forked from mirrors/linux
97a0efea65
Fix a few spelling and grammar errors, and two places where fast/safe in the documentation did not match the function. Link: http://lkml.kernel.org/r/20190321014452.13297-1-tomlevy93@gmail.com Signed-off-by: Tom Levy <tomlevy93@gmail.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Jiri Kosina <trivial@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
648 lines
26 KiB
C
648 lines
26 KiB
C
/* LZ4 Kernel Interface
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*
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* Copyright (C) 2013, LG Electronics, Kyungsik Lee <kyungsik.lee@lge.com>
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* Copyright (C) 2016, Sven Schmidt <4sschmid@informatik.uni-hamburg.de>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This file is based on the original header file
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* for LZ4 - Fast LZ compression algorithm.
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*
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* LZ4 - Fast LZ compression algorithm
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* Copyright (C) 2011-2016, Yann Collet.
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* BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the following disclaimer
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* in the documentation and/or other materials provided with the
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* distribution.
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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* You can contact the author at :
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* - LZ4 homepage : http://www.lz4.org
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* - LZ4 source repository : https://github.com/lz4/lz4
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*/
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#ifndef __LZ4_H__
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#define __LZ4_H__
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#include <linux/types.h>
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#include <linux/string.h> /* memset, memcpy */
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/*-************************************************************************
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* CONSTANTS
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**************************************************************************/
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/*
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* LZ4_MEMORY_USAGE :
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* Memory usage formula : N->2^N Bytes
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* (examples : 10 -> 1KB; 12 -> 4KB ; 16 -> 64KB; 20 -> 1MB; etc.)
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* Increasing memory usage improves compression ratio
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* Reduced memory usage can improve speed, due to cache effect
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* Default value is 14, for 16KB, which nicely fits into Intel x86 L1 cache
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*/
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#define LZ4_MEMORY_USAGE 14
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#define LZ4_MAX_INPUT_SIZE 0x7E000000 /* 2 113 929 216 bytes */
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#define LZ4_COMPRESSBOUND(isize) (\
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(unsigned int)(isize) > (unsigned int)LZ4_MAX_INPUT_SIZE \
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? 0 \
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: (isize) + ((isize)/255) + 16)
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#define LZ4_ACCELERATION_DEFAULT 1
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#define LZ4_HASHLOG (LZ4_MEMORY_USAGE-2)
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#define LZ4_HASHTABLESIZE (1 << LZ4_MEMORY_USAGE)
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#define LZ4_HASH_SIZE_U32 (1 << LZ4_HASHLOG)
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#define LZ4HC_MIN_CLEVEL 3
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#define LZ4HC_DEFAULT_CLEVEL 9
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#define LZ4HC_MAX_CLEVEL 16
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#define LZ4HC_DICTIONARY_LOGSIZE 16
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#define LZ4HC_MAXD (1<<LZ4HC_DICTIONARY_LOGSIZE)
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#define LZ4HC_MAXD_MASK (LZ4HC_MAXD - 1)
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#define LZ4HC_HASH_LOG (LZ4HC_DICTIONARY_LOGSIZE - 1)
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#define LZ4HC_HASHTABLESIZE (1 << LZ4HC_HASH_LOG)
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#define LZ4HC_HASH_MASK (LZ4HC_HASHTABLESIZE - 1)
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/*-************************************************************************
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* STREAMING CONSTANTS AND STRUCTURES
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**************************************************************************/
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#define LZ4_STREAMSIZE_U64 ((1 << (LZ4_MEMORY_USAGE - 3)) + 4)
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#define LZ4_STREAMSIZE (LZ4_STREAMSIZE_U64 * sizeof(unsigned long long))
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#define LZ4_STREAMHCSIZE 262192
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#define LZ4_STREAMHCSIZE_SIZET (262192 / sizeof(size_t))
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#define LZ4_STREAMDECODESIZE_U64 4
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#define LZ4_STREAMDECODESIZE (LZ4_STREAMDECODESIZE_U64 * \
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sizeof(unsigned long long))
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/*
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* LZ4_stream_t - information structure to track an LZ4 stream.
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*/
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typedef struct {
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uint32_t hashTable[LZ4_HASH_SIZE_U32];
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uint32_t currentOffset;
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uint32_t initCheck;
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const uint8_t *dictionary;
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uint8_t *bufferStart;
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uint32_t dictSize;
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} LZ4_stream_t_internal;
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typedef union {
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unsigned long long table[LZ4_STREAMSIZE_U64];
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LZ4_stream_t_internal internal_donotuse;
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} LZ4_stream_t;
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/*
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* LZ4_streamHC_t - information structure to track an LZ4HC stream.
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*/
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typedef struct {
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unsigned int hashTable[LZ4HC_HASHTABLESIZE];
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unsigned short chainTable[LZ4HC_MAXD];
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/* next block to continue on current prefix */
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const unsigned char *end;
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/* All index relative to this position */
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const unsigned char *base;
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/* alternate base for extDict */
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const unsigned char *dictBase;
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/* below that point, need extDict */
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unsigned int dictLimit;
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/* below that point, no more dict */
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unsigned int lowLimit;
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/* index from which to continue dict update */
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unsigned int nextToUpdate;
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unsigned int compressionLevel;
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} LZ4HC_CCtx_internal;
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typedef union {
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size_t table[LZ4_STREAMHCSIZE_SIZET];
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LZ4HC_CCtx_internal internal_donotuse;
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} LZ4_streamHC_t;
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/*
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* LZ4_streamDecode_t - information structure to track an
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* LZ4 stream during decompression.
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*
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* init this structure using LZ4_setStreamDecode (or memset()) before first use
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*/
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typedef struct {
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const uint8_t *externalDict;
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size_t extDictSize;
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const uint8_t *prefixEnd;
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size_t prefixSize;
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} LZ4_streamDecode_t_internal;
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typedef union {
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unsigned long long table[LZ4_STREAMDECODESIZE_U64];
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LZ4_streamDecode_t_internal internal_donotuse;
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} LZ4_streamDecode_t;
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/*-************************************************************************
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* SIZE OF STATE
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**************************************************************************/
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#define LZ4_MEM_COMPRESS LZ4_STREAMSIZE
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#define LZ4HC_MEM_COMPRESS LZ4_STREAMHCSIZE
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/*-************************************************************************
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* Compression Functions
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**************************************************************************/
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/**
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* LZ4_compressBound() - Max. output size in worst case szenarios
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* @isize: Size of the input data
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*
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* Return: Max. size LZ4 may output in a "worst case" szenario
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* (data not compressible)
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*/
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static inline int LZ4_compressBound(size_t isize)
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{
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return LZ4_COMPRESSBOUND(isize);
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}
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/**
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* LZ4_compress_default() - Compress data from source to dest
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* @source: source address of the original data
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* @dest: output buffer address of the compressed data
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* @inputSize: size of the input data. Max supported value is LZ4_MAX_INPUT_SIZE
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* @maxOutputSize: full or partial size of buffer 'dest'
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* which must be already allocated
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* @wrkmem: address of the working memory.
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* This requires 'workmem' of LZ4_MEM_COMPRESS.
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*
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* Compresses 'sourceSize' bytes from buffer 'source'
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* into already allocated 'dest' buffer of size 'maxOutputSize'.
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* Compression is guaranteed to succeed if
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* 'maxOutputSize' >= LZ4_compressBound(inputSize).
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* It also runs faster, so it's a recommended setting.
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* If the function cannot compress 'source' into a more limited 'dest' budget,
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* compression stops *immediately*, and the function result is zero.
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* As a consequence, 'dest' content is not valid.
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*
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* Return: Number of bytes written into buffer 'dest'
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* (necessarily <= maxOutputSize) or 0 if compression fails
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*/
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int LZ4_compress_default(const char *source, char *dest, int inputSize,
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int maxOutputSize, void *wrkmem);
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/**
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* LZ4_compress_fast() - As LZ4_compress_default providing an acceleration param
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* @source: source address of the original data
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* @dest: output buffer address of the compressed data
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* @inputSize: size of the input data. Max supported value is LZ4_MAX_INPUT_SIZE
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* @maxOutputSize: full or partial size of buffer 'dest'
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* which must be already allocated
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* @acceleration: acceleration factor
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* @wrkmem: address of the working memory.
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* This requires 'workmem' of LZ4_MEM_COMPRESS.
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*
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* Same as LZ4_compress_default(), but allows to select an "acceleration"
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* factor. The larger the acceleration value, the faster the algorithm,
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* but also the lesser the compression. It's a trade-off. It can be fine tuned,
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* with each successive value providing roughly +~3% to speed.
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* An acceleration value of "1" is the same as regular LZ4_compress_default()
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* Values <= 0 will be replaced by LZ4_ACCELERATION_DEFAULT, which is 1.
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*
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* Return: Number of bytes written into buffer 'dest'
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* (necessarily <= maxOutputSize) or 0 if compression fails
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*/
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int LZ4_compress_fast(const char *source, char *dest, int inputSize,
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int maxOutputSize, int acceleration, void *wrkmem);
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/**
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* LZ4_compress_destSize() - Compress as much data as possible
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* from source to dest
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* @source: source address of the original data
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* @dest: output buffer address of the compressed data
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* @sourceSizePtr: will be modified to indicate how many bytes where read
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* from 'source' to fill 'dest'. New value is necessarily <= old value.
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* @targetDestSize: Size of buffer 'dest' which must be already allocated
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* @wrkmem: address of the working memory.
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* This requires 'workmem' of LZ4_MEM_COMPRESS.
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*
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* Reverse the logic, by compressing as much data as possible
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* from 'source' buffer into already allocated buffer 'dest'
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* of size 'targetDestSize'.
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* This function either compresses the entire 'source' content into 'dest'
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* if it's large enough, or fill 'dest' buffer completely with as much data as
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* possible from 'source'.
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*
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* Return: Number of bytes written into 'dest' (necessarily <= targetDestSize)
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* or 0 if compression fails
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*/
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int LZ4_compress_destSize(const char *source, char *dest, int *sourceSizePtr,
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int targetDestSize, void *wrkmem);
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/*-************************************************************************
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* Decompression Functions
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**************************************************************************/
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/**
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* LZ4_decompress_fast() - Decompresses data from 'source' into 'dest'
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* @source: source address of the compressed data
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* @dest: output buffer address of the uncompressed data
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* which must be already allocated with 'originalSize' bytes
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* @originalSize: is the original and therefore uncompressed size
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*
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* Decompresses data from 'source' into 'dest'.
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* This function fully respect memory boundaries for properly formed
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* compressed data.
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* It is a bit faster than LZ4_decompress_safe().
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* However, it does not provide any protection against intentionally
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* modified data stream (malicious input).
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* Use this function in trusted environment only
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* (data to decode comes from a trusted source).
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*
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* Return: number of bytes read from the source buffer
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* or a negative result if decompression fails.
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*/
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int LZ4_decompress_fast(const char *source, char *dest, int originalSize);
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/**
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* LZ4_decompress_safe() - Decompression protected against buffer overflow
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* @source: source address of the compressed data
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* @dest: output buffer address of the uncompressed data
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* which must be already allocated
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* @compressedSize: is the precise full size of the compressed block
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* @maxDecompressedSize: is the size of 'dest' buffer
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*
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* Decompresses data from 'source' into 'dest'.
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* If the source stream is detected malformed, the function will
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* stop decoding and return a negative result.
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* This function is protected against buffer overflow exploits,
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* including malicious data packets. It never writes outside output buffer,
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* nor reads outside input buffer.
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*
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* Return: number of bytes decompressed into destination buffer
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* (necessarily <= maxDecompressedSize)
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* or a negative result in case of error
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*/
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int LZ4_decompress_safe(const char *source, char *dest, int compressedSize,
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int maxDecompressedSize);
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/**
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* LZ4_decompress_safe_partial() - Decompress a block of size 'compressedSize'
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* at position 'source' into buffer 'dest'
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* @source: source address of the compressed data
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* @dest: output buffer address of the decompressed data which must be
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* already allocated
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* @compressedSize: is the precise full size of the compressed block.
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* @targetOutputSize: the decompression operation will try
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* to stop as soon as 'targetOutputSize' has been reached
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* @maxDecompressedSize: is the size of destination buffer
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*
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* This function decompresses a compressed block of size 'compressedSize'
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* at position 'source' into destination buffer 'dest'
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* of size 'maxDecompressedSize'.
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* The function tries to stop decompressing operation as soon as
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* 'targetOutputSize' has been reached, reducing decompression time.
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* This function never writes outside of output buffer,
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* and never reads outside of input buffer.
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* It is therefore protected against malicious data packets.
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*
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* Return: the number of bytes decoded in the destination buffer
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* (necessarily <= maxDecompressedSize)
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* or a negative result in case of error
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*
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*/
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int LZ4_decompress_safe_partial(const char *source, char *dest,
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int compressedSize, int targetOutputSize, int maxDecompressedSize);
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/*-************************************************************************
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* LZ4 HC Compression
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**************************************************************************/
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/**
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* LZ4_compress_HC() - Compress data from `src` into `dst`, using HC algorithm
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* @src: source address of the original data
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* @dst: output buffer address of the compressed data
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* @srcSize: size of the input data. Max supported value is LZ4_MAX_INPUT_SIZE
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* @dstCapacity: full or partial size of buffer 'dst',
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* which must be already allocated
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* @compressionLevel: Recommended values are between 4 and 9, although any
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* value between 1 and LZ4HC_MAX_CLEVEL will work.
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* Values >LZ4HC_MAX_CLEVEL behave the same as 16.
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* @wrkmem: address of the working memory.
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* This requires 'wrkmem' of size LZ4HC_MEM_COMPRESS.
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*
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* Compress data from 'src' into 'dst', using the more powerful
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* but slower "HC" algorithm. Compression is guaranteed to succeed if
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* `dstCapacity >= LZ4_compressBound(srcSize)
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*
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* Return : the number of bytes written into 'dst' or 0 if compression fails.
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*/
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int LZ4_compress_HC(const char *src, char *dst, int srcSize, int dstCapacity,
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int compressionLevel, void *wrkmem);
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/**
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* LZ4_resetStreamHC() - Init an allocated 'LZ4_streamHC_t' structure
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* @streamHCPtr: pointer to the 'LZ4_streamHC_t' structure
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* @compressionLevel: Recommended values are between 4 and 9, although any
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* value between 1 and LZ4HC_MAX_CLEVEL will work.
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* Values >LZ4HC_MAX_CLEVEL behave the same as 16.
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*
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* An LZ4_streamHC_t structure can be allocated once
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* and re-used multiple times.
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* Use this function to init an allocated `LZ4_streamHC_t` structure
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* and start a new compression.
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*/
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void LZ4_resetStreamHC(LZ4_streamHC_t *streamHCPtr, int compressionLevel);
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/**
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* LZ4_loadDictHC() - Load a static dictionary into LZ4_streamHC
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* @streamHCPtr: pointer to the LZ4HC_stream_t
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* @dictionary: dictionary to load
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* @dictSize: size of dictionary
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*
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* Use this function to load a static dictionary into LZ4HC_stream.
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* Any previous data will be forgotten, only 'dictionary'
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* will remain in memory.
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* Loading a size of 0 is allowed.
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*
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* Return : dictionary size, in bytes (necessarily <= 64 KB)
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*/
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int LZ4_loadDictHC(LZ4_streamHC_t *streamHCPtr, const char *dictionary,
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int dictSize);
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/**
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* LZ4_compress_HC_continue() - Compress 'src' using data from previously
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* compressed blocks as a dictionary using the HC algorithm
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* @streamHCPtr: Pointer to the previous 'LZ4_streamHC_t' structure
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* @src: source address of the original data
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* @dst: output buffer address of the compressed data,
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* which must be already allocated
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* @srcSize: size of the input data. Max supported value is LZ4_MAX_INPUT_SIZE
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* @maxDstSize: full or partial size of buffer 'dest'
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* which must be already allocated
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*
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* These functions compress data in successive blocks of any size, using
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* previous blocks as dictionary. One key assumption is that previous
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* blocks (up to 64 KB) remain read-accessible while
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* compressing next blocks. There is an exception for ring buffers,
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* which can be smaller than 64 KB.
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* Ring buffers scenario is automatically detected and handled by
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* LZ4_compress_HC_continue().
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* Before starting compression, state must be properly initialized,
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* using LZ4_resetStreamHC().
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* A first "fictional block" can then be designated as
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* initial dictionary, using LZ4_loadDictHC() (Optional).
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* Then, use LZ4_compress_HC_continue()
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* to compress each successive block. Previous memory blocks
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* (including initial dictionary when present) must remain accessible
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* and unmodified during compression.
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* 'dst' buffer should be sized to handle worst case scenarios, using
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* LZ4_compressBound(), to ensure operation success.
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* If, for any reason, previous data blocks can't be preserved unmodified
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* in memory during next compression block,
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* you must save it to a safer memory space, using LZ4_saveDictHC().
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* Return value of LZ4_saveDictHC() is the size of dictionary
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* effectively saved into 'safeBuffer'.
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*
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* Return: Number of bytes written into buffer 'dst' or 0 if compression fails
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*/
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int LZ4_compress_HC_continue(LZ4_streamHC_t *streamHCPtr, const char *src,
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char *dst, int srcSize, int maxDstSize);
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/**
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* LZ4_saveDictHC() - Save static dictionary from LZ4HC_stream
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* @streamHCPtr: pointer to the 'LZ4HC_stream_t' structure
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* @safeBuffer: buffer to save dictionary to, must be already allocated
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* @maxDictSize: size of 'safeBuffer'
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*
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* If previously compressed data block is not guaranteed
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* to remain available at its memory location,
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* save it into a safer place (char *safeBuffer).
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* Note : you don't need to call LZ4_loadDictHC() afterwards,
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* dictionary is immediately usable, you can therefore call
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* LZ4_compress_HC_continue().
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*
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* Return : saved dictionary size in bytes (necessarily <= maxDictSize),
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* or 0 if error.
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*/
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int LZ4_saveDictHC(LZ4_streamHC_t *streamHCPtr, char *safeBuffer,
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int maxDictSize);
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/*-*********************************************
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* Streaming Compression Functions
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***********************************************/
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/**
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* LZ4_resetStream() - Init an allocated 'LZ4_stream_t' structure
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* @LZ4_stream: pointer to the 'LZ4_stream_t' structure
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*
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* An LZ4_stream_t structure can be allocated once
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* and re-used multiple times.
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* Use this function to init an allocated `LZ4_stream_t` structure
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* and start a new compression.
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*/
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void LZ4_resetStream(LZ4_stream_t *LZ4_stream);
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/**
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* LZ4_loadDict() - Load a static dictionary into LZ4_stream
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* @streamPtr: pointer to the LZ4_stream_t
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* @dictionary: dictionary to load
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* @dictSize: size of dictionary
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*
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* Use this function to load a static dictionary into LZ4_stream.
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* Any previous data will be forgotten, only 'dictionary'
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* will remain in memory.
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* Loading a size of 0 is allowed.
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*
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* Return : dictionary size, in bytes (necessarily <= 64 KB)
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*/
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int LZ4_loadDict(LZ4_stream_t *streamPtr, const char *dictionary,
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int dictSize);
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/**
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* LZ4_saveDict() - Save static dictionary from LZ4_stream
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* @streamPtr: pointer to the 'LZ4_stream_t' structure
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* @safeBuffer: buffer to save dictionary to, must be already allocated
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* @dictSize: size of 'safeBuffer'
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*
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* If previously compressed data block is not guaranteed
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* to remain available at its memory location,
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* save it into a safer place (char *safeBuffer).
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* Note : you don't need to call LZ4_loadDict() afterwards,
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* dictionary is immediately usable, you can therefore call
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* LZ4_compress_fast_continue().
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*
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* Return : saved dictionary size in bytes (necessarily <= dictSize),
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* or 0 if error.
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*/
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int LZ4_saveDict(LZ4_stream_t *streamPtr, char *safeBuffer, int dictSize);
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/**
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* LZ4_compress_fast_continue() - Compress 'src' using data from previously
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* compressed blocks as a dictionary
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* @streamPtr: Pointer to the previous 'LZ4_stream_t' structure
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* @src: source address of the original data
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* @dst: output buffer address of the compressed data,
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* which must be already allocated
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* @srcSize: size of the input data. Max supported value is LZ4_MAX_INPUT_SIZE
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* @maxDstSize: full or partial size of buffer 'dest'
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* which must be already allocated
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* @acceleration: acceleration factor
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*
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* Compress buffer content 'src', using data from previously compressed blocks
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* as dictionary to improve compression ratio.
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* Important : Previous data blocks are assumed to still
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* be present and unmodified !
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* If maxDstSize >= LZ4_compressBound(srcSize),
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* compression is guaranteed to succeed, and runs faster.
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*
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* Return: Number of bytes written into buffer 'dst' or 0 if compression fails
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*/
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int LZ4_compress_fast_continue(LZ4_stream_t *streamPtr, const char *src,
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char *dst, int srcSize, int maxDstSize, int acceleration);
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/**
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* LZ4_setStreamDecode() - Instruct where to find dictionary
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* @LZ4_streamDecode: the 'LZ4_streamDecode_t' structure
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* @dictionary: dictionary to use
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* @dictSize: size of dictionary
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*
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* Use this function to instruct where to find the dictionary.
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* Setting a size of 0 is allowed (same effect as reset).
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*
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* Return: 1 if OK, 0 if error
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*/
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int LZ4_setStreamDecode(LZ4_streamDecode_t *LZ4_streamDecode,
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const char *dictionary, int dictSize);
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/**
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* LZ4_decompress_safe_continue() - Decompress blocks in streaming mode
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* @LZ4_streamDecode: the 'LZ4_streamDecode_t' structure
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* @source: source address of the compressed data
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* @dest: output buffer address of the uncompressed data
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* which must be already allocated
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* @compressedSize: is the precise full size of the compressed block
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* @maxDecompressedSize: is the size of 'dest' buffer
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*
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* This decoding function allows decompression of multiple blocks
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* in "streaming" mode.
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* Previously decoded blocks *must* remain available at the memory position
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* where they were decoded (up to 64 KB)
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* In the case of a ring buffers, decoding buffer must be either :
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* - Exactly same size as encoding buffer, with same update rule
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* (block boundaries at same positions) In which case,
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* the decoding & encoding ring buffer can have any size,
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* including very small ones ( < 64 KB).
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* - Larger than encoding buffer, by a minimum of maxBlockSize more bytes.
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* maxBlockSize is implementation dependent.
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* It's the maximum size you intend to compress into a single block.
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* In which case, encoding and decoding buffers do not need
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* to be synchronized, and encoding ring buffer can have any size,
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* including small ones ( < 64 KB).
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* - _At least_ 64 KB + 8 bytes + maxBlockSize.
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* In which case, encoding and decoding buffers do not need to be
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* synchronized, and encoding ring buffer can have any size,
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* including larger than decoding buffer. W
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* Whenever these conditions are not possible, save the last 64KB of decoded
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* data into a safe buffer, and indicate where it is saved
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* using LZ4_setStreamDecode()
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*
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* Return: number of bytes decompressed into destination buffer
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* (necessarily <= maxDecompressedSize)
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* or a negative result in case of error
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*/
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int LZ4_decompress_safe_continue(LZ4_streamDecode_t *LZ4_streamDecode,
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const char *source, char *dest, int compressedSize,
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int maxDecompressedSize);
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/**
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* LZ4_decompress_fast_continue() - Decompress blocks in streaming mode
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* @LZ4_streamDecode: the 'LZ4_streamDecode_t' structure
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* @source: source address of the compressed data
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* @dest: output buffer address of the uncompressed data
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* which must be already allocated with 'originalSize' bytes
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* @originalSize: is the original and therefore uncompressed size
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*
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* This decoding function allows decompression of multiple blocks
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* in "streaming" mode.
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* Previously decoded blocks *must* remain available at the memory position
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* where they were decoded (up to 64 KB)
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* In the case of a ring buffers, decoding buffer must be either :
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* - Exactly same size as encoding buffer, with same update rule
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* (block boundaries at same positions) In which case,
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* the decoding & encoding ring buffer can have any size,
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* including very small ones ( < 64 KB).
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* - Larger than encoding buffer, by a minimum of maxBlockSize more bytes.
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* maxBlockSize is implementation dependent.
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* It's the maximum size you intend to compress into a single block.
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* In which case, encoding and decoding buffers do not need
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* to be synchronized, and encoding ring buffer can have any size,
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* including small ones ( < 64 KB).
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* - _At least_ 64 KB + 8 bytes + maxBlockSize.
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* In which case, encoding and decoding buffers do not need to be
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* synchronized, and encoding ring buffer can have any size,
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* including larger than decoding buffer. W
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* Whenever these conditions are not possible, save the last 64KB of decoded
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* data into a safe buffer, and indicate where it is saved
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* using LZ4_setStreamDecode()
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*
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* Return: number of bytes decompressed into destination buffer
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* (necessarily <= maxDecompressedSize)
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* or a negative result in case of error
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*/
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int LZ4_decompress_fast_continue(LZ4_streamDecode_t *LZ4_streamDecode,
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const char *source, char *dest, int originalSize);
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/**
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* LZ4_decompress_safe_usingDict() - Same as LZ4_setStreamDecode()
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* followed by LZ4_decompress_safe_continue()
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* @source: source address of the compressed data
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* @dest: output buffer address of the uncompressed data
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* which must be already allocated
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* @compressedSize: is the precise full size of the compressed block
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* @maxDecompressedSize: is the size of 'dest' buffer
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* @dictStart: pointer to the start of the dictionary in memory
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* @dictSize: size of dictionary
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*
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* This decoding function works the same as
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* a combination of LZ4_setStreamDecode() followed by
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* LZ4_decompress_safe_continue()
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* It is stand-alone, and doesn't need an LZ4_streamDecode_t structure.
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*
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* Return: number of bytes decompressed into destination buffer
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* (necessarily <= maxDecompressedSize)
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* or a negative result in case of error
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*/
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int LZ4_decompress_safe_usingDict(const char *source, char *dest,
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int compressedSize, int maxDecompressedSize, const char *dictStart,
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int dictSize);
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/**
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* LZ4_decompress_fast_usingDict() - Same as LZ4_setStreamDecode()
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* followed by LZ4_decompress_fast_continue()
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* @source: source address of the compressed data
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* @dest: output buffer address of the uncompressed data
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* which must be already allocated with 'originalSize' bytes
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* @originalSize: is the original and therefore uncompressed size
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* @dictStart: pointer to the start of the dictionary in memory
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* @dictSize: size of dictionary
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*
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* This decoding function works the same as
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* a combination of LZ4_setStreamDecode() followed by
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* LZ4_decompress_fast_continue()
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* It is stand-alone, and doesn't need an LZ4_streamDecode_t structure.
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*
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* Return: number of bytes decompressed into destination buffer
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* (necessarily <= maxDecompressedSize)
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* or a negative result in case of error
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*/
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int LZ4_decompress_fast_usingDict(const char *source, char *dest,
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int originalSize, const char *dictStart, int dictSize);
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#endif
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