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no reason to prefer inline assembly over MSVC _BitScanReverse intrinsic on x86 (nw)

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This commit is contained in:
Vas Crabb 2017-07-09 14:42:35 +10:00
parent 9aff6e781d
commit 74525566db
1 changed files with 7 additions and 64 deletions
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71
src/osd/eivcx86.h
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@ -8,8 +8,10 @@
//
//============================================================
#ifndef __EIVCX86__
#define __EIVCX86__
#ifndef MAME_OSD_EIVCX86_H
#define MAME_OSD_EIVCX86_H
#pragma once
#ifdef PTR64
#include <emmintrin.h>
@ -393,71 +395,12 @@ static inline uint32_t _modu_64x32(uint64_t a, uint32_t b)
#define recip_approx _recip_approx
static inline float _recip_approx(float z)
{
__m128 mz = _mm_set_ss(z);
__m128 mooz = _mm_rcp_ss(mz);
__m128 const mz = _mm_set_ss(z);
__m128 const mooz = _mm_rcp_ss(mz);
float ooz;
_mm_store_ss(&ooz, mooz);
return ooz;
}
#endif
/***************************************************************************
INLINE BIT MANIPULATION FUNCTIONS
***************************************************************************/
/*-------------------------------------------------
count_leading_zeros - return the number of
leading zero bits in a 32-bit value
-------------------------------------------------*/
#ifndef PTR64
#define count_leading_zeros _count_leading_zeros
static inline uint8_t _count_leading_zeros(uint32_t value)
{
int32_t result;
__asm
{
bsr eax,value
jnz skip
mov eax,63
skip:
xor eax,31
mov result,eax
}
return result;
}
#endif
/*-------------------------------------------------
count_leading_ones - return the number of
leading one bits in a 32-bit value
-------------------------------------------------*/
#ifndef PTR64
#define count_leading_ones _count_leading_ones
static inline uint8_t _count_leading_ones(uint32_t value)
{
int32_t result;
__asm
{
mov eax,value
not eax
bsr eax,eax
jnz skip
mov eax,63
skip:
xor eax,31
mov result,eax
}
return result;
}
#endif
#endif /* __EIVCX86__ */
#endif // MAME_OSD_EIVCX86_H