/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil ; -*- */
/*
 *
 *  (C) 2003 by Argonne National Laboratory.
 *      See COPYRIGHT in top-level directory.
 */
#include "mpi.h"
#include <stdio.h>
#include <stdlib.h>
#include "mpitest.h"

/*
static char MTEST_Descrip[] = "Test comm split";
*/

int main(int argc, char *argv[])
{
    int errs = 0;
    int rank, size, color, srank;
    MPI_Comm comm, scomm;

    MTest_Init(&argc, &argv);

    MPI_Comm_dup(MPI_COMM_WORLD, &comm);

    MPI_Comm_rank(comm, &rank);
    MPI_Comm_size(comm, &size);

    if (size < 4) {
        fprintf(stderr, "This test requires at least four processes.");
        MPI_Abort(MPI_COMM_WORLD, 1);
    }

    color = MPI_UNDEFINED;
    if (rank < 2)
        color = 1;
    MPI_Comm_split(comm, color, size - rank, &scomm);

    if (rank < 2) {
        /* Check that the ranks are ordered correctly */
        MPI_Comm_rank(scomm, &srank);
        if (srank != 1 - rank) {
            errs++;
        }
        MPI_Comm_free(&scomm);
    }
    else {
        if (scomm != MPI_COMM_NULL) {
            errs++;
        }
    }
    MPI_Comm_free(&comm);
    MTest_Finalize(errs);
    MPI_Finalize();
    return 0;
}