small decompression speed improvement
This commit is contained in:
Yann Collet
parent
2ec0cf21f8
commit
107c5755f4
81
lib/zstd.c
81
lib/zstd.c
@ -84,7 +84,7 @@
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#endif
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/********************************************************
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/* *******************************************************
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* Constants
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*********************************************************/
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#define HASH_LOG (ZSTD_MEMORY_USAGE - 2)
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@ -129,9 +129,9 @@ static const size_t ZSTD_blockHeaderSize = 3;
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static const size_t ZSTD_frameHeaderSize = 4;
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/********************************************************
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/* *******************************************************
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* Memory operations
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*********************************************************/
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**********************************************************/
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static size_t ZSTD_read_ARCH(const void* p) { size_t r; memcpy(&r, p, sizeof(r)); return r; }
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static void ZSTD_copy4(void* dst, const void* src) { memcpy(dst, src, 4); }
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@ -140,18 +140,19 @@ static void ZSTD_copy8(void* dst, const void* src) { memcpy(dst, src, 8); }
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#define COPY8(d,s) { ZSTD_copy8(d,s); d+=8; s+=8; }
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/*! ZSTD_wildcopy : custom version of memcpy(), can copy up to 7-8 bytes too many */
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static void ZSTD_wildcopy(void* dst, const void* src, size_t length)
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{
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const BYTE* ip = (const BYTE*)src;
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BYTE* op = (BYTE*)dst;
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BYTE* const oend = op + length;
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while (op < oend) COPY8(op, ip);
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do COPY8(op, ip) while (op < oend);
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}
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/**************************************
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/* **************************************
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* Local structures
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***************************************/
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****************************************/
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typedef enum { bt_compressed, bt_raw, bt_rle, bt_end } blockType_t;
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typedef struct
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@ -228,9 +229,9 @@ size_t ZSTD_freeCCtx(ZSTD_Cctx* ctx)
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}
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/**************************************
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/* *************************************
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* Error Management
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**************************************/
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***************************************/
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/*! ZSTD_isError
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* tells if a return value is an error code */
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unsigned ZSTD_isError(size_t code) { return ERR_isError(code); }
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@ -240,9 +241,9 @@ unsigned ZSTD_isError(size_t code) { return ERR_isError(code); }
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const char* ZSTD_getErrorName(size_t code) { return ERR_getErrorName(code); }
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/**************************************
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/* *************************************
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* Tool functions
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**************************************/
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***************************************/
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unsigned ZSTD_versionNumber (void) { return ZSTD_VERSION_NUMBER; }
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static unsigned ZSTD_highbit(U32 val)
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@ -354,7 +355,7 @@ static unsigned ZSTD_count(const BYTE* pIn, const BYTE* pMatch, const BYTE* pInL
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}
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/********************************************************
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/* *******************************************************
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* Compression
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*********************************************************/
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size_t ZSTD_compressBound(size_t srcSize) /* maximum compressed size */
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@ -998,9 +999,9 @@ size_t ZSTD_compress(void* dst, size_t maxDstSize, const void* src, size_t srcSi
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}
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/**************************************************************
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* Decompression code
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**************************************************************/
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/* *************************************************************
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* Decompression section
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***************************************************************/
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struct ZSTD_Dctx_s
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{
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U32 LLTable[FSE_DTABLE_SIZE_U32(LLFSELog)];
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@ -1015,7 +1016,7 @@ struct ZSTD_Dctx_s
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size_t litBufSize;
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size_t litSize;
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BYTE litBuffer[BLOCKSIZE];
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}; /* typedef'd to ZSTD_Dctx */
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}; /* typedef'd to ZSTD_Dctx within "zstd_static.h" */
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size_t ZSTD_getcBlockSize(const void* src, size_t srcSize, blockProperties_t* bpPtr)
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{
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@ -1256,16 +1257,14 @@ static void ZSTD_decodeSequence(seq_t* seq, seqState_t* seqState)
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seqState->prevOffset = seq->offset;
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if (litLength == MaxLL)
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{
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U32 add = dumps<de ? *dumps++ : 0;
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U32 add = *dumps++;
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if (add < 255) litLength += add;
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else
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{
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if (dumps<=(de-3))
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{
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litLength = MEM_readLE32(dumps) & 0xFFFFFF; /* no pb : dumps is always followed by seq tables > 1 byte */
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dumps += 3;
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}
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litLength = MEM_readLE32(dumps) & 0xFFFFFF; /* no pb : dumps is always followed by seq tables > 1 byte */
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dumps += 3;
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}
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if (dumps >= de) dumps = de-1; /* late correction, to avoid read overflow (data is now corrupted anyway) */
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}
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/* Offset */
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@ -1277,23 +1276,21 @@ static void ZSTD_decodeSequence(seq_t* seq, seqState_t* seqState)
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if (offsetCode==0) nbBits = 0; /* cmove */
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offset = ((size_t)1 << (nbBits & ((sizeof(offset)*8)-1))) + BIT_readBits(&(seqState->DStream), nbBits);
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if (MEM_32bits()) BIT_reloadDStream(&(seqState->DStream));
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if (offsetCode==0) offset = prevOffset;
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if (offsetCode==0) offset = prevOffset; /* cmove */
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}
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/* MatchLength */
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matchLength = FSE_decodeSymbol(&(seqState->stateML), &(seqState->DStream));
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if (matchLength == MaxML)
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{
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U32 add = dumps<de ? *dumps++ : 0;
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U32 add = *dumps++;
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if (add < 255) matchLength += add;
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else
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{
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if (dumps<=(de-3))
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{
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matchLength = MEM_readLE32(dumps) & 0xFFFFFF; /* no pb : dumps is always followed by seq tables > 1 byte */
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dumps += 3;
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}
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matchLength = MEM_readLE32(dumps) & 0xFFFFFF; /* no pb : dumps is always followed by seq tables > 1 byte */
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dumps += 3;
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}
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if (dumps >= de) dumps = de-1; /* late correction, to avoid read overflow (data is now corrupted anyway) */
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}
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matchLength += MINMATCH;
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@ -1313,33 +1310,32 @@ static size_t ZSTD_execSequence(BYTE* op,
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static const int dec32table[] = {0, 1, 2, 1, 4, 4, 4, 4}; /* added */
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static const int dec64table[] = {8, 8, 8, 7, 8, 9,10,11}; /* substracted */
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const BYTE* const ostart = op;
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const size_t litLength = sequence.litLength;
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BYTE* const endMatch = op + litLength + sequence.matchLength; /* risk : address space overflow (32-bits) */
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const size_t litLength = sequence.litLength; /* for some reason, doing the same with matchLength decreases speed ... */
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BYTE* const oMatchEnd = op + litLength + sequence.matchLength; /* risk : address space overflow (32-bits) */
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const BYTE* const litEnd = *litPtr + litLength;
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/* check */
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if (endMatch > oend) return ERROR(dstSize_tooSmall); /* overwrite beyond dst buffer */
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if (oMatchEnd > oend) return ERROR(dstSize_tooSmall); /* overwrite beyond dst buffer */
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if (litEnd > litLimit) return ERROR(corruption_detected);
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if (sequence.matchLength > (size_t)(*litPtr-op)) return ERROR(dstSize_tooSmall); /* overwrite literal segment */
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/* copy Literals */
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if (((size_t)(*litPtr - op) < 8) || ((size_t)(oend-litEnd) < 8) || (op+litLength > oend-8))
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memmove(op, *litPtr, litLength); /* overwrite risk */
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if (op+litLength > oend-8) /* ZSTD_wildcopy() risks overwrite */
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memmove(op, *litPtr, litLength);
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else
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ZSTD_wildcopy(op, *litPtr, litLength);
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op += litLength;
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*litPtr = litEnd; /* update for next sequence */
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/* check : last match must be at a minimum distance of 8 from end of dest buffer */
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/* check : last match must be at a minimum distance of 8 from end of dst buffer */
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if (oend-op < 8) return ERROR(dstSize_tooSmall);
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/* copy Match */
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{
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const BYTE* match = op - sequence.offset; /* possible underflow at op - offset ? */
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const BYTE* match = op - sequence.offset;
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/* check */
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if (match < base) return ERROR(corruption_detected);
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if (sequence.offset > (size_t)base) return ERROR(corruption_detected);
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if (match > op) return ERROR(corruption_detected); /* address space overflow test */
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/* close range match, overlap */
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if (sequence.offset < 8)
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@ -1355,7 +1351,7 @@ static size_t ZSTD_execSequence(BYTE* op,
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} else { ZSTD_copy8(op, match); }
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op += 8; match += 8;
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if (endMatch > oend-12)
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if (oMatchEnd > oend-12)
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{
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if (op < oend-8)
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{
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@ -1363,15 +1359,18 @@ static size_t ZSTD_execSequence(BYTE* op,
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match += (oend-8) - op;
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op = oend-8;
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}
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while (op<endMatch) *op++ = *match++;
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while (op < oMatchEnd) *op++ = *match++;
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}
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else
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{
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ZSTD_wildcopy(op, match, sequence.matchLength-8); /* works even if matchLength < 8 */
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}
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}
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return endMatch-ostart;
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return oMatchEnd - ostart;
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}
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static size_t ZSTD_decompressSequences(
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void* ctx,
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void* dst, size_t maxDstSize,
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@ -1480,7 +1479,7 @@ static size_t ZSTD_decompressDCtx(void* ctx, void* dst, size_t maxDstSize, const
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magicNumber = MEM_readLE32(src);
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#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT==1)
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if (magicNumber == ZSTDv01_magicNumberLE) return ZSTDv01_decompressDCtx(ctx, dst, maxDstSize, src, srcSize);
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#endif // defined
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#endif /* ZSTD_LEGACY_SUPPORT */
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if (magicNumber != ZSTD_magicNumber) return ERROR(prefix_unknown);
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ip += ZSTD_frameHeaderSize; remainingSize -= ZSTD_frameHeaderSize;
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