accum_omp.c

/*-----------------------------------------------------------------------------+
 |  Extended Memory Semantics (EMS)                            Version 1.0.0   |
 |  Synthetic Semantics       http://www.synsem.com/       mogill@synsem.com   |
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 +-----------------------------------------------------------------------------*/
#include <omp.h>
#include <stdio.h>
#define SIZE 3200

int main() {
  int i;
  int a[ SIZE ];

  for(i = 0; i < SIZE;  i++)  a[i] = 0;

#define NITER 100000000

#pragma omp parallel for
  for(i = 0;  i < NITER; i++) {
    int retval = __sync_fetch_and_add( &(a[i% SIZE]), 1 );
  }


  int sum = 0;
  for(i = 0; i < SIZE;  i++) {
    sum += a[i];
  }
  printf("sum = %d\n", sum);

  return(0);
}