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Updated FSE

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This commit is contained in:
Yann Collet
2015-08-26 19:22:01 +01:00
parent ddf39e91c5
commit 6b5198fe3a
1 changed files with 3 additions and 2 deletions
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lib/fse.c
+3 -2
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@@ -135,7 +135,7 @@ typedef signed long long S64;
* Method 1 : `__packed` statement. It depends on compiler extension (ie, not portable). * Method 1 : `__packed` statement. It depends on compiler extension (ie, not portable).
* This method is safe if your compiler supports it, and *generally* as fast or faster than `memcpy`. * This method is safe if your compiler supports it, and *generally* as fast or faster than `memcpy`.
* Method 2 : direct access. This method is portable but violate C standard. * Method 2 : direct access. This method is portable but violate C standard.
* It can generate buggy code on targets which generate assembly depending on alignment. * It can generate buggy code on targets generating assembly depending on alignment.
* But in some circumstances, it's the only known way to get the most performance (ie GCC + ARMv6) * But in some circumstances, it's the only known way to get the most performance (ie GCC + ARMv6)
* See http://fastcompression.blogspot.fr/2015/08/accessing-unaligned-memory.html for details. * See http://fastcompression.blogspot.fr/2015/08/accessing-unaligned-memory.html for details.
* Prefer these methods in priority order (0 > 1 > 2) * Prefer these methods in priority order (0 > 1 > 2)
@@ -1398,6 +1398,7 @@ size_t FSE_compress2 (void* dst, size_t dstSize, const void* src, size_t srcSize
errorCode = FSE_count (count, &maxSymbolValue, ip, srcSize); errorCode = FSE_count (count, &maxSymbolValue, ip, srcSize);
if (FSE_isError(errorCode)) return errorCode; if (FSE_isError(errorCode)) return errorCode;
if (errorCode == srcSize) return 1; if (errorCode == srcSize) return 1;
if (errorCode == 1) return 0; /* each symbol only present once */
if (errorCode < (srcSize >> 7)) return 0; /* Heuristic : not compressible enough */ if (errorCode < (srcSize >> 7)) return 0; /* Heuristic : not compressible enough */
tableLog = FSE_optimalTableLog(tableLog, srcSize, maxSymbolValue); tableLog = FSE_optimalTableLog(tableLog, srcSize, maxSymbolValue);
@@ -1534,7 +1535,7 @@ static size_t FSE_lookBits(FSE_DStream_t* bitD, U32 nbBits)
static size_t FSE_lookBitsFast(FSE_DStream_t* bitD, U32 nbBits) /* only if nbBits >= 1 !! */ static size_t FSE_lookBitsFast(FSE_DStream_t* bitD, U32 nbBits) /* only if nbBits >= 1 !! */
{ {
return (bitD->bitContainer << bitD->bitsConsumed) >> ((sizeof(bitD->bitContainer)*8)-nbBits); return (bitD->bitContainer << (bitD->bitsConsumed & ((sizeof(bitD->bitContainer)*8)-1))) >> ((sizeof(bitD->bitContainer)*8)-nbBits);
} }
static void FSE_skipBits(FSE_DStream_t* bitD, U32 nbBits) static void FSE_skipBits(FSE_DStream_t* bitD, U32 nbBits)