Contents of /tags/mkinitrd-6_2_3/busybox/archival/lzo1x_9x.c
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Mon May 31 20:54:44 2010 UTC (14 years, 3 months ago) by niro
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Mon May 31 20:54:44 2010 UTC (14 years, 3 months ago) by niro
File MIME type: text/plain
File size: 21043 byte(s)
tagged 'mkinitrd-6_2_3'
1 | /* lzo1x_9x.c -- implementation of the LZO1X-999 compression algorithm |
2 | |
3 | This file is part of the LZO real-time data compression library. |
4 | |
5 | Copyright (C) 2008 Markus Franz Xaver Johannes Oberhumer |
6 | Copyright (C) 2007 Markus Franz Xaver Johannes Oberhumer |
7 | Copyright (C) 2006 Markus Franz Xaver Johannes Oberhumer |
8 | Copyright (C) 2005 Markus Franz Xaver Johannes Oberhumer |
9 | Copyright (C) 2004 Markus Franz Xaver Johannes Oberhumer |
10 | Copyright (C) 2003 Markus Franz Xaver Johannes Oberhumer |
11 | Copyright (C) 2002 Markus Franz Xaver Johannes Oberhumer |
12 | Copyright (C) 2001 Markus Franz Xaver Johannes Oberhumer |
13 | Copyright (C) 2000 Markus Franz Xaver Johannes Oberhumer |
14 | Copyright (C) 1999 Markus Franz Xaver Johannes Oberhumer |
15 | Copyright (C) 1998 Markus Franz Xaver Johannes Oberhumer |
16 | Copyright (C) 1997 Markus Franz Xaver Johannes Oberhumer |
17 | Copyright (C) 1996 Markus Franz Xaver Johannes Oberhumer |
18 | All Rights Reserved. |
19 | |
20 | The LZO library is free software; you can redistribute it and/or |
21 | modify it under the terms of the GNU General Public License as |
22 | published by the Free Software Foundation; either version 2 of |
23 | the License, or (at your option) any later version. |
24 | |
25 | The LZO library is distributed in the hope that it will be useful, |
26 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
27 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
28 | GNU General Public License for more details. |
29 | |
30 | You should have received a copy of the GNU General Public License |
31 | along with the LZO library; see the file COPYING. |
32 | If not, write to the Free Software Foundation, Inc., |
33 | 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. |
34 | |
35 | Markus F.X.J. Oberhumer |
36 | <markus@oberhumer.com> |
37 | http://www.oberhumer.com/opensource/lzo/ |
38 | */ |
39 | #include "libbb.h" |
40 | |
41 | /* The following is probably only safe on Intel-compatible processors ... */ |
42 | #define LZO_UNALIGNED_OK_2 |
43 | #define LZO_UNALIGNED_OK_4 |
44 | |
45 | #include "liblzo.h" |
46 | |
47 | #define LZO_MAX(a,b) ((a) >= (b) ? (a) : (b)) |
48 | #define LZO_MIN(a,b) ((a) <= (b) ? (a) : (b)) |
49 | #define LZO_MAX3(a,b,c) ((a) >= (b) ? LZO_MAX(a,c) : LZO_MAX(b,c)) |
50 | |
51 | /*********************************************************************** |
52 | // |
53 | ************************************************************************/ |
54 | #define SWD_N M4_MAX_OFFSET /* size of ring buffer */ |
55 | #define SWD_F 2048 /* upper limit for match length */ |
56 | |
57 | #define SWD_BEST_OFF (LZO_MAX3(M2_MAX_LEN, M3_MAX_LEN, M4_MAX_LEN) + 1) |
58 | |
59 | typedef struct { |
60 | int init; |
61 | |
62 | unsigned look; /* bytes in lookahead buffer */ |
63 | |
64 | unsigned m_len; |
65 | unsigned m_off; |
66 | |
67 | const uint8_t *bp; |
68 | const uint8_t *ip; |
69 | const uint8_t *in; |
70 | const uint8_t *in_end; |
71 | uint8_t *out; |
72 | |
73 | unsigned r1_lit; |
74 | |
75 | } lzo1x_999_t; |
76 | |
77 | #define getbyte(c) ((c).ip < (c).in_end ? *((c).ip)++ : (-1)) |
78 | |
79 | /* lzo_swd.c -- sliding window dictionary */ |
80 | |
81 | /*********************************************************************** |
82 | // |
83 | ************************************************************************/ |
84 | #define SWD_UINT_MAX USHRT_MAX |
85 | |
86 | #ifndef SWD_HSIZE |
87 | # define SWD_HSIZE 16384 |
88 | #endif |
89 | #ifndef SWD_MAX_CHAIN |
90 | # define SWD_MAX_CHAIN 2048 |
91 | #endif |
92 | |
93 | #define HEAD3(b, p) \ |
94 | ( ((0x9f5f * ((((b[p]<<5)^b[p+1])<<5) ^ b[p+2])) >> 5) & (SWD_HSIZE-1) ) |
95 | |
96 | #if defined(LZO_UNALIGNED_OK_2) |
97 | # define HEAD2(b,p) (* (uint16_t *) &(b[p])) |
98 | #else |
99 | # define HEAD2(b,p) (b[p] ^ ((unsigned)b[p+1]<<8)) |
100 | #endif |
101 | #define NIL2 SWD_UINT_MAX |
102 | |
103 | typedef struct lzo_swd { |
104 | /* public - "built-in" */ |
105 | |
106 | /* public - configuration */ |
107 | unsigned max_chain; |
108 | int use_best_off; |
109 | |
110 | /* public - output */ |
111 | unsigned m_len; |
112 | unsigned m_off; |
113 | unsigned look; |
114 | int b_char; |
115 | #if defined(SWD_BEST_OFF) |
116 | unsigned best_off[SWD_BEST_OFF]; |
117 | #endif |
118 | |
119 | /* semi public */ |
120 | lzo1x_999_t *c; |
121 | unsigned m_pos; |
122 | #if defined(SWD_BEST_OFF) |
123 | unsigned best_pos[SWD_BEST_OFF]; |
124 | #endif |
125 | |
126 | /* private */ |
127 | unsigned ip; /* input pointer (lookahead) */ |
128 | unsigned bp; /* buffer pointer */ |
129 | unsigned rp; /* remove pointer */ |
130 | |
131 | unsigned node_count; |
132 | unsigned first_rp; |
133 | |
134 | uint8_t b[SWD_N + SWD_F]; |
135 | uint8_t b_wrap[SWD_F]; /* must follow b */ |
136 | uint16_t head3[SWD_HSIZE]; |
137 | uint16_t succ3[SWD_N + SWD_F]; |
138 | uint16_t best3[SWD_N + SWD_F]; |
139 | uint16_t llen3[SWD_HSIZE]; |
140 | #ifdef HEAD2 |
141 | uint16_t head2[65536L]; |
142 | #endif |
143 | } lzo_swd_t, *lzo_swd_p; |
144 | |
145 | #define SIZEOF_LZO_SWD_T (sizeof(lzo_swd_t)) |
146 | |
147 | |
148 | /* Access macro for head3. |
149 | * head3[key] may be uninitialized, but then its value will never be used. |
150 | */ |
151 | #define s_get_head3(s,key) s->head3[key] |
152 | |
153 | |
154 | /*********************************************************************** |
155 | // |
156 | ************************************************************************/ |
157 | #define B_SIZE (SWD_N + SWD_F) |
158 | |
159 | static int swd_init(lzo_swd_p s) |
160 | { |
161 | /* defaults */ |
162 | s->node_count = SWD_N; |
163 | |
164 | memset(s->llen3, 0, sizeof(s->llen3[0]) * (unsigned)SWD_HSIZE); |
165 | #ifdef HEAD2 |
166 | memset(s->head2, 0xff, sizeof(s->head2[0]) * 65536L); |
167 | assert(s->head2[0] == NIL2); |
168 | #endif |
169 | |
170 | s->ip = 0; |
171 | s->bp = s->ip; |
172 | s->first_rp = s->ip; |
173 | |
174 | assert(s->ip + SWD_F <= B_SIZE); |
175 | s->look = (unsigned) (s->c->in_end - s->c->ip); |
176 | if (s->look > 0) { |
177 | if (s->look > SWD_F) |
178 | s->look = SWD_F; |
179 | memcpy(&s->b[s->ip],s->c->ip,s->look); |
180 | s->c->ip += s->look; |
181 | s->ip += s->look; |
182 | } |
183 | if (s->ip == B_SIZE) |
184 | s->ip = 0; |
185 | |
186 | s->rp = s->first_rp; |
187 | if (s->rp >= s->node_count) |
188 | s->rp -= s->node_count; |
189 | else |
190 | s->rp += B_SIZE - s->node_count; |
191 | |
192 | return LZO_E_OK; |
193 | } |
194 | |
195 | #define swd_pos2off(s,pos) \ |
196 | (s->bp > (pos) ? s->bp - (pos) : B_SIZE - ((pos) - s->bp)) |
197 | |
198 | |
199 | /*********************************************************************** |
200 | // |
201 | ************************************************************************/ |
202 | static void swd_getbyte(lzo_swd_p s) |
203 | { |
204 | int c; |
205 | |
206 | if ((c = getbyte(*(s->c))) < 0) { |
207 | if (s->look > 0) |
208 | --s->look; |
209 | } else { |
210 | s->b[s->ip] = c; |
211 | if (s->ip < SWD_F) |
212 | s->b_wrap[s->ip] = c; |
213 | } |
214 | if (++s->ip == B_SIZE) |
215 | s->ip = 0; |
216 | if (++s->bp == B_SIZE) |
217 | s->bp = 0; |
218 | if (++s->rp == B_SIZE) |
219 | s->rp = 0; |
220 | } |
221 | |
222 | |
223 | /*********************************************************************** |
224 | // remove node from lists |
225 | ************************************************************************/ |
226 | static void swd_remove_node(lzo_swd_p s, unsigned node) |
227 | { |
228 | if (s->node_count == 0) { |
229 | unsigned key; |
230 | |
231 | key = HEAD3(s->b,node); |
232 | assert(s->llen3[key] > 0); |
233 | --s->llen3[key]; |
234 | |
235 | #ifdef HEAD2 |
236 | key = HEAD2(s->b,node); |
237 | assert(s->head2[key] != NIL2); |
238 | if ((unsigned) s->head2[key] == node) |
239 | s->head2[key] = NIL2; |
240 | #endif |
241 | } else |
242 | --s->node_count; |
243 | } |
244 | |
245 | |
246 | /*********************************************************************** |
247 | // |
248 | ************************************************************************/ |
249 | static void swd_accept(lzo_swd_p s, unsigned n) |
250 | { |
251 | assert(n <= s->look); |
252 | |
253 | while (n--) { |
254 | unsigned key; |
255 | |
256 | swd_remove_node(s,s->rp); |
257 | |
258 | /* add bp into HEAD3 */ |
259 | key = HEAD3(s->b,s->bp); |
260 | s->succ3[s->bp] = s_get_head3(s,key); |
261 | s->head3[key] = s->bp; |
262 | s->best3[s->bp] = SWD_F + 1; |
263 | s->llen3[key]++; |
264 | assert(s->llen3[key] <= SWD_N); |
265 | |
266 | #ifdef HEAD2 |
267 | /* add bp into HEAD2 */ |
268 | key = HEAD2(s->b,s->bp); |
269 | s->head2[key] = s->bp; |
270 | #endif |
271 | |
272 | swd_getbyte(s); |
273 | } |
274 | } |
275 | |
276 | |
277 | /*********************************************************************** |
278 | // |
279 | ************************************************************************/ |
280 | static void swd_search(lzo_swd_p s, unsigned node, unsigned cnt) |
281 | { |
282 | const uint8_t *p1; |
283 | const uint8_t *p2; |
284 | const uint8_t *px; |
285 | unsigned m_len = s->m_len; |
286 | const uint8_t *b = s->b; |
287 | const uint8_t *bp = s->b + s->bp; |
288 | const uint8_t *bx = s->b + s->bp + s->look; |
289 | unsigned char scan_end1; |
290 | |
291 | assert(s->m_len > 0); |
292 | |
293 | scan_end1 = bp[m_len - 1]; |
294 | for ( ; cnt-- > 0; node = s->succ3[node]) { |
295 | p1 = bp; |
296 | p2 = b + node; |
297 | px = bx; |
298 | |
299 | assert(m_len < s->look); |
300 | |
301 | if (p2[m_len - 1] == scan_end1 && |
302 | p2[m_len] == p1[m_len] && |
303 | p2[0] == p1[0] && |
304 | p2[1] == p1[1]) { |
305 | unsigned i; |
306 | assert(lzo_memcmp(bp,&b[node],3) == 0); |
307 | |
308 | p1 += 2; p2 += 2; |
309 | do {} while (++p1 < px && *p1 == *++p2); |
310 | i = p1-bp; |
311 | |
312 | assert(lzo_memcmp(bp,&b[node],i) == 0); |
313 | |
314 | #if defined(SWD_BEST_OFF) |
315 | if (i < SWD_BEST_OFF) { |
316 | if (s->best_pos[i] == 0) |
317 | s->best_pos[i] = node + 1; |
318 | } |
319 | #endif |
320 | if (i > m_len) { |
321 | s->m_len = m_len = i; |
322 | s->m_pos = node; |
323 | if (m_len == s->look) |
324 | return; |
325 | if (m_len >= SWD_F) |
326 | return; |
327 | if (m_len > (unsigned) s->best3[node]) |
328 | return; |
329 | scan_end1 = bp[m_len - 1]; |
330 | } |
331 | } |
332 | } |
333 | } |
334 | |
335 | |
336 | /*********************************************************************** |
337 | // |
338 | ************************************************************************/ |
339 | #ifdef HEAD2 |
340 | |
341 | static int swd_search2(lzo_swd_p s) |
342 | { |
343 | unsigned key; |
344 | |
345 | assert(s->look >= 2); |
346 | assert(s->m_len > 0); |
347 | |
348 | key = s->head2[ HEAD2(s->b,s->bp) ]; |
349 | if (key == NIL2) |
350 | return 0; |
351 | assert(lzo_memcmp(&s->b[s->bp],&s->b[key],2) == 0); |
352 | #if defined(SWD_BEST_OFF) |
353 | if (s->best_pos[2] == 0) |
354 | s->best_pos[2] = key + 1; |
355 | #endif |
356 | |
357 | if (s->m_len < 2) { |
358 | s->m_len = 2; |
359 | s->m_pos = key; |
360 | } |
361 | return 1; |
362 | } |
363 | |
364 | #endif |
365 | |
366 | |
367 | /*********************************************************************** |
368 | // |
369 | ************************************************************************/ |
370 | static void swd_findbest(lzo_swd_p s) |
371 | { |
372 | unsigned key; |
373 | unsigned cnt, node; |
374 | unsigned len; |
375 | |
376 | assert(s->m_len > 0); |
377 | |
378 | /* get current head, add bp into HEAD3 */ |
379 | key = HEAD3(s->b,s->bp); |
380 | node = s->succ3[s->bp] = s_get_head3(s,key); |
381 | cnt = s->llen3[key]++; |
382 | assert(s->llen3[key] <= SWD_N + SWD_F); |
383 | if (cnt > s->max_chain) |
384 | cnt = s->max_chain; |
385 | s->head3[key] = s->bp; |
386 | |
387 | s->b_char = s->b[s->bp]; |
388 | len = s->m_len; |
389 | if (s->m_len >= s->look) { |
390 | if (s->look == 0) |
391 | s->b_char = -1; |
392 | s->m_off = 0; |
393 | s->best3[s->bp] = SWD_F + 1; |
394 | } else { |
395 | #ifdef HEAD2 |
396 | if (swd_search2(s)) |
397 | #endif |
398 | if (s->look >= 3) |
399 | swd_search(s,node,cnt); |
400 | if (s->m_len > len) |
401 | s->m_off = swd_pos2off(s,s->m_pos); |
402 | s->best3[s->bp] = s->m_len; |
403 | |
404 | #if defined(SWD_BEST_OFF) |
405 | if (s->use_best_off) { |
406 | int i; |
407 | for (i = 2; i < SWD_BEST_OFF; i++) |
408 | if (s->best_pos[i] > 0) |
409 | s->best_off[i] = swd_pos2off(s,s->best_pos[i]-1); |
410 | else |
411 | s->best_off[i] = 0; |
412 | } |
413 | #endif |
414 | } |
415 | |
416 | swd_remove_node(s,s->rp); |
417 | |
418 | #ifdef HEAD2 |
419 | /* add bp into HEAD2 */ |
420 | key = HEAD2(s->b,s->bp); |
421 | s->head2[key] = s->bp; |
422 | #endif |
423 | } |
424 | |
425 | #undef HEAD3 |
426 | #undef HEAD2 |
427 | #undef s_get_head3 |
428 | |
429 | |
430 | /*********************************************************************** |
431 | // |
432 | ************************************************************************/ |
433 | static int init_match(lzo1x_999_t *c, lzo_swd_p s, uint32_t use_best_off) |
434 | { |
435 | int r; |
436 | |
437 | assert(!c->init); |
438 | c->init = 1; |
439 | |
440 | s->c = c; |
441 | |
442 | r = swd_init(s); |
443 | if (r != 0) |
444 | return r; |
445 | |
446 | s->use_best_off = use_best_off; |
447 | return r; |
448 | } |
449 | |
450 | |
451 | /*********************************************************************** |
452 | // |
453 | ************************************************************************/ |
454 | static int find_match(lzo1x_999_t *c, lzo_swd_p s, |
455 | unsigned this_len, unsigned skip) |
456 | { |
457 | assert(c->init); |
458 | |
459 | if (skip > 0) { |
460 | assert(this_len >= skip); |
461 | swd_accept(s, this_len - skip); |
462 | } else { |
463 | assert(this_len <= 1); |
464 | } |
465 | |
466 | s->m_len = 1; |
467 | s->m_len = 1; |
468 | #ifdef SWD_BEST_OFF |
469 | if (s->use_best_off) |
470 | memset(s->best_pos,0,sizeof(s->best_pos)); |
471 | #endif |
472 | swd_findbest(s); |
473 | c->m_len = s->m_len; |
474 | c->m_off = s->m_off; |
475 | |
476 | swd_getbyte(s); |
477 | |
478 | if (s->b_char < 0) { |
479 | c->look = 0; |
480 | c->m_len = 0; |
481 | } else { |
482 | c->look = s->look + 1; |
483 | } |
484 | c->bp = c->ip - c->look; |
485 | |
486 | return LZO_E_OK; |
487 | } |
488 | |
489 | /* this is a public functions, but there is no prototype in a header file */ |
490 | static int lzo1x_999_compress_internal(const uint8_t *in , unsigned in_len, |
491 | uint8_t *out, unsigned *out_len, |
492 | void *wrkmem, |
493 | unsigned good_length, |
494 | unsigned max_lazy, |
495 | unsigned max_chain, |
496 | uint32_t use_best_off); |
497 | |
498 | |
499 | /*********************************************************************** |
500 | // |
501 | ************************************************************************/ |
502 | static uint8_t *code_match(lzo1x_999_t *c, |
503 | uint8_t *op, unsigned m_len, unsigned m_off) |
504 | { |
505 | assert(op > c->out); |
506 | if (m_len == 2) { |
507 | assert(m_off <= M1_MAX_OFFSET); |
508 | assert(c->r1_lit > 0); assert(c->r1_lit < 4); |
509 | m_off -= 1; |
510 | *op++ = M1_MARKER | ((m_off & 3) << 2); |
511 | *op++ = m_off >> 2; |
512 | } else if (m_len <= M2_MAX_LEN && m_off <= M2_MAX_OFFSET) { |
513 | assert(m_len >= 3); |
514 | m_off -= 1; |
515 | *op++ = ((m_len - 1) << 5) | ((m_off & 7) << 2); |
516 | *op++ = m_off >> 3; |
517 | assert(op[-2] >= M2_MARKER); |
518 | } else if (m_len == M2_MIN_LEN && m_off <= MX_MAX_OFFSET && c->r1_lit >= 4) { |
519 | assert(m_len == 3); |
520 | assert(m_off > M2_MAX_OFFSET); |
521 | m_off -= 1 + M2_MAX_OFFSET; |
522 | *op++ = M1_MARKER | ((m_off & 3) << 2); |
523 | *op++ = m_off >> 2; |
524 | } else if (m_off <= M3_MAX_OFFSET) { |
525 | assert(m_len >= 3); |
526 | m_off -= 1; |
527 | if (m_len <= M3_MAX_LEN) |
528 | *op++ = M3_MARKER | (m_len - 2); |
529 | else { |
530 | m_len -= M3_MAX_LEN; |
531 | *op++ = M3_MARKER | 0; |
532 | while (m_len > 255) |
533 | { |
534 | m_len -= 255; |
535 | *op++ = 0; |
536 | } |
537 | assert(m_len > 0); |
538 | *op++ = m_len; |
539 | } |
540 | *op++ = m_off << 2; |
541 | *op++ = m_off >> 6; |
542 | } else { |
543 | unsigned k; |
544 | |
545 | assert(m_len >= 3); |
546 | assert(m_off > 0x4000); assert(m_off <= 0xbfff); |
547 | m_off -= 0x4000; |
548 | k = (m_off & 0x4000) >> 11; |
549 | if (m_len <= M4_MAX_LEN) |
550 | *op++ = M4_MARKER | k | (m_len - 2); |
551 | else { |
552 | m_len -= M4_MAX_LEN; |
553 | *op++ = M4_MARKER | k | 0; |
554 | while (m_len > 255) |
555 | { |
556 | m_len -= 255; |
557 | *op++ = 0; |
558 | } |
559 | assert(m_len > 0); |
560 | *op++ = m_len; |
561 | } |
562 | *op++ = m_off << 2; |
563 | *op++ = m_off >> 6; |
564 | } |
565 | |
566 | return op; |
567 | } |
568 | |
569 | |
570 | static uint8_t *STORE_RUN(lzo1x_999_t *c, uint8_t *op, |
571 | const uint8_t *ii, unsigned t) |
572 | { |
573 | if (op == c->out && t <= 238) { |
574 | *op++ = 17 + t; |
575 | } else if (t <= 3) { |
576 | op[-2] |= t; |
577 | } else if (t <= 18) { |
578 | *op++ = t - 3; |
579 | } else { |
580 | unsigned tt = t - 18; |
581 | |
582 | *op++ = 0; |
583 | while (tt > 255) { |
584 | tt -= 255; |
585 | *op++ = 0; |
586 | } |
587 | assert(tt > 0); |
588 | *op++ = tt; |
589 | } |
590 | do *op++ = *ii++; while (--t > 0); |
591 | |
592 | return op; |
593 | } |
594 | |
595 | |
596 | static uint8_t *code_run(lzo1x_999_t *c, uint8_t *op, const uint8_t *ii, |
597 | unsigned lit) |
598 | { |
599 | if (lit > 0) { |
600 | assert(m_len >= 2); |
601 | op = STORE_RUN(c,op,ii,lit); |
602 | } else { |
603 | assert(m_len >= 3); |
604 | } |
605 | c->r1_lit = lit; |
606 | |
607 | return op; |
608 | } |
609 | |
610 | |
611 | /*********************************************************************** |
612 | // |
613 | ************************************************************************/ |
614 | static int len_of_coded_match(unsigned m_len, unsigned m_off, unsigned lit) |
615 | { |
616 | int n = 4; |
617 | |
618 | if (m_len < 2) |
619 | return -1; |
620 | if (m_len == 2) |
621 | return (m_off <= M1_MAX_OFFSET && lit > 0 && lit < 4) ? 2 : -1; |
622 | if (m_len <= M2_MAX_LEN && m_off <= M2_MAX_OFFSET) |
623 | return 2; |
624 | if (m_len == M2_MIN_LEN && m_off <= MX_MAX_OFFSET && lit >= 4) |
625 | return 2; |
626 | if (m_off <= M3_MAX_OFFSET) { |
627 | if (m_len <= M3_MAX_LEN) |
628 | return 3; |
629 | m_len -= M3_MAX_LEN; |
630 | } else if (m_off <= M4_MAX_OFFSET) { |
631 | if (m_len <= M4_MAX_LEN) |
632 | return 3; |
633 | m_len -= M4_MAX_LEN; |
634 | } else |
635 | return -1; |
636 | while (m_len > 255) { |
637 | m_len -= 255; |
638 | n++; |
639 | } |
640 | return n; |
641 | } |
642 | |
643 | |
644 | static int min_gain(unsigned ahead, unsigned lit1, |
645 | unsigned lit2, int l1, int l2, int l3) |
646 | { |
647 | int lazy_match_min_gain = 0; |
648 | |
649 | assert (ahead >= 1); |
650 | lazy_match_min_gain += ahead; |
651 | |
652 | if (lit1 <= 3) |
653 | lazy_match_min_gain += (lit2 <= 3) ? 0 : 2; |
654 | else if (lit1 <= 18) |
655 | lazy_match_min_gain += (lit2 <= 18) ? 0 : 1; |
656 | |
657 | lazy_match_min_gain += (l2 - l1) * 2; |
658 | if (l3 > 0) |
659 | lazy_match_min_gain -= (ahead - l3) * 2; |
660 | |
661 | if (lazy_match_min_gain < 0) |
662 | lazy_match_min_gain = 0; |
663 | |
664 | return lazy_match_min_gain; |
665 | } |
666 | |
667 | |
668 | /*********************************************************************** |
669 | // |
670 | ************************************************************************/ |
671 | #if defined(SWD_BEST_OFF) |
672 | |
673 | static void better_match(const lzo_swd_p swd, |
674 | unsigned *m_len, unsigned *m_off) |
675 | { |
676 | |
677 | if (*m_len <= M2_MIN_LEN) |
678 | return; |
679 | |
680 | if (*m_off <= M2_MAX_OFFSET) |
681 | return; |
682 | |
683 | /* M3/M4 -> M2 */ |
684 | if (*m_off > M2_MAX_OFFSET && |
685 | *m_len >= M2_MIN_LEN + 1 && *m_len <= M2_MAX_LEN + 1 && |
686 | swd->best_off[*m_len-1] && swd->best_off[*m_len-1] <= M2_MAX_OFFSET) |
687 | { |
688 | *m_len = *m_len - 1; |
689 | *m_off = swd->best_off[*m_len]; |
690 | return; |
691 | } |
692 | |
693 | /* M4 -> M2 */ |
694 | if (*m_off > M3_MAX_OFFSET && |
695 | *m_len >= M4_MAX_LEN + 1 && *m_len <= M2_MAX_LEN + 2 && |
696 | swd->best_off[*m_len-2] && swd->best_off[*m_len-2] <= M2_MAX_OFFSET) |
697 | { |
698 | *m_len = *m_len - 2; |
699 | *m_off = swd->best_off[*m_len]; |
700 | return; |
701 | } |
702 | /* M4 -> M3 */ |
703 | if (*m_off > M3_MAX_OFFSET && |
704 | *m_len >= M4_MAX_LEN + 1 && *m_len <= M3_MAX_LEN + 1 && |
705 | swd->best_off[*m_len-1] && swd->best_off[*m_len-1] <= M3_MAX_OFFSET) |
706 | { |
707 | *m_len = *m_len - 1; |
708 | *m_off = swd->best_off[*m_len]; |
709 | } |
710 | } |
711 | |
712 | #endif |
713 | |
714 | |
715 | /*********************************************************************** |
716 | // |
717 | ************************************************************************/ |
718 | static int lzo1x_999_compress_internal(const uint8_t *in, unsigned in_len, |
719 | uint8_t *out, unsigned *out_len, |
720 | void *wrkmem, |
721 | unsigned good_length, |
722 | unsigned max_lazy, |
723 | unsigned max_chain, |
724 | uint32_t use_best_off) |
725 | { |
726 | uint8_t *op; |
727 | const uint8_t *ii; |
728 | unsigned lit; |
729 | unsigned m_len, m_off; |
730 | lzo1x_999_t cc; |
731 | lzo1x_999_t * const c = &cc; |
732 | lzo_swd_p const swd = (lzo_swd_p) wrkmem; |
733 | int r; |
734 | |
735 | c->init = 0; |
736 | c->ip = c->in = in; |
737 | c->in_end = in + in_len; |
738 | c->out = out; |
739 | |
740 | op = out; |
741 | ii = c->ip; /* point to start of literal run */ |
742 | lit = 0; |
743 | c->r1_lit = 0; |
744 | |
745 | r = init_match(c, swd, use_best_off); |
746 | if (r != 0) |
747 | return r; |
748 | swd->max_chain = max_chain; |
749 | |
750 | r = find_match(c, swd, 0, 0); |
751 | if (r != 0) |
752 | return r; |
753 | |
754 | while (c->look > 0) { |
755 | unsigned ahead; |
756 | unsigned max_ahead; |
757 | int l1, l2, l3; |
758 | |
759 | m_len = c->m_len; |
760 | m_off = c->m_off; |
761 | |
762 | assert(c->bp == c->ip - c->look); |
763 | assert(c->bp >= in); |
764 | if (lit == 0) |
765 | ii = c->bp; |
766 | assert(ii + lit == c->bp); |
767 | assert(swd->b_char == *(c->bp)); |
768 | |
769 | if ( m_len < 2 || |
770 | (m_len == 2 && (m_off > M1_MAX_OFFSET || lit == 0 || lit >= 4)) || |
771 | /* Do not accept this match for compressed-data compatibility |
772 | * with LZO v1.01 and before |
773 | * [ might be a problem for decompress() and optimize() ] |
774 | */ |
775 | (m_len == 2 && op == out) || |
776 | (op == out && lit == 0)) |
777 | { |
778 | /* a literal */ |
779 | m_len = 0; |
780 | } |
781 | else if (m_len == M2_MIN_LEN) { |
782 | /* compression ratio improves if we code a literal in some cases */ |
783 | if (m_off > MX_MAX_OFFSET && lit >= 4) |
784 | m_len = 0; |
785 | } |
786 | |
787 | if (m_len == 0) { |
788 | /* a literal */ |
789 | lit++; |
790 | swd->max_chain = max_chain; |
791 | r = find_match(c,swd,1,0); |
792 | assert(r == 0); |
793 | continue; |
794 | } |
795 | |
796 | /* a match */ |
797 | #if defined(SWD_BEST_OFF) |
798 | if (swd->use_best_off) |
799 | better_match(swd,&m_len,&m_off); |
800 | #endif |
801 | |
802 | /* shall we try a lazy match ? */ |
803 | ahead = 0; |
804 | if (m_len >= max_lazy) { |
805 | /* no */ |
806 | l1 = 0; |
807 | max_ahead = 0; |
808 | } else { |
809 | /* yes, try a lazy match */ |
810 | l1 = len_of_coded_match(m_len,m_off,lit); |
811 | assert(l1 > 0); |
812 | max_ahead = LZO_MIN(2, (unsigned)l1 - 1); |
813 | } |
814 | |
815 | |
816 | while (ahead < max_ahead && c->look > m_len) { |
817 | int lazy_match_min_gain; |
818 | |
819 | if (m_len >= good_length) |
820 | swd->max_chain = max_chain >> 2; |
821 | else |
822 | swd->max_chain = max_chain; |
823 | r = find_match(c,swd,1,0); |
824 | ahead++; |
825 | |
826 | assert(r == 0); |
827 | assert(c->look > 0); |
828 | assert(ii + lit + ahead == c->bp); |
829 | |
830 | if (c->m_len < m_len) |
831 | continue; |
832 | if (c->m_len == m_len && c->m_off >= m_off) |
833 | continue; |
834 | #if defined(SWD_BEST_OFF) |
835 | if (swd->use_best_off) |
836 | better_match(swd,&c->m_len,&c->m_off); |
837 | #endif |
838 | l2 = len_of_coded_match(c->m_len,c->m_off,lit+ahead); |
839 | if (l2 < 0) |
840 | continue; |
841 | |
842 | /* compressed-data compatibility [see above] */ |
843 | l3 = (op == out) ? -1 : len_of_coded_match(ahead,m_off,lit); |
844 | |
845 | lazy_match_min_gain = min_gain(ahead,lit,lit+ahead,l1,l2,l3); |
846 | if (c->m_len >= m_len + lazy_match_min_gain) { |
847 | if (l3 > 0) { |
848 | /* code previous run */ |
849 | op = code_run(c,op,ii,lit); |
850 | lit = 0; |
851 | /* code shortened match */ |
852 | op = code_match(c,op,ahead,m_off); |
853 | } else { |
854 | lit += ahead; |
855 | assert(ii + lit == c->bp); |
856 | } |
857 | goto lazy_match_done; |
858 | } |
859 | } |
860 | |
861 | assert(ii + lit + ahead == c->bp); |
862 | |
863 | /* 1 - code run */ |
864 | op = code_run(c,op,ii,lit); |
865 | lit = 0; |
866 | |
867 | /* 2 - code match */ |
868 | op = code_match(c,op,m_len,m_off); |
869 | swd->max_chain = max_chain; |
870 | r = find_match(c,swd,m_len,1+ahead); |
871 | assert(r == 0); |
872 | |
873 | lazy_match_done: ; |
874 | } |
875 | |
876 | /* store final run */ |
877 | if (lit > 0) |
878 | op = STORE_RUN(c,op,ii,lit); |
879 | |
880 | #if defined(LZO_EOF_CODE) |
881 | *op++ = M4_MARKER | 1; |
882 | *op++ = 0; |
883 | *op++ = 0; |
884 | #endif |
885 | |
886 | *out_len = op - out; |
887 | |
888 | return LZO_E_OK; |
889 | } |
890 | |
891 | |
892 | /*********************************************************************** |
893 | // |
894 | ************************************************************************/ |
895 | int lzo1x_999_compress_level(const uint8_t *in, unsigned in_len, |
896 | uint8_t *out, unsigned *out_len, |
897 | void *wrkmem, |
898 | int compression_level) |
899 | { |
900 | static const struct { |
901 | uint16_t good_length; |
902 | uint16_t max_lazy; |
903 | uint16_t max_chain; |
904 | uint16_t use_best_off; |
905 | } c[3] = { |
906 | { 8, 32, 256, 0 }, |
907 | { 32, 128, 2048, 1 }, |
908 | { SWD_F, SWD_F, 4096, 1 } /* max. compression */ |
909 | }; |
910 | |
911 | if (compression_level < 7 || compression_level > 9) |
912 | return LZO_E_ERROR; |
913 | |
914 | compression_level -= 7; |
915 | return lzo1x_999_compress_internal(in, in_len, out, out_len, wrkmem, |
916 | c[compression_level].good_length, |
917 | c[compression_level].max_lazy, |
918 | c[compression_level].max_chain, |
919 | c[compression_level].use_best_off); |
920 | } |