/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil ; -*- */

/*

 *  (C) 2009 by Argonne National Laboratory.

 *      See COPYRIGHT in top-level directory.

 */

/*

 * Test of reduce scatter block.

 *

 * Each process contributes its rank + the index to the reduction,

 * then receives the ith sum

 *

 * Can be called with any number of processes.

 */

#include "mpi.h"

#include "mpitest.h"

#include <stdio.h>

#include <stdlib.h>

int main(int argc, char **argv)

{

    int err = 0;

    int toterr, size, rank, i, sumval;

    int *sendbuf;

    int *recvbuf;

    MPI_Comm comm;

    MPI_Init(&argc, &argv);

    comm = MPI_COMM_WORLD;

    MPI_Comm_size(comm, &size);

    MPI_Comm_rank(comm, &rank;;

#if MTEST_HAVE_MIN_MPI_VERSION(2,2)

    /* MPI_Reduce_scatter block was added in MPI-2.2 */

    sendbuf = (int *) malloc(size * sizeof(int));

    recvbuf = (int *) malloc(size * sizeof(int));

    if (!sendbuf || !recvbuf) {

        err++;

        fprintf(stderr, "unable to allocate send/recv buffers, aborting");

        MPI_Abort(MPI_COMM_WORLD, 1);

    }

    for (i = 0; i < size; i++)

        sendbuf[i] = rank + i;

    MPI_Reduce_scatter_block(sendbuf, recvbuf, 1, MPI_INT, MPI_SUM, comm);

    sumval = size * rank + ((size - 1) * size) / 2;

    if (recvbuf[0] != sumval) {

        err++;

        fprintf(stdout, "Did not get expected value for reduce scatter block\n");

        fprintf(stdout, "[%d] Got %d expected %d\n", rank, recvbuf[0], sumval);

    }

    free(sendbuf);

    /* let's try it again with MPI_IN_PLACE this time */

    for (i = 0; i < size; i++)

        recvbuf[i] = rank + i;

    MPI_Reduce_scatter_block(MPI_IN_PLACE, recvbuf, 1, MPI_INT, MPI_SUM, comm);

    sumval = size * rank + ((size - 1) * size) / 2;

    if (recvbuf[0] != sumval) {

        err++;

        fprintf(stdout, "Did not get expected value for reduce scatter block\n");

        fprintf(stdout, "[%d] Got %d expected %d\n", rank, recvbuf[0], sumval);

    }

    free(recvbuf);

#endif

    MPI_Allreduce(&err, &toterr, 1, MPI_INT, MPI_SUM, MPI_COMM_WORLD);

    if (rank == 0 && toterr == 0) {

        printf(" No Errors\n");

    }

    MPI_Finalize();

    return toterr;

}