topo_base_graph_neighbors.c

来自「MPI stands for the Message Passing Inter」· C语言 代码 · 共 63 行

/*
 * Copyright (c) 2004-2005 The Trustees of Indiana University and Indiana
 *                         University Research and Technology
 *                         Corporation.  All rights reserved.
 * Copyright (c) 2004-2005 The University of Tennessee and The University
 *                         of Tennessee Research Foundation.  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 "ompi/mca/topo/base/base.h"
#include "ompi/communicator/communicator.h"
#include "ompi/mca/topo/topo.h"

/*
 * function - returns the neighbors of a node associated
 *            with a graph topology
 *
 * @param comm communicator with graph topology (handle)
 * @param rank rank of process in group of comm (integer)
 * @param maxneighbors size of array neighbors (integer)
 * @param neighbors ranks of processes that are neighbors to specified process
 *               (array of integer)
 *
 * @retval MPI_SUCCESS
 */

int mca_topo_base_graph_neighbors (MPI_Comm comm,
                               int rank,
                               int maxneighbors,
                               int *neighbors){
    int nnbrs;
    int i;
    int *p;

    /*
     * Fill the neighbours.
     */
     nnbrs = comm->c_topo_comm->mtc_dims_or_index[rank];
     p = comm->c_topo_comm->mtc_periods_or_edges;

     if (rank > 0) {
        i = comm->c_topo_comm->mtc_dims_or_index[rank - 1];
        nnbrs -= i;
        p += i;
     }

     for (i = 0; (i < maxneighbors) && (i < nnbrs); ++i, ++p) {
        *neighbors++ = *p;
     }

     return MPI_SUCCESS;
}