上交所的添加和转换

SSE addition and conversion

本文关键字：转换 添加 上交所      更新时间：2023-10-16

事情是这样的，如何使用SSE添加两个无符号字符数组并将结果存储在无符号短数组中。谁能给我一些帮助或提示。这就是我到目前为止所做的。我只是不知道错误在哪里。需要一些帮助

#include<iostream>
#include<intrin.h>
#include<windows.h>
#include<emmintrin.h>
#include<iterator>
using namespace std;
void sse_add(unsigned char * input1, unsigned char *input2, unsigned short  *output, const int N)
{   
unsigned char *op3 = new unsigned char[N];
unsigned char *op4 = new unsigned char[N];
__m128i *sse_op3 = (__m128i*)op3;
__m128i *sse_op4 = (__m128i*)op4;
__m128i *sse_result = (__m128i*)output;
for (int i = 0; i < N; i = i + 16)
{
__m128i src = _mm_loadu_si128((__m128i*)input1);
__m128i zero = _mm_setzero_si128();
__m128i higher = _mm_unpackhi_epi8(src, zero);
__m128i lower = _mm_unpacklo_epi8(src, zero);
_mm_storeu_si128(sse_op3, lower);
sse_op3 = sse_op3 + 1;
_mm_storeu_si128(sse_op3, higher);
sse_op3 = sse_op3 + 1;
input1 = input1 + 16;
}
for (int j = 0; j < N; j = j + 16)
{
__m128i src1 = _mm_loadu_si128((__m128i*)input2);
__m128i zero1 = _mm_setzero_si128();
__m128i higher1 = _mm_unpackhi_epi8(src1, zero1);
__m128i lower1 = _mm_unpacklo_epi8(src1, zero1);
_mm_storeu_si128(sse_op4, lower1);
sse_op4 = sse_op4 + 1;
_mm_storeu_si128(sse_op4, higher1);
sse_op4 = sse_op4 + 1;
input2 = input2 + 16;
}
__m128i *sse_op3_new = (__m128i*)op3;
__m128i *sse_op4_new = (__m128i*)op4;
for (int y = 0; y < N; y = y + 8)
{
*sse_result = _mm_adds_epi16(*sse_op3_new, *sse_op4_new);
sse_result = sse_result + 1;
sse_op3_new = sse_op3_new + 1;
sse_op4_new = sse_op4_new + 1;
}
}
void C_add(unsigned char * input1, unsigned char *input2, unsigned short *output, int N)
{
for (int i = 0; i < N; i++)
output[i] = (unsigned short)input1[i] + (unsigned short)input2[i];
}

int main()
{
int n = 1023;
unsigned char *p0 = new unsigned char[n];
unsigned char *p1 = new unsigned char[n];
unsigned short *p21 = new unsigned short[n];
unsigned short *p22 = new unsigned short[n];
for (int j = 0; j < n; j++)
{
p21[j] = rand() % 256;
p22[j] = rand() % 256;
}
C_add(p0, p1, p22, n);
cout << "C_add finished!" << endl;
sse_add(p0, p1, p21, n);
cout << "sse_add finished!" << endl;
for (int j = 0; j < n; j++)
{
if (p21[j] != p22[j])
{
cout << "diff!!!!!@@@@@@@" << endl;
}
}
//system("pause");
delete[] p0;
delete[] p1;
delete[] p21;
delete[] p22;
return 0;

}

假设所有内容都与_Alignof(__m128i)对齐并且数组的大小是sizeof(__m128i)的倍数，这样的事情应该可以工作：

void addw(size_t size, uint16_t res[size], uint8_t a[size], uint8_t b[size]) {
__m128i* r = (__m128i*) res;
__m128i* ap = (__m128i*) a;
__m128i* bp = (__m128i*) b;
for (size_t i = 0 ; i < (size / sizeof(__m128i)) ; i++) {
r[(i * 2)]     = _mm_add_epi16(_mm_cvtepu8_epi16(ap[i]), _mm_cvtepu8_epi16(bp[i]));
r[(i * 2) + 1] = _mm_add_epi16(_mm_cvtepu8_epi16(_mm_srli_si128(ap[i], 8)), _mm_cvtepu8_epi16(_mm_srli_si128(bp[i], 8)));
}
}

FWIW，NEON会更简单一些(使用vaddl_u8和vaddl_high_u8)。

如果您正在处理未对齐的数据，您可以使用_mm_loadu_si128/_mm_storeu_si128. 如果大小不是 16 的倍数，则只需在没有 SSE 的情况下完成其余部分。

请注意，这可能是您的编译器可以自动执行的操作(我尚未检查)。 您可能想尝试这样的事情：

#pragma omp simd
for (size_t i = 0 ; i < size ; i++) {
res[i] = ((uint16_t) a[i]) + ((uint16_t) b[i]);
}

它使用OpenMP 4，但也有Cilk++(#pragma simd)，clang(#pragma clang loop vectorize(enable))，gcc(#pragma GCC ivdep)，或者你可以希望编译器足够聪明，没有编译指示提示。

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