summaryrefslogtreecommitdiffstats
path: root/include/linux/lz4.h
blob: 394e3d9213b8d58cab811737cc8dbf1029650852 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
/* LZ4 Kernel Interface
 *
 * Copyright (C) 2013, LG Electronics, Kyungsik Lee <kyungsik.lee@lge.com>
 * Copyright (C) 2016, Sven Schmidt <4sschmid@informatik.uni-hamburg.de>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This file is based on the original header file
 * for LZ4 - Fast LZ compression algorithm.
 *
 * LZ4 - Fast LZ compression algorithm
 * Copyright (C) 2011-2016, Yann Collet.
 * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *	* Redistributions of source code must retain the above copyright
 *	  notice, this list of conditions and the following disclaimer.
 *	* Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * You can contact the author at :
 *	- LZ4 homepage : http://www.lz4.org
 *	- LZ4 source repository : https://github.com/lz4/lz4
 */

#ifndef __LZ4_H__
#define __LZ4_H__

#include <linux/types.h>
#include <linux/string.h>	 /* memset, memcpy */

/*-************************************************************************
 *	CONSTANTS
 **************************************************************************/
/*
 * LZ4_MEMORY_USAGE :
 * Memory usage formula : N->2^N Bytes
 * (examples : 10 -> 1KB; 12 -> 4KB ; 16 -> 64KB; 20 -> 1MB; etc.)
 * Increasing memory usage improves compression ratio
 * Reduced memory usage can improve speed, due to cache effect
 * Default value is 14, for 16KB, which nicely fits into Intel x86 L1 cache
 */
#define LZ4_MEMORY_USAGE 14

#define LZ4_MAX_INPUT_SIZE	0x7E000000 /* 2 113 929 216 bytes */
#define LZ4_COMPRESSBOUND(isize)	(\
	(unsigned int)(isize) > (unsigned int)LZ4_MAX_INPUT_SIZE \
	? 0 \
	: (isize) + ((isize)/255) + 16)

#define LZ4_ACCELERATION_DEFAULT 1
#define LZ4_HASHLOG	 (LZ4_MEMORY_USAGE-2)
#define LZ4_HASHTABLESIZE (1 << LZ4_MEMORY_USAGE)
#define LZ4_HASH_SIZE_U32 (1 << LZ4_HASHLOG)

#define LZ4HC_MIN_CLEVEL			3
#define LZ4HC_DEFAULT_CLEVEL			9
#define LZ4HC_MAX_CLEVEL			16

#define LZ4HC_DICTIONARY_LOGSIZE 16
#define LZ4HC_MAXD (1<<LZ4HC_DICTIONARY_LOGSIZE)
#define LZ4HC_MAXD_MASK (LZ4HC_MAXD - 1)
#define LZ4HC_HASH_LOG (LZ4HC_DICTIONARY_LOGSIZE - 1)
#define LZ4HC_HASHTABLESIZE (1 << LZ4HC_HASH_LOG)
#define LZ4HC_HASH_MASK (LZ4HC_HASHTABLESIZE - 1)

/*-************************************************************************
 *	STREAMING CONSTANTS AND STRUCTURES
 **************************************************************************/
#define LZ4_STREAMSIZE_U64 ((1 << (LZ4_MEMORY_USAGE - 3)) + 4)
#define LZ4_STREAMSIZE	(LZ4_STREAMSIZE_U64 * sizeof(unsigned long long))

#define LZ4_STREAMHCSIZE        262192
#define LZ4_STREAMHCSIZE_SIZET (262192 / sizeof(size_t))

#define LZ4_STREAMDECODESIZE_U64	4
#define LZ4_STREAMDECODESIZE		 (LZ4_STREAMDECODESIZE_U64 * \
	sizeof(unsigned long long))

/*
 * LZ4_stream_t - information structure to track an LZ4 stream.
 */
typedef struct {
	uint32_t hashTable[LZ4_HASH_SIZE_U32];
	uint32_t currentOffset;
	uint32_t initCheck;
	const uint8_t *dictionary;
	uint8_t *bufferStart;
	uint32_t dictSize;
} LZ4_stream_t_internal;
typedef union {
	unsigned long long table[LZ4_STREAMSIZE_U64];
	LZ4_stream_t_internal internal_donotuse;
} LZ4_stream_t;

/*
 * LZ4_streamHC_t - information structure to track an LZ4HC stream.
 */
typedef struct {
	unsigned int	 hashTable[LZ4HC_HASHTABLESIZE];
	unsigned short	 chainTable[LZ4HC_MAXD];
	/* next block to continue on current prefix */
	const unsigned char *end;
	/* All index relative to this position */
	const unsigned char *base;
	/* alternate base for extDict */
	const unsigned char *dictBase;
	/* below that point, need extDict */
	unsigned int	 dictLimit;
	/* below that point, no more dict */
	unsigned int	 lowLimit;
	/* index from which to continue dict update */
	unsigned int	 nextToUpdate;
	unsigned int	 compressionLevel;
} LZ4HC_CCtx_internal;
typedef union {
	size_t table[LZ4_STREAMHCSIZE_SIZET];
	LZ4HC_CCtx_internal internal_donotuse;
} LZ4_streamHC_t;

/*
 * LZ4_streamDecode_t - information structure to track an
 *	LZ4 stream during decompression.
 *
 * init this structure using LZ4_setStreamDecode (or memset()) before first use
 */
typedef struct {
	const uint8_t *externalDict;
	size_t extDictSize;
	const uint8_t *prefixEnd;
	size_t prefixSize;
} LZ4_streamDecode_t_internal;
typedef union {
	unsigned long long table[LZ4_STREAMDECODESIZE_U64];
	LZ4_streamDecode_t_internal internal_donotuse;
} LZ4_streamDecode_t;

/*-************************************************************************
 *	SIZE OF STATE
 **************************************************************************/
#define LZ4_MEM_COMPRESS	LZ4_STREAMSIZE
#define LZ4HC_MEM_COMPRESS	LZ4_STREAMHCSIZE

/*-************************************************************************
 *	Compression Functions
 **************************************************************************/

/**
 * LZ4_compressBound() - Max. output size in worst case szenarios
 * @isize: Size of the input data
 *
 * Return: Max. size LZ4 may output in a "worst case" szenario
 * (data not compressible)
 */
static inline int LZ4_compressBound(size_t isize)
{
	return LZ4_COMPRESSBOUND(isize);
}

/**
 * LZ4_compress_default() - Compress data from source to dest
 * @source: source address of the original data
 * @dest: output buffer address of the compressed data
 * @inputSize: size of the input data. Max supported value is LZ4_MAX_INPUT_SIZE
 * @maxOutputSize: full or partial size of buffer 'dest'
 *	which must be already allocated
 * @wrkmem: address of the working memory.
 *	This requires 'workmem' of LZ4_MEM_COMPRESS.
 *
 * Compresses 'sourceSize' bytes from buffer 'source'
 * into already allocated 'dest' buffer of size 'maxOutputSize'.
 * Compression is guaranteed to succeed if
 * 'maxOutputSize' >= LZ4_compressBound(inputSize).
 * It also runs faster, so it's a recommended setting.
 * If the function cannot compress 'source' into a more limited 'dest' budget,
 * compression stops *immediately*, and the function result is zero.
 * As a consequence, 'dest' content is not valid.
 *
 * Return: Number of bytes written into buffer 'dest'
 *	(necessarily <= maxOutputSize) or 0 if compression fails
 */
int LZ4_compress_default(const char *source, char *dest, int inputSize,
	int maxOutputSize, void *wrkmem);

/**
 * LZ4_compress_fast() - As LZ4_compress_default providing an acceleration param
 * @source: source address of the original data
 * @dest: output buffer address of the compressed data
 * @inputSize: size of the input data. Max supported value is LZ4_MAX_INPUT_SIZE
 * @maxOutputSize: full or partial size of buffer 'dest'
 *	which must be already allocated
 * @acceleration: acceleration factor
 * @wrkmem: address of the working memory.
 *	This requires 'workmem' of LZ4_MEM_COMPRESS.
 *
 * Same as LZ4_compress_default(), but allows to select an "acceleration"
 * factor. The larger the acceleration value, the faster the algorithm,
 * but also the lesser the compression. It's a trade-off. It can be fine tuned,
 * with each successive value providing roughly +~3% to speed.
 * An acceleration value of "1" is the same as regular LZ4_compress_default()
 * Values <= 0 will be replaced by LZ4_ACCELERATION_DEFAULT, which is 1.
 *
 * Return: Number of bytes written into buffer 'dest'
 *	(necessarily <= maxOutputSize) or 0 if compression fails
 */
int LZ4_compress_fast(const char *source, char *dest, int inputSize,
	int maxOutputSize, int acceleration, void *wrkmem);

/**
 * LZ4_compress_destSize() - Compress as much data as possible
 *	from source to dest
 * @source: source address of the original data
 * @dest: output buffer address of the compressed data
 * @sourceSizePtr: will be modified to indicate how many bytes where read
 *	from 'source' to fill 'dest'. New value is necessarily <= old value.
 * @targetDestSize: Size of buffer 'dest' which must be already allocated
 * @wrkmem: address of the working memory.
 *	This requires 'workmem' of LZ4_MEM_COMPRESS.
 *
 * Reverse the logic, by compressing as much data as possible
 * from 'source' buffer into already allocated buffer 'dest'
 * of size 'targetDestSize'.
 * This function either compresses the entire 'source' content into 'dest'
 * if it's large enough, or fill 'dest' buffer completely with as much data as
 * possible from 'source'.
 *
 * Return: Number of bytes written into 'dest' (necessarily <= targetDestSize)
 *	or 0 if compression fails
 */
int LZ4_compress_destSize(const char *source, char *dest, int *sourceSizePtr,
	int targetDestSize, void *wrkmem);

/*-************************************************************************
 *	Decompression Functions
 **************************************************************************/

/**
 * LZ4_decompress_fast() - Decompresses data from 'source' into 'dest'
 * @source: source address of the compressed data
 * @dest: output buffer address of the uncompressed data
 *	which must be already allocated with 'originalSize' bytes
 * @originalSize: is the original and therefore uncompressed size
 *
 * Decompresses data from 'source' into 'dest'.
 * This function fully respect memory boundaries for properly formed
 * compressed data.
 * It is a bit faster than LZ4_decompress_safe().
 * However, it does not provide any protection against intentionally
 * modified data stream (malicious input).
 * Use this function in trusted environment only
 * (data to decode comes from a trusted source).
 *
 * Return: number of bytes read from the source buffer
 *	or a negative result if decompression fails.
 */
int LZ4_decompress_fast(const char *source, char *dest, int originalSize);

/**
 * LZ4_decompress_safe() - Decompression protected against buffer overflow
 * @source: source address of the compressed data
 * @dest: output buffer address of the uncompressed data
 *	which must be already allocated
 * @compressedSize: is the precise full size of the compressed block
 * @maxDecompressedSize: is the size of 'dest' buffer
 *
 * Decompresses data fom 'source' into 'dest'.
 * If the source stream is detected malformed, the function will
 * stop decoding and return a negative result.
 * This function is protected against buffer overflow exploits,
 * including malicious data packets. It never writes outside output buffer,
 * nor reads outside input buffer.
 *
 * Return: number of bytes decompressed into destination buffer
 *	(necessarily <= maxDecompressedSize)
 *	or a negative result in case of error
 */
int LZ4_decompress_safe(const char *source, char *dest, int compressedSize,
	int maxDecompressedSize);

/**
 * LZ4_decompress_safe_partial() - Decompress a block of size 'compressedSize'
 *	at position 'source' into buffer 'dest'
 * @source: source address of the compressed data
 * @dest: output buffer address of the decompressed data which must be
 *	already allocated
 * @compressedSize: is the precise full size of the compressed block.
 * @targetOutputSize: the decompression operation will try
 *	to stop as soon as 'targetOutputSize' has been reached
 * @maxDecompressedSize: is the size of destination buffer
 *
 * This function decompresses a compressed block of size 'compressedSize'
 * at position 'source' into destination buffer 'dest'
 * of size 'maxDecompressedSize'.
 * The function tries to stop decompressing operation as soon as
 * 'targetOutputSize' has been reached, reducing decompression time.
 * This function never writes outside of output buffer,
 * and never reads outside of input buffer.
 * It is therefore protected against malicious data packets.
 *
 * Return: the number of bytes decoded in the destination buffer
 *	(necessarily <= maxDecompressedSize)
 *	or a negative result in case of error
 *
 */
int LZ4_decompress_safe_partial(const char *source, char *dest,
	int compressedSize, int targetOutputSize, int maxDecompressedSize);

/*-************************************************************************
 *	LZ4 HC Compression
 **************************************************************************/

/**
 * LZ4_compress_HC() - Compress data from `src` into `dst`, using HC algorithm
 * @src: source address of the original data
 * @dst: output buffer address of the compressed data
 * @srcSize: size of the input data. Max supported value is LZ4_MAX_INPUT_SIZE
 * @dstCapacity: full or partial size of buffer 'dst',
 *	which must be already allocated
 * @compressionLevel: Recommended values are between 4 and 9, although any
 *	value between 1 and LZ4HC_MAX_CLEVEL will work.
 *	Values >LZ4HC_MAX_CLEVEL behave the same as 16.
 * @wrkmem: address of the working memory.
 *	This requires 'wrkmem' of size LZ4HC_MEM_COMPRESS.
 *
 * Compress data from 'src' into 'dst', using the more powerful
 * but slower "HC" algorithm. Compression is guaranteed to succeed if
 * `dstCapacity >= LZ4_compressBound(srcSize)
 *
 * Return : the number of bytes written into 'dst' or 0 if compression fails.
 */
int LZ4_compress_HC(const char *src, char *dst, int srcSize, int dstCapacity,
	int compressionLevel, void *wrkmem);

/**
 * LZ4_resetStreamHC() - Init an allocated 'LZ4_streamHC_t' structure
 * @streamHCPtr: pointer to the 'LZ4_streamHC_t' structure
 * @compressionLevel: Recommended values are between 4 and 9, although any
 *	value between 1 and LZ4HC_MAX_CLEVEL will work.
 *	Values >LZ4HC_MAX_CLEVEL behave the same as 16.
 *
 * An LZ4_streamHC_t structure can be allocated once
 * and re-used multiple times.
 * Use this function to init an allocated `LZ4_streamHC_t` structure
 * and start a new compression.
 */
void LZ4_resetStreamHC(LZ4_streamHC_t *streamHCPtr, int compressionLevel);

/**
 * LZ4_loadDictHC() - Load a static dictionary into LZ4_streamHC
 * @streamHCPtr: pointer to the LZ4HC_stream_t
 * @dictionary: dictionary to load
 * @dictSize: size of dictionary
 *
 * Use this function to load a static dictionary into LZ4HC_stream.
 * Any previous data will be forgotten, only 'dictionary'
 * will remain in memory.
 * Loading a size of 0 is allowed.
 *
 * Return : dictionary size, in bytes (necessarily <= 64 KB)
 */
int	LZ4_loadDictHC(LZ4_streamHC_t *streamHCPtr, const char *dictionary,
	int dictSize);

/**
 * LZ4_compress_HC_continue() - Compress 'src' using data from previously
 *	compressed blocks as a dictionary using the HC algorithm
 * @streamHCPtr: Pointer to the previous 'LZ4_streamHC_t' structure
 * @src: source address of the original data
 * @dst: output buffer address of the compressed data,
 *	which must be already allocated
 * @srcSize: size of the input data. Max supported value is LZ4_MAX_INPUT_SIZE
 * @maxDstSize: full or partial size of buffer 'dest'
 *	which must be already allocated
 *
 * These functions compress data in successive blocks of any size, using
 * previous blocks as dictionary. One key assumption is that previous
 * blocks (up to 64 KB) remain read-accessible while
 * compressing next blocks. There is an exception for ring buffers,
 * which can be smaller than 64 KB.
 * Ring buffers scenario is automatically detected and handled by
 * LZ4_compress_HC_continue().
 * Before starting compression, state must be properly initialized,
 * using LZ4_resetStreamHC().
 * A first "fictional block" can then be designated as
 * initial dictionary, using LZ4_loadDictHC() (Optional).
 * Then, use LZ4_compress_HC_continue()
 * to compress each successive block. Previous memory blocks
 * (including initial dictionary when present) must remain accessible
 * and unmodified during compression.
 * 'dst' buffer should be sized to handle worst case scenarios, using
 *  LZ4_compressBound(), to ensure operation success.
 *  If, for any reason, previous data blocks can't be preserved unmodified
 *  in memory during next compression block,
 *  you must save it to a safer memory space, using LZ4_saveDictHC().
 * Return value of LZ4_saveDictHC() is the size of dictionary
 * effectively saved into 'safeBuffer'.
 *
 * Return: Number of bytes written into buffer 'dst'  or 0 if compression fails
 */
int LZ4_compress_HC_continue(LZ4_streamHC_t *streamHCPtr, const char *src,
	char *dst, int srcSize, int maxDstSize);

/**
 * LZ4_saveDictHC() - Save static dictionary from LZ4HC_stream
 * @streamHCPtr: pointer to the 'LZ4HC_stream_t' structure
 * @safeBuffer: buffer to save dictionary to, must be already allocated
 * @maxDictSize: size of 'safeBuffer'
 *
 * If previously compressed data block is not guaranteed
 * to remain available at its memory location,
 * save it into a safer place (char *safeBuffer).
 * Note : you don't need to call LZ4_loadDictHC() afterwards,
 * dictionary is immediately usable, you can therefore call
 * LZ4_compress_HC_continue().
 *
 * Return : saved dictionary size in bytes (necessarily <= maxDictSize),
 *	or 0 if error.
 */
int LZ4_saveDictHC(LZ4_streamHC_t *streamHCPtr, char *safeBuffer,
	int maxDictSize);

/*-*********************************************
 *	Streaming Compression Functions
 ***********************************************/

/**
 * LZ4_resetStream() - Init an allocated 'LZ4_stream_t' structure
 * @LZ4_stream: pointer to the 'LZ4_stream_t' structure
 *
 * An LZ4_stream_t structure can be allocated once
 * and re-used multiple times.
 * Use this function to init an allocated `LZ4_stream_t` structure
 * and start a new compression.
 */
void LZ4_resetStream(LZ4_stream_t *LZ4_stream);

/**
 * LZ4_loadDict() - Load a static dictionary into LZ4_stream
 * @streamPtr: pointer to the LZ4_stream_t
 * @dictionary: dictionary to load
 * @dictSize: size of dictionary
 *
 * Use this function to load a static dictionary into LZ4_stream.
 * Any previous data will be forgotten, only 'dictionary'
 * will remain in memory.
 * Loading a size of 0 is allowed.
 *
 * Return : dictionary size, in bytes (necessarily <= 64 KB)
 */
int LZ4_loadDict(LZ4_stream_t *streamPtr, const char *dictionary,
	int dictSize);

/**
 * LZ4_saveDict() - Save static dictionary from LZ4_stream
 * @streamPtr: pointer to the 'LZ4_stream_t' structure
 * @safeBuffer: buffer to save dictionary to, must be already allocated
 * @dictSize: size of 'safeBuffer'
 *
 * If previously compressed data block is not guaranteed
 * to remain available at its memory location,
 * save it into a safer place (char *safeBuffer).
 * Note : you don't need to call LZ4_loadDict() afterwards,
 * dictionary is immediately usable, you can therefore call
 * LZ4_compress_fast_continue().
 *
 * Return : saved dictionary size in bytes (necessarily <= dictSize),
 *	or 0 if error.
 */
int LZ4_saveDict(LZ4_stream_t *streamPtr, char *safeBuffer, int dictSize);

/**
 * LZ4_compress_fast_continue() - Compress 'src' using data from previously
 *	compressed blocks as a dictionary
 * @streamPtr: Pointer to the previous 'LZ4_stream_t' structure
 * @src: source address of the original data
 * @dst: output buffer address of the compressed data,
 *	which must be already allocated
 * @srcSize: size of the input data. Max supported value is LZ4_MAX_INPUT_SIZE
 * @maxDstSize: full or partial size of buffer 'dest'
 *	which must be already allocated
 * @acceleration: acceleration factor
 *
 * Compress buffer content 'src', using data from previously compressed blocks
 * as dictionary to improve compression ratio.
 * Important : Previous data blocks are assumed to still
 * be present and unmodified !
 * If maxDstSize >= LZ4_compressBound(srcSize),
 * compression is guaranteed to succeed, and runs faster.
 *
 * Return: Number of bytes written into buffer 'dst'  or 0 if compression fails
 */
int LZ4_compress_fast_continue(LZ4_stream_t *streamPtr, const char *src,
	char *dst, int srcSize, int maxDstSize, int acceleration);

/**
 * LZ4_setStreamDecode() - Instruct where to find dictionary
 * @LZ4_streamDecode: the 'LZ4_streamDecode_t' structure
 * @dictionary: dictionary to use
 * @dictSize: size of dictionary
 *
 * Use this function to instruct where to find the dictionary.
 *	Setting a size of 0 is allowed (same effect as reset).
 *
 * Return: 1 if OK, 0 if error
 */
int LZ4_setStreamDecode(LZ4_streamDecode_t *LZ4_streamDecode,
	const char *dictionary, int dictSize);

/**
 * LZ4_decompress_fast_continue() - Decompress blocks in streaming mode
 * @LZ4_streamDecode: the 'LZ4_streamDecode_t' structure
 * @source: source address of the compressed data
 * @dest: output buffer address of the uncompressed data
 *	which must be already allocated
 * @compressedSize: is the precise full size of the compressed block
 * @maxDecompressedSize: is the size of 'dest' buffer
 *
 * These decoding function allows decompression of multiple blocks
 * in "streaming" mode.
 * Previously decoded blocks *must* remain available at the memory position
 * where they were decoded (up to 64 KB)
 * In the case of a ring buffers, decoding buffer must be either :
 *    - Exactly same size as encoding buffer, with same update rule
 *      (block boundaries at same positions) In which case,
 *      the decoding & encoding ring buffer can have any size,
 *      including very small ones ( < 64 KB).
 *    - Larger than encoding buffer, by a minimum of maxBlockSize more bytes.
 *      maxBlockSize is implementation dependent.
 *      It's the maximum size you intend to compress into a single block.
 *      In which case, encoding and decoding buffers do not need
 *      to be synchronized, and encoding ring buffer can have any size,
 *      including small ones ( < 64 KB).
 *    - _At least_ 64 KB + 8 bytes + maxBlockSize.
 *      In which case, encoding and decoding buffers do not need to be
 *      synchronized, and encoding ring buffer can have any size,
 *      including larger than decoding buffer. W
 * Whenever these conditions are not possible, save the last 64KB of decoded
 * data into a safe buffer, and indicate where it is saved
 * using LZ4_setStreamDecode()
 *
 * Return: number of bytes decompressed into destination buffer
 *	(necessarily <= maxDecompressedSize)
 *	or a negative result in case of error
 */
int LZ4_decompress_safe_continue(LZ4_streamDecode_t *LZ4_streamDecode,
	const char *source, char *dest, int compressedSize,
	int maxDecompressedSize);

/**
 * LZ4_decompress_fast_continue() - Decompress blocks in streaming mode
 * @LZ4_streamDecode: the 'LZ4_streamDecode_t' structure
 * @source: source address of the compressed data
 * @dest: output buffer address of the uncompressed data
 *	which must be already allocated with 'originalSize' bytes
 * @originalSize: is the original and therefore uncompressed size
 *
 * These decoding function allows decompression of multiple blocks
 * in "streaming" mode.
 * Previously decoded blocks *must* remain available at the memory position
 * where they were decoded (up to 64 KB)
 * In the case of a ring buffers, decoding buffer must be either :
 *    - Exactly same size as encoding buffer, with same update rule
 *      (block boundaries at same positions) In which case,
 *      the decoding & encoding ring buffer can have any size,
 *      including very small ones ( < 64 KB).
 *    - Larger than encoding buffer, by a minimum of maxBlockSize more bytes.
 *      maxBlockSize is implementation dependent.
 *      It's the maximum size you intend to compress into a single block.
 *      In which case, encoding and decoding buffers do not need
 *      to be synchronized, and encoding ring buffer can have any size,
 *      including small ones ( < 64 KB).
 *    - _At least_ 64 KB + 8 bytes + maxBlockSize.
 *      In which case, encoding and decoding buffers do not need to be
 *      synchronized, and encoding ring buffer can have any size,
 *      including larger than decoding buffer. W
 * Whenever these conditions are not possible, save the last 64KB of decoded
 * data into a safe buffer, and indicate where it is saved
 * using LZ4_setStreamDecode()
 *
 * Return: number of bytes decompressed into destination buffer
 *	(necessarily <= maxDecompressedSize)
 *	or a negative result in case of error
 */
int LZ4_decompress_fast_continue(LZ4_streamDecode_t *LZ4_streamDecode,
	const char *source, char *dest, int originalSize);

/**
 * LZ4_decompress_safe_usingDict() - Same as LZ4_setStreamDecode()
 *	followed by LZ4_decompress_safe_continue()
 * @source: source address of the compressed data
 * @dest: output buffer address of the uncompressed data
 *	which must be already allocated
 * @compressedSize: is the precise full size of the compressed block
 * @maxDecompressedSize: is the size of 'dest' buffer
 * @dictStart: pointer to the start of the dictionary in memory
 * @dictSize: size of dictionary
 *
 * These decoding function works the same as
 * a combination of LZ4_setStreamDecode() followed by
 * LZ4_decompress_safe_continue()
 * It is stand-alone, and don'tn eed a LZ4_streamDecode_t structure.
 *
 * Return: number of bytes decompressed into destination buffer
 *	(necessarily <= maxDecompressedSize)
 *	or a negative result in case of error
 */
int LZ4_decompress_safe_usingDict(const char *source, char *dest,
	int compressedSize, int maxDecompressedSize, const char *dictStart,
	int dictSize);

/**
 * LZ4_decompress_fast_usingDict() - Same as LZ4_setStreamDecode()
 *	followed by LZ4_decompress_fast_continue()
 * @source: source address of the compressed data
 * @dest: output buffer address of the uncompressed data
 *	which must be already allocated with 'originalSize' bytes
 * @originalSize: is the original and therefore uncompressed size
 * @dictStart: pointer to the start of the dictionary in memory
 * @dictSize: size of dictionary
 *
 * These decoding function works the same as
 * a combination of LZ4_setStreamDecode() followed by
 * LZ4_decompress_safe_continue()
 * It is stand-alone, and don'tn eed a LZ4_streamDecode_t structure.
 *
 * Return: number of bytes decompressed into destination buffer
 *	(necessarily <= maxDecompressedSize)
 *	or a negative result in case of error
 */
int LZ4_decompress_fast_usingDict(const char *source, char *dest,
	int originalSize, const char *dictStart, int dictSize);

#endif
OpenPOWER on IntegriCloud