source: CIVL/mods/dev.civl.com/examples/contracts/contractsMPI/nekbone_mpi/driver.cvl@ cb4d4f4

#include "allreduce.h"
#include "stdlib.h"

#define VEC_N  10

int main() {
  MPI_Init(NULL, NULL);

  struct comm * comm = (struct comm*)malloc(sizeof(struct comm));
  
  comm->c = MPI_COMM_WORLD;
  MPI_Comm_rank(comm->c, &comm->id);
  MPI_Comm_size(comm->c, &comm->np);

  int vn = VEC_N;
  int v[VEC_N], buf[VEC_N];

  for (int i = 0; i < VEC_N; i++) v[i] = 1;

  comm_allreduce(comm, gs_int, gs_add,
                 v, vn, buf);

  $assert($forall (int i : 0 .. VEC_N-1) buf[i] == comm->np);

  MPI_Finalize();  
  free(comm);
}