AuroraMiddleware/zstd
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Added BMI instructions

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This commit is contained in:
Yann Collet 2016-03-23 18:45:23 +01:00
parent 6cf45dac81
commit 862a85976f
1 changed files with 11 additions and 1 deletions
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12
lib/bitstream.h
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@ -292,9 +292,14 @@ MEM_STATIC size_t BIT_getUpperBits(size_t bitD, U32 const start)
return bitD >> start; return bitD >> start;
} }
#include <immintrin.h>
MEM_STATIC size_t BIT_getMiddleBits(size_t bitD, U32 const nbBits, U32 const start) MEM_STATIC size_t BIT_getMiddleBits(size_t bitD, U32 const nbBits, U32 const start)
{ {
#if defined(__BMI__) && defined(__GNUC__)
return __builtin_ia32_bextr_u64(bitD, (nbBits<<8) | start );
#else
return (bitD >> start) & BIT_mask[nbBits]; return (bitD >> start) & BIT_mask[nbBits];
#endif
} }
MEM_STATIC size_t BIT_getLowerBits(size_t bitD, U32 const nbBits) MEM_STATIC size_t BIT_getLowerBits(size_t bitD, U32 const nbBits)
@ -309,10 +314,15 @@ MEM_STATIC size_t BIT_getLowerBits(size_t bitD, U32 const nbBits)
* On 64-bits, maxNbBits==56. * On 64-bits, maxNbBits==56.
* @return : value extracted * @return : value extracted
*/ */
MEM_STATIC size_t BIT_lookBits(const BIT_DStream_t* bitD, U32 nbBits) MEM_STATIC size_t BIT_lookBits(const BIT_DStream_t* bitD, U32 nbBits)
{ {
#if defined(__BMI__) && defined(__GNUC__)
return __builtin_ia32_bextr_u64(bitD->bitContainer, (nbBits<<8) | (64 - bitD->bitsConsumed - nbBits) );
#else
U32 const bitMask = sizeof(bitD->bitContainer)*8 - 1; U32 const bitMask = sizeof(bitD->bitContainer)*8 - 1;
return ((bitD->bitContainer << (bitD->bitsConsumed & bitMask)) >> 1) >> ((bitMask-nbBits) & bitMask); return ((bitD->bitContainer << (bitD->bitsConsumed & bitMask)) >> 1) >> ((bitMask-nbBits) & bitMask);
//return (bitD->bitContainer >> (64 - bitD->bitsConsumed - nbBits)) & BIT_mask[nbBits];
#endif
} }
/*! BIT_lookBitsFast() : /*! BIT_lookBitsFast() :