gcc test

g++ memcpy_test.cpp -o memcpy_test -O2 -msse2

#include<stdio.h>
#include<string.h>
#include<malloc.h>

#include "emmintrin.h"

#ifdef _WIN32
#include<Windows.h>
unsigned int getTime()
{
    return GetTickCount();
}

void *malloc_aligned(size_t size)
{
    return _aligned_malloc(size, 16);
}

void free_aligned(void *p)
{
    _aligned_free(p);
}
#else

#include<sys/time.h>
#include<stdlib.h>

unsigned int getTime()
{
    struct timeval t;
    gettimeofday( &t, NULL );
    return t.tv_sec * 1000 + t.tv_usec / 1000;
}

void *malloc_aligned(size_t size)
{
    void *tmp;
    if(posix_memalign(&tmp, 16, size)) {
        return NULL;
    }

    return tmp;
}

void free_aligned(void *p)
{
    free(p);
}
#endif


void memcpy_sse(void *dest, const void *src, size_t count)
{
	__m128i *srcPtr = (__m128i *)src;
	__m128i *destPtr = (__m128i *)dest;

	unsigned int index = 0;
	while(count) {

		__m128i x = _mm_load_si128(&srcPtr[index]);
		_mm_stream_si128(&destPtr[index], x);

		count -= 16;
		index++;
	}
}

void run_test(void *dest, void *src, size_t count, int iterations, bool sse)
{
	if(sse) {
		for(int i = 0; i < iterations; i++) {
			memcpy_sse(dest, src, count);
		}
	} else {
		for(int i = 0; i < iterations; i++) {
			memcpy(dest, src, count);
		}
	}
}

int main(int argc, char **argv)
{
    const unsigned int BUFFER_SIZE = 128 * 1024 * 1024;
	int iterations = 100;
	unsigned char *buf1 = (unsigned char *)malloc_aligned(BUFFER_SIZE);
	unsigned char *buf2 = (unsigned char *)malloc_aligned(BUFFER_SIZE);
	
	printf("Running memcpy()
");
	unsigned int t0 = getTime();
	run_test(buf1, buf2, BUFFER_SIZE, iterations, false);
	unsigned int t1 = getTime() - t0;

	printf("%.3fs
", (float)t1/1000);

	printf("Running memcpy_sse()
");
	t0 = getTime();
	run_test(buf1, buf2, BUFFER_SIZE, iterations, true);
	t1 = getTime() - t0;

	printf("%.3fs
", (float)t1/1000);

	free_aligned(buf1);
	free_aligned(buf2);

	return 0;
}

#include <stdio.h>
#include <stdlib.h>
#include <time.h>


const int NUM = 1000000;
 
int   i;
char* pstr;
char* p;
int   len;  
int   st, et;  

void main(int argc, char* args[]){
   clock_t st, et;
   st = clock(); 

   pstr = (char *)malloc(sizeof(char) * NUM) ;
   p = pstr;

   srand((unsigned)time(NULL));
   for (i = 0; i <= NUM - 1; i++){ 
       *pstr = (char)(65 + rand()%26);
        pstr++;
   }
   *pstr = '';

   len = 0;    
   pstr = p;   
   while(*pstr++ != '') 
   {
    //   printf("%c ", *pstr);
       len++;    
   }
   free(p);

   et = clock(); 
   printf("len = %d, cost time  = %d
", len, et - st);   
   return;
}