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diff --git a/include/linux/lz4.h b/include/linux/lz4.h new file mode 100644 index 000000000..b16e15b95 --- /dev/null +++ b/include/linux/lz4.h @@ -0,0 +1,648 @@ +/* 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 from '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_safe_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 + * + * This 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 + * + * This 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 + * + * This decoding function works the same as + * a combination of LZ4_setStreamDecode() followed by + * LZ4_decompress_safe_continue() + * It is stand-alone, and doesn't need an 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 + * + * This decoding function works the same as + * a combination of LZ4_setStreamDecode() followed by + * LZ4_decompress_fast_continue() + * It is stand-alone, and doesn't need an 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 |