SSE指令学习笔记

#include "stdafx.h"
#include <stdlib.h>
#include <windows.h>
#include <xmmintrin.h>

void sse_add(float *srcA, float *srcB, float *dest, int n)
{
 	int len = n >> 2;
 	for (int i = 0; i < len; i++)
 	{
 		*(__m128*)(dest + i*4) = _mm_add_ps(*(__m128*)(srcA + i*4), *(__m128*)(srcB + i*4));
 	}
}

void normal_add(float *srcA, float *srcB, float *dest, int n)
{
	for (int i = 0; i < n; i++)
	{
		dest[i] = srcA[i] + srcB[i];
	}
}

int main(int argc, _TCHAR* argv[])
{
	DWORD timeStart = 0, timeEnd = 0;
	const int size = 10000, count = 10000;
	// 分配16字节对齐的内存
	_MM_ALIGN16 float *srcA = (_MM_ALIGN16 float*)_mm_malloc(sizeof(float)*size, 16);
	_MM_ALIGN16 float *srcB = (_MM_ALIGN16 float*)_mm_malloc(sizeof(float)*size, 16);
	_MM_ALIGN16 float *dest = (_MM_ALIGN16 float*)_mm_malloc(sizeof(float)*size, 16);
	
	// 初始化
	for (int i = 0; i < size; i++)
	{
		srcA[i] = (float)i;
	}
	memcpy_s(srcB, sizeof(float) * size, srcA, sizeof(float) * size);

	// 标准加法
	timeStart = GetTickCount();
	for (int i = 0; i < count; i++)
	{
		normal_add(srcA, srcB, dest, size);
	}
	timeEnd  = GetTickCount();
	printf("normal test...time  ---> %f \n", (timeEnd - timeStart) * 0.001);

	// SSE指令加法
	timeStart = GetTickCount();
	for (int i = 0; i < count; i++)
	{
		sse_add(srcA, srcB, dest, size);
	}
	timeEnd  = GetTickCount();
	printf("sse test...time  ---> %f \n", (timeEnd - timeStart) * 0.001);

	// 释放内存
	_mm_free(srcA);
	_mm_free(srcB);
	_mm_free(dest);

    system("pause");
	return 0;
}