#include <float.h>
#include <stdio.h>
#include <string.h>
#include <time.h>
#include <stdlib.h>
int main(){
	int j,k,i;
	double times;
	struct timespec tv0,tv;
	int sz[] = {16, 32, 48, 64, 96, 200, 300, 400, 600, 1<<10, 1<<11, 1<<12, 1<<13, 1<<14, 1<<15, 1<<16, 0};
	int off[16] = {0, 0, 0, -8, 8, 16, 0, 0, -16, -12, 0, 4, -4, 0, 0, 12};
	int al[16] = {0, 0, 8, 4, 8, 0, 8, 16, 8, 16, 4, 2, 1, 8, 16, 1};

	char *buf = malloc((1<<16)+32);
	if (buf == NULL) {
           printf("malloc failed\n");
           exit(1);
        }
	// warm up
        for (j=0; sz[j]; j++)
	    for (k=0; k<20; k++)
	        for (i=0; i<256; i++)
		    memset(buf + al[i%16], 0, sz[j] + off[i%16]);

	printf("%-15s %-20s %-20s\n", "size(bytes)", "min_time(s)", "speed(GB/s)");
	for (j=0; sz[j]; j++) {
	        double min_time = DBL_MAX;
		for (k=0; k<20; k++) {
			clock_gettime(CLOCK_REALTIME, &tv0);
			// large loop count is important for small sizes
			for (i=0; i<256; i++)
				memset(buf + al[i%16], 0, sz[j] + off[i%16]);
			clock_gettime(CLOCK_REALTIME, &tv);
			tv.tv_sec -= tv0.tv_sec;
			if ((tv.tv_nsec -= tv0.tv_nsec) < 0) {
				tv.tv_nsec += 1000000000;
				tv.tv_sec--;
			}
			times = tv.tv_sec + (double)tv.tv_nsec/1e9;
			min_time = min_time < times ? min_time : times;
		}
                printf("%-15d %-20.9lf %-20.2lf\n",sz[j], min_time, 256*sz[j] / (min_time * 1e9));
        }
	return 0;
}