facebook
/
zstd
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Added BMI instructions

dev
Yann Collet 2016-03-23 18:45:23 +01:00
parent 6cf45dac81
commit 862a85976f
1 changed files with 11 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
lib/bitstream.h
View File

@ -292,9 +292,14 @@ MEM_STATIC size_t BIT_getUpperBits(size_t bitD, U32 const start)
return bitD >> start;
}
#include <immintrin.h>
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];
#endif
}
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.
* @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;
return ((bitD->bitContainer << (bitD->bitsConsumed & bitMask)) >> 1) >> ((bitMask-nbBits) & bitMask);
//return (bitD->bitContainer >> (64 - bitD->bitsConsumed - nbBits)) & BIT_mask[nbBits];
#endif
}
/*! BIT_lookBitsFast() :