source: CIVL/examples/concurrency/adder.cvl

/* Commandline execution:
 *              civl verify -inputB=5 adder.cvl
 * */
#include <civlc.cvh>

$input int B = 5; // upper bound on array length
$input int N;     // length of array
$assume(1<=N && N<=B);
$input double a[N];

double adderSeq(double *p, int n) {
  double s = 0.0;
  
  for (int i = 0; i < n; i++) {
    s += p[i]; 
  }
  return s;
}

double adderPar(double *p, int n) {
  double s = 0.0; // sum shared by workers
  int mutex = 0; // mutex shared by workers
  $proc workers[n]; // one worker for each element! UNUSED

  void worker(int i) {
    double t;

    $when (mutex == 0) mutex = 1;
    t = s;
    t += p[i];
    s = t;
    mutex = 0;
  }

  $parfor (int j : 0 .. n-1)
    worker(j);
  return s;
}

void main() {
  double seq = adderSeq(&a[0], N);
  double par = adderPar(&a[0], N);

  $assert(seq == par);
}