/* -*- 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.

 *

 * Checks that non-commutative operations are not commuted and that

 * all of the operations are performed.

 *

 * Can be called with any number of processors.

 */

#include "mpi.h"

#include <stdio.h>

#include <stdlib.h>

#include "mpitest.h"

int err = 0;

/* left(x,y) ==> x */

void left(void *a, void *b, int *count, MPI_Datatype * type);

void left(void *a, void *b, int *count, MPI_Datatype * type)

{

    int *in = a;

    int *inout = b;

    int i;

    for (i = 0; i < *count; ++i) {

        if (in[i] > inout[i])

            ++err;

        inout[i] = in[i];

    }

}

/* right(x,y) ==> y */

void right(void *a, void *b, int *count, MPI_Datatype * type);

void right(void *a, void *b, int *count, MPI_Datatype * type)

{

    int *in = a;

    int *inout = b;

    int i;

    for (i = 0; i < *count; ++i) {

        if (in[i] > inout[i])

            ++err;

        inout[i] = inout[i];

    }

}

/* Just performs a simple sum but can be marked as non-commutative to

   potentially tigger different logic in the implementation. */

void nc_sum(void *a, void *b, int *count, MPI_Datatype * type);

void nc_sum(void *a, void *b, int *count, MPI_Datatype * type)

{

    int *in = a;

    int *inout = b;

    int i;

    for (i = 0; i < *count; ++i) {

        inout[i] = in[i] + inout[i];

    }

}

#define MAX_BLOCK_SIZE 256

int main(int argc, char **argv)

{

    int *sendbuf;

    int block_size;

    int *recvbuf;

    int size, rank, i;

    MPI_Comm comm;

    MPI_Op left_op, right_op, nc_sum_op;

    MTest_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 */

    MPI_Op_create(&left, 0 /*non-commutative */ , &left_op);

    MPI_Op_create(&right, 0 /*non-commutative */ , &right_op);

    MPI_Op_create(&nc_sum, 0 /*non-commutative */ , &nc_sum_op);

    for (block_size = 1; block_size < MAX_BLOCK_SIZE; block_size *= 2) {

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

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

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

            sendbuf[i] = rank + i;

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

            recvbuf[i] = 0xdeadbeef;

        MPI_Reduce_scatter_block(sendbuf, recvbuf, block_size, MPI_INT, left_op, comm);

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

            if (recvbuf[i] != (rank * block_size + i))

                ++err;

        MPI_Reduce_scatter_block(sendbuf, recvbuf, block_size, MPI_INT, right_op, comm);

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

            if (recvbuf[i] != ((size - 1) + (rank * block_size) + i))

                ++err;

        MPI_Reduce_scatter_block(sendbuf, recvbuf, block_size, MPI_INT, nc_sum_op, comm);

        for (i = 0; i < block_size; ++i) {

            int x = rank * block_size + i;

            if (recvbuf[i] != (size * x + (size - 1) * size / 2))

                ++err;

        }

        free(recvbuf);

        free(sendbuf);

    }

    MPI_Op_free(&left_op);

    MPI_Op_free(&right_op);

    MPI_Op_free(&nc_sum_op);

#endif

    MTest_Finalize(err);

    MPI_Finalize();

    return err;

}