/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil ; -*- */
/*
 *  (C) 2010 by Argonne National Laboratory.
 *      See COPYRIGHT in top-level directory.
 */
/*
 * Test of reduce scatter with large data (needed in MPICH to trigger the
 * long-data algorithm)
 *
 * Each processor contributes its rank + the index to the reduction,
 * then receives the ith sum
 *
 * Can be called with any number of processors.
 */

#include "mpi.h"
#include <stdio.h>
#include <stdlib.h>
#include "mpitest.h"

int main(int argc, char **argv)
{
    int err = 0;
    int *sendbuf, *recvbuf;
    int size, rank, i, j, idx, mycount, sumval;
    MPI_Comm comm;


    MTest_Init(&argc, &argv);
    comm = MPI_COMM_WORLD;

    MPI_Comm_size(comm, &size);
    MPI_Comm_rank(comm, &rank);
    mycount = (1024 * 1024) / size;

    sendbuf = (int *) malloc(mycount * size * sizeof(int));
    if (!sendbuf) {
        fprintf(stderr, "Could not allocate %d ints for sendbuf\n", mycount * size);
        MPI_Abort(MPI_COMM_WORLD, 1);
    }
    idx = 0;
    for (i = 0; i < size; i++) {
        for (j = 0; j < mycount; j++) {
            sendbuf[idx++] = rank + i;
        }
    }
    recvbuf = (int *) malloc(mycount * sizeof(int));
    if (!recvbuf) {
        fprintf(stderr, "Could not allocate %d ints for recvbuf\n", mycount);
        MPI_Abort(MPI_COMM_WORLD, 1);
    }

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

    sumval = size * rank + ((size - 1) * size) / 2;
    /* recvbuf should be size * (rank + i) */
    for (i = 0; i < mycount; i++) {
        if (recvbuf[i] != sumval) {
            err++;
            fprintf(stdout, "Did not get expected value for reduce scatter\n");
            fprintf(stdout, "[%d] Got %d expected %d\n", rank, recvbuf[i], sumval);
        }
    }

    MPI_Reduce_scatter_block(MPI_IN_PLACE, sendbuf, mycount, MPI_INT, MPI_SUM, comm);

    sumval = size * rank + ((size - 1) * size) / 2;
    /* recv'ed values for my process should be size * (rank + i) */
    for (i = 0; i < mycount; i++) {
        if (sendbuf[i] != sumval) {
            err++;
            fprintf(stdout, "Did not get expected value for reduce scatter (in place)\n");
            fprintf(stdout, "[%d] Got %d expected %d\n", rank, sendbuf[i], sumval);
        }
    }

    free(sendbuf);
    free(recvbuf);

    MTest_Finalize(err);

    MPI_Finalize();

    return 0;
}