/* Create nprocs processes.  Have them exchange data in a cycle.
 * Run with:
 *     civl verify -inputNPROCS=2 mpithreads.cvl 
 */
#include<civlc.h>

$input int NPROCS;
$proc __procs[NPROCS];
_Bool __start = 0;
$comm MPI_COMM_WORLD;

void MPI_Process (int rank);

void init() {
  for (int i=0; i<NPROCS; i++)
    __procs[i] = $spawn MPI_Process(i);
  MPI_COMM_WORLD = $comm_create(NPROCS, __procs);
  __start=1;
}

void finalize() {
  for (int i=0; i<NPROCS; i++)
    $wait __procs[i];
}

void MPI_Process (int rank) {
  double x, y;
  $message out, in;

  $when (__start);
  x=rank;
  out = $message_pack(rank, (rank+1)%NPROCS, 0, &x, sizeof(double));
  $comm_enqueue(&MPI_COMM_WORLD, out);
  in = $comm_dequeue(&MPI_COMM_WORLD, (rank+NPROCS-1)%NPROCS, rank, 0);
  $message_unpack(in, &y, sizeof(double));
  $assert y==(rank+NPROCS-1)%NPROCS;
}

void main() {
  init();
  finalize();
}