1/* +++ deflate.c */
2/* deflate.c -- compress data using the deflation algorithm
3 * Copyright (C) 1995-1996 Jean-loup Gailly.
4 * For conditions of distribution and use, see copyright notice in zlib.h
5 */
6
7/*
8 * ALGORITHM
9 *
10 * The "deflation" process depends on being able to identify portions
11 * of the input text which are identical to earlier input (within a
12 * sliding window trailing behind the input currently being processed).
13 *
14 * The most straightforward technique turns out to be the fastest for
15 * most input files: try all possible matches and select the longest.
16 * The key feature of this algorithm is that insertions into the string
17 * dictionary are very simple and thus fast, and deletions are avoided
18 * completely. Insertions are performed at each input character, whereas
19 * string matches are performed only when the previous match ends. So it
20 * is preferable to spend more time in matches to allow very fast string
21 * insertions and avoid deletions. The matching algorithm for small
22 * strings is inspired from that of Rabin & Karp. A brute force approach
23 * is used to find longer strings when a small match has been found.
24 * A similar algorithm is used in comic (by Jan-Mark Wams) and freeze
25 * (by Leonid Broukhis).
26 * A previous version of this file used a more sophisticated algorithm
27 * (by Fiala and Greene) which is guaranteed to run in linear amortized
28 * time, but has a larger average cost, uses more memory and is patented.
29 * However the F&G algorithm may be faster for some highly redundant
30 * files if the parameter max_chain_length (described below) is too large.
31 *
32 * ACKNOWLEDGEMENTS
33 *
34 * The idea of lazy evaluation of matches is due to Jan-Mark Wams, and
35 * I found it in 'freeze' written by Leonid Broukhis.
36 * Thanks to many people for bug reports and testing.
37 *
38 * REFERENCES
39 *
40 * Deutsch, L.P.,"DEFLATE Compressed Data Format Specification".
41 * Available in ftp://ds.internic.net/rfc/rfc1951.txt
42 *
43 * A description of the Rabin and Karp algorithm is given in the book
44 * "Algorithms" by R. Sedgewick, Addison-Wesley, p252.
45 *
46 * Fiala,E.R., and Greene,D.H.
47 * Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595
48 *
49 */
50
51#include <linux/module.h>
52#include <linux/zutil.h>
53#include "defutil.h"
54
55/* architecture-specific bits */
56#ifdef CONFIG_ZLIB_DFLTCC
57# include "../zlib_dfltcc/dfltcc_deflate.h"
58#else
59#define DEFLATE_RESET_HOOK(strm) do {} while (0)
60#define DEFLATE_HOOK(strm, flush, bstate) 0
61#define DEFLATE_NEED_CHECKSUM(strm) 1
62#define DEFLATE_DFLTCC_ENABLED() 0
63#endif
64
65/* ===========================================================================
66 * Function prototypes.
67 */
68
69typedef block_state (*compress_func) (deflate_state *s, int flush);
70/* Compression function. Returns the block state after the call. */
71
72static void fill_window (deflate_state *s);
73static block_state deflate_stored (deflate_state *s, int flush);
74static block_state deflate_fast (deflate_state *s, int flush);
75static block_state deflate_slow (deflate_state *s, int flush);
76static void lm_init (deflate_state *s);
77static void putShortMSB (deflate_state *s, uInt b);
78static int read_buf (z_streamp strm, Byte *buf, unsigned size);
79static uInt longest_match (deflate_state *s, IPos cur_match);
80
81#ifdef DEBUG_ZLIB
82static void check_match (deflate_state *s, IPos start, IPos match,
83 int length);
84#endif
85
86/* ===========================================================================
87 * Local data
88 */
89
90#define NIL 0
91/* Tail of hash chains */
92
93#ifndef TOO_FAR
94# define TOO_FAR 4096
95#endif
96/* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
97
98#define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
99/* Minimum amount of lookahead, except at the end of the input file.
100 * See deflate.c for comments about the MIN_MATCH+1.
101 */
102
103/* Workspace to be allocated for deflate processing */
104typedef struct deflate_workspace {
105 /* State memory for the deflator */
106 deflate_state deflate_memory;
107#ifdef CONFIG_ZLIB_DFLTCC
108 /* State memory for s390 hardware deflate */
109 struct dfltcc_deflate_state dfltcc_memory;
110#endif
111 Byte *window_memory;
112 Pos *prev_memory;
113 Pos *head_memory;
114 char *overlay_memory;
115} deflate_workspace;
116
117#ifdef CONFIG_ZLIB_DFLTCC
118/* dfltcc_state must be doubleword aligned for DFLTCC call */
119static_assert(offsetof(struct deflate_workspace, dfltcc_memory) % 8 == 0);
120#endif
121
122/* Values for max_lazy_match, good_match and max_chain_length, depending on
123 * the desired pack level (0..9). The values given below have been tuned to
124 * exclude worst case performance for pathological files. Better values may be
125 * found for specific files.
126 */
127typedef struct config_s {
128 ush good_length; /* reduce lazy search above this match length */
129 ush max_lazy; /* do not perform lazy search above this match length */
130 ush nice_length; /* quit search above this match length */
131 ush max_chain;
132 compress_func func;
133} config;
134
135static const config configuration_table[10] = {
136/* good lazy nice chain */
137/* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */
138/* 1 */ {4, 4, 8, 4, deflate_fast}, /* maximum speed, no lazy matches */
139/* 2 */ {4, 5, 16, 8, deflate_fast},
140/* 3 */ {4, 6, 32, 32, deflate_fast},
141
142/* 4 */ {4, 4, 16, 16, deflate_slow}, /* lazy matches */
143/* 5 */ {8, 16, 32, 32, deflate_slow},
144/* 6 */ {8, 16, 128, 128, deflate_slow},
145/* 7 */ {8, 32, 128, 256, deflate_slow},
146/* 8 */ {32, 128, 258, 1024, deflate_slow},
147/* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* maximum compression */
148
149/* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
150 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
151 * meaning.
152 */
153
154#define EQUAL 0
155/* result of memcmp for equal strings */
156
157/* ===========================================================================
158 * Update a hash value with the given input byte
159 * IN assertion: all calls to UPDATE_HASH are made with consecutive
160 * input characters, so that a running hash key can be computed from the
161 * previous key instead of complete recalculation each time.
162 */
163#define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)
164
165
166/* ===========================================================================
167 * Insert string str in the dictionary and set match_head to the previous head
168 * of the hash chain (the most recent string with same hash key). Return
169 * the previous length of the hash chain.
170 * IN assertion: all calls to INSERT_STRING are made with consecutive
171 * input characters and the first MIN_MATCH bytes of str are valid
172 * (except for the last MIN_MATCH-1 bytes of the input file).
173 */
174#define INSERT_STRING(s, str, match_head) \
175 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
176 s->prev[(str) & s->w_mask] = match_head = s->head[s->ins_h], \
177 s->head[s->ins_h] = (Pos)(str))
178
179/* ===========================================================================
180 * Initialize the hash table (avoiding 64K overflow for 16 bit systems).
181 * prev[] will be initialized on the fly.
182 */
183#define CLEAR_HASH(s) \
184 s->head[s->hash_size-1] = NIL; \
185 memset((char *)s->head, 0, (unsigned)(s->hash_size-1)*sizeof(*s->head));
186
187/* ========================================================================= */
188int zlib_deflateInit2(
189 z_streamp strm,
190 int level,
191 int method,
192 int windowBits,
193 int memLevel,
194 int strategy
195)
196{
197 deflate_state *s;
198 int noheader = 0;
199 deflate_workspace *mem;
200 char *next;
201
202 ush *overlay;
203 /* We overlay pending_buf and d_buf+l_buf. This works since the average
204 * output size for (length,distance) codes is <= 24 bits.
205 */
206
207 if (strm == NULL) return Z_STREAM_ERROR;
208
209 strm->msg = NULL;
210
211 if (level == Z_DEFAULT_COMPRESSION) level = 6;
212
213 mem = (deflate_workspace *) strm->workspace;
214
215 if (windowBits < 0) { /* undocumented feature: suppress zlib header */
216 noheader = 1;
217 windowBits = -windowBits;
218 }
219 if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||
220 windowBits < 9 || windowBits > 15 || level < 0 || level > 9 ||
221 strategy < 0 || strategy > Z_HUFFMAN_ONLY) {
222 return Z_STREAM_ERROR;
223 }
224
225 /*
226 * Direct the workspace's pointers to the chunks that were allocated
227 * along with the deflate_workspace struct.
228 */
229 next = (char *) mem;
230 next += sizeof(*mem);
231#ifdef CONFIG_ZLIB_DFLTCC
232 /*
233 * DFLTCC requires the window to be page aligned.
234 * Thus, we overallocate and take the aligned portion of the buffer.
235 */
236 mem->window_memory = (Byte *) PTR_ALIGN(next, PAGE_SIZE);
237#else
238 mem->window_memory = (Byte *) next;
239#endif
240 next += zlib_deflate_window_memsize(windowBits);
241 mem->prev_memory = (Pos *) next;
242 next += zlib_deflate_prev_memsize(windowBits);
243 mem->head_memory = (Pos *) next;
244 next += zlib_deflate_head_memsize(memLevel);
245 mem->overlay_memory = next;
246
247 s = (deflate_state *) &(mem->deflate_memory);
248 strm->state = (struct internal_state *)s;
249 s->strm = strm;
250
251 s->noheader = noheader;
252 s->w_bits = windowBits;
253 s->w_size = 1 << s->w_bits;
254 s->w_mask = s->w_size - 1;
255
256 s->hash_bits = memLevel + 7;
257 s->hash_size = 1 << s->hash_bits;
258 s->hash_mask = s->hash_size - 1;
259 s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);
260
261 s->window = (Byte *) mem->window_memory;
262 s->prev = (Pos *) mem->prev_memory;
263 s->head = (Pos *) mem->head_memory;
264
265 s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
266
267 overlay = (ush *) mem->overlay_memory;
268 s->pending_buf = (uch *) overlay;
269 s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L);
270
271 s->d_buf = overlay + s->lit_bufsize/sizeof(ush);
272 s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;
273
274 s->level = level;
275 s->strategy = strategy;
276 s->method = (Byte)method;
277
278 return zlib_deflateReset(strm);
279}
280
281/* ========================================================================= */
282int zlib_deflateReset(
283 z_streamp strm
284)
285{
286 deflate_state *s;
287
288 if (strm == NULL || strm->state == NULL)
289 return Z_STREAM_ERROR;
290
291 strm->total_in = strm->total_out = 0;
292 strm->msg = NULL;
293 strm->data_type = Z_UNKNOWN;
294
295 s = (deflate_state *)strm->state;
296 s->pending = 0;
297 s->pending_out = s->pending_buf;
298
299 if (s->noheader < 0) {
300 s->noheader = 0; /* was set to -1 by deflate(..., Z_FINISH); */
301 }
302 s->status = s->noheader ? BUSY_STATE : INIT_STATE;
303 strm->adler = 1;
304 s->last_flush = Z_NO_FLUSH;
305
306 zlib_tr_init(s);
307 lm_init(s);
308
309 DEFLATE_RESET_HOOK(strm);
310
311 return Z_OK;
312}
313
314/* =========================================================================
315 * Put a short in the pending buffer. The 16-bit value is put in MSB order.
316 * IN assertion: the stream state is correct and there is enough room in
317 * pending_buf.
318 */
319static void putShortMSB(
320 deflate_state *s,
321 uInt b
322)
323{
324 put_byte(s, (Byte)(b >> 8));
325 put_byte(s, (Byte)(b & 0xff));
326}
327
328/* ========================================================================= */
329int zlib_deflate(
330 z_streamp strm,
331 int flush
332)
333{
334 int old_flush; /* value of flush param for previous deflate call */
335 deflate_state *s;
336
337 if (strm == NULL || strm->state == NULL ||
338 flush > Z_FINISH || flush < 0) {
339 return Z_STREAM_ERROR;
340 }
341 s = (deflate_state *) strm->state;
342
343 if ((strm->next_in == NULL && strm->avail_in != 0) ||
344 (s->status == FINISH_STATE && flush != Z_FINISH)) {
345 return Z_STREAM_ERROR;
346 }
347 if (strm->avail_out == 0) return Z_BUF_ERROR;
348
349 s->strm = strm; /* just in case */
350 old_flush = s->last_flush;
351 s->last_flush = flush;
352
353 /* Write the zlib header */
354 if (s->status == INIT_STATE) {
355
356 uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
357 uInt level_flags = (s->level-1) >> 1;
358
359 if (level_flags > 3) level_flags = 3;
360 header |= (level_flags << 6);
361 if (s->strstart != 0) header |= PRESET_DICT;
362 header += 31 - (header % 31);
363
364 s->status = BUSY_STATE;
365 putShortMSB(s, b: header);
366
367 /* Save the adler32 of the preset dictionary: */
368 if (s->strstart != 0) {
369 putShortMSB(s, b: (uInt)(strm->adler >> 16));
370 putShortMSB(s, b: (uInt)(strm->adler & 0xffff));
371 }
372 strm->adler = 1L;
373 }
374
375 /* Flush as much pending output as possible */
376 if (s->pending != 0) {
377 flush_pending(strm);
378 if (strm->avail_out == 0) {
379 /* Since avail_out is 0, deflate will be called again with
380 * more output space, but possibly with both pending and
381 * avail_in equal to zero. There won't be anything to do,
382 * but this is not an error situation so make sure we
383 * return OK instead of BUF_ERROR at next call of deflate:
384 */
385 s->last_flush = -1;
386 return Z_OK;
387 }
388
389 /* Make sure there is something to do and avoid duplicate consecutive
390 * flushes. For repeated and useless calls with Z_FINISH, we keep
391 * returning Z_STREAM_END instead of Z_BUFF_ERROR.
392 */
393 } else if (strm->avail_in == 0 && flush <= old_flush &&
394 flush != Z_FINISH) {
395 return Z_BUF_ERROR;
396 }
397
398 /* User must not provide more input after the first FINISH: */
399 if (s->status == FINISH_STATE && strm->avail_in != 0) {
400 return Z_BUF_ERROR;
401 }
402
403 /* Start a new block or continue the current one.
404 */
405 if (strm->avail_in != 0 || s->lookahead != 0 ||
406 (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {
407 block_state bstate;
408
409 bstate = DEFLATE_HOOK(strm, flush, &bstate) ? bstate :
410 (*(configuration_table[s->level].func))(s, flush);
411
412 if (bstate == finish_started || bstate == finish_done) {
413 s->status = FINISH_STATE;
414 }
415 if (bstate == need_more || bstate == finish_started) {
416 if (strm->avail_out == 0) {
417 s->last_flush = -1; /* avoid BUF_ERROR next call, see above */
418 }
419 return Z_OK;
420 /* If flush != Z_NO_FLUSH && avail_out == 0, the next call
421 * of deflate should use the same flush parameter to make sure
422 * that the flush is complete. So we don't have to output an
423 * empty block here, this will be done at next call. This also
424 * ensures that for a very small output buffer, we emit at most
425 * one empty block.
426 */
427 }
428 if (bstate == block_done) {
429 if (flush == Z_PARTIAL_FLUSH) {
430 zlib_tr_align(s);
431 } else if (flush == Z_PACKET_FLUSH) {
432 /* Output just the 3-bit `stored' block type value,
433 but not a zero length. */
434 zlib_tr_stored_type_only(s);
435 } else { /* FULL_FLUSH or SYNC_FLUSH */
436 zlib_tr_stored_block(s, buf: (char*)0, stored_len: 0L, eof: 0);
437 /* For a full flush, this empty block will be recognized
438 * as a special marker by inflate_sync().
439 */
440 if (flush == Z_FULL_FLUSH) {
441 CLEAR_HASH(s); /* forget history */
442 }
443 }
444 flush_pending(strm);
445 if (strm->avail_out == 0) {
446 s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
447 return Z_OK;
448 }
449 }
450 }
451 Assert(strm->avail_out > 0, "bug2");
452
453 if (flush != Z_FINISH) return Z_OK;
454
455 if (!s->noheader) {
456 /* Write zlib trailer (adler32) */
457 putShortMSB(s, b: (uInt)(strm->adler >> 16));
458 putShortMSB(s, b: (uInt)(strm->adler & 0xffff));
459 }
460 flush_pending(strm);
461 /* If avail_out is zero, the application will call deflate again
462 * to flush the rest.
463 */
464 if (!s->noheader) {
465 s->noheader = -1; /* write the trailer only once! */
466 }
467 if (s->pending == 0) {
468 Assert(s->bi_valid == 0, "bi_buf not flushed");
469 return Z_STREAM_END;
470 }
471 return Z_OK;
472}
473
474/* ========================================================================= */
475int zlib_deflateEnd(
476 z_streamp strm
477)
478{
479 int status;
480 deflate_state *s;
481
482 if (strm == NULL || strm->state == NULL) return Z_STREAM_ERROR;
483 s = (deflate_state *) strm->state;
484
485 status = s->status;
486 if (status != INIT_STATE && status != BUSY_STATE &&
487 status != FINISH_STATE) {
488 return Z_STREAM_ERROR;
489 }
490
491 strm->state = NULL;
492
493 return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
494}
495
496/* ===========================================================================
497 * Read a new buffer from the current input stream, update the adler32
498 * and total number of bytes read. All deflate() input goes through
499 * this function so some applications may wish to modify it to avoid
500 * allocating a large strm->next_in buffer and copying from it.
501 * (See also flush_pending()).
502 */
503static int read_buf(
504 z_streamp strm,
505 Byte *buf,
506 unsigned size
507)
508{
509 unsigned len = strm->avail_in;
510
511 if (len > size) len = size;
512 if (len == 0) return 0;
513
514 strm->avail_in -= len;
515
516 if (!DEFLATE_NEED_CHECKSUM(strm)) {}
517 else if (!((deflate_state *)(strm->state))->noheader) {
518 strm->adler = zlib_adler32(adler: strm->adler, buf: strm->next_in, len);
519 }
520 memcpy(buf, strm->next_in, len);
521 strm->next_in += len;
522 strm->total_in += len;
523
524 return (int)len;
525}
526
527/* ===========================================================================
528 * Initialize the "longest match" routines for a new zlib stream
529 */
530static void lm_init(
531 deflate_state *s
532)
533{
534 s->window_size = (ulg)2L*s->w_size;
535
536 CLEAR_HASH(s);
537
538 /* Set the default configuration parameters:
539 */
540 s->max_lazy_match = configuration_table[s->level].max_lazy;
541 s->good_match = configuration_table[s->level].good_length;
542 s->nice_match = configuration_table[s->level].nice_length;
543 s->max_chain_length = configuration_table[s->level].max_chain;
544
545 s->strstart = 0;
546 s->block_start = 0L;
547 s->lookahead = 0;
548 s->match_length = s->prev_length = MIN_MATCH-1;
549 s->match_available = 0;
550 s->ins_h = 0;
551}
552
553/* ===========================================================================
554 * Set match_start to the longest match starting at the given string and
555 * return its length. Matches shorter or equal to prev_length are discarded,
556 * in which case the result is equal to prev_length and match_start is
557 * garbage.
558 * IN assertions: cur_match is the head of the hash chain for the current
559 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
560 * OUT assertion: the match length is not greater than s->lookahead.
561 */
562/* For 80x86 and 680x0, an optimized version will be provided in match.asm or
563 * match.S. The code will be functionally equivalent.
564 */
565static uInt longest_match(
566 deflate_state *s,
567 IPos cur_match /* current match */
568)
569{
570 unsigned chain_length = s->max_chain_length;/* max hash chain length */
571 register Byte *scan = s->window + s->strstart; /* current string */
572 register Byte *match; /* matched string */
573 register int len; /* length of current match */
574 int best_len = s->prev_length; /* best match length so far */
575 int nice_match = s->nice_match; /* stop if match long enough */
576 IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
577 s->strstart - (IPos)MAX_DIST(s) : NIL;
578 /* Stop when cur_match becomes <= limit. To simplify the code,
579 * we prevent matches with the string of window index 0.
580 */
581 Pos *prev = s->prev;
582 uInt wmask = s->w_mask;
583
584#ifdef UNALIGNED_OK
585 /* Compare two bytes at a time. Note: this is not always beneficial.
586 * Try with and without -DUNALIGNED_OK to check.
587 */
588 register Byte *strend = s->window + s->strstart + MAX_MATCH - 1;
589 register ush scan_start = *(ush*)scan;
590 register ush scan_end = *(ush*)(scan+best_len-1);
591#else
592 register Byte *strend = s->window + s->strstart + MAX_MATCH;
593 register Byte scan_end1 = scan[best_len-1];
594 register Byte scan_end = scan[best_len];
595#endif
596
597 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
598 * It is easy to get rid of this optimization if necessary.
599 */
600 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
601
602 /* Do not waste too much time if we already have a good match: */
603 if (s->prev_length >= s->good_match) {
604 chain_length >>= 2;
605 }
606 /* Do not look for matches beyond the end of the input. This is necessary
607 * to make deflate deterministic.
608 */
609 if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;
610
611 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
612
613 do {
614 Assert(cur_match < s->strstart, "no future");
615 match = s->window + cur_match;
616
617 /* Skip to next match if the match length cannot increase
618 * or if the match length is less than 2:
619 */
620#if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
621 /* This code assumes sizeof(unsigned short) == 2. Do not use
622 * UNALIGNED_OK if your compiler uses a different size.
623 */
624 if (*(ush*)(match+best_len-1) != scan_end ||
625 *(ush*)match != scan_start) continue;
626
627 /* It is not necessary to compare scan[2] and match[2] since they are
628 * always equal when the other bytes match, given that the hash keys
629 * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
630 * strstart+3, +5, ... up to strstart+257. We check for insufficient
631 * lookahead only every 4th comparison; the 128th check will be made
632 * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
633 * necessary to put more guard bytes at the end of the window, or
634 * to check more often for insufficient lookahead.
635 */
636 Assert(scan[2] == match[2], "scan[2]?");
637 scan++, match++;
638 do {
639 } while (*(ush*)(scan+=2) == *(ush*)(match+=2) &&
640 *(ush*)(scan+=2) == *(ush*)(match+=2) &&
641 *(ush*)(scan+=2) == *(ush*)(match+=2) &&
642 *(ush*)(scan+=2) == *(ush*)(match+=2) &&
643 scan < strend);
644 /* The funny "do {}" generates better code on most compilers */
645
646 /* Here, scan <= window+strstart+257 */
647 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
648 if (*scan == *match) scan++;
649
650 len = (MAX_MATCH - 1) - (int)(strend-scan);
651 scan = strend - (MAX_MATCH-1);
652
653#else /* UNALIGNED_OK */
654
655 if (match[best_len] != scan_end ||
656 match[best_len-1] != scan_end1 ||
657 *match != *scan ||
658 *++match != scan[1]) continue;
659
660 /* The check at best_len-1 can be removed because it will be made
661 * again later. (This heuristic is not always a win.)
662 * It is not necessary to compare scan[2] and match[2] since they
663 * are always equal when the other bytes match, given that
664 * the hash keys are equal and that HASH_BITS >= 8.
665 */
666 scan += 2, match++;
667 Assert(*scan == *match, "match[2]?");
668
669 /* We check for insufficient lookahead only every 8th comparison;
670 * the 256th check will be made at strstart+258.
671 */
672 do {
673 } while (*++scan == *++match && *++scan == *++match &&
674 *++scan == *++match && *++scan == *++match &&
675 *++scan == *++match && *++scan == *++match &&
676 *++scan == *++match && *++scan == *++match &&
677 scan < strend);
678
679 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
680
681 len = MAX_MATCH - (int)(strend - scan);
682 scan = strend - MAX_MATCH;
683
684#endif /* UNALIGNED_OK */
685
686 if (len > best_len) {
687 s->match_start = cur_match;
688 best_len = len;
689 if (len >= nice_match) break;
690#ifdef UNALIGNED_OK
691 scan_end = *(ush*)(scan+best_len-1);
692#else
693 scan_end1 = scan[best_len-1];
694 scan_end = scan[best_len];
695#endif
696 }
697 } while ((cur_match = prev[cur_match & wmask]) > limit
698 && --chain_length != 0);
699
700 if ((uInt)best_len <= s->lookahead) return best_len;
701 return s->lookahead;
702}
703
704#ifdef DEBUG_ZLIB
705/* ===========================================================================
706 * Check that the match at match_start is indeed a match.
707 */
708static void check_match(
709 deflate_state *s,
710 IPos start,
711 IPos match,
712 int length
713)
714{
715 /* check that the match is indeed a match */
716 if (memcmp((char *)s->window + match,
717 (char *)s->window + start, length) != EQUAL) {
718 fprintf(stderr, " start %u, match %u, length %d\n",
719 start, match, length);
720 do {
721 fprintf(stderr, "%c%c", s->window[match++], s->window[start++]);
722 } while (--length != 0);
723 z_error("invalid match");
724 }
725 if (z_verbose > 1) {
726 fprintf(stderr,"\\[%d,%d]", start-match, length);
727 do { putc(s->window[start++], stderr); } while (--length != 0);
728 }
729}
730#else
731# define check_match(s, start, match, length)
732#endif
733
734/* ===========================================================================
735 * Fill the window when the lookahead becomes insufficient.
736 * Updates strstart and lookahead.
737 *
738 * IN assertion: lookahead < MIN_LOOKAHEAD
739 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
740 * At least one byte has been read, or avail_in == 0; reads are
741 * performed for at least two bytes (required for the zip translate_eol
742 * option -- not supported here).
743 */
744static void fill_window(
745 deflate_state *s
746)
747{
748 register unsigned n, m;
749 register Pos *p;
750 unsigned more; /* Amount of free space at the end of the window. */
751 uInt wsize = s->w_size;
752
753 do {
754 more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);
755
756 /* Deal with !@#$% 64K limit: */
757 if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
758 more = wsize;
759
760 } else if (more == (unsigned)(-1)) {
761 /* Very unlikely, but possible on 16 bit machine if strstart == 0
762 * and lookahead == 1 (input done one byte at time)
763 */
764 more--;
765
766 /* If the window is almost full and there is insufficient lookahead,
767 * move the upper half to the lower one to make room in the upper half.
768 */
769 } else if (s->strstart >= wsize+MAX_DIST(s)) {
770
771 memcpy((char *)s->window, (char *)s->window+wsize,
772 (unsigned)wsize);
773 s->match_start -= wsize;
774 s->strstart -= wsize; /* we now have strstart >= MAX_DIST */
775 s->block_start -= (long) wsize;
776
777 /* Slide the hash table (could be avoided with 32 bit values
778 at the expense of memory usage). We slide even when level == 0
779 to keep the hash table consistent if we switch back to level > 0
780 later. (Using level 0 permanently is not an optimal usage of
781 zlib, so we don't care about this pathological case.)
782 */
783 n = s->hash_size;
784 p = &s->head[n];
785 do {
786 m = *--p;
787 *p = (Pos)(m >= wsize ? m-wsize : NIL);
788 } while (--n);
789
790 n = wsize;
791 p = &s->prev[n];
792 do {
793 m = *--p;
794 *p = (Pos)(m >= wsize ? m-wsize : NIL);
795 /* If n is not on any hash chain, prev[n] is garbage but
796 * its value will never be used.
797 */
798 } while (--n);
799 more += wsize;
800 }
801 if (s->strm->avail_in == 0) return;
802
803 /* If there was no sliding:
804 * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
805 * more == window_size - lookahead - strstart
806 * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
807 * => more >= window_size - 2*WSIZE + 2
808 * In the BIG_MEM or MMAP case (not yet supported),
809 * window_size == input_size + MIN_LOOKAHEAD &&
810 * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
811 * Otherwise, window_size == 2*WSIZE so more >= 2.
812 * If there was sliding, more >= WSIZE. So in all cases, more >= 2.
813 */
814 Assert(more >= 2, "more < 2");
815
816 n = read_buf(strm: s->strm, buf: s->window + s->strstart + s->lookahead, size: more);
817 s->lookahead += n;
818
819 /* Initialize the hash value now that we have some input: */
820 if (s->lookahead >= MIN_MATCH) {
821 s->ins_h = s->window[s->strstart];
822 UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
823#if MIN_MATCH != 3
824 Call UPDATE_HASH() MIN_MATCH-3 more times
825#endif
826 }
827 /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
828 * but this is not important since only literal bytes will be emitted.
829 */
830
831 } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0);
832}
833
834/* ===========================================================================
835 * Flush the current block, with given end-of-file flag.
836 * IN assertion: strstart is set to the end of the current match.
837 */
838#define FLUSH_BLOCK_ONLY(s, eof) { \
839 zlib_tr_flush_block(s, (s->block_start >= 0L ? \
840 (char *)&s->window[(unsigned)s->block_start] : \
841 NULL), \
842 (ulg)((long)s->strstart - s->block_start), \
843 (eof)); \
844 s->block_start = s->strstart; \
845 flush_pending(s->strm); \
846 Tracev((stderr,"[FLUSH]")); \
847}
848
849/* Same but force premature exit if necessary. */
850#define FLUSH_BLOCK(s, eof) { \
851 FLUSH_BLOCK_ONLY(s, eof); \
852 if (s->strm->avail_out == 0) return (eof) ? finish_started : need_more; \
853}
854
855/* ===========================================================================
856 * Copy without compression as much as possible from the input stream, return
857 * the current block state.
858 * This function does not insert new strings in the dictionary since
859 * uncompressible data is probably not useful. This function is used
860 * only for the level=0 compression option.
861 * NOTE: this function should be optimized to avoid extra copying from
862 * window to pending_buf.
863 */
864static block_state deflate_stored(
865 deflate_state *s,
866 int flush
867)
868{
869 /* Stored blocks are limited to 0xffff bytes, pending_buf is limited
870 * to pending_buf_size, and each stored block has a 5 byte header:
871 */
872 ulg max_block_size = 0xffff;
873 ulg max_start;
874
875 if (max_block_size > s->pending_buf_size - 5) {
876 max_block_size = s->pending_buf_size - 5;
877 }
878
879 /* Copy as much as possible from input to output: */
880 for (;;) {
881 /* Fill the window as much as possible: */
882 if (s->lookahead <= 1) {
883
884 Assert(s->strstart < s->w_size+MAX_DIST(s) ||
885 s->block_start >= (long)s->w_size, "slide too late");
886
887 fill_window(s);
888 if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more;
889
890 if (s->lookahead == 0) break; /* flush the current block */
891 }
892 Assert(s->block_start >= 0L, "block gone");
893
894 s->strstart += s->lookahead;
895 s->lookahead = 0;
896
897 /* Emit a stored block if pending_buf will be full: */
898 max_start = s->block_start + max_block_size;
899 if (s->strstart == 0 || (ulg)s->strstart >= max_start) {
900 /* strstart == 0 is possible when wraparound on 16-bit machine */
901 s->lookahead = (uInt)(s->strstart - max_start);
902 s->strstart = (uInt)max_start;
903 FLUSH_BLOCK(s, 0);
904 }
905 /* Flush if we may have to slide, otherwise block_start may become
906 * negative and the data will be gone:
907 */
908 if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) {
909 FLUSH_BLOCK(s, 0);
910 }
911 }
912 FLUSH_BLOCK(s, flush == Z_FINISH);
913 return flush == Z_FINISH ? finish_done : block_done;
914}
915
916/* ===========================================================================
917 * Compress as much as possible from the input stream, return the current
918 * block state.
919 * This function does not perform lazy evaluation of matches and inserts
920 * new strings in the dictionary only for unmatched strings or for short
921 * matches. It is used only for the fast compression options.
922 */
923static block_state deflate_fast(
924 deflate_state *s,
925 int flush
926)
927{
928 IPos hash_head = NIL; /* head of the hash chain */
929 int bflush; /* set if current block must be flushed */
930
931 for (;;) {
932 /* Make sure that we always have enough lookahead, except
933 * at the end of the input file. We need MAX_MATCH bytes
934 * for the next match, plus MIN_MATCH bytes to insert the
935 * string following the next match.
936 */
937 if (s->lookahead < MIN_LOOKAHEAD) {
938 fill_window(s);
939 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
940 return need_more;
941 }
942 if (s->lookahead == 0) break; /* flush the current block */
943 }
944
945 /* Insert the string window[strstart .. strstart+2] in the
946 * dictionary, and set hash_head to the head of the hash chain:
947 */
948 if (s->lookahead >= MIN_MATCH) {
949 INSERT_STRING(s, s->strstart, hash_head);
950 }
951
952 /* Find the longest match, discarding those <= prev_length.
953 * At this point we have always match_length < MIN_MATCH
954 */
955 if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) {
956 /* To simplify the code, we prevent matches with the string
957 * of window index 0 (in particular we have to avoid a match
958 * of the string with itself at the start of the input file).
959 */
960 if (s->strategy != Z_HUFFMAN_ONLY) {
961 s->match_length = longest_match (s, cur_match: hash_head);
962 }
963 /* longest_match() sets match_start */
964 }
965 if (s->match_length >= MIN_MATCH) {
966 check_match(s, s->strstart, s->match_start, s->match_length);
967
968 bflush = zlib_tr_tally(s, dist: s->strstart - s->match_start,
969 lc: s->match_length - MIN_MATCH);
970
971 s->lookahead -= s->match_length;
972
973 /* Insert new strings in the hash table only if the match length
974 * is not too large. This saves time but degrades compression.
975 */
976 if (s->match_length <= s->max_insert_length &&
977 s->lookahead >= MIN_MATCH) {
978 s->match_length--; /* string at strstart already in hash table */
979 do {
980 s->strstart++;
981 INSERT_STRING(s, s->strstart, hash_head);
982 /* strstart never exceeds WSIZE-MAX_MATCH, so there are
983 * always MIN_MATCH bytes ahead.
984 */
985 } while (--s->match_length != 0);
986 s->strstart++;
987 } else {
988 s->strstart += s->match_length;
989 s->match_length = 0;
990 s->ins_h = s->window[s->strstart];
991 UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
992#if MIN_MATCH != 3
993 Call UPDATE_HASH() MIN_MATCH-3 more times
994#endif
995 /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
996 * matter since it will be recomputed at next deflate call.
997 */
998 }
999 } else {
1000 /* No match, output a literal byte */
1001 Tracevv((stderr,"%c", s->window[s->strstart]));
1002 bflush = zlib_tr_tally (s, dist: 0, lc: s->window[s->strstart]);
1003 s->lookahead--;
1004 s->strstart++;
1005 }
1006 if (bflush) FLUSH_BLOCK(s, 0);
1007 }
1008 FLUSH_BLOCK(s, flush == Z_FINISH);
1009 return flush == Z_FINISH ? finish_done : block_done;
1010}
1011
1012/* ===========================================================================
1013 * Same as above, but achieves better compression. We use a lazy
1014 * evaluation for matches: a match is finally adopted only if there is
1015 * no better match at the next window position.
1016 */
1017static block_state deflate_slow(
1018 deflate_state *s,
1019 int flush
1020)
1021{
1022 IPos hash_head = NIL; /* head of hash chain */
1023 int bflush; /* set if current block must be flushed */
1024
1025 /* Process the input block. */
1026 for (;;) {
1027 /* Make sure that we always have enough lookahead, except
1028 * at the end of the input file. We need MAX_MATCH bytes
1029 * for the next match, plus MIN_MATCH bytes to insert the
1030 * string following the next match.
1031 */
1032 if (s->lookahead < MIN_LOOKAHEAD) {
1033 fill_window(s);
1034 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1035 return need_more;
1036 }
1037 if (s->lookahead == 0) break; /* flush the current block */
1038 }
1039
1040 /* Insert the string window[strstart .. strstart+2] in the
1041 * dictionary, and set hash_head to the head of the hash chain:
1042 */
1043 if (s->lookahead >= MIN_MATCH) {
1044 INSERT_STRING(s, s->strstart, hash_head);
1045 }
1046
1047 /* Find the longest match, discarding those <= prev_length.
1048 */
1049 s->prev_length = s->match_length, s->prev_match = s->match_start;
1050 s->match_length = MIN_MATCH-1;
1051
1052 if (hash_head != NIL && s->prev_length < s->max_lazy_match &&
1053 s->strstart - hash_head <= MAX_DIST(s)) {
1054 /* To simplify the code, we prevent matches with the string
1055 * of window index 0 (in particular we have to avoid a match
1056 * of the string with itself at the start of the input file).
1057 */
1058 if (s->strategy != Z_HUFFMAN_ONLY) {
1059 s->match_length = longest_match (s, cur_match: hash_head);
1060 }
1061 /* longest_match() sets match_start */
1062
1063 if (s->match_length <= 5 && (s->strategy == Z_FILTERED ||
1064 (s->match_length == MIN_MATCH &&
1065 s->strstart - s->match_start > TOO_FAR))) {
1066
1067 /* If prev_match is also MIN_MATCH, match_start is garbage
1068 * but we will ignore the current match anyway.
1069 */
1070 s->match_length = MIN_MATCH-1;
1071 }
1072 }
1073 /* If there was a match at the previous step and the current
1074 * match is not better, output the previous match:
1075 */
1076 if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) {
1077 uInt max_insert = s->strstart + s->lookahead - MIN_MATCH;
1078 /* Do not insert strings in hash table beyond this. */
1079
1080 check_match(s, s->strstart-1, s->prev_match, s->prev_length);
1081
1082 bflush = zlib_tr_tally(s, dist: s->strstart -1 - s->prev_match,
1083 lc: s->prev_length - MIN_MATCH);
1084
1085 /* Insert in hash table all strings up to the end of the match.
1086 * strstart-1 and strstart are already inserted. If there is not
1087 * enough lookahead, the last two strings are not inserted in
1088 * the hash table.
1089 */
1090 s->lookahead -= s->prev_length-1;
1091 s->prev_length -= 2;
1092 do {
1093 if (++s->strstart <= max_insert) {
1094 INSERT_STRING(s, s->strstart, hash_head);
1095 }
1096 } while (--s->prev_length != 0);
1097 s->match_available = 0;
1098 s->match_length = MIN_MATCH-1;
1099 s->strstart++;
1100
1101 if (bflush) FLUSH_BLOCK(s, 0);
1102
1103 } else if (s->match_available) {
1104 /* If there was no match at the previous position, output a
1105 * single literal. If there was a match but the current match
1106 * is longer, truncate the previous match to a single literal.
1107 */
1108 Tracevv((stderr,"%c", s->window[s->strstart-1]));
1109 if (zlib_tr_tally (s, dist: 0, lc: s->window[s->strstart-1])) {
1110 FLUSH_BLOCK_ONLY(s, 0);
1111 }
1112 s->strstart++;
1113 s->lookahead--;
1114 if (s->strm->avail_out == 0) return need_more;
1115 } else {
1116 /* There is no previous match to compare with, wait for
1117 * the next step to decide.
1118 */
1119 s->match_available = 1;
1120 s->strstart++;
1121 s->lookahead--;
1122 }
1123 }
1124 Assert (flush != Z_NO_FLUSH, "no flush?");
1125 if (s->match_available) {
1126 Tracevv((stderr,"%c", s->window[s->strstart-1]));
1127 zlib_tr_tally (s, dist: 0, lc: s->window[s->strstart-1]);
1128 s->match_available = 0;
1129 }
1130 FLUSH_BLOCK(s, flush == Z_FINISH);
1131 return flush == Z_FINISH ? finish_done : block_done;
1132}
1133
1134int zlib_deflate_workspacesize(int windowBits, int memLevel)
1135{
1136 if (windowBits < 0) /* undocumented feature: suppress zlib header */
1137 windowBits = -windowBits;
1138
1139 /* Since the return value is typically passed to vmalloc() unchecked... */
1140 BUG_ON(memLevel < 1 || memLevel > MAX_MEM_LEVEL || windowBits < 9 ||
1141 windowBits > 15);
1142
1143 return sizeof(deflate_workspace)
1144 + zlib_deflate_window_memsize(windowBits)
1145 + zlib_deflate_prev_memsize(windowBits)
1146 + zlib_deflate_head_memsize(memLevel)
1147 + zlib_deflate_overlay_memsize(memLevel);
1148}
1149
1150int zlib_deflate_dfltcc_enabled(void)
1151{
1152 return DEFLATE_DFLTCC_ENABLED();
1153}
1154

source code of linux/lib/zlib_deflate/deflate.c