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fix SSE2 implementation of find_change

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This commit is contained in:
Jamiras 2021-01-21 22:26:45 -07:00
parent 2520337ddc
commit 78ab9853a7
2 changed files with 7 additions and 4 deletions
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2
libretro-common/include/compat/intrinsics.h
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@ -63,7 +63,7 @@ static INLINE int compat_ctz(unsigned x)
return __builtin_ctz(x); return __builtin_ctz(x);
#elif _MSC_VER >= 1400 && !defined(_XBOX) && !defined(__WINRT__) #elif _MSC_VER >= 1400 && !defined(_XBOX) && !defined(__WINRT__)
unsigned long r = 0; unsigned long r = 0;
_BitScanReverse((unsigned long*)&r, x); _BitScanForward((unsigned long*)&r, x);
return (int)r; return (int)r;
#else #else
/* Only checks at nibble granularity, /* Only checks at nibble granularity,

9
state_manager.c
View File

@ -94,14 +94,17 @@ static size_t find_change(const uint16_t *a, const uint16_t *b)
{ {
__m128i v0 = _mm_loadu_si128(a128); __m128i v0 = _mm_loadu_si128(a128);
__m128i v1 = _mm_loadu_si128(b128); __m128i v1 = _mm_loadu_si128(b128);
__m128i c = _mm_cmpeq_epi32(v0, v1); __m128i c = _mm_cmpeq_epi8(v0, v1);
uint32_t mask = _mm_movemask_epi8(c); uint32_t mask = _mm_movemask_epi8(c);
if (mask != 0xffff) /* Something has changed, figure out where. */ if (mask != 0xffff) /* Something has changed, figure out where. */
{ {
/* calculate the real offset to the differing byte */
size_t ret = (((uint8_t*)a128 - (uint8_t*)a) | size_t ret = (((uint8_t*)a128 - (uint8_t*)a) |
(compat_ctz(~mask))) >> 1; (compat_ctz(~mask)));
return ret | (a[ret] == b[ret]);
/* and convert that to the uint16_t offset */
return (ret >> 1);
} }
a128++; a128++;