In Makefile:

CC = gcc
CFLAGS = -O4 -Wall -mavx2 -I $(TIMER_DIR)
TIMER_DIR = /home/class_projects/cycle-counter
TIMER = $(TIMER_DIR)/clock.o $(TIMER_DIR)/fcycmm.o

all: mm

mm: mm.c mm.h
	$(CC) $(CFLAGS) -o mm mm.c $(TIMER)

clean:
	rm -f *.o mm *~

In mm.c:

// HEADER HERE :)

#include <stdio.h>
#include <stdlib.h>
#include "mm.h"
#include "fcycmm.h"
#include "clock.h"

/* whether or not fcyc should clear the cache */
#define CLEARCACHE 1

/* global arrays [ ok for this kind of hacking, but not in production ] */
array ga, gb, gc;

/* purpose: check the result array for correctness
 * input: the product array, c, and its size, n
 * returns: nothing (complains in an error message if result is wrong)
 */
void checkresult(array c, int n)
{
  int i, j;

  for (i = 0; i < n; i++)
    for (j = 0; j < n; j++)
      if (c[i][j] != (double)n)
      {
        printf("Error: bad number (%f) in result matrix (%d,%d)\n",
            c[i][j], i, j);
        fflush(stdout);
        exit(0);
      }
}


/* purpose: Run function f and return clocks per inner loop iteration
 * input: a function, f, and the matrix size, n
 * returns: the number of cycles taken per inner loop iteration
 */
double run(test_funct f, int n)
{
  double cpi;

  cpi = fcyc(f, n, CLEARCACHE) / (n*n*n);
  checkresult(gc, n);
  return cpi;
}


/* purpose: reset result array to zero
 * input: the array, c, and its size, n
 * returns: the array updated to all zeros.
 */
void reset(array c, int n)
{
  int i,j;

  for (i = 0; i < n; i++)
    for (j = 0; j < n; j++)
      c[i][j] = 0.0;
}


/* purpose: initialize input arrays to 1
 * input: the input arrays, a and b, and their size, n
 * returns: the arrays updated to all ones.
 */
void init(array a, array b, int n)
{
  int i,j;

  for (i = 0; i < n; i++)
  {
    for (j = 0; j < n; j++)
    {
      a[i][j] = 1.0;
      b[i][j] = 1.0;
    }
  }
}


/* purpose: print an array
 * input:   an array, a, and its size, n
 * returns: nothing (printing is a side effect)
 */
void printarray(array a, int n)
{
  int i, j;

  for (i = 0; i < n; i++)
  {
    for (j = 0; j < n; j++)
      printf("%5.1f ", a[i][j]);

    printf("\n");
  }
}


/* purpose:
 * input:
 * returns:
 */
void multiply(array A, array B, array C, int n)
{
  // ...
}


/* purpose: test the multiplcatoin of two 2x2 matricies
 * input: nothing (the test is hard coded)
 * returns: nothing (prints result to standard out)
 */
void test()
{
  ga[0][0] = 1;
  ga[0][1] = 2;
  ga[1][0] = 3;
  ga[1][1] = 4;
  gb[0][0] = 5;
  gb[0][1] = 6;
  gb[1][0] = 7;
  gb[1][1] = 8;
  printf("product of \n");
  printarray(ga, 2);
  printf("and\n");
  printarray(gb, 2);
  multiply(ga, gb, gc, 2);
  printf("=\n");
  printarray(gc, 2);

  if (gc[0][0] == 19 && gc[0][1] == 22 && gc[1][0] == 43 && gc[1][1] == 50)
    printf("Passed!!\n");
  else
    printf("Fail!!\n");
}



/*
 * Run matrix multiply and display performance
 * as clock cycles per inner loop iteration.
 */
int main()
{
  int n;

  init(ga, gb, MAXN);
  // test();
  // exit(0);

  printf("matmult cycles/loop iteration\n");
  fflush(stdout);
  for (n = MINN; n <= MAXN; n += INCN)
  {
    printf("%3d ", n);

    printf("%9.2f ", run(multiply, n));
    printf("\n");
    fflush(stdout);
  }

  exit(0);
}

In mm.h:

#define MINN 50
#define MAXN 700
#define INCN 50

typedef double array[MAXN][MAXN+513];

#define min(x,y) (x<y?x:y)