/******************************************************************************
* FILE: omp_mm.c
* DESCRIPTION:
*   OpenMp Example - Matrix Multiply - C Version
*   Demonstrates a matrix multiply using OpenMP. Threads share row iterations
*   according to a predefined chunk size.
******************************************************************************/
#include <omp.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/time.h>
#include <unistd.h>

#define NRA 62                 /* number of rows in matrix A */
#define NCA 15                 /* number of columns in matrix A */
#define NCB 7                  /* number of columns in matrix B */


// pour windows
//double get_time(){ return ((double) clock())/CLOCKS_PER_SEC;}

//pour linux
double get_time() {
       struct timeval tv;
       gettimeofday(&tv, (void *)0);
       return (double) tv.tv_sec + tv.tv_usec*1e-6;
}

int main (int argc, char *argv[])
{
int	tid, nthreads, i, j, k, chunk;
double	a[NRA][NCA],           /* matrix A to be multiplied */
	    b[NCA][NCB],           /* matrix B to be multiplied */
	    c[NRA][NCB];           /* result matrix C */

chunk = 10;                    /* set loop iteration chunk size */

double start, stop;

start = omp_get_wtime();

/*** Spawn a parallel region explicitly scoping all variables ***/
#pragma omp parallel shared(a,b,c,nthreads,chunk) private(tid,i,j,k)
  {
  tid = omp_get_thread_num();
  if (tid == 0) // #pragma omp master
    {
    nthreads = omp_get_num_threads();
    printf("Starting matrix multiple example with %d threads\n",nthreads);
    printf("Initializing matrices...\n");
    }
  #pragma omp barrier

  /*** Initialize matrices ***/
  #pragma omp for schedule (static, chunk)
  for (i=0; i<NRA; i++)
    for (j=0; j<NCA; j++)
      a[i][j]= i+j;

  #pragma omp for schedule (static, chunk)
  for (i=0; i<NCA; i++)
    for (j=0; j<NCB; j++)
      b[i][j]= i*j;

  #pragma omp for schedule (static, chunk)
  for (i=0; i<NRA; i++)
    for (j=0; j<NCB; j++)
      c[i][j]= 0;

  /*** Do matrix multiply sharing iterations on outer loop ***/
  /*** Display who does which iterations for demonstration purposes ***/
  printf("Thread %d starting matrix multiply...\n",tid);
  #pragma omp for schedule (static, chunk)
  for (i=0; i<NRA; i++)
    {
    printf("Thread=%d did row=%d\n",tid,i);
    for(j=0; j<NCB; j++)
      for (k=0; k<NCA; k++)
        c[i][j] += a[i][k] * b[k][j];
    }
  }   /*** End of parallel region ***/

   stop = omp_get_wtime();
   printf("%f   ", stop - start);
/*** Print results ***/
printf("******************************************************\n");
printf("Result Matrix:\n");
for (i=0; i<NRA; i++)
  {
  for (j=0; j<NCB; j++)
    printf("%0.2f   ", c[i][j]);
    printf("\n");
  }
printf("******************************************************\n");
printf ("Done.\n");

}