/* Micro-benchmark code for CS 612 Assignment #1
   Taken from: Computer Architecture A Quantitative Approach, 2nd Edition
   John Hennessy & David Patterson, pg. 477.
*/

#include <stdio.h>
#include <sys/times.h>
#include <sys/types.h>
#include <time.h>
#define CACHE_MIN (1024)
#define CACHE_MAX (16*1024*1024)
#define SAMPLE 5
#define SIZE 1000


int x[CACHE_MAX];

double get_seconds() {
  struct tms rusage;
  times(&rusage);
  return (double) (rusage.tms_utime)/CLK_TCK;
}

int main() {
  int register i, index, stride, limit, temp;
  int steps, tsteps, csize;
  double sec0, sec;
  
  for (csize = CACHE_MIN; csize <= CACHE_MAX; csize = csize*2)
    for (stride = 1; stride <= csize/2; stride = stride*2 ){
      sec = 0;
      limit = csize - stride + 1;
      steps = 0;
      do {
	sec0  = get_seconds();
	for (i = SAMPLE*stride;i!=0;i=i-1)
	  for (index =0; index < limit; index = index + stride)
	    x[index] = x[index] + 1;
	steps = steps + 1;
	sec = sec + (get_seconds() - sec0);
      } while (sec < 1.0);
      
      tsteps = 0;
      
      do {
	sec0  = get_seconds();
	for (i = SAMPLE*stride;i!=0;i=i-1)
	  for (index =0; index < limit; index = index + stride)
	    temp = temp + index;
	tsteps = tsteps + 1;
	sec = sec - (get_seconds() - sec0);
      } while (tsteps < steps);
      printf("size: %7d  stride: %7d  time: %14.0f\n",
	     csize*sizeof(int), stride*sizeof(int), (double)
	     sec*1e9/(steps*SAMPLE*stride*((limit-1)/stride+1)));
      
    };
    return 1;
}