openmpi/ompi/mca/coll/basic/coll_basic_scatterv.c

/*
 * Copyright (c) 2004-2005 The Trustees of Indiana University.
 *                         All rights reserved.
 * Copyright (c) 2004-2005 The Trustees of the University of Tennessee.
 *                         All rights reserved.
 * Copyright (c) 2004-2005 High Performance Computing Center Stuttgart, 
 *                         University of Stuttgart.  All rights reserved.
 * Copyright (c) 2004-2005 The Regents of the University of California.
 *                         All rights reserved.
 * $COPYRIGHT$
 * 
 * Additional copyrights may follow
 * 
 * $HEADER$
 */

#include "ompi_config.h"
#include "coll_basic.h"

#include "mpi.h"
#include "ompi/include/constants.h"
#include "datatype/datatype.h"
#include "mca/coll/coll.h"
#include "mca/coll/base/coll_tags.h"
#include "mca/pml/pml.h"
#include "coll_basic.h"


/*
 *	scatterv_intra
 *
 *	Function:	- scatterv operation
 *	Accepts:	- same arguments as MPI_Scatterv()
 *	Returns:	- MPI_SUCCESS or error code
 */
int
mca_coll_basic_scatterv_intra(void *sbuf, int *scounts,
                              int *disps, struct ompi_datatype_t *sdtype,
                              void *rbuf, int rcount,
                              struct ompi_datatype_t *rdtype, int root,
                              struct ompi_communicator_t *comm)
{
    int i;
    int rank;
    int size;
    int err;
    char *ptmp;
    long lb;
    long extent;

    /* Initialize */

    rank = ompi_comm_rank(comm);
    size = ompi_comm_size(comm);

    /* If not root, receive data. */

    if (rank != root) {
        /* Only receive if there is something to receive */
        if (rcount > 0) {
            return MCA_PML_CALL(recv(rbuf, rcount, rdtype,
                                     root, MCA_COLL_BASE_TAG_SCATTERV,
                                     comm, MPI_STATUS_IGNORE));
        }
        return MPI_SUCCESS;
    }

    /* I am the root, loop sending data. */

    err = ompi_ddt_get_extent(rdtype, &lb, &extent);
    if (OMPI_SUCCESS != err) {
        return OMPI_ERROR;
    }

    for (i = 0; i < size; ++i) {
        ptmp = ((char *) sbuf) + (extent * disps[i]);

        /* simple optimization */

        if (i == rank) {
            /* simple optimization or a local operation */
            if (0 == scounts[i]) {
                continue;
            }
            err = ompi_ddt_sndrcv(ptmp, scounts[i], sdtype, rbuf, rcount,
                                  rdtype);
        } else {
            /* Only send if there is something to send */
            if (scounts[i] > 0) {
                err = MCA_PML_CALL(send(ptmp, scounts[i], sdtype, i,
                                        MCA_COLL_BASE_TAG_SCATTERV,
                                        MCA_PML_BASE_SEND_STANDARD, comm));
                if (MPI_SUCCESS != err) {
                    return err;
                }
            }
        }
    }

    /* All done */

    return MPI_SUCCESS;
}


/*
 *	scatterv_inter
 *
 *	Function:	- scatterv operation
 *	Accepts:	- same arguments as MPI_Scatterv()
 *	Returns:	- MPI_SUCCESS or error code
 */
int
mca_coll_basic_scatterv_inter(void *sbuf, int *scounts,
                              int *disps, struct ompi_datatype_t *sdtype,
                              void *rbuf, int rcount,
                              struct ompi_datatype_t *rdtype, int root,
                              struct ompi_communicator_t *comm)
{
    int i;
    int rank;
    int size;
    int err;
    char *ptmp;
    long lb;
    long extent;
    ompi_request_t **reqs = comm->c_coll_basic_data->mccb_reqs;

    /* Initialize */

    rank = ompi_comm_rank(comm);
    size = ompi_comm_remote_size(comm);

    /* If not root, receive data.  Note that we will only get here if
     * rcount > 0 or rank == root. */

    if (MPI_PROC_NULL == root) {
        /* do nothing */
        err = OMPI_SUCCESS;
    } else if (MPI_ROOT != root) {
        /* If not root, receive data. */
        err = MCA_PML_CALL(recv(rbuf, rcount, rdtype,
                                root, MCA_COLL_BASE_TAG_SCATTERV,
                                comm, MPI_STATUS_IGNORE));
    } else {
        /* I am the root, loop sending data. */
        err = ompi_ddt_get_extent(rdtype, &lb, &extent);
        if (OMPI_SUCCESS != err) {
            return OMPI_ERROR;
        }

        for (i = 0; i < size; ++i) {
            ptmp = ((char *) sbuf) + (extent * disps[i]);
            err = MCA_PML_CALL(isend(ptmp, scounts[i], sdtype, i,
                                     MCA_COLL_BASE_TAG_SCATTERV,
                                     MCA_PML_BASE_SEND_STANDARD, comm,
                                     &(reqs[i])));
            if (OMPI_SUCCESS != err) {
                return err;
            }
        }

        err = ompi_request_wait_all(size, reqs, MPI_STATUSES_IGNORE);
    }

    /* All done */
    return err;
}