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