xref: /linux/include/linux/lz4.h (revision 97a0efea)
1 /* LZ4 Kernel Interface
2  *
3  * Copyright (C) 2013, LG Electronics, Kyungsik Lee <kyungsik.lee@lge.com>
4  * Copyright (C) 2016, Sven Schmidt <4sschmid@informatik.uni-hamburg.de>
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License version 2 as
8  * published by the Free Software Foundation.
9  *
10  * This file is based on the original header file
11  * for LZ4 - Fast LZ compression algorithm.
12  *
13  * LZ4 - Fast LZ compression algorithm
14  * Copyright (C) 2011-2016, Yann Collet.
15  * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
16  * Redistribution and use in source and binary forms, with or without
17  * modification, are permitted provided that the following conditions are
18  * met:
19  *	* Redistributions of source code must retain the above copyright
20  *	  notice, this list of conditions and the following disclaimer.
21  *	* Redistributions in binary form must reproduce the above
22  * copyright notice, this list of conditions and the following disclaimer
23  * in the documentation and/or other materials provided with the
24  * distribution.
25  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
26  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
27  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
28  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
29  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
30  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
31  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
32  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
33  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
34  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
35  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
36  * You can contact the author at :
37  *	- LZ4 homepage : http://www.lz4.org
38  *	- LZ4 source repository : https://github.com/lz4/lz4
39  */
40 
41 #ifndef __LZ4_H__
42 #define __LZ4_H__
43 
44 #include <linux/types.h>
45 #include <linux/string.h>	 /* memset, memcpy */
46 
47 /*-************************************************************************
48  *	CONSTANTS
49  **************************************************************************/
50 /*
51  * LZ4_MEMORY_USAGE :
52  * Memory usage formula : N->2^N Bytes
53  * (examples : 10 -> 1KB; 12 -> 4KB ; 16 -> 64KB; 20 -> 1MB; etc.)
54  * Increasing memory usage improves compression ratio
55  * Reduced memory usage can improve speed, due to cache effect
56  * Default value is 14, for 16KB, which nicely fits into Intel x86 L1 cache
57  */
58 #define LZ4_MEMORY_USAGE 14
59 
60 #define LZ4_MAX_INPUT_SIZE	0x7E000000 /* 2 113 929 216 bytes */
61 #define LZ4_COMPRESSBOUND(isize)	(\
62 	(unsigned int)(isize) > (unsigned int)LZ4_MAX_INPUT_SIZE \
63 	? 0 \
64 	: (isize) + ((isize)/255) + 16)
65 
66 #define LZ4_ACCELERATION_DEFAULT 1
67 #define LZ4_HASHLOG	 (LZ4_MEMORY_USAGE-2)
68 #define LZ4_HASHTABLESIZE (1 << LZ4_MEMORY_USAGE)
69 #define LZ4_HASH_SIZE_U32 (1 << LZ4_HASHLOG)
70 
71 #define LZ4HC_MIN_CLEVEL			3
72 #define LZ4HC_DEFAULT_CLEVEL			9
73 #define LZ4HC_MAX_CLEVEL			16
74 
75 #define LZ4HC_DICTIONARY_LOGSIZE 16
76 #define LZ4HC_MAXD (1<<LZ4HC_DICTIONARY_LOGSIZE)
77 #define LZ4HC_MAXD_MASK (LZ4HC_MAXD - 1)
78 #define LZ4HC_HASH_LOG (LZ4HC_DICTIONARY_LOGSIZE - 1)
79 #define LZ4HC_HASHTABLESIZE (1 << LZ4HC_HASH_LOG)
80 #define LZ4HC_HASH_MASK (LZ4HC_HASHTABLESIZE - 1)
81 
82 /*-************************************************************************
83  *	STREAMING CONSTANTS AND STRUCTURES
84  **************************************************************************/
85 #define LZ4_STREAMSIZE_U64 ((1 << (LZ4_MEMORY_USAGE - 3)) + 4)
86 #define LZ4_STREAMSIZE	(LZ4_STREAMSIZE_U64 * sizeof(unsigned long long))
87 
88 #define LZ4_STREAMHCSIZE        262192
89 #define LZ4_STREAMHCSIZE_SIZET (262192 / sizeof(size_t))
90 
91 #define LZ4_STREAMDECODESIZE_U64	4
92 #define LZ4_STREAMDECODESIZE		 (LZ4_STREAMDECODESIZE_U64 * \
93 	sizeof(unsigned long long))
94 
95 /*
96  * LZ4_stream_t - information structure to track an LZ4 stream.
97  */
98 typedef struct {
99 	uint32_t hashTable[LZ4_HASH_SIZE_U32];
100 	uint32_t currentOffset;
101 	uint32_t initCheck;
102 	const uint8_t *dictionary;
103 	uint8_t *bufferStart;
104 	uint32_t dictSize;
105 } LZ4_stream_t_internal;
106 typedef union {
107 	unsigned long long table[LZ4_STREAMSIZE_U64];
108 	LZ4_stream_t_internal internal_donotuse;
109 } LZ4_stream_t;
110 
111 /*
112  * LZ4_streamHC_t - information structure to track an LZ4HC stream.
113  */
114 typedef struct {
115 	unsigned int	 hashTable[LZ4HC_HASHTABLESIZE];
116 	unsigned short	 chainTable[LZ4HC_MAXD];
117 	/* next block to continue on current prefix */
118 	const unsigned char *end;
119 	/* All index relative to this position */
120 	const unsigned char *base;
121 	/* alternate base for extDict */
122 	const unsigned char *dictBase;
123 	/* below that point, need extDict */
124 	unsigned int	 dictLimit;
125 	/* below that point, no more dict */
126 	unsigned int	 lowLimit;
127 	/* index from which to continue dict update */
128 	unsigned int	 nextToUpdate;
129 	unsigned int	 compressionLevel;
130 } LZ4HC_CCtx_internal;
131 typedef union {
132 	size_t table[LZ4_STREAMHCSIZE_SIZET];
133 	LZ4HC_CCtx_internal internal_donotuse;
134 } LZ4_streamHC_t;
135 
136 /*
137  * LZ4_streamDecode_t - information structure to track an
138  *	LZ4 stream during decompression.
139  *
140  * init this structure using LZ4_setStreamDecode (or memset()) before first use
141  */
142 typedef struct {
143 	const uint8_t *externalDict;
144 	size_t extDictSize;
145 	const uint8_t *prefixEnd;
146 	size_t prefixSize;
147 } LZ4_streamDecode_t_internal;
148 typedef union {
149 	unsigned long long table[LZ4_STREAMDECODESIZE_U64];
150 	LZ4_streamDecode_t_internal internal_donotuse;
151 } LZ4_streamDecode_t;
152 
153 /*-************************************************************************
154  *	SIZE OF STATE
155  **************************************************************************/
156 #define LZ4_MEM_COMPRESS	LZ4_STREAMSIZE
157 #define LZ4HC_MEM_COMPRESS	LZ4_STREAMHCSIZE
158 
159 /*-************************************************************************
160  *	Compression Functions
161  **************************************************************************/
162 
163 /**
164  * LZ4_compressBound() - Max. output size in worst case szenarios
165  * @isize: Size of the input data
166  *
167  * Return: Max. size LZ4 may output in a "worst case" szenario
168  * (data not compressible)
169  */
LZ4_compressBound(size_t isize)170 static inline int LZ4_compressBound(size_t isize)
171 {
172 	return LZ4_COMPRESSBOUND(isize);
173 }
174 
175 /**
176  * LZ4_compress_default() - Compress data from source to dest
177  * @source: source address of the original data
178  * @dest: output buffer address of the compressed data
179  * @inputSize: size of the input data. Max supported value is LZ4_MAX_INPUT_SIZE
180  * @maxOutputSize: full or partial size of buffer 'dest'
181  *	which must be already allocated
182  * @wrkmem: address of the working memory.
183  *	This requires 'workmem' of LZ4_MEM_COMPRESS.
184  *
185  * Compresses 'sourceSize' bytes from buffer 'source'
186  * into already allocated 'dest' buffer of size 'maxOutputSize'.
187  * Compression is guaranteed to succeed if
188  * 'maxOutputSize' >= LZ4_compressBound(inputSize).
189  * It also runs faster, so it's a recommended setting.
190  * If the function cannot compress 'source' into a more limited 'dest' budget,
191  * compression stops *immediately*, and the function result is zero.
192  * As a consequence, 'dest' content is not valid.
193  *
194  * Return: Number of bytes written into buffer 'dest'
195  *	(necessarily <= maxOutputSize) or 0 if compression fails
196  */
197 int LZ4_compress_default(const char *source, char *dest, int inputSize,
198 	int maxOutputSize, void *wrkmem);
199 
200 /**
201  * LZ4_compress_fast() - As LZ4_compress_default providing an acceleration param
202  * @source: source address of the original data
203  * @dest: output buffer address of the compressed data
204  * @inputSize: size of the input data. Max supported value is LZ4_MAX_INPUT_SIZE
205  * @maxOutputSize: full or partial size of buffer 'dest'
206  *	which must be already allocated
207  * @acceleration: acceleration factor
208  * @wrkmem: address of the working memory.
209  *	This requires 'workmem' of LZ4_MEM_COMPRESS.
210  *
211  * Same as LZ4_compress_default(), but allows to select an "acceleration"
212  * factor. The larger the acceleration value, the faster the algorithm,
213  * but also the lesser the compression. It's a trade-off. It can be fine tuned,
214  * with each successive value providing roughly +~3% to speed.
215  * An acceleration value of "1" is the same as regular LZ4_compress_default()
216  * Values <= 0 will be replaced by LZ4_ACCELERATION_DEFAULT, which is 1.
217  *
218  * Return: Number of bytes written into buffer 'dest'
219  *	(necessarily <= maxOutputSize) or 0 if compression fails
220  */
221 int LZ4_compress_fast(const char *source, char *dest, int inputSize,
222 	int maxOutputSize, int acceleration, void *wrkmem);
223 
224 /**
225  * LZ4_compress_destSize() - Compress as much data as possible
226  *	from source to dest
227  * @source: source address of the original data
228  * @dest: output buffer address of the compressed data
229  * @sourceSizePtr: will be modified to indicate how many bytes where read
230  *	from 'source' to fill 'dest'. New value is necessarily <= old value.
231  * @targetDestSize: Size of buffer 'dest' which must be already allocated
232  * @wrkmem: address of the working memory.
233  *	This requires 'workmem' of LZ4_MEM_COMPRESS.
234  *
235  * Reverse the logic, by compressing as much data as possible
236  * from 'source' buffer into already allocated buffer 'dest'
237  * of size 'targetDestSize'.
238  * This function either compresses the entire 'source' content into 'dest'
239  * if it's large enough, or fill 'dest' buffer completely with as much data as
240  * possible from 'source'.
241  *
242  * Return: Number of bytes written into 'dest' (necessarily <= targetDestSize)
243  *	or 0 if compression fails
244  */
245 int LZ4_compress_destSize(const char *source, char *dest, int *sourceSizePtr,
246 	int targetDestSize, void *wrkmem);
247 
248 /*-************************************************************************
249  *	Decompression Functions
250  **************************************************************************/
251 
252 /**
253  * LZ4_decompress_fast() - Decompresses data from 'source' into 'dest'
254  * @source: source address of the compressed data
255  * @dest: output buffer address of the uncompressed data
256  *	which must be already allocated with 'originalSize' bytes
257  * @originalSize: is the original and therefore uncompressed size
258  *
259  * Decompresses data from 'source' into 'dest'.
260  * This function fully respect memory boundaries for properly formed
261  * compressed data.
262  * It is a bit faster than LZ4_decompress_safe().
263  * However, it does not provide any protection against intentionally
264  * modified data stream (malicious input).
265  * Use this function in trusted environment only
266  * (data to decode comes from a trusted source).
267  *
268  * Return: number of bytes read from the source buffer
269  *	or a negative result if decompression fails.
270  */
271 int LZ4_decompress_fast(const char *source, char *dest, int originalSize);
272 
273 /**
274  * LZ4_decompress_safe() - Decompression protected against buffer overflow
275  * @source: source address of the compressed data
276  * @dest: output buffer address of the uncompressed data
277  *	which must be already allocated
278  * @compressedSize: is the precise full size of the compressed block
279  * @maxDecompressedSize: is the size of 'dest' buffer
280  *
281  * Decompresses data from 'source' into 'dest'.
282  * If the source stream is detected malformed, the function will
283  * stop decoding and return a negative result.
284  * This function is protected against buffer overflow exploits,
285  * including malicious data packets. It never writes outside output buffer,
286  * nor reads outside input buffer.
287  *
288  * Return: number of bytes decompressed into destination buffer
289  *	(necessarily <= maxDecompressedSize)
290  *	or a negative result in case of error
291  */
292 int LZ4_decompress_safe(const char *source, char *dest, int compressedSize,
293 	int maxDecompressedSize);
294 
295 /**
296  * LZ4_decompress_safe_partial() - Decompress a block of size 'compressedSize'
297  *	at position 'source' into buffer 'dest'
298  * @source: source address of the compressed data
299  * @dest: output buffer address of the decompressed data which must be
300  *	already allocated
301  * @compressedSize: is the precise full size of the compressed block.
302  * @targetOutputSize: the decompression operation will try
303  *	to stop as soon as 'targetOutputSize' has been reached
304  * @maxDecompressedSize: is the size of destination buffer
305  *
306  * This function decompresses a compressed block of size 'compressedSize'
307  * at position 'source' into destination buffer 'dest'
308  * of size 'maxDecompressedSize'.
309  * The function tries to stop decompressing operation as soon as
310  * 'targetOutputSize' has been reached, reducing decompression time.
311  * This function never writes outside of output buffer,
312  * and never reads outside of input buffer.
313  * It is therefore protected against malicious data packets.
314  *
315  * Return: the number of bytes decoded in the destination buffer
316  *	(necessarily <= maxDecompressedSize)
317  *	or a negative result in case of error
318  *
319  */
320 int LZ4_decompress_safe_partial(const char *source, char *dest,
321 	int compressedSize, int targetOutputSize, int maxDecompressedSize);
322 
323 /*-************************************************************************
324  *	LZ4 HC Compression
325  **************************************************************************/
326 
327 /**
328  * LZ4_compress_HC() - Compress data from `src` into `dst`, using HC algorithm
329  * @src: source address of the original data
330  * @dst: output buffer address of the compressed data
331  * @srcSize: size of the input data. Max supported value is LZ4_MAX_INPUT_SIZE
332  * @dstCapacity: full or partial size of buffer 'dst',
333  *	which must be already allocated
334  * @compressionLevel: Recommended values are between 4 and 9, although any
335  *	value between 1 and LZ4HC_MAX_CLEVEL will work.
336  *	Values >LZ4HC_MAX_CLEVEL behave the same as 16.
337  * @wrkmem: address of the working memory.
338  *	This requires 'wrkmem' of size LZ4HC_MEM_COMPRESS.
339  *
340  * Compress data from 'src' into 'dst', using the more powerful
341  * but slower "HC" algorithm. Compression is guaranteed to succeed if
342  * `dstCapacity >= LZ4_compressBound(srcSize)
343  *
344  * Return : the number of bytes written into 'dst' or 0 if compression fails.
345  */
346 int LZ4_compress_HC(const char *src, char *dst, int srcSize, int dstCapacity,
347 	int compressionLevel, void *wrkmem);
348 
349 /**
350  * LZ4_resetStreamHC() - Init an allocated 'LZ4_streamHC_t' structure
351  * @streamHCPtr: pointer to the 'LZ4_streamHC_t' structure
352  * @compressionLevel: Recommended values are between 4 and 9, although any
353  *	value between 1 and LZ4HC_MAX_CLEVEL will work.
354  *	Values >LZ4HC_MAX_CLEVEL behave the same as 16.
355  *
356  * An LZ4_streamHC_t structure can be allocated once
357  * and re-used multiple times.
358  * Use this function to init an allocated `LZ4_streamHC_t` structure
359  * and start a new compression.
360  */
361 void LZ4_resetStreamHC(LZ4_streamHC_t *streamHCPtr, int compressionLevel);
362 
363 /**
364  * LZ4_loadDictHC() - Load a static dictionary into LZ4_streamHC
365  * @streamHCPtr: pointer to the LZ4HC_stream_t
366  * @dictionary: dictionary to load
367  * @dictSize: size of dictionary
368  *
369  * Use this function to load a static dictionary into LZ4HC_stream.
370  * Any previous data will be forgotten, only 'dictionary'
371  * will remain in memory.
372  * Loading a size of 0 is allowed.
373  *
374  * Return : dictionary size, in bytes (necessarily <= 64 KB)
375  */
376 int	LZ4_loadDictHC(LZ4_streamHC_t *streamHCPtr, const char *dictionary,
377 	int dictSize);
378 
379 /**
380  * LZ4_compress_HC_continue() - Compress 'src' using data from previously
381  *	compressed blocks as a dictionary using the HC algorithm
382  * @streamHCPtr: Pointer to the previous 'LZ4_streamHC_t' structure
383  * @src: source address of the original data
384  * @dst: output buffer address of the compressed data,
385  *	which must be already allocated
386  * @srcSize: size of the input data. Max supported value is LZ4_MAX_INPUT_SIZE
387  * @maxDstSize: full or partial size of buffer 'dest'
388  *	which must be already allocated
389  *
390  * These functions compress data in successive blocks of any size, using
391  * previous blocks as dictionary. One key assumption is that previous
392  * blocks (up to 64 KB) remain read-accessible while
393  * compressing next blocks. There is an exception for ring buffers,
394  * which can be smaller than 64 KB.
395  * Ring buffers scenario is automatically detected and handled by
396  * LZ4_compress_HC_continue().
397  * Before starting compression, state must be properly initialized,
398  * using LZ4_resetStreamHC().
399  * A first "fictional block" can then be designated as
400  * initial dictionary, using LZ4_loadDictHC() (Optional).
401  * Then, use LZ4_compress_HC_continue()
402  * to compress each successive block. Previous memory blocks
403  * (including initial dictionary when present) must remain accessible
404  * and unmodified during compression.
405  * 'dst' buffer should be sized to handle worst case scenarios, using
406  *  LZ4_compressBound(), to ensure operation success.
407  *  If, for any reason, previous data blocks can't be preserved unmodified
408  *  in memory during next compression block,
409  *  you must save it to a safer memory space, using LZ4_saveDictHC().
410  * Return value of LZ4_saveDictHC() is the size of dictionary
411  * effectively saved into 'safeBuffer'.
412  *
413  * Return: Number of bytes written into buffer 'dst'  or 0 if compression fails
414  */
415 int LZ4_compress_HC_continue(LZ4_streamHC_t *streamHCPtr, const char *src,
416 	char *dst, int srcSize, int maxDstSize);
417 
418 /**
419  * LZ4_saveDictHC() - Save static dictionary from LZ4HC_stream
420  * @streamHCPtr: pointer to the 'LZ4HC_stream_t' structure
421  * @safeBuffer: buffer to save dictionary to, must be already allocated
422  * @maxDictSize: size of 'safeBuffer'
423  *
424  * If previously compressed data block is not guaranteed
425  * to remain available at its memory location,
426  * save it into a safer place (char *safeBuffer).
427  * Note : you don't need to call LZ4_loadDictHC() afterwards,
428  * dictionary is immediately usable, you can therefore call
429  * LZ4_compress_HC_continue().
430  *
431  * Return : saved dictionary size in bytes (necessarily <= maxDictSize),
432  *	or 0 if error.
433  */
434 int LZ4_saveDictHC(LZ4_streamHC_t *streamHCPtr, char *safeBuffer,
435 	int maxDictSize);
436 
437 /*-*********************************************
438  *	Streaming Compression Functions
439  ***********************************************/
440 
441 /**
442  * LZ4_resetStream() - Init an allocated 'LZ4_stream_t' structure
443  * @LZ4_stream: pointer to the 'LZ4_stream_t' structure
444  *
445  * An LZ4_stream_t structure can be allocated once
446  * and re-used multiple times.
447  * Use this function to init an allocated `LZ4_stream_t` structure
448  * and start a new compression.
449  */
450 void LZ4_resetStream(LZ4_stream_t *LZ4_stream);
451 
452 /**
453  * LZ4_loadDict() - Load a static dictionary into LZ4_stream
454  * @streamPtr: pointer to the LZ4_stream_t
455  * @dictionary: dictionary to load
456  * @dictSize: size of dictionary
457  *
458  * Use this function to load a static dictionary into LZ4_stream.
459  * Any previous data will be forgotten, only 'dictionary'
460  * will remain in memory.
461  * Loading a size of 0 is allowed.
462  *
463  * Return : dictionary size, in bytes (necessarily <= 64 KB)
464  */
465 int LZ4_loadDict(LZ4_stream_t *streamPtr, const char *dictionary,
466 	int dictSize);
467 
468 /**
469  * LZ4_saveDict() - Save static dictionary from LZ4_stream
470  * @streamPtr: pointer to the 'LZ4_stream_t' structure
471  * @safeBuffer: buffer to save dictionary to, must be already allocated
472  * @dictSize: size of 'safeBuffer'
473  *
474  * If previously compressed data block is not guaranteed
475  * to remain available at its memory location,
476  * save it into a safer place (char *safeBuffer).
477  * Note : you don't need to call LZ4_loadDict() afterwards,
478  * dictionary is immediately usable, you can therefore call
479  * LZ4_compress_fast_continue().
480  *
481  * Return : saved dictionary size in bytes (necessarily <= dictSize),
482  *	or 0 if error.
483  */
484 int LZ4_saveDict(LZ4_stream_t *streamPtr, char *safeBuffer, int dictSize);
485 
486 /**
487  * LZ4_compress_fast_continue() - Compress 'src' using data from previously
488  *	compressed blocks as a dictionary
489  * @streamPtr: Pointer to the previous 'LZ4_stream_t' structure
490  * @src: source address of the original data
491  * @dst: output buffer address of the compressed data,
492  *	which must be already allocated
493  * @srcSize: size of the input data. Max supported value is LZ4_MAX_INPUT_SIZE
494  * @maxDstSize: full or partial size of buffer 'dest'
495  *	which must be already allocated
496  * @acceleration: acceleration factor
497  *
498  * Compress buffer content 'src', using data from previously compressed blocks
499  * as dictionary to improve compression ratio.
500  * Important : Previous data blocks are assumed to still
501  * be present and unmodified !
502  * If maxDstSize >= LZ4_compressBound(srcSize),
503  * compression is guaranteed to succeed, and runs faster.
504  *
505  * Return: Number of bytes written into buffer 'dst'  or 0 if compression fails
506  */
507 int LZ4_compress_fast_continue(LZ4_stream_t *streamPtr, const char *src,
508 	char *dst, int srcSize, int maxDstSize, int acceleration);
509 
510 /**
511  * LZ4_setStreamDecode() - Instruct where to find dictionary
512  * @LZ4_streamDecode: the 'LZ4_streamDecode_t' structure
513  * @dictionary: dictionary to use
514  * @dictSize: size of dictionary
515  *
516  * Use this function to instruct where to find the dictionary.
517  *	Setting a size of 0 is allowed (same effect as reset).
518  *
519  * Return: 1 if OK, 0 if error
520  */
521 int LZ4_setStreamDecode(LZ4_streamDecode_t *LZ4_streamDecode,
522 	const char *dictionary, int dictSize);
523 
524 /**
525  * LZ4_decompress_safe_continue() - Decompress blocks in streaming mode
526  * @LZ4_streamDecode: the 'LZ4_streamDecode_t' structure
527  * @source: source address of the compressed data
528  * @dest: output buffer address of the uncompressed data
529  *	which must be already allocated
530  * @compressedSize: is the precise full size of the compressed block
531  * @maxDecompressedSize: is the size of 'dest' buffer
532  *
533  * This decoding function allows decompression of multiple blocks
534  * in "streaming" mode.
535  * Previously decoded blocks *must* remain available at the memory position
536  * where they were decoded (up to 64 KB)
537  * In the case of a ring buffers, decoding buffer must be either :
538  *    - Exactly same size as encoding buffer, with same update rule
539  *      (block boundaries at same positions) In which case,
540  *      the decoding & encoding ring buffer can have any size,
541  *      including very small ones ( < 64 KB).
542  *    - Larger than encoding buffer, by a minimum of maxBlockSize more bytes.
543  *      maxBlockSize is implementation dependent.
544  *      It's the maximum size you intend to compress into a single block.
545  *      In which case, encoding and decoding buffers do not need
546  *      to be synchronized, and encoding ring buffer can have any size,
547  *      including small ones ( < 64 KB).
548  *    - _At least_ 64 KB + 8 bytes + maxBlockSize.
549  *      In which case, encoding and decoding buffers do not need to be
550  *      synchronized, and encoding ring buffer can have any size,
551  *      including larger than decoding buffer. W
552  * Whenever these conditions are not possible, save the last 64KB of decoded
553  * data into a safe buffer, and indicate where it is saved
554  * using LZ4_setStreamDecode()
555  *
556  * Return: number of bytes decompressed into destination buffer
557  *	(necessarily <= maxDecompressedSize)
558  *	or a negative result in case of error
559  */
560 int LZ4_decompress_safe_continue(LZ4_streamDecode_t *LZ4_streamDecode,
561 	const char *source, char *dest, int compressedSize,
562 	int maxDecompressedSize);
563 
564 /**
565  * LZ4_decompress_fast_continue() - Decompress blocks in streaming mode
566  * @LZ4_streamDecode: the 'LZ4_streamDecode_t' structure
567  * @source: source address of the compressed data
568  * @dest: output buffer address of the uncompressed data
569  *	which must be already allocated with 'originalSize' bytes
570  * @originalSize: is the original and therefore uncompressed size
571  *
572  * This decoding function allows decompression of multiple blocks
573  * in "streaming" mode.
574  * Previously decoded blocks *must* remain available at the memory position
575  * where they were decoded (up to 64 KB)
576  * In the case of a ring buffers, decoding buffer must be either :
577  *    - Exactly same size as encoding buffer, with same update rule
578  *      (block boundaries at same positions) In which case,
579  *      the decoding & encoding ring buffer can have any size,
580  *      including very small ones ( < 64 KB).
581  *    - Larger than encoding buffer, by a minimum of maxBlockSize more bytes.
582  *      maxBlockSize is implementation dependent.
583  *      It's the maximum size you intend to compress into a single block.
584  *      In which case, encoding and decoding buffers do not need
585  *      to be synchronized, and encoding ring buffer can have any size,
586  *      including small ones ( < 64 KB).
587  *    - _At least_ 64 KB + 8 bytes + maxBlockSize.
588  *      In which case, encoding and decoding buffers do not need to be
589  *      synchronized, and encoding ring buffer can have any size,
590  *      including larger than decoding buffer. W
591  * Whenever these conditions are not possible, save the last 64KB of decoded
592  * data into a safe buffer, and indicate where it is saved
593  * using LZ4_setStreamDecode()
594  *
595  * Return: number of bytes decompressed into destination buffer
596  *	(necessarily <= maxDecompressedSize)
597  *	or a negative result in case of error
598  */
599 int LZ4_decompress_fast_continue(LZ4_streamDecode_t *LZ4_streamDecode,
600 	const char *source, char *dest, int originalSize);
601 
602 /**
603  * LZ4_decompress_safe_usingDict() - Same as LZ4_setStreamDecode()
604  *	followed by LZ4_decompress_safe_continue()
605  * @source: source address of the compressed data
606  * @dest: output buffer address of the uncompressed data
607  *	which must be already allocated
608  * @compressedSize: is the precise full size of the compressed block
609  * @maxDecompressedSize: is the size of 'dest' buffer
610  * @dictStart: pointer to the start of the dictionary in memory
611  * @dictSize: size of dictionary
612  *
613  * This decoding function works the same as
614  * a combination of LZ4_setStreamDecode() followed by
615  * LZ4_decompress_safe_continue()
616  * It is stand-alone, and doesn't need an LZ4_streamDecode_t structure.
617  *
618  * Return: number of bytes decompressed into destination buffer
619  *	(necessarily <= maxDecompressedSize)
620  *	or a negative result in case of error
621  */
622 int LZ4_decompress_safe_usingDict(const char *source, char *dest,
623 	int compressedSize, int maxDecompressedSize, const char *dictStart,
624 	int dictSize);
625 
626 /**
627  * LZ4_decompress_fast_usingDict() - Same as LZ4_setStreamDecode()
628  *	followed by LZ4_decompress_fast_continue()
629  * @source: source address of the compressed data
630  * @dest: output buffer address of the uncompressed data
631  *	which must be already allocated with 'originalSize' bytes
632  * @originalSize: is the original and therefore uncompressed size
633  * @dictStart: pointer to the start of the dictionary in memory
634  * @dictSize: size of dictionary
635  *
636  * This decoding function works the same as
637  * a combination of LZ4_setStreamDecode() followed by
638  * LZ4_decompress_fast_continue()
639  * It is stand-alone, and doesn't need an LZ4_streamDecode_t structure.
640  *
641  * Return: number of bytes decompressed into destination buffer
642  *	(necessarily <= maxDecompressedSize)
643  *	or a negative result in case of error
644  */
645 int LZ4_decompress_fast_usingDict(const char *source, char *dest,
646 	int originalSize, const char *dictStart, int dictSize);
647 
648 #endif
649