2 FastLZ - lightning-fast lossless compression library
4 Copyright (C) 2007 Ariya Hidayat (ariya@kde.org)
5 Copyright (C) 2006 Ariya Hidayat (ariya@kde.org)
6 Copyright (C) 2005 Ariya Hidayat (ariya@kde.org)
8 Permission is hereby granted, free of charge, to any person obtaining a copy
9 of this software and associated documentation files (the "Software"), to deal
10 in the Software without restriction, including without limitation the rights
11 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
12 copies of the Software, and to permit persons to whom the Software is
13 furnished to do so, subject to the following conditions:
15 The above copyright notice and this permission notice shall be included in
16 all copies or substantial portions of the Software.
18 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
21 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
22 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
23 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
27 #if !defined(FASTLZ__COMPRESSOR) && !defined(FASTLZ_DECOMPRESSOR)
30 * Always check for bound when decompressing.
31 * Generally it is best to leave it defined.
36 * Give hints to the compiler for branch prediction optimization.
38 #if defined(__GNUC__) && (__GNUC__ > 2)
39 #define FASTLZ_EXPECT_CONDITIONAL(c) (__builtin_expect((c), 1))
40 #define FASTLZ_UNEXPECT_CONDITIONAL(c) (__builtin_expect((c), 0))
42 #define FASTLZ_EXPECT_CONDITIONAL(c) (c)
43 #define FASTLZ_UNEXPECT_CONDITIONAL(c) (c)
47 * Use inlined functions for supported systems.
49 #if defined(__GNUC__) || defined(__DMC__) || defined(__POCC__) || defined(__WATCOMC__) || defined(__SUNPRO_C)
50 #define FASTLZ_INLINE inline
51 #elif defined(__BORLANDC__) || defined(_MSC_VER) || defined(__LCC__)
52 #define FASTLZ_INLINE __inline
58 * Prevent accessing more than 8-bit at once, except on x86 architectures.
60 #if !defined(FASTLZ_STRICT_ALIGN)
61 #define FASTLZ_STRICT_ALIGN
62 #if defined(__i386__) || defined(__386) /* GNU C, Sun Studio */
63 #undef FASTLZ_STRICT_ALIGN
64 #elif defined(__i486__) || defined(__i586__) || defined(__i686__) /* GNU C */
65 #undef FASTLZ_STRICT_ALIGN
66 #elif defined(_M_IX86) /* Intel, MSVC */
67 #undef FASTLZ_STRICT_ALIGN
69 #undef FASTLZ_STRICT_ALIGN
70 #elif defined(_X86_) /* MinGW */
71 #undef FASTLZ_STRICT_ALIGN
72 #elif defined(__I86__) /* Digital Mars */
73 #undef FASTLZ_STRICT_ALIGN
78 * FIXME: use preprocessor magic to set this on different platforms!
80 typedef unsigned char flzuint8;
81 typedef unsigned short flzuint16;
82 typedef unsigned int flzuint32;
85 int fastlz_compress(const void* input, int length, void* output);
86 int fastlz_compress_level(int level, const void* input, int length, void* output);
87 int fastlz_decompress(const void* input, int length, void* output, int maxout);
90 #define MAX_LEN 264 /* 256 + 8 */
91 #define MAX_DISTANCE 8192
93 #if !defined(FASTLZ_STRICT_ALIGN)
94 #define FASTLZ_READU16(p) *((const flzuint16*)(p))
96 #define FASTLZ_READU16(p) ((p)[0] | (p)[1]<<8)
100 #define HASH_SIZE (1<< HASH_LOG)
101 #define HASH_MASK (HASH_SIZE-1)
102 #define HASH_FUNCTION(v,p) { v = FASTLZ_READU16(p); v ^= FASTLZ_READU16(p+1)^(v>>(16-HASH_LOG));v &= HASH_MASK; }
105 #define FASTLZ_LEVEL 1
107 #undef FASTLZ_COMPRESSOR
108 #undef FASTLZ_DECOMPRESSOR
109 #define FASTLZ_COMPRESSOR fastlz1_compress
110 #define FASTLZ_DECOMPRESSOR fastlz1_decompress
111 static FASTLZ_INLINE int FASTLZ_COMPRESSOR(const void* input, int length, void* output);
112 static FASTLZ_INLINE int FASTLZ_DECOMPRESSOR(const void* input, int length, void* output, int maxout);
116 #define FASTLZ_LEVEL 2
119 #define MAX_DISTANCE 8191
120 #define MAX_FARDISTANCE (65535+MAX_DISTANCE-1)
122 #undef FASTLZ_COMPRESSOR
123 #undef FASTLZ_DECOMPRESSOR
124 #define FASTLZ_COMPRESSOR fastlz2_compress
125 #define FASTLZ_DECOMPRESSOR fastlz2_decompress
126 static FASTLZ_INLINE int FASTLZ_COMPRESSOR(const void* input, int length, void* output);
127 static FASTLZ_INLINE int FASTLZ_DECOMPRESSOR(const void* input, int length, void* output, int maxout);
130 int fastlz_compress(const void* input, int length, void* output)
132 /* for short block, choose fastlz1 */
134 return fastlz1_compress(input, length, output);
137 return fastlz2_compress(input, length, output);
140 int fastlz_decompress(const void* input, int length, void* output, int maxout)
142 /* magic identifier for compression level */
143 int level = ((*(const flzuint8*)input) >> 5) + 1;
146 return fastlz1_decompress(input, length, output, maxout);
148 return fastlz2_decompress(input, length, output, maxout);
150 /* unknown level, trigger error */
154 int fastlz_compress_level(int level, const void* input, int length, void* output)
157 return fastlz1_compress(input, length, output);
159 return fastlz2_compress(input, length, output);
164 #else /* !defined(FASTLZ_COMPRESSOR) && !defined(FASTLZ_DECOMPRESSOR) */
166 static FASTLZ_INLINE int FASTLZ_COMPRESSOR(const void* input, int length, void* output)
168 const flzuint8* ip = (const flzuint8*) input;
169 const flzuint8* ip_bound = ip + length - 2;
170 const flzuint8* ip_limit = ip + length - 12;
171 flzuint8* op = (flzuint8*) output;
173 const flzuint8* htab[HASH_SIZE];
174 const flzuint8** hslot;
180 if(FASTLZ_UNEXPECT_CONDITIONAL(length < 4))
184 /* create literal copy only */
187 while(ip <= ip_bound)
195 /* initializes hash table */
196 for (hslot = htab; hslot < htab + HASH_SIZE; hslot++)
199 /* we start with literal copy */
206 while(FASTLZ_EXPECT_CONDITIONAL(ip < ip_limit))
211 /* minimum match length */
214 /* comparison starting-point */
215 const flzuint8* anchor = ip;
217 /* check for a run */
219 if(ip[0] == ip[-1] && FASTLZ_READU16(ip-1)==FASTLZ_READU16(ip+1))
223 ref = anchor - 1 + 3;
228 /* find potential match */
229 HASH_FUNCTION(hval,ip);
233 /* calculate distance to the match */
234 distance = anchor - ref;
236 /* update hash table */
239 /* is this a match? check the first 3 bytes */
242 (distance >= MAX_DISTANCE) ||
244 (distance >= MAX_FARDISTANCE) ||
246 *ref++ != *ip++ || *ref++!=*ip++ || *ref++!=*ip++)
250 /* far, needs at least 5-byte match */
251 if(distance >= MAX_DISTANCE)
253 if(*ip++ != *ref++ || *ip++!= *ref++)
261 /* last matched byte */
264 /* distance is biased */
269 /* zero distance means a run */
272 if(*ref++ != x) break; else ip++;
277 /* safe because the outer check against ip limit */
278 if(*ref++ != *ip++) break;
279 if(*ref++ != *ip++) break;
280 if(*ref++ != *ip++) break;
281 if(*ref++ != *ip++) break;
282 if(*ref++ != *ip++) break;
283 if(*ref++ != *ip++) break;
284 if(*ref++ != *ip++) break;
285 if(*ref++ != *ip++) break;
287 if(*ref++ != *ip++) break;
291 /* if we have copied something, adjust the copy count */
293 /* copy is biased, '0' means 1 byte copy */
294 *(op-copy-1) = copy-1;
296 /* back, to overwrite the copy count */
299 /* reset literal counter */
302 /* length is biased, '1' means a match of 3 bytes */
306 /* encode the match */
308 if(distance < MAX_DISTANCE)
312 *op++ = (len << 5) + (distance >> 8);
313 *op++ = (distance & 255);
317 *op++ = (7 << 5) + (distance >> 8);
318 for(len-=7; len >= 255; len-= 255)
321 *op++ = (distance & 255);
326 /* far away, but not yet in the another galaxy... */
329 distance -= MAX_DISTANCE;
330 *op++ = (len << 5) + 31;
332 *op++ = distance >> 8;
333 *op++ = distance & 255;
337 distance -= MAX_DISTANCE;
338 *op++ = (7 << 5) + 31;
339 for(len-=7; len >= 255; len-= 255)
343 *op++ = distance >> 8;
344 *op++ = distance & 255;
349 if(FASTLZ_UNEXPECT_CONDITIONAL(len > MAX_LEN-2))
350 while(len > MAX_LEN-2)
352 *op++ = (7 << 5) + (distance >> 8);
353 *op++ = MAX_LEN - 2 - 7 -2;
354 *op++ = (distance & 255);
360 *op++ = (len << 5) + (distance >> 8);
361 *op++ = (distance & 255);
365 *op++ = (7 << 5) + (distance >> 8);
367 *op++ = (distance & 255);
371 /* update the hash at match boundary */
372 HASH_FUNCTION(hval,ip);
374 HASH_FUNCTION(hval,ip);
377 /* assuming literal copy */
386 if(FASTLZ_UNEXPECT_CONDITIONAL(copy == MAX_COPY))
393 /* left-over as literal copy */
395 while(ip <= ip_bound)
406 /* if we have copied something, adjust the copy length */
408 *(op-copy-1) = copy-1;
413 /* marker for fastlz2 */
414 *(flzuint8*)output |= (1 << 5);
417 return op - (flzuint8*)output;
420 static FASTLZ_INLINE int FASTLZ_DECOMPRESSOR(const void* input, int length, void* output, int maxout)
422 const flzuint8* ip = (const flzuint8*) input;
423 const flzuint8* ip_limit = ip + length;
424 flzuint8* op = (flzuint8*) output;
425 flzuint8* op_limit = op + maxout;
426 flzuint32 ctrl = (*ip++) & 31;
431 const flzuint8* ref = op;
432 flzuint32 len = ctrl >> 5;
433 flzuint32 ofs = (ctrl & 31) << 8;
455 /* match from 16-bit distance */
456 if(FASTLZ_UNEXPECT_CONDITIONAL(code==255))
457 if(FASTLZ_EXPECT_CONDITIONAL(ofs==(31 << 8)))
461 ref = op - ofs - MAX_DISTANCE;
466 if (FASTLZ_UNEXPECT_CONDITIONAL(op + len + 3 > op_limit))
469 if (FASTLZ_UNEXPECT_CONDITIONAL(ref-1 < (flzuint8 *)output))
473 if(FASTLZ_EXPECT_CONDITIONAL(ip < ip_limit))
480 /* optimize copy for a run */
481 flzuint8 b = ref[-1];
490 #if !defined(FASTLZ_STRICT_ALIGN)
494 /* copy from reference */
500 #if !defined(FASTLZ_STRICT_ALIGN)
501 /* copy a byte, so that now it's word aligned */
508 /* copy 16-bit at once */
511 p = (const flzuint16*) ref;
512 for(len>>=1; len > 4; len-=4)
531 if (FASTLZ_UNEXPECT_CONDITIONAL(op + ctrl > op_limit))
533 if (FASTLZ_UNEXPECT_CONDITIONAL(ip + ctrl > ip_limit))
538 for(--ctrl; ctrl; ctrl--)
541 loop = FASTLZ_EXPECT_CONDITIONAL(ip < ip_limit);
546 while(FASTLZ_EXPECT_CONDITIONAL(loop));
548 return op - (flzuint8*)output;
551 #endif /* !defined(FASTLZ_COMPRESSOR) && !defined(FASTLZ_DECOMPRESSOR) */