1 /*
2 * Copyright (c) 2004-2005 The Trustees of Indiana University and Indiana
3 * University Research and Technology
4 * Corporation. All rights reserved.
5 * Copyright (c) 2004-2013 The University of Tennessee and The University
6 * of Tennessee Research Foundation. All rights
7 * reserved.
8 * Copyright (c) 2004-2005 High Performance Computing Center Stuttgart,
9 * University of Stuttgart. All rights reserved.
10 * Copyright (c) 2004-2005 The Regents of the University of California.
11 * All rights reserved.
12 * Copyright (c) 2012-2013 Inria. All rights reserved.
13 * Copyright (c) 2014 Research Organization for Information Science
14 * and Technology (RIST). All rights reserved.
15 * $COPYRIGHT$
16 *
17 * Additional copyrights may follow
18 *
19 * $HEADER$
20 */
21
22 #include "ompi_config.h"
23 #include "ompi/mca/topo/base/base.h"
24 #include "ompi/communicator/communicator.h"
25
26 /*
27 * function - returns the neighbors of a node associated
28 * with a graph topology
29 *
30 * @param comm communicator with graph topology (handle)
31 * @param rank rank of process in group of comm (integer)
32 * @param maxneighbors size of array neighbors (integer)
33 * @param neighbors ranks of processes that are neighbors to specified process
34 * (array of integer)
35 *
36 * @retval MPI_SUCCESS
37 */
38
39 int mca_topo_base_graph_neighbors (ompi_communicator_t* comm,
40 int rank,
41 int maxneighbors,
42 int *neighbors)
43 {
44 mca_topo_base_comm_graph_2_2_0_t* graph = comm->c_topo->mtc.graph;
45 int nnbrs, i, *p;
46
47 /*
48 * Fill the neighbours.
49 */
50 nnbrs = graph->index[rank];
51 p = graph->edges;
52
53 if (rank > 0) {
54 i = graph->index[rank - 1];
55 nnbrs -= i;
56 p += i;
57 }
58
59 for (i = 0; (i < maxneighbors) && (i < nnbrs); ++i, ++p) {
60 *neighbors++ = *p;
61 }
62
63 return MPI_SUCCESS;
64 }