« back to all changes in this revision
Viewing changes to com/jcraft/jzlib/Deflate.java
- browse files at revision 8
- compare with another revision
- download diff
- download tarball
- view history from revision 8
- Committer: Bazaar Package Importer
- Author(s): Damien Raude-Morvan
- Date: 2011-10-06 23:51:14 UTC
- mfrom: (1.1.3 upstream)
- Revision ID: james.westby@ubuntu.com-20111006235114-5yhe9d6q9fzgm546
Tags: 1.1.0-1
* New upstream release (since 2008)!
- d/copyright: Update source location to github and copyright's years.
- d/copyright: Use DEP-5 format.
* d/libjzlib-java.poms: Drop debian/pom.xml and use upstream pom.xml.
* d/{control,rules}: Use javahelper to build jzlib instead of ant.
- d/build.xml: Dropped.
- d/javabuild and d/libjzlib-java.jlibs: Added for javahelper.
- d/copyright: Update source location to github and copyright's years.
- d/copyright: Use DEP-5 format.
* d/libjzlib-java.poms: Drop debian/pom.xml and use upstream pom.xml.
* d/{control,rules}: Use javahelper to build jzlib instead of ant.
- d/build.xml: Dropped.
- d/javabuild and d/libjzlib-java.jlibs: Added for javahelper.
- files added:
- .gitignore
- project
- project/build
- src
- src/main
- src/main/java
- src/main/java/com
- src/main/java/com/jcraft
- src/main/java/com/jcraft/jzlib
- src/test
- src/test/scala
- files removed:
- com
- com/jcraft
- com/jcraft/jzlib
- files modified:
- ChangeLog
added
removed
com/jcraft/jzlib/Deflate.java
1
/* -*-mode:java; c-basic-offset:2; -*- */
2
/*
3
Copyright (c) 2000,2001,2002,2003 ymnk, JCraft,Inc. All rights reserved.
4
5
Redistribution and use in source and binary forms, with or without
6
modification, are permitted provided that the following conditions are met:
7
8
1. Redistributions of source code must retain the above copyright notice,
9
this list of conditions and the following disclaimer.
10
11
2. Redistributions in binary form must reproduce the above copyright
12
notice, this list of conditions and the following disclaimer in
13
the documentation and/or other materials provided with the distribution.
14
15
3. The names of the authors may not be used to endorse or promote products
16
derived from this software without specific prior written permission.
17
18
THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
19
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
20
FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL JCRAFT,
21
INC. OR ANY CONTRIBUTORS TO THIS SOFTWARE BE LIABLE FOR ANY DIRECT, INDIRECT,
22
INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
23
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
24
OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
25
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
26
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
27
EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28
*/
29
/*
30
* This program is based on zlib-1.1.3, so all credit should go authors
31
* Jean-loup Gailly(jloup@gzip.org) and Mark Adler(madler@alumni.caltech.edu)
32
* and contributors of zlib.
33
*/
34
35
package com.jcraft.jzlib;
36
37
public
38
final class Deflate{
39
40
static final private int MAX_MEM_LEVEL=9;
41
42
static final private int Z_DEFAULT_COMPRESSION=-1;
43
44
static final private int MAX_WBITS=15; // 32K LZ77 window
45
static final private int DEF_MEM_LEVEL=8;
46
47
static class Config{
48
int good_length; // reduce lazy search above this match length
49
int max_lazy; // do not perform lazy search above this match length
50
int nice_length; // quit search above this match length
51
int max_chain;
52
int func;
53
Config(int good_length, int max_lazy,
54
int nice_length, int max_chain, int func){
55
this.good_length=good_length;
56
this.max_lazy=max_lazy;
57
this.nice_length=nice_length;
58
this.max_chain=max_chain;
59
this.func=func;
60
}
61
}
62
63
static final private int STORED=0;
64
static final private int FAST=1;
65
static final private int SLOW=2;
66
static final private Config[] config_table;
67
static{
68
config_table=new Config[10];
69
// good lazy nice chain
70
config_table[0]=new Config(0, 0, 0, 0, STORED);
71
config_table[1]=new Config(4, 4, 8, 4, FAST);
72
config_table[2]=new Config(4, 5, 16, 8, FAST);
73
config_table[3]=new Config(4, 6, 32, 32, FAST);
74
75
config_table[4]=new Config(4, 4, 16, 16, SLOW);
76
config_table[5]=new Config(8, 16, 32, 32, SLOW);
77
config_table[6]=new Config(8, 16, 128, 128, SLOW);
78
config_table[7]=new Config(8, 32, 128, 256, SLOW);
79
config_table[8]=new Config(32, 128, 258, 1024, SLOW);
80
config_table[9]=new Config(32, 258, 258, 4096, SLOW);
81
}
82
83
static final private String[] z_errmsg = {
84
"need dictionary", // Z_NEED_DICT 2
85
"stream end", // Z_STREAM_END 1
86
"", // Z_OK 0
87
"file error", // Z_ERRNO (-1)
88
"stream error", // Z_STREAM_ERROR (-2)
89
"data error", // Z_DATA_ERROR (-3)
90
"insufficient memory", // Z_MEM_ERROR (-4)
91
"buffer error", // Z_BUF_ERROR (-5)
92
"incompatible version",// Z_VERSION_ERROR (-6)
93
""
94
};
95
96
// block not completed, need more input or more output
97
static final private int NeedMore=0;
98
99
// block flush performed
100
static final private int BlockDone=1;
101
102
// finish started, need only more output at next deflate
103
static final private int FinishStarted=2;
104
105
// finish done, accept no more input or output
106
static final private int FinishDone=3;
107
108
// preset dictionary flag in zlib header
109
static final private int PRESET_DICT=0x20;
110
111
static final private int Z_FILTERED=1;
112
static final private int Z_HUFFMAN_ONLY=2;
113
static final private int Z_DEFAULT_STRATEGY=0;
114
115
static final private int Z_NO_FLUSH=0;
116
static final private int Z_PARTIAL_FLUSH=1;
117
static final private int Z_SYNC_FLUSH=2;
118
static final private int Z_FULL_FLUSH=3;
119
static final private int Z_FINISH=4;
120
121
static final private int Z_OK=0;
122
static final private int Z_STREAM_END=1;
123
static final private int Z_NEED_DICT=2;
124
static final private int Z_ERRNO=-1;
125
static final private int Z_STREAM_ERROR=-2;
126
static final private int Z_DATA_ERROR=-3;
127
static final private int Z_MEM_ERROR=-4;
128
static final private int Z_BUF_ERROR=-5;
129
static final private int Z_VERSION_ERROR=-6;
130
131
static final private int INIT_STATE=42;
132
static final private int BUSY_STATE=113;
133
static final private int FINISH_STATE=666;
134
135
// The deflate compression method
136
static final private int Z_DEFLATED=8;
137
138
static final private int STORED_BLOCK=0;
139
static final private int STATIC_TREES=1;
140
static final private int DYN_TREES=2;
141
142
// The three kinds of block type
143
static final private int Z_BINARY=0;
144
static final private int Z_ASCII=1;
145
static final private int Z_UNKNOWN=2;
146
147
static final private int Buf_size=8*2;
148
149
// repeat previous bit length 3-6 times (2 bits of repeat count)
150
static final private int REP_3_6=16;
151
152
// repeat a zero length 3-10 times (3 bits of repeat count)
153
static final private int REPZ_3_10=17;
154
155
// repeat a zero length 11-138 times (7 bits of repeat count)
156
static final private int REPZ_11_138=18;
157
158
static final private int MIN_MATCH=3;
159
static final private int MAX_MATCH=258;
160
static final private int MIN_LOOKAHEAD=(MAX_MATCH+MIN_MATCH+1);
161
162
static final private int MAX_BITS=15;
163
static final private int D_CODES=30;
164
static final private int BL_CODES=19;
165
static final private int LENGTH_CODES=29;
166
static final private int LITERALS=256;
167
static final private int L_CODES=(LITERALS+1+LENGTH_CODES);
168
static final private int HEAP_SIZE=(2*L_CODES+1);
169
170
static final private int END_BLOCK=256;
171
172
ZStream strm; // pointer back to this zlib stream
173
int status; // as the name implies
174
byte[] pending_buf; // output still pending
175
int pending_buf_size; // size of pending_buf
176
int pending_out; // next pending byte to output to the stream
177
int pending; // nb of bytes in the pending buffer
178
int noheader; // suppress zlib header and adler32
179
byte data_type; // UNKNOWN, BINARY or ASCII
180
byte method; // STORED (for zip only) or DEFLATED
181
int last_flush; // value of flush param for previous deflate call
182
183
int w_size; // LZ77 window size (32K by default)
184
int w_bits; // log2(w_size) (8..16)
185
int w_mask; // w_size - 1
186
187
byte[] window;
188
// Sliding window. Input bytes are read into the second half of the window,
189
// and move to the first half later to keep a dictionary of at least wSize
190
// bytes. With this organization, matches are limited to a distance of
191
// wSize-MAX_MATCH bytes, but this ensures that IO is always
192
// performed with a length multiple of the block size. Also, it limits
193
// the window size to 64K, which is quite useful on MSDOS.
194
// To do: use the user input buffer as sliding window.
195
196
int window_size;
197
// Actual size of window: 2*wSize, except when the user input buffer
198
// is directly used as sliding window.
199
200
short[] prev;
201
// Link to older string with same hash index. To limit the size of this
202
// array to 64K, this link is maintained only for the last 32K strings.
203
// An index in this array is thus a window index modulo 32K.
204
205
short[] head; // Heads of the hash chains or NIL.
206
207
int ins_h; // hash index of string to be inserted
208
int hash_size; // number of elements in hash table
209
int hash_bits; // log2(hash_size)
210
int hash_mask; // hash_size-1
211
212
// Number of bits by which ins_h must be shifted at each input
213
// step. It must be such that after MIN_MATCH steps, the oldest
214
// byte no longer takes part in the hash key, that is:
215
// hash_shift * MIN_MATCH >= hash_bits
216
int hash_shift;
217
218
// Window position at the beginning of the current output block. Gets
219
// negative when the window is moved backwards.
220
221
int block_start;
222
223
int match_length; // length of best match
224
int prev_match; // previous match
225
int match_available; // set if previous match exists
226
int strstart; // start of string to insert
227
int match_start; // start of matching string
228
int lookahead; // number of valid bytes ahead in window
229
230
// Length of the best match at previous step. Matches not greater than this
231
// are discarded. This is used in the lazy match evaluation.
232
int prev_length;
233
234
// To speed up deflation, hash chains are never searched beyond this
235
// length. A higher limit improves compression ratio but degrades the speed.
236
int max_chain_length;
237
238
// Attempt to find a better match only when the current match is strictly
239
// smaller than this value. This mechanism is used only for compression
240
// levels >= 4.
241
int max_lazy_match;
242
243
// Insert new strings in the hash table only if the match length is not
244
// greater than this length. This saves time but degrades compression.
245
// max_insert_length is used only for compression levels <= 3.
246
247
int level; // compression level (1..9)
248
int strategy; // favor or force Huffman coding
249
250
// Use a faster search when the previous match is longer than this
251
int good_match;
252
253
// Stop searching when current match exceeds this
254
int nice_match;
255
256
short[] dyn_ltree; // literal and length tree
257
short[] dyn_dtree; // distance tree
258
short[] bl_tree; // Huffman tree for bit lengths
259
260
Tree l_desc=new Tree(); // desc for literal tree
261
Tree d_desc=new Tree(); // desc for distance tree
262
Tree bl_desc=new Tree(); // desc for bit length tree
263
264
// number of codes at each bit length for an optimal tree
265
short[] bl_count=new short[MAX_BITS+1];
266
267
// heap used to build the Huffman trees
268
int[] heap=new int[2*L_CODES+1];
269
270
int heap_len; // number of elements in the heap
271
int heap_max; // element of largest frequency
272
// The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
273
// The same heap array is used to build all trees.
274
275
// Depth of each subtree used as tie breaker for trees of equal frequency
276
byte[] depth=new byte[2*L_CODES+1];
277
278
int l_buf; // index for literals or lengths */
279
280
// Size of match buffer for literals/lengths. There are 4 reasons for
281
// limiting lit_bufsize to 64K:
282
// - frequencies can be kept in 16 bit counters
283
// - if compression is not successful for the first block, all input
284
// data is still in the window so we can still emit a stored block even
285
// when input comes from standard input. (This can also be done for
286
// all blocks if lit_bufsize is not greater than 32K.)
287
// - if compression is not successful for a file smaller than 64K, we can
288
// even emit a stored file instead of a stored block (saving 5 bytes).
289
// This is applicable only for zip (not gzip or zlib).
290
// - creating new Huffman trees less frequently may not provide fast
291
// adaptation to changes in the input data statistics. (Take for
292
// example a binary file with poorly compressible code followed by
293
// a highly compressible string table.) Smaller buffer sizes give
294
// fast adaptation but have of course the overhead of transmitting
295
// trees more frequently.
296
// - I can't count above 4
297
int lit_bufsize;
298
299
int last_lit; // running index in l_buf
300
301
// Buffer for distances. To simplify the code, d_buf and l_buf have
302
// the same number of elements. To use different lengths, an extra flag
303
// array would be necessary.
304
305
int d_buf; // index of pendig_buf
306
307
int opt_len; // bit length of current block with optimal trees
308
int static_len; // bit length of current block with static trees
309
int matches; // number of string matches in current block
310
int last_eob_len; // bit length of EOB code for last block
311
312
// Output buffer. bits are inserted starting at the bottom (least
313
// significant bits).
314
short bi_buf;
315
316
// Number of valid bits in bi_buf. All bits above the last valid bit
317
// are always zero.
318
int bi_valid;
319
320
Deflate(){
321
dyn_ltree=new short[HEAP_SIZE*2];
322
dyn_dtree=new short[(2*D_CODES+1)*2]; // distance tree
323
bl_tree=new short[(2*BL_CODES+1)*2]; // Huffman tree for bit lengths
324
}
325
326
void lm_init() {
327
window_size=2*w_size;
328
329
head[hash_size-1]=0;
330
for(int i=0; i<hash_size-1; i++){
331
head[i]=0;
332
}
333
334
// Set the default configuration parameters:
335
max_lazy_match = Deflate.config_table[level].max_lazy;
336
good_match = Deflate.config_table[level].good_length;
337
nice_match = Deflate.config_table[level].nice_length;
338
max_chain_length = Deflate.config_table[level].max_chain;
339
340
strstart = 0;
341
block_start = 0;
342
lookahead = 0;
343
match_length = prev_length = MIN_MATCH-1;
344
match_available = 0;
345
ins_h = 0;
346
}
347
348
// Initialize the tree data structures for a new zlib stream.
349
void tr_init(){
350
351
l_desc.dyn_tree = dyn_ltree;
352
l_desc.stat_desc = StaticTree.static_l_desc;
353
354
d_desc.dyn_tree = dyn_dtree;
355
d_desc.stat_desc = StaticTree.static_d_desc;
356
357
bl_desc.dyn_tree = bl_tree;
358
bl_desc.stat_desc = StaticTree.static_bl_desc;
359
360
bi_buf = 0;
361
bi_valid = 0;
362
last_eob_len = 8; // enough lookahead for inflate
363
364
// Initialize the first block of the first file:
365
init_block();
366
}
367
368
void init_block(){
369
// Initialize the trees.
370
for(int i = 0; i < L_CODES; i++) dyn_ltree[i*2] = 0;
371
for(int i= 0; i < D_CODES; i++) dyn_dtree[i*2] = 0;
372
for(int i= 0; i < BL_CODES; i++) bl_tree[i*2] = 0;
373
374
dyn_ltree[END_BLOCK*2] = 1;
375
opt_len = static_len = 0;
376
last_lit = matches = 0;
377
}
378
379
// Restore the heap property by moving down the tree starting at node k,
380
// exchanging a node with the smallest of its two sons if necessary, stopping
381
// when the heap property is re-established (each father smaller than its
382
// two sons).
383
void pqdownheap(short[] tree, // the tree to restore
384
int k // node to move down
385
){
386
int v = heap[k];
387
int j = k << 1; // left son of k
388
while (j <= heap_len) {
389
// Set j to the smallest of the two sons:
390
if (j < heap_len &&
391
smaller(tree, heap[j+1], heap[j], depth)){
392
j++;
393
}
394
// Exit if v is smaller than both sons
395
if(smaller(tree, v, heap[j], depth)) break;
396
397
// Exchange v with the smallest son
398
heap[k]=heap[j]; k = j;
399
// And continue down the tree, setting j to the left son of k
400
j <<= 1;
401
}
402
heap[k] = v;
403
}
404
405
static boolean smaller(short[] tree, int n, int m, byte[] depth){
406
short tn2=tree[n*2];
407
short tm2=tree[m*2];
408
return (tn2<tm2 ||
409
(tn2==tm2 && depth[n] <= depth[m]));
410
}
411
412
// Scan a literal or distance tree to determine the frequencies of the codes
413
// in the bit length tree.
414
void scan_tree (short[] tree,// the tree to be scanned
415
int max_code // and its largest code of non zero frequency
416
){
417
int n; // iterates over all tree elements
418
int prevlen = -1; // last emitted length
419
int curlen; // length of current code
420
int nextlen = tree[0*2+1]; // length of next code
421
int count = 0; // repeat count of the current code
422
int max_count = 7; // max repeat count
423
int min_count = 4; // min repeat count
424
425
if (nextlen == 0){ max_count = 138; min_count = 3; }
426
tree[(max_code+1)*2+1] = (short)0xffff; // guard
427
428
for(n = 0; n <= max_code; n++) {
429
curlen = nextlen; nextlen = tree[(n+1)*2+1];
430
if(++count < max_count && curlen == nextlen) {
431
continue;
432
}
433
else if(count < min_count) {
434
bl_tree[curlen*2] += count;
435
}
436
else if(curlen != 0) {
437
if(curlen != prevlen) bl_tree[curlen*2]++;
438
bl_tree[REP_3_6*2]++;
439
}
440
else if(count <= 10) {
441
bl_tree[REPZ_3_10*2]++;
442
}
443
else{
444
bl_tree[REPZ_11_138*2]++;
445
}
446
count = 0; prevlen = curlen;
447
if(nextlen == 0) {
448
max_count = 138; min_count = 3;
449
}
450
else if(curlen == nextlen) {
451
max_count = 6; min_count = 3;
452
}
453
else{
454
max_count = 7; min_count = 4;
455
}
456
}
457
}
458
459
// Construct the Huffman tree for the bit lengths and return the index in
460
// bl_order of the last bit length code to send.
461
int build_bl_tree(){
462
int max_blindex; // index of last bit length code of non zero freq
463
464
// Determine the bit length frequencies for literal and distance trees
465
scan_tree(dyn_ltree, l_desc.max_code);
466
scan_tree(dyn_dtree, d_desc.max_code);
467
468
// Build the bit length tree:
469
bl_desc.build_tree(this);
470
// opt_len now includes the length of the tree representations, except
471
// the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
472
473
// Determine the number of bit length codes to send. The pkzip format
474
// requires that at least 4 bit length codes be sent. (appnote.txt says
475
// 3 but the actual value used is 4.)
476
for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
477
if (bl_tree[Tree.bl_order[max_blindex]*2+1] != 0) break;
478
}
479
// Update opt_len to include the bit length tree and counts
480
opt_len += 3*(max_blindex+1) + 5+5+4;
481
482
return max_blindex;
483
}
484
485
486
// Send the header for a block using dynamic Huffman trees: the counts, the
487
// lengths of the bit length codes, the literal tree and the distance tree.
488
// IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
489
void send_all_trees(int lcodes, int dcodes, int blcodes){
490
int rank; // index in bl_order
491
492
send_bits(lcodes-257, 5); // not +255 as stated in appnote.txt
493
send_bits(dcodes-1, 5);
494
send_bits(blcodes-4, 4); // not -3 as stated in appnote.txt
495
for (rank = 0; rank < blcodes; rank++) {
496
send_bits(bl_tree[Tree.bl_order[rank]*2+1], 3);
497
}
498
send_tree(dyn_ltree, lcodes-1); // literal tree
499
send_tree(dyn_dtree, dcodes-1); // distance tree
500
}
501
502
// Send a literal or distance tree in compressed form, using the codes in
503
// bl_tree.
504
void send_tree (short[] tree,// the tree to be sent
505
int max_code // and its largest code of non zero frequency
506
){
507
int n; // iterates over all tree elements
508
int prevlen = -1; // last emitted length
509
int curlen; // length of current code
510
int nextlen = tree[0*2+1]; // length of next code
511
int count = 0; // repeat count of the current code
512
int max_count = 7; // max repeat count
513
int min_count = 4; // min repeat count
514
515
if (nextlen == 0){ max_count = 138; min_count = 3; }
516
517
for (n = 0; n <= max_code; n++) {
518
curlen = nextlen; nextlen = tree[(n+1)*2+1];
519
if(++count < max_count && curlen == nextlen) {
520
continue;
521
}
522
else if(count < min_count) {
523
do { send_code(curlen, bl_tree); } while (--count != 0);
524
}
525
else if(curlen != 0){
526
if(curlen != prevlen){
527
send_code(curlen, bl_tree); count--;
528
}
529
send_code(REP_3_6, bl_tree);
530
send_bits(count-3, 2);
531
}
532
else if(count <= 10){
533
send_code(REPZ_3_10, bl_tree);
534
send_bits(count-3, 3);
535
}
536
else{
537
send_code(REPZ_11_138, bl_tree);
538
send_bits(count-11, 7);
539
}
540
count = 0; prevlen = curlen;
541
if(nextlen == 0){
542
max_count = 138; min_count = 3;
543
}
544
else if(curlen == nextlen){
545
max_count = 6; min_count = 3;
546
}
547
else{
548
max_count = 7; min_count = 4;
549
}
550
}
551
}
552
553
// Output a byte on the stream.
554
// IN assertion: there is enough room in pending_buf.
555
final void put_byte(byte[] p, int start, int len){
556
System.arraycopy(p, start, pending_buf, pending, len);
557
pending+=len;
558
}
559
560
final void put_byte(byte c){
561
pending_buf[pending++]=c;
562
}
563
final void put_short(int w) {
564
put_byte((byte)(w/*&0xff*/));
565
put_byte((byte)(w>>>8));
566
}
567
final void putShortMSB(int b){
568
put_byte((byte)(b>>8));
569
put_byte((byte)(b/*&0xff*/));
570
}
571
572
final void send_code(int c, short[] tree){
573
int c2=c*2;
574
send_bits((tree[c2]&0xffff), (tree[c2+1]&0xffff));
575
}
576
577
void send_bits(int value, int length){
578
int len = length;
579
if (bi_valid > (int)Buf_size - len) {
580
int val = value;
581
// bi_buf |= (val << bi_valid);
582
bi_buf |= ((val << bi_valid)&0xffff);
583
put_short(bi_buf);
584
bi_buf = (short)(val >>> (Buf_size - bi_valid));
585
bi_valid += len - Buf_size;
586
} else {
587
// bi_buf |= (value) << bi_valid;
588
bi_buf |= (((value) << bi_valid)&0xffff);
589
bi_valid += len;
590
}
591
}
592
593
// Send one empty static block to give enough lookahead for inflate.
594
// This takes 10 bits, of which 7 may remain in the bit buffer.
595
// The current inflate code requires 9 bits of lookahead. If the
596
// last two codes for the previous block (real code plus EOB) were coded
597
// on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode
598
// the last real code. In this case we send two empty static blocks instead
599
// of one. (There are no problems if the previous block is stored or fixed.)
600
// To simplify the code, we assume the worst case of last real code encoded
601
// on one bit only.
602
void _tr_align(){
603
send_bits(STATIC_TREES<<1, 3);
604
send_code(END_BLOCK, StaticTree.static_ltree);
605
606
bi_flush();
607
608
// Of the 10 bits for the empty block, we have already sent
609
// (10 - bi_valid) bits. The lookahead for the last real code (before
610
// the EOB of the previous block) was thus at least one plus the length
611
// of the EOB plus what we have just sent of the empty static block.
612
if (1 + last_eob_len + 10 - bi_valid < 9) {
613
send_bits(STATIC_TREES<<1, 3);
614
send_code(END_BLOCK, StaticTree.static_ltree);
615
bi_flush();
616
}
617
last_eob_len = 7;
618
}
619
620
621
// Save the match info and tally the frequency counts. Return true if
622
// the current block must be flushed.
623
boolean _tr_tally (int dist, // distance of matched string
624
int lc // match length-MIN_MATCH or unmatched char (if dist==0)
625
){
626
627
pending_buf[d_buf+last_lit*2] = (byte)(dist>>>8);
628
pending_buf[d_buf+last_lit*2+1] = (byte)dist;
629
630
pending_buf[l_buf+last_lit] = (byte)lc; last_lit++;
631
632
if (dist == 0) {
633
// lc is the unmatched char
634
dyn_ltree[lc*2]++;
635
}
636
else {
637
matches++;
638
// Here, lc is the match length - MIN_MATCH
639
dist--; // dist = match distance - 1
640
dyn_ltree[(Tree._length_code[lc]+LITERALS+1)*2]++;
641
dyn_dtree[Tree.d_code(dist)*2]++;
642
}
643
644
if ((last_lit & 0x1fff) == 0 && level > 2) {
645
// Compute an upper bound for the compressed length
646
int out_length = last_lit*8;
647
int in_length = strstart - block_start;
648
int dcode;
649
for (dcode = 0; dcode < D_CODES; dcode++) {
650
out_length += (int)dyn_dtree[dcode*2] *
651
(5L+Tree.extra_dbits[dcode]);
652
}
653
out_length >>>= 3;
654
if ((matches < (last_lit/2)) && out_length < in_length/2) return true;
655
}
656
657
return (last_lit == lit_bufsize-1);
658
// We avoid equality with lit_bufsize because of wraparound at 64K
659
// on 16 bit machines and because stored blocks are restricted to
660
// 64K-1 bytes.
661
}
662
663
// Send the block data compressed using the given Huffman trees
664
void compress_block(short[] ltree, short[] dtree){
665
int dist; // distance of matched string
666
int lc; // match length or unmatched char (if dist == 0)
667
int lx = 0; // running index in l_buf
668
int code; // the code to send
669
int extra; // number of extra bits to send
670
671
if (last_lit != 0){
672
do{
673
dist=((pending_buf[d_buf+lx*2]<<8)&0xff00)|
674
(pending_buf[d_buf+lx*2+1]&0xff);
675
lc=(pending_buf[l_buf+lx])&0xff; lx++;
676
677
if(dist == 0){
678
send_code(lc, ltree); // send a literal byte
679
}
680
else{
681
// Here, lc is the match length - MIN_MATCH
682
code = Tree._length_code[lc];
683
684
send_code(code+LITERALS+1, ltree); // send the length code
685
extra = Tree.extra_lbits[code];
686
if(extra != 0){
687
lc -= Tree.base_length[code];
688
send_bits(lc, extra); // send the extra length bits
689
}
690
dist--; // dist is now the match distance - 1
691
code = Tree.d_code(dist);
692
693
send_code(code, dtree); // send the distance code
694
extra = Tree.extra_dbits[code];
695
if (extra != 0) {
696
dist -= Tree.base_dist[code];
697
send_bits(dist, extra); // send the extra distance bits
698
}
699
} // literal or match pair ?
700
701
// Check that the overlay between pending_buf and d_buf+l_buf is ok:
702
}
703
while (lx < last_lit);
704
}
705
706
send_code(END_BLOCK, ltree);
707
last_eob_len = ltree[END_BLOCK*2+1];
708
}
709
710
// Set the data type to ASCII or BINARY, using a crude approximation:
711
// binary if more than 20% of the bytes are <= 6 or >= 128, ascii otherwise.
712
// IN assertion: the fields freq of dyn_ltree are set and the total of all
713
// frequencies does not exceed 64K (to fit in an int on 16 bit machines).
714
void set_data_type(){
715
int n = 0;
716
int ascii_freq = 0;
717
int bin_freq = 0;
718
while(n<7){ bin_freq += dyn_ltree[n*2]; n++;}
719
while(n<128){ ascii_freq += dyn_ltree[n*2]; n++;}
720
while(n<LITERALS){ bin_freq += dyn_ltree[n*2]; n++;}
721
data_type=(byte)(bin_freq > (ascii_freq >>> 2) ? Z_BINARY : Z_ASCII);
722
}
723
724
// Flush the bit buffer, keeping at most 7 bits in it.
725
void bi_flush(){
726
if (bi_valid == 16) {
727
put_short(bi_buf);
728
bi_buf=0;
729
bi_valid=0;
730
}
731
else if (bi_valid >= 8) {
732
put_byte((byte)bi_buf);
733
bi_buf>>>=8;
734
bi_valid-=8;
735
}
736
}
737
738
// Flush the bit buffer and align the output on a byte boundary
739
void bi_windup(){
740
if (bi_valid > 8) {
741
put_short(bi_buf);
742
} else if (bi_valid > 0) {
743
put_byte((byte)bi_buf);
744
}
745
bi_buf = 0;
746
bi_valid = 0;
747
}
748
749
// Copy a stored block, storing first the length and its
750
// one's complement if requested.
751
void copy_block(int buf, // the input data
752
int len, // its length
753
boolean header // true if block header must be written
754
){
755
int index=0;
756
bi_windup(); // align on byte boundary
757
last_eob_len = 8; // enough lookahead for inflate
758
759
if (header) {
760
put_short((short)len);
761
put_short((short)~len);
762
}
763
764
// while(len--!=0) {
765
// put_byte(window[buf+index]);
766
// index++;
767
// }
768
put_byte(window, buf, len);
769
}
770
771
void flush_block_only(boolean eof){
772
_tr_flush_block(block_start>=0 ? block_start : -1,
773
strstart-block_start,
774
eof);
775
block_start=strstart;
776
strm.flush_pending();
777
}
778
779
// Copy without compression as much as possible from the input stream, return
780
// the current block state.
781
// This function does not insert new strings in the dictionary since
782
// uncompressible data is probably not useful. This function is used
783
// only for the level=0 compression option.
784
// NOTE: this function should be optimized to avoid extra copying from
785
// window to pending_buf.
786
int deflate_stored(int flush){
787
// Stored blocks are limited to 0xffff bytes, pending_buf is limited
788
// to pending_buf_size, and each stored block has a 5 byte header:
789
790
int max_block_size = 0xffff;
791
int max_start;
792
793
if(max_block_size > pending_buf_size - 5) {
794
max_block_size = pending_buf_size - 5;
795
}
796
797
// Copy as much as possible from input to output:
798
while(true){
799
// Fill the window as much as possible:
800
if(lookahead<=1){
801
fill_window();
802
if(lookahead==0 && flush==Z_NO_FLUSH) return NeedMore;
803
if(lookahead==0) break; // flush the current block
804
}
805
806
strstart+=lookahead;
807
lookahead=0;
808
809
// Emit a stored block if pending_buf will be full:
810
max_start=block_start+max_block_size;
811
if(strstart==0|| strstart>=max_start) {
812
// strstart == 0 is possible when wraparound on 16-bit machine
813
lookahead = (int)(strstart-max_start);
814
strstart = (int)max_start;
815
816
flush_block_only(false);
817
if(strm.avail_out==0) return NeedMore;
818
819
}
820
821
// Flush if we may have to slide, otherwise block_start may become
822
// negative and the data will be gone:
823
if(strstart-block_start >= w_size-MIN_LOOKAHEAD) {
824
flush_block_only(false);
825
if(strm.avail_out==0) return NeedMore;
826
}
827
}
828
829
flush_block_only(flush == Z_FINISH);
830
if(strm.avail_out==0)
831
return (flush == Z_FINISH) ? FinishStarted : NeedMore;
832
833
return flush == Z_FINISH ? FinishDone : BlockDone;
834
}
835
836
// Send a stored block
837
void _tr_stored_block(int buf, // input block
838
int stored_len, // length of input block
839
boolean eof // true if this is the last block for a file
840
){
841
send_bits((STORED_BLOCK<<1)+(eof?1:0), 3); // send block type
842
copy_block(buf, stored_len, true); // with header
843
}
844
845
// Determine the best encoding for the current block: dynamic trees, static
846
// trees or store, and output the encoded block to the zip file.
847
void _tr_flush_block(int buf, // input block, or NULL if too old
848
int stored_len, // length of input block
849
boolean eof // true if this is the last block for a file
850
) {
851
int opt_lenb, static_lenb;// opt_len and static_len in bytes
852
int max_blindex = 0; // index of last bit length code of non zero freq
853
854
// Build the Huffman trees unless a stored block is forced
855
if(level > 0) {
856
// Check if the file is ascii or binary
857
if(data_type == Z_UNKNOWN) set_data_type();
858
859
// Construct the literal and distance trees
860
l_desc.build_tree(this);
861
862
d_desc.build_tree(this);
863
864
// At this point, opt_len and static_len are the total bit lengths of
865
// the compressed block data, excluding the tree representations.
866
867
// Build the bit length tree for the above two trees, and get the index
868
// in bl_order of the last bit length code to send.
869
max_blindex=build_bl_tree();
870
871
// Determine the best encoding. Compute first the block length in bytes
872
opt_lenb=(opt_len+3+7)>>>3;
873
static_lenb=(static_len+3+7)>>>3;
874
875
if(static_lenb<=opt_lenb) opt_lenb=static_lenb;
876
}
877
else {
878
opt_lenb=static_lenb=stored_len+5; // force a stored block
879
}
880
881
if(stored_len+4<=opt_lenb && buf != -1){
882
// 4: two words for the lengths
883
// The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
884
// Otherwise we can't have processed more than WSIZE input bytes since
885
// the last block flush, because compression would have been
886
// successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
887
// transform a block into a stored block.
888
_tr_stored_block(buf, stored_len, eof);
889
}
890
else if(static_lenb == opt_lenb){
891
send_bits((STATIC_TREES<<1)+(eof?1:0), 3);
892
compress_block(StaticTree.static_ltree, StaticTree.static_dtree);
893
}
894
else{
895
send_bits((DYN_TREES<<1)+(eof?1:0), 3);
896
send_all_trees(l_desc.max_code+1, d_desc.max_code+1, max_blindex+1);
897
compress_block(dyn_ltree, dyn_dtree);
898
}
899
900
// The above check is made mod 2^32, for files larger than 512 MB
901
// and uLong implemented on 32 bits.
902
903
init_block();
904
905
if(eof){
906
bi_windup();
907
}
908
}
909
910
// Fill the window when the lookahead becomes insufficient.
911
// Updates strstart and lookahead.
912
//
913
// IN assertion: lookahead < MIN_LOOKAHEAD
914
// OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
915
// At least one byte has been read, or avail_in == 0; reads are
916
// performed for at least two bytes (required for the zip translate_eol
917
// option -- not supported here).
918
void fill_window(){
919
int n, m;
920
int p;
921
int more; // Amount of free space at the end of the window.
922
923
do{
924
more = (window_size-lookahead-strstart);
925
926
// Deal with !@#$% 64K limit:
927
if(more==0 && strstart==0 && lookahead==0){
928
more = w_size;
929
}
930
else if(more==-1) {
931
// Very unlikely, but possible on 16 bit machine if strstart == 0
932
// and lookahead == 1 (input done one byte at time)
933
more--;
934
935
// If the window is almost full and there is insufficient lookahead,
936
// move the upper half to the lower one to make room in the upper half.
937
}
938
else if(strstart >= w_size+ w_size-MIN_LOOKAHEAD) {
939
System.arraycopy(window, w_size, window, 0, w_size);
940
match_start-=w_size;
941
strstart-=w_size; // we now have strstart >= MAX_DIST
942
block_start-=w_size;
943
944
// Slide the hash table (could be avoided with 32 bit values
945
// at the expense of memory usage). We slide even when level == 0
946
// to keep the hash table consistent if we switch back to level > 0
947
// later. (Using level 0 permanently is not an optimal usage of
948
// zlib, so we don't care about this pathological case.)
949
950
n = hash_size;
951
p=n;
952
do {
953
m = (head[--p]&0xffff);
954
head[p]=(m>=w_size ? (short)(m-w_size) : 0);
955
}
956
while (--n != 0);
957
958
n = w_size;
959
p = n;
960
do {
961
m = (prev[--p]&0xffff);
962
prev[p] = (m >= w_size ? (short)(m-w_size) : 0);
963
// If n is not on any hash chain, prev[n] is garbage but
964
// its value will never be used.
965
}
966
while (--n!=0);
967
more += w_size;
968
}
969
970
if (strm.avail_in == 0) return;
971
972
// If there was no sliding:
973
// strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
974
// more == window_size - lookahead - strstart
975
// => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
976
// => more >= window_size - 2*WSIZE + 2
977
// In the BIG_MEM or MMAP case (not yet supported),
978
// window_size == input_size + MIN_LOOKAHEAD &&
979
// strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
980
// Otherwise, window_size == 2*WSIZE so more >= 2.
981
// If there was sliding, more >= WSIZE. So in all cases, more >= 2.
982
983
n = strm.read_buf(window, strstart + lookahead, more);
984
lookahead += n;
985
986
// Initialize the hash value now that we have some input:
987
if(lookahead >= MIN_MATCH) {
988
ins_h = window[strstart]&0xff;
989
ins_h=(((ins_h)<<hash_shift)^(window[strstart+1]&0xff))&hash_mask;
990
}
991
// If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
992
// but this is not important since only literal bytes will be emitted.
993
}
994
while (lookahead < MIN_LOOKAHEAD && strm.avail_in != 0);
995
}
996
997
// Compress as much as possible from the input stream, return the current
998
// block state.
999
// This function does not perform lazy evaluation of matches and inserts
1000
// new strings in the dictionary only for unmatched strings or for short
1001
// matches. It is used only for the fast compression options.
1002
int deflate_fast(int flush){
1003
// short hash_head = 0; // head of the hash chain
1004
int hash_head = 0; // head of the hash chain
1005
boolean bflush; // set if current block must be flushed
1006
1007
while(true){
1008
// Make sure that we always have enough lookahead, except
1009
// at the end of the input file. We need MAX_MATCH bytes
1010
// for the next match, plus MIN_MATCH bytes to insert the
1011
// string following the next match.
1012
if(lookahead < MIN_LOOKAHEAD){
1013
fill_window();
1014
if(lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH){
1015
return NeedMore;
1016
}
1017
if(lookahead == 0) break; // flush the current block
1018
}
1019
1020
// Insert the string window[strstart .. strstart+2] in the
1021
// dictionary, and set hash_head to the head of the hash chain:
1022
if(lookahead >= MIN_MATCH){
1023
ins_h=(((ins_h)<<hash_shift)^(window[(strstart)+(MIN_MATCH-1)]&0xff))&hash_mask;
1024
1025
// prev[strstart&w_mask]=hash_head=head[ins_h];
1026
hash_head=(head[ins_h]&0xffff);
1027
prev[strstart&w_mask]=head[ins_h];
1028
head[ins_h]=(short)strstart;
1029
}
1030
1031
// Find the longest match, discarding those <= prev_length.
1032
// At this point we have always match_length < MIN_MATCH
1033
1034
if(hash_head!=0L &&
1035
((strstart-hash_head)&0xffff) <= w_size-MIN_LOOKAHEAD
1036
){
1037
// To simplify the code, we prevent matches with the string
1038
// of window index 0 (in particular we have to avoid a match
1039
// of the string with itself at the start of the input file).
1040
if(strategy != Z_HUFFMAN_ONLY){
1041
match_length=longest_match (hash_head);
1042
}
1043
// longest_match() sets match_start
1044
}
1045
if(match_length>=MIN_MATCH){
1046
// check_match(strstart, match_start, match_length);
1047
1048
bflush=_tr_tally(strstart-match_start, match_length-MIN_MATCH);
1049
1050
lookahead -= match_length;
1051
1052
// Insert new strings in the hash table only if the match length
1053
// is not too large. This saves time but degrades compression.
1054
if(match_length <= max_lazy_match &&
1055
lookahead >= MIN_MATCH) {
1056
match_length--; // string at strstart already in hash table
1057
do{
1058
strstart++;
1059
1060
ins_h=((ins_h<<hash_shift)^(window[(strstart)+(MIN_MATCH-1)]&0xff))&hash_mask;
1061
// prev[strstart&w_mask]=hash_head=head[ins_h];
1062
hash_head=(head[ins_h]&0xffff);
1063
prev[strstart&w_mask]=head[ins_h];
1064
head[ins_h]=(short)strstart;
1065
1066
// strstart never exceeds WSIZE-MAX_MATCH, so there are
1067
// always MIN_MATCH bytes ahead.
1068
}
1069
while (--match_length != 0);
1070
strstart++;
1071
}
1072
else{
1073
strstart += match_length;
1074
match_length = 0;
1075
ins_h = window[strstart]&0xff;
1076
1077
ins_h=(((ins_h)<<hash_shift)^(window[strstart+1]&0xff))&hash_mask;
1078
// If lookahead < MIN_MATCH, ins_h is garbage, but it does not
1079
// matter since it will be recomputed at next deflate call.
1080
}
1081
}
1082
else {
1083
// No match, output a literal byte
1084
1085
bflush=_tr_tally(0, window[strstart]&0xff);
1086
lookahead--;
1087
strstart++;
1088
}
1089
if (bflush){
1090
1091
flush_block_only(false);
1092
if(strm.avail_out==0) return NeedMore;
1093
}
1094
}
1095
1096
flush_block_only(flush == Z_FINISH);
1097
if(strm.avail_out==0){
1098
if(flush == Z_FINISH) return FinishStarted;
1099
else return NeedMore;
1100
}
1101
return flush==Z_FINISH ? FinishDone : BlockDone;
1102
}
1103
1104
// Same as above, but achieves better compression. We use a lazy
1105
// evaluation for matches: a match is finally adopted only if there is
1106
// no better match at the next window position.
1107
int deflate_slow(int flush){
1108
// short hash_head = 0; // head of hash chain
1109
int hash_head = 0; // head of hash chain
1110
boolean bflush; // set if current block must be flushed
1111
1112
// Process the input block.
1113
while(true){
1114
// Make sure that we always have enough lookahead, except
1115
// at the end of the input file. We need MAX_MATCH bytes
1116
// for the next match, plus MIN_MATCH bytes to insert the
1117
// string following the next match.
1118
1119
if (lookahead < MIN_LOOKAHEAD) {
1120
fill_window();
1121
if(lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1122
return NeedMore;
1123
}
1124
if(lookahead == 0) break; // flush the current block
1125
}
1126
1127
// Insert the string window[strstart .. strstart+2] in the
1128
// dictionary, and set hash_head to the head of the hash chain:
1129
1130
if(lookahead >= MIN_MATCH) {
1131
ins_h=(((ins_h)<<hash_shift)^(window[(strstart)+(MIN_MATCH-1)]&0xff)) & hash_mask;
1132
// prev[strstart&w_mask]=hash_head=head[ins_h];
1133
hash_head=(head[ins_h]&0xffff);
1134
prev[strstart&w_mask]=head[ins_h];
1135
head[ins_h]=(short)strstart;
1136
}
1137
1138
// Find the longest match, discarding those <= prev_length.
1139
prev_length = match_length; prev_match = match_start;
1140
match_length = MIN_MATCH-1;
1141
1142
if (hash_head != 0 && prev_length < max_lazy_match &&
1143
((strstart-hash_head)&0xffff) <= w_size-MIN_LOOKAHEAD
1144
){
1145
// To simplify the code, we prevent matches with the string
1146
// of window index 0 (in particular we have to avoid a match
1147
// of the string with itself at the start of the input file).
1148
1149
if(strategy != Z_HUFFMAN_ONLY) {
1150
match_length = longest_match(hash_head);
1151
}
1152
// longest_match() sets match_start
1153
1154
if (match_length <= 5 && (strategy == Z_FILTERED ||
1155
(match_length == MIN_MATCH &&
1156
strstart - match_start > 4096))) {
1157
1158
// If prev_match is also MIN_MATCH, match_start is garbage
1159
// but we will ignore the current match anyway.
1160
match_length = MIN_MATCH-1;
1161
}
1162
}
1163
1164
// If there was a match at the previous step and the current
1165
// match is not better, output the previous match:
1166
if(prev_length >= MIN_MATCH && match_length <= prev_length) {
1167
int max_insert = strstart + lookahead - MIN_MATCH;
1168
// Do not insert strings in hash table beyond this.
1169
1170
// check_match(strstart-1, prev_match, prev_length);
1171
1172
bflush=_tr_tally(strstart-1-prev_match, prev_length - MIN_MATCH);
1173
1174
// Insert in hash table all strings up to the end of the match.
1175
// strstart-1 and strstart are already inserted. If there is not
1176
// enough lookahead, the last two strings are not inserted in
1177
// the hash table.
1178
lookahead -= prev_length-1;
1179
prev_length -= 2;
1180
do{
1181
if(++strstart <= max_insert) {
1182
ins_h=(((ins_h)<<hash_shift)^(window[(strstart)+(MIN_MATCH-1)]&0xff))&hash_mask;
1183
//prev[strstart&w_mask]=hash_head=head[ins_h];
1184
hash_head=(head[ins_h]&0xffff);
1185
prev[strstart&w_mask]=head[ins_h];
1186
head[ins_h]=(short)strstart;
1187
}
1188
}
1189
while(--prev_length != 0);
1190
match_available = 0;
1191
match_length = MIN_MATCH-1;
1192
strstart++;
1193
1194
if (bflush){
1195
flush_block_only(false);
1196
if(strm.avail_out==0) return NeedMore;
1197
}
1198
} else if (match_available!=0) {
1199
1200
// If there was no match at the previous position, output a
1201
// single literal. If there was a match but the current match
1202
// is longer, truncate the previous match to a single literal.
1203
1204
bflush=_tr_tally(0, window[strstart-1]&0xff);
1205
1206
if (bflush) {
1207
flush_block_only(false);
1208
}
1209
strstart++;
1210
lookahead--;
1211
if(strm.avail_out == 0) return NeedMore;
1212
} else {
1213
// There is no previous match to compare with, wait for
1214
// the next step to decide.
1215
1216
match_available = 1;
1217
strstart++;
1218
lookahead--;
1219
}
1220
}
1221
1222
if(match_available!=0) {
1223
bflush=_tr_tally(0, window[strstart-1]&0xff);
1224
match_available = 0;
1225
}
1226
flush_block_only(flush == Z_FINISH);
1227
1228
if(strm.avail_out==0){
1229
if(flush == Z_FINISH) return FinishStarted;
1230
else return NeedMore;
1231
}
1232
1233
return flush == Z_FINISH ? FinishDone : BlockDone;
1234
}
1235
1236
int longest_match(int cur_match){
1237
int chain_length = max_chain_length; // max hash chain length
1238
int scan = strstart; // current string
1239
int match; // matched string
1240
int len; // length of current match
1241
int best_len = prev_length; // best match length so far
1242
int limit = strstart>(w_size-MIN_LOOKAHEAD) ?
1243
strstart-(w_size-MIN_LOOKAHEAD) : 0;
1244
int nice_match=this.nice_match;
1245
1246
// Stop when cur_match becomes <= limit. To simplify the code,
1247
// we prevent matches with the string of window index 0.
1248
1249
int wmask = w_mask;
1250
1251
int strend = strstart + MAX_MATCH;
1252
byte scan_end1 = window[scan+best_len-1];
1253
byte scan_end = window[scan+best_len];
1254
1255
// The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1256
// It is easy to get rid of this optimization if necessary.
1257
1258
// Do not waste too much time if we already have a good match:
1259
if (prev_length >= good_match) {
1260
chain_length >>= 2;
1261
}
1262
1263
// Do not look for matches beyond the end of the input. This is necessary
1264
// to make deflate deterministic.
1265
if (nice_match > lookahead) nice_match = lookahead;
1266
1267
do {
1268
match = cur_match;
1269
1270
// Skip to next match if the match length cannot increase
1271
// or if the match length is less than 2:
1272
if (window[match+best_len] != scan_end ||
1273
window[match+best_len-1] != scan_end1 ||
1274
window[match] != window[scan] ||
1275
window[++match] != window[scan+1]) continue;
1276
1277
// The check at best_len-1 can be removed because it will be made
1278
// again later. (This heuristic is not always a win.)
1279
// It is not necessary to compare scan[2] and match[2] since they
1280
// are always equal when the other bytes match, given that
1281
// the hash keys are equal and that HASH_BITS >= 8.
1282
scan += 2; match++;
1283
1284
// We check for insufficient lookahead only every 8th comparison;
1285
// the 256th check will be made at strstart+258.
1286
do {
1287
} while (window[++scan] == window[++match] &&
1288
window[++scan] == window[++match] &&
1289
window[++scan] == window[++match] &&
1290
window[++scan] == window[++match] &&
1291
window[++scan] == window[++match] &&
1292
window[++scan] == window[++match] &&
1293
window[++scan] == window[++match] &&
1294
window[++scan] == window[++match] &&
1295
scan < strend);
1296
1297
len = MAX_MATCH - (int)(strend - scan);
1298
scan = strend - MAX_MATCH;
1299
1300
if(len>best_len) {
1301
match_start = cur_match;
1302
best_len = len;
1303
if (len >= nice_match) break;
1304
scan_end1 = window[scan+best_len-1];
1305
scan_end = window[scan+best_len];
1306
}
1307
1308
} while ((cur_match = (prev[cur_match & wmask]&0xffff)) > limit
1309
&& --chain_length != 0);
1310
1311
if (best_len <= lookahead) return best_len;
1312
return lookahead;
1313
}
1314
1315
int deflateInit(ZStream strm, int level, int bits){
1316
return deflateInit2(strm, level, Z_DEFLATED, bits, DEF_MEM_LEVEL,
1317
Z_DEFAULT_STRATEGY);
1318
}
1319
int deflateInit(ZStream strm, int level){
1320
return deflateInit(strm, level, MAX_WBITS);
1321
}
1322
int deflateInit2(ZStream strm, int level, int method, int windowBits,
1323
int memLevel, int strategy){
1324
int noheader = 0;
1325
// byte[] my_version=ZLIB_VERSION;
1326
1327
//
1328
// if (version == null || version[0] != my_version[0]
1329
// || stream_size != sizeof(z_stream)) {
1330
// return Z_VERSION_ERROR;
1331
// }
1332
1333
strm.msg = null;
1334
1335
if (level == Z_DEFAULT_COMPRESSION) level = 6;
1336
1337
if (windowBits < 0) { // undocumented feature: suppress zlib header
1338
noheader = 1;
1339
windowBits = -windowBits;
1340
}
1341
1342
if (memLevel < 1 || memLevel > MAX_MEM_LEVEL ||
1343
method != Z_DEFLATED ||
1344
windowBits < 9 || windowBits > 15 || level < 0 || level > 9 ||
1345
strategy < 0 || strategy > Z_HUFFMAN_ONLY) {
1346
return Z_STREAM_ERROR;
1347
}
1348
1349
strm.dstate = (Deflate)this;
1350
1351
this.noheader = noheader;
1352
w_bits = windowBits;
1353
w_size = 1 << w_bits;
1354
w_mask = w_size - 1;
1355
1356
hash_bits = memLevel + 7;
1357
hash_size = 1 << hash_bits;
1358
hash_mask = hash_size - 1;
1359
hash_shift = ((hash_bits+MIN_MATCH-1)/MIN_MATCH);
1360
1361
window = new byte[w_size*2];
1362
prev = new short[w_size];
1363
head = new short[hash_size];
1364
1365
lit_bufsize = 1 << (memLevel + 6); // 16K elements by default
1366
1367
// We overlay pending_buf and d_buf+l_buf. This works since the average
1368
// output size for (length,distance) codes is <= 24 bits.
1369
pending_buf = new byte[lit_bufsize*4];
1370
pending_buf_size = lit_bufsize*4;
1371
1372
d_buf = lit_bufsize/2;
1373
l_buf = (1+2)*lit_bufsize;
1374
1375
this.level = level;
1376
1377
//System.out.println("level="+level);
1378
1379
this.strategy = strategy;
1380
this.method = (byte)method;
1381
1382
return deflateReset(strm);
1383
}
1384
1385
int deflateReset(ZStream strm){
1386
strm.total_in = strm.total_out = 0;
1387
strm.msg = null; //
1388
strm.data_type = Z_UNKNOWN;
1389
1390
pending = 0;
1391
pending_out = 0;
1392
1393
if(noheader < 0) {
1394
noheader = 0; // was set to -1 by deflate(..., Z_FINISH);
1395
}
1396
status = (noheader!=0) ? BUSY_STATE : INIT_STATE;
1397
strm.adler=strm._adler.adler32(0, null, 0, 0);
1398
1399
last_flush = Z_NO_FLUSH;
1400
1401
tr_init();
1402
lm_init();
1403
return Z_OK;
1404
}
1405
1406
int deflateEnd(){
1407
if(status!=INIT_STATE && status!=BUSY_STATE && status!=FINISH_STATE){
1408
return Z_STREAM_ERROR;
1409
}
1410
// Deallocate in reverse order of allocations:
1411
pending_buf=null;
1412
head=null;
1413
prev=null;
1414
window=null;
1415
// free
1416
// dstate=null;
1417
return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
1418
}
1419
1420
int deflateParams(ZStream strm, int _level, int _strategy){
1421
int err=Z_OK;
1422
1423
if(_level == Z_DEFAULT_COMPRESSION){
1424
_level = 6;
1425
}
1426
if(_level < 0 || _level > 9 ||
1427
_strategy < 0 || _strategy > Z_HUFFMAN_ONLY) {
1428
return Z_STREAM_ERROR;
1429
}
1430
1431
if(config_table[level].func!=config_table[_level].func &&
1432
strm.total_in != 0) {
1433
// Flush the last buffer:
1434
err = strm.deflate(Z_PARTIAL_FLUSH);
1435
}
1436
1437
if(level != _level) {
1438
level = _level;
1439
max_lazy_match = config_table[level].max_lazy;
1440
good_match = config_table[level].good_length;
1441
nice_match = config_table[level].nice_length;
1442
max_chain_length = config_table[level].max_chain;
1443
}
1444
strategy = _strategy;
1445
return err;
1446
}
1447
1448
int deflateSetDictionary (ZStream strm, byte[] dictionary, int dictLength){
1449
int length = dictLength;
1450
int index=0;
1451
1452
if(dictionary == null || status != INIT_STATE)
1453
return Z_STREAM_ERROR;
1454
1455
strm.adler=strm._adler.adler32(strm.adler, dictionary, 0, dictLength);
1456
1457
if(length < MIN_MATCH) return Z_OK;
1458
if(length > w_size-MIN_LOOKAHEAD){
1459
length = w_size-MIN_LOOKAHEAD;
1460
index=dictLength-length; // use the tail of the dictionary
1461
}
1462
System.arraycopy(dictionary, index, window, 0, length);
1463
strstart = length;
1464
block_start = length;
1465
1466
// Insert all strings in the hash table (except for the last two bytes).
1467
// s->lookahead stays null, so s->ins_h will be recomputed at the next
1468
// call of fill_window.
1469
1470
ins_h = window[0]&0xff;
1471
ins_h=(((ins_h)<<hash_shift)^(window[1]&0xff))&hash_mask;
1472
1473
for(int n=0; n<=length-MIN_MATCH; n++){
1474
ins_h=(((ins_h)<<hash_shift)^(window[(n)+(MIN_MATCH-1)]&0xff))&hash_mask;
1475
prev[n&w_mask]=head[ins_h];
1476
head[ins_h]=(short)n;
1477
}
1478
return Z_OK;
1479
}
1480
1481
int deflate(ZStream strm, int flush){
1482
int old_flush;
1483
1484
if(flush>Z_FINISH || flush<0){
1485
return Z_STREAM_ERROR;
1486
}
1487
1488
if(strm.next_out == null ||
1489
(strm.next_in == null && strm.avail_in != 0) ||
1490
(status == FINISH_STATE && flush != Z_FINISH)) {
1491
strm.msg=z_errmsg[Z_NEED_DICT-(Z_STREAM_ERROR)];
1492
return Z_STREAM_ERROR;
1493
}
1494
if(strm.avail_out == 0){
1495
strm.msg=z_errmsg[Z_NEED_DICT-(Z_BUF_ERROR)];
1496
return Z_BUF_ERROR;
1497
}
1498
1499
this.strm = strm; // just in case
1500
old_flush = last_flush;
1501
last_flush = flush;
1502
1503
// Write the zlib header
1504
if(status == INIT_STATE) {
1505
int header = (Z_DEFLATED+((w_bits-8)<<4))<<8;
1506
int level_flags=((level-1)&0xff)>>1;
1507
1508
if(level_flags>3) level_flags=3;
1509
header |= (level_flags<<6);
1510
if(strstart!=0) header |= PRESET_DICT;
1511
header+=31-(header % 31);
1512
1513
status=BUSY_STATE;
1514
putShortMSB(header);
1515
1516
1517
// Save the adler32 of the preset dictionary:
1518
if(strstart!=0){
1519
putShortMSB((int)(strm.adler>>>16));
1520
putShortMSB((int)(strm.adler&0xffff));
1521
}
1522
strm.adler=strm._adler.adler32(0, null, 0, 0);
1523
}
1524
1525
// Flush as much pending output as possible
1526
if(pending != 0) {
1527
strm.flush_pending();
1528
if(strm.avail_out == 0) {
1529
//System.out.println(" avail_out==0");
1530
// Since avail_out is 0, deflate will be called again with
1531
// more output space, but possibly with both pending and
1532
// avail_in equal to zero. There won't be anything to do,
1533
// but this is not an error situation so make sure we
1534
// return OK instead of BUF_ERROR at next call of deflate:
1535
last_flush = -1;
1536
return Z_OK;
1537
}
1538
1539
// Make sure there is something to do and avoid duplicate consecutive
1540
// flushes. For repeated and useless calls with Z_FINISH, we keep
1541
// returning Z_STREAM_END instead of Z_BUFF_ERROR.
1542
}
1543
else if(strm.avail_in==0 && flush <= old_flush &&
1544
flush != Z_FINISH) {
1545
strm.msg=z_errmsg[Z_NEED_DICT-(Z_BUF_ERROR)];
1546
return Z_BUF_ERROR;
1547
}
1548
1549
// User must not provide more input after the first FINISH:
1550
if(status == FINISH_STATE && strm.avail_in != 0) {
1551
strm.msg=z_errmsg[Z_NEED_DICT-(Z_BUF_ERROR)];
1552
return Z_BUF_ERROR;
1553
}
1554
1555
// Start a new block or continue the current one.
1556
if(strm.avail_in!=0 || lookahead!=0 ||
1557
(flush != Z_NO_FLUSH && status != FINISH_STATE)) {
1558
int bstate=-1;
1559
switch(config_table[level].func){
1560
case STORED:
1561
bstate = deflate_stored(flush);
1562
break;
1563
case FAST:
1564
bstate = deflate_fast(flush);
1565
break;
1566
case SLOW:
1567
bstate = deflate_slow(flush);
1568
break;
1569
default:
1570
}
1571
1572
if (bstate==FinishStarted || bstate==FinishDone) {
1573
status = FINISH_STATE;
1574
}
1575
if (bstate==NeedMore || bstate==FinishStarted) {
1576
if(strm.avail_out == 0) {
1577
last_flush = -1; // avoid BUF_ERROR next call, see above
1578
}
1579
return Z_OK;
1580
// If flush != Z_NO_FLUSH && avail_out == 0, the next call
1581
// of deflate should use the same flush parameter to make sure
1582
// that the flush is complete. So we don't have to output an
1583
// empty block here, this will be done at next call. This also
1584
// ensures that for a very small output buffer, we emit at most
1585
// one empty block.
1586
}
1587
1588
if (bstate==BlockDone) {
1589
if(flush == Z_PARTIAL_FLUSH) {
1590
_tr_align();
1591
}
1592
else { // FULL_FLUSH or SYNC_FLUSH
1593
_tr_stored_block(0, 0, false);
1594
// For a full flush, this empty block will be recognized
1595
// as a special marker by inflate_sync().
1596
if(flush == Z_FULL_FLUSH) {
1597
//state.head[s.hash_size-1]=0;
1598
for(int i=0; i<hash_size/*-1*/; i++) // forget history
1599
head[i]=0;
1600
}
1601
}
1602
strm.flush_pending();
1603
if(strm.avail_out == 0) {
1604
last_flush = -1; // avoid BUF_ERROR at next call, see above
1605
return Z_OK;
1606
}
1607
}
1608
}
1609
1610
if(flush!=Z_FINISH) return Z_OK;
1611
if(noheader!=0) return Z_STREAM_END;
1612
1613
// Write the zlib trailer (adler32)
1614
putShortMSB((int)(strm.adler>>>16));
1615
putShortMSB((int)(strm.adler&0xffff));
1616
strm.flush_pending();
1617
1618
// If avail_out is zero, the application will call deflate again
1619
// to flush the rest.
1620
noheader = -1; // write the trailer only once!
1621
return pending != 0 ? Z_OK : Z_STREAM_END;
1622
}
1623
}
Loggerhead is a web-based interface for Breezy
Version: 2.0.1