two words for the lengths */
976 #endif
977  /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
978  * Otherwise we can't have processed more than WSIZE input bytes since
979  * the last block flush, because compression would have been
980  * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
981  * transform a block into a stored block.
982  */
983  _tr_stored_block(s, buf, stored_len, eof);
984 
985 #ifdef FORCE_STATIC
986  } else if (static_lenb >= 0) { /* force static trees */
987 #else
988  } else if (static_lenb == opt_lenb) {
989 #endif
990  send_bits(s, (STATIC_TREES<<1)+eof, 3);
991  compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree);
992 #ifdef DEBUG
993  s->compressed_len += 3 + s->static_len;
994 #endif
995  } else {
996  send_bits(s, (DYN_TREES<<1)+eof, 3);
997  send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
998  max_blindex+1);
999  compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree);
1000 #ifdef DEBUG
1001  s->compressed_len += 3 + s->opt_len;
1002 #endif
1003  }
1004  Assert (s->compressed_len == s->bits_sent, "bad compressed size");
1005  /* The above check is made mod 2^32, for files larger than 512 MB
1006  * and uLong implemented on 32 bits.
1007  */
1008  init_block(s);
1009 
1010  if (eof) {
1011  bi_windup(s);
1012 #ifdef DEBUG
1013  s->compressed_len += 7; /* align on byte boundary */
1014 #endif
1015  }
1016  Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
1017  s->compressed_len-7*eof));
1018 }
1019 
1020 /* ===========================================================================
1021  * Save the match info and tally the frequency counts. Return true if
1022  * the current block must be flushed.
1023  */
1024 int _tr_tally (s, dist, lc)
1025  deflate_state *s;
1026  unsigned dist; /* distance of matched string */
1027  unsigned lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */
1028 {
1029  s->d_buf[s->last_lit] = (ush)dist;
1030  s->l_buf[s->last_lit++] = (uch)lc;
1031  if (dist == 0) {
1032  /* lc is the unmatched char */
1033  s->dyn_ltree[lc].Freq++;
1034  } else {
1035  s->matches++;
1036  /* Here, lc is the match length - MIN_MATCH */
1037  dist--; /* dist = match distance - 1 */
1038  Assert((ush)dist < (ush)MAX_DIST(s) &&
1039  (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
1040  (ush)d_code(dist) < (ush)D_CODES, "_tr_tally: bad match");
1041 
1042  s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
1043  s->dyn_dtree[d_code(dist)].Freq++;
1044  }
1045 
1046 #ifdef TRUNCATE_BLOCK
1047  /* Try to guess if it is profitable to stop the current block here */
1048  if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
1049  /* Compute an upper bound for the compressed length */
1050  ulg out_length = (ulg)s->last_lit*8L;
1051  ulg in_length = (ulg)((long)s->strstart - s->block_start);
1052  int dcode;
1053  for (dcode = 0; dcode < D_CODES; dcode++) {
1054  out_length += (ulg)s->dyn_dtree[dcode].Freq *
1055  (5L+extra_dbits[dcode]);
1056  }
1057  out_length >>= 3;
1058  Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
1059  s->last_lit, in_length, out_length,
1060  100L - out_length*100L/in_length));
1061  if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
1062  }
1063 #endif
1064  return (s->last_lit == s->lit_bufsize-1);
1065  /* We avoid equality with lit_bufsize because of wraparound at 64K
1066  * on 16 bit machines and because stored blocks are restricted to
1067  * 64K-1 bytes.
1068  */
1069 }
1070 
1071 /* ===========================================================================
1072  * Send the block data compressed using the given Huffman trees
1073  */
1074 local void compress_block(s, ltree, dtree)
1075  deflate_state *s;
1076  ct_data *ltree; /* literal tree */
1077  ct_data *dtree; /* distance tree */
1078 {
1079  unsigned dist; /* distance of matched string */
1080  int lc; /* match length or unmatched char (if dist == 0) */
1081  unsigned lx = 0; /* running index in l_buf */
1082  unsigned code; /* the code to send */
1083  int extra; /* number of extra bits to send */
1084 
1085  if (s->last_lit != 0) do {
1086  dist = s->d_buf[lx];
1087  lc = s->l_buf[lx++];
1088  if (dist == 0) {
1089  send_code(s, lc, ltree); /* send a literal byte */
1090  Tracecv(isgraph(lc), (stderr," '%c' ", lc));
1091  } else {
1092  /* Here, lc is the match length - MIN_MATCH */
1093  code = _length_code[lc];
1094  send_code(s, code+LITERALS+1, ltree); /* send the length code */
1095  extra = extra_lbits[code];
1096  if (extra != 0) {
1097  lc -= base_length[code];
1098  send_bits(s, lc, extra); /* send the extra length bits */
1099  }
1100  dist--; /* dist is now the match distance - 1 */
1101  code = d_code(dist);
1102  Assert (code < D_CODES, "bad d_code");
1103 
1104  send_code(s, code, dtree); /* send the distance code */
1105  extra = extra_dbits[code];
1106  if (extra != 0) {
1107  dist -= base_dist[code];
1108  send_bits(s, dist, extra); /* send the extra distance bits */
1109  }
1110  } /* literal or match pair ? */
1111 
1112  /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
1113  Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx,
1114  "pendingBuf overflow");
1115 
1116  } while (lx < s->last_lit);
1117 
1118  send_code(s, END_BLOCK, ltree);
1119  s->last_eob_len = ltree[END_BLOCK].Len;
1120 }
1121 
1122 /* ===========================================================================
1123  * Set the data type to ASCII or BINARY, using a crude approximation:
1124  * binary if more than 20% of the bytes are <= 6 or >= 128, ascii otherwise.
1125  * IN assertion: the fields freq of dyn_ltree are set and the total of all
1126  * frequencies does not exceed 64K (to fit in an int on 16 bit machines).
1127  */
1128 local void set_data_type(s)
1129  deflate_state *s;
1130 {
1131  int n = 0;
1132  unsigned ascii_freq = 0;
1133  unsigned bin_freq = 0;
1134  while (n < 7) bin_freq += s->dyn_ltree[n++].Freq;
1135  while (n < 128) ascii_freq += s->dyn_ltree[n++].Freq;
1136  while (n < LITERALS) bin_freq += s->dyn_ltree[n++].Freq;
1137  s->data_type = (Byte)(bin_freq > (ascii_freq >> 2) ? Z_BINARY : Z_ASCII);
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  */
1145 local 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  */
1160 local 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  */
1177 local 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;
1187 #ifdef DEBUG
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  */
1196 local 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) {
1206  put_short(s, (ush)len);
1207  put_short(s, (ush)~len);
1208 #ifdef DEBUG
1209  s->bits_sent += 2*16;
1210 #endif
1211  }
1212 #ifdef DEBUG
1213  s->bits_sent += (ulg)len<<3;
1214 #endif
1215  while (len--) {
1216  put_byte(s, *buf++);
1217  }
1218 }
1219 #endif /* USE_GZIP */
1220 
Core definitions.
Definition: zinftree.h:24