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 */
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