AuroraMiddleware/zstd
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Niadb 2020-07-28 02:52:15 -06:00 committed by GitHub
parent 01261bc8b6
commit 493fd40dca
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3 changed files with 33 additions and 4 deletions
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16
lib/common/bitstream.h
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@ -141,8 +141,12 @@ MEM_STATIC unsigned BIT_highbit32 (U32 val)
assert(val != 0);
{
# if defined(_MSC_VER) /* Visual */
unsigned long r=0;
return _BitScanReverse ( &r, val ) ? (unsigned)r : 0;
# if STATIC_BMI2 == 1
return _lzcnt_u32(val) ^ 31;
# else
unsigned long r = 0;
return _BitScanReverse(&r, val) ? (unsigned)r : 0;
# endif
# elif defined(__GNUC__) && (__GNUC__ >= 3) /* Use GCC Intrinsic */
return __builtin_clz (val) ^ 31;
# elif defined(__ICCARM__) /* IAR Intrinsic */
@ -324,16 +328,24 @@ MEM_STATIC size_t BIT_getUpperBits(size_t bitContainer, U32 const start)
MEM_STATIC size_t BIT_getMiddleBits(size_t bitContainer, U32 const start, U32 const nbBits)
{
#if STATIC_BMI2
return _bextr_u64(bitContainer, start, nbBits);
#else
U32 const regMask = sizeof(bitContainer)*8 - 1;
/* if start > regMask, bitstream is corrupted, and result is undefined */
assert(nbBits < BIT_MASK_SIZE);
return (bitContainer >> (start & regMask)) & BIT_mask[nbBits];
#endif
}
MEM_STATIC size_t BIT_getLowerBits(size_t bitContainer, U32 const nbBits)
{
#if STATIC_BMI2
return _bzhi_u64(bitContainer, nbBits);
#else
assert(nbBits < BIT_MASK_SIZE);
return bitContainer & BIT_mask[nbBits];
#endif
}
/*! BIT_lookBits() :

13
lib/common/compiler.h
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@ -183,4 +183,17 @@
# pragma warning(disable : 4324) /* disable: C4324: padded structure */
#endif
/*Like DYNAMIC_BMI2 but for compile time determination of BMI2 support*/
#ifndef STATIC_BMI2
# if defined(_MSC_VER) && (defined(_M_X64) || defined(_M_I86))
# ifdef __AVX2__ //MSVC does not have a BMI2 specific flag, but every CPU that supports AVX2 also supports BMI2
# define STATIC_BMI2 1
# endif
# endif
#endif
#ifndef STATIC_BMI2
#define STATIC_BMI2 0
#endif
#endif /* ZSTD_COMPILER_H */

8
lib/common/zstd_internal.h
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@ -394,8 +394,12 @@ MEM_STATIC U32 ZSTD_highbit32(U32 val) /* compress, dictBuilder, decodeCorpus
assert(val != 0);
{
# if defined(_MSC_VER) /* Visual */
unsigned long r=0;
return _BitScanReverse(&r, val) ? (unsigned)r : 0;
# if STATIC_BMI2 == 1
return _lzcnt_u32(val)^31;
# else
unsigned long r=0;
return _BitScanReverse(&r, val) ? (unsigned)r : 0;
# endif
# elif defined(__GNUC__) && (__GNUC__ >= 3) /* GCC Intrinsic */
return __builtin_clz (val) ^ 31;
# elif defined(__ICCARM__) /* IAR Intrinsic */