282 lines
10 KiB
C++
282 lines
10 KiB
C++
/*
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LZ4 - Fast LZ compression algorithm
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Copyright (C) 2011-2015, 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 source repository : https://github.com/Cyan4973/lz4
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- LZ4 public forum : https://groups.google.com/forum/#!forum/lz4c
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*/
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/**************************************
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* Reading and writing into memory
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**************************************/
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/* customized variant of memcpy, which can overwrite up to 7 bytes beyond dstEnd */
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static void LZ4_wildCopy(void* dstPtr, const void* srcPtr, void* dstEnd)
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{
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BYTE* d = (BYTE*)dstPtr;
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const BYTE* s = (const BYTE*)srcPtr;
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BYTE* const e = (BYTE*)dstEnd;
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#if 0
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const size_t l2 = 8 - (((size_t)d) & (sizeof(void*)-1));
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LZ4_copy8(d,s); if (d>e-9) return;
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d+=l2; s+=l2;
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#endif /* join to align */
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do { LZ4_copy8(d,s); d+=8; s+=8; } while (d<e);
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}
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/**************************************
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* Common Constants
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**************************************/
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#define MINMATCH 4
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#define WILDCOPYLENGTH 8
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#define LASTLITERALS 5
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#define MFLIMIT (WILDCOPYLENGTH+MINMATCH)
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static const int LZ4_minLength = (MFLIMIT+1);
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#define KB *(1 << 10)
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#define MB *(1 << 20)
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#define GB *(1U << 30)
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#define MAXD_LOG 16
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#define MAX_DISTANCE ((1 << MAXD_LOG) - 1)
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#define ML_BITS 4
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#define ML_MASK ((1U << ML_BITS)-1)
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#define RUN_BITS (8-ML_BITS)
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#define RUN_MASK ((1U << RUN_BITS)-1)
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/**************************************
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* Local Structures and types
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**************************************/
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typedef enum { noDict = 0, withPrefix64k, usingExtDict } dict_directive;
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typedef enum { endOnOutputSize = 0, endOnInputSize = 1 } endCondition_directive;
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typedef enum { full = 0, partial = 1 } earlyEnd_directive;
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/*******************************
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* Decompression functions
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*******************************/
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/*
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* This generic decompression function cover all use cases.
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* It shall be instantiated several times, using different sets of directives
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* Note that it is essential this generic function is really inlined,
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* in order to remove useless branches during compilation optimization.
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*/
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FORCE_INLINE int LZ4_decompress_generic(
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const char* const source,
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char* const dest,
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int inputSize,
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int outputSize, /* If endOnInput==endOnInputSize, this value is the max size of Output Buffer. */
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int endOnInput, /* endOnOutputSize, endOnInputSize */
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int partialDecoding, /* full, partial */
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int targetOutputSize, /* only used if partialDecoding==partial */
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int dict, /* noDict, withPrefix64k, usingExtDict */
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const BYTE* const lowPrefix, /* == dest if dict == noDict */
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const BYTE* const dictStart, /* only if dict==usingExtDict */
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const size_t dictSize /* note : = 0 if noDict */
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)
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{
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/* Local Variables */
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const BYTE* ip = (const BYTE*) source;
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const BYTE* const iend = ip + inputSize;
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BYTE* op = (BYTE*) dest;
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BYTE* const oend = op + outputSize;
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BYTE* cpy;
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BYTE* oexit = op + targetOutputSize;
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const BYTE* const lowLimit = lowPrefix - dictSize;
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const BYTE* const dictEnd = (const BYTE*)dictStart + dictSize;
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const unsigned dec32table[] = {4, 1, 2, 1, 4, 4, 4, 4};
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const int dec64table[] = {0, 0, 0, -1, 0, 1, 2, 3};
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const int safeDecode = (endOnInput==endOnInputSize);
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const int checkOffset = ((safeDecode) && (dictSize < (int)(64 KB)));
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const int inPlaceDecode = ((ip >= op) && (ip < oend));
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/* Special cases */
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if ((partialDecoding) && (oexit> oend-MFLIMIT)) oexit = oend-MFLIMIT; /* targetOutputSize too high => decode everything */
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if ((endOnInput) && (unlikely(outputSize==0))) return ((inputSize==1) && (*ip==0)) ? 0 : -1; /* Empty output buffer */
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if ((!endOnInput) && (unlikely(outputSize==0))) return (*ip==0?1:-1);
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/* Main Loop */
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while (1)
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{
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unsigned token;
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size_t length;
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const BYTE* match;
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size_t offset;
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if (unlikely((inPlaceDecode) && (op + WILDCOPYLENGTH > ip))) goto _output_error; /* output stream ran over input stream */
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/* get literal length */
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token = *ip++;
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if ((length=(token>>ML_BITS)) == RUN_MASK)
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{
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unsigned s;
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if ((endOnInput) && unlikely(ip>=iend-RUN_MASK)) goto _output_error; /* overflow detection */
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do
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{
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s = *ip++;
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length += s;
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}
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while ( likely(endOnInput ? ip<iend-RUN_MASK : 1) && (s==255) );
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if ((safeDecode) && unlikely((size_t)(op+length)<(size_t)(op))) goto _output_error; /* overflow detection */
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if ((safeDecode) && unlikely((size_t)(ip+length)<(size_t)(ip))) goto _output_error; /* overflow detection */
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}
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/* copy literals */
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cpy = op+length;
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if (((endOnInput) && ((cpy>(partialDecoding?oexit:oend-MFLIMIT)) || (ip+length>iend-(2+1+LASTLITERALS))) )
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|| ((!endOnInput) && (cpy>oend-WILDCOPYLENGTH)))
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{
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if (partialDecoding)
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{
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if (cpy > oend) goto _output_error; /* Error : write attempt beyond end of output buffer */
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if ((endOnInput) && (ip+length > iend)) goto _output_error; /* Error : read attempt beyond end of input buffer */
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}
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else
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{
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if ((!endOnInput) && (cpy != oend)) goto _output_error; /* Error : block decoding must stop exactly there */
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if ((endOnInput) && ((ip+length != iend) || (cpy > oend))) goto _output_error; /* Error : input must be consumed */
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}
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memmove(op, ip, length);
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ip += length;
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op += length;
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break; /* Necessarily EOF, due to parsing restrictions */
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}
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LZ4_wildCopy(op, ip, cpy);
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ip += length; op = cpy;
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/* get offset */
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offset = LZ4_readLE16(ip); ip+=2;
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match = op - offset;
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if ((checkOffset) && (unlikely(match < lowLimit))) goto _output_error; /* Error : offset outside buffers */
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/* get matchlength */
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length = token & ML_MASK;
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if (length == ML_MASK)
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{
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unsigned s;
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do
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{
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if ((endOnInput) && (ip > iend-LASTLITERALS)) goto _output_error;
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s = *ip++;
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length += s;
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} while (s==255);
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if ((safeDecode) && unlikely((size_t)(op+length)<(size_t)op)) goto _output_error; /* overflow detection */
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}
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length += MINMATCH;
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/* check external dictionary */
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if ((dict==usingExtDict) && (match < lowPrefix))
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{
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if (unlikely(op+length > oend-LASTLITERALS)) goto _output_error; /* doesn't respect parsing restriction */
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if (length <= (size_t)(lowPrefix-match))
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{
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/* match can be copied as a single segment from external dictionary */
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match = dictEnd - (lowPrefix-match);
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memmove(op, match, length); op += length;
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}
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else
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{
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/* match encompass external dictionary and current block */
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size_t copySize = (size_t)(lowPrefix-match);
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memcpy(op, dictEnd - copySize, copySize);
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op += copySize;
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copySize = length - copySize;
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if (copySize > (size_t)(op-lowPrefix)) /* overlap copy */
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{
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BYTE* const endOfMatch = op + copySize;
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const BYTE* copyFrom = lowPrefix;
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while (op < endOfMatch) *op++ = *copyFrom++;
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}
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else
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{
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memcpy(op, lowPrefix, copySize);
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op += copySize;
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}
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}
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continue;
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}
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/* copy match within block */
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cpy = op + length;
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if (unlikely(offset<8))
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{
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const int dec64 = dec64table[offset];
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op[0] = match[0];
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op[1] = match[1];
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op[2] = match[2];
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op[3] = match[3];
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match += dec32table[offset];
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memcpy(op+4, match, 4);
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match -= dec64;
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} else { LZ4_copy8(op, match); match+=8; }
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op += 8;
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if (unlikely(cpy>oend-12))
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{
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BYTE* const oCopyLimit = oend-(WILDCOPYLENGTH-1);
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if (cpy > oend-LASTLITERALS) goto _output_error; /* Error : last LASTLITERALS bytes must be literals (uncompressed) */
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if (op < oCopyLimit)
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{
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LZ4_wildCopy(op, match, oCopyLimit);
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match += oCopyLimit - op;
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op = oCopyLimit;
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}
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while (op<cpy) *op++ = *match++;
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}
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else
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LZ4_wildCopy(op, match, cpy);
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op=cpy; /* correction */
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}
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/* end of decoding */
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if (endOnInput)
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return (int) (((char*)op)-dest); /* Nb of output bytes decoded */
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else
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return (int) (((const char*)ip)-source); /* Nb of input bytes read */
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/* Overflow error detected */
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_output_error:
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return (int) (-(((const char*)ip)-source))-1;
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}
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