如何使用SSE來計算位於某個範圍內的字節數？

Question

我想寫它計算在一系列的字節數AC程序a ... c與下面的代碼：

char a[16], b[16], c[16]; 
int counter = 0; 
for(i = 0; i < 16; i++) 
{ 
    if((a[i] < b[i]) && (b[i] < c[i])) 
    counter++; 
} 
return counter; 

我打算做這樣的事情

__m128i result1 = _mm_cmpgt_epi8 (b, a); 
__m128i result2 = _mm_cmplt_epi8 (b, c); 
unsigned short out1 = _mm_movemask_epi8(result1); 
unsigned short out2 = _mm_movemask_epi8(result2); 
unsigned short out3 = out1 & out2; 
unsigned short out4 = _mm_popcnt_u32(out3); 

是我的方法正確嗎？有沒有更好的方法來做到這一點？

Answer 1

你的方法看起來很合理。我認爲你可以通過在SIMD寄存器中執行AND來保存指令，如下所示：

__m128i result1 = _mm_cmpgt_epi8 (b, a); 
__m128i result2 = _mm_cmplt_epi8 (b, c); 
__m128i mask = _mm_and_si128(result1, result2); 
int mask2 = _mm_movemask_epi8(mask); 
int counter = _mm_popcnt_u32(mask2);