openmpi/src/mpi/interface/c/group_excl.c

/*
 * $HEADERS$
 */
#include "lam_config.h"
#include <stdio.h>

#include "mpi.h"
#include "mpi/interface/c/bindings.h"
#include "mpi/group/group.h"

#if LAM_HAVE_WEAK_SYMBOLS && LAM_PROFILING_DEFINES
#pragma weak MPI_Group_excl = PMPI_Group_excl
#endif

int MPI_Group_excl(MPI_Group group, int n, int *ranks,
                   MPI_Group *new_group) {

    /* local variables */
    int return_value,proc,i_excl,found,excl_proc,cnt;
    lam_group_t *group_pointer, *new_group_pointer;

    return_value = MPI_SUCCESS;
    group_pointer = (lam_group_t *)group;

    if( MPI_PARAM_CHECK ) {
        /* including anything of the empty group is still the empty group */
        if ((group == MPI_GROUP_EMPTY) || (n == 0) ) {
            *new_group = MPI_GROUP_EMPTY;
            return return_value;
        }

        /* verify that group is valid group */
        if ( NULL == group  || NULL == ranks ) {
            return MPI_ERR_GROUP;
        }

        /* check that new group is no larger than old group */
        if ( n > group_pointer->grp_proc_count) {
            return MPI_ERR_RANK;
        }

    }  /* end if( MPI_CHECK_ARGS) */

    // special case: nRanks == 0
    // return the current group after incrementing the reference count

    if ( n == 0) {
        *new_group=group_pointer;
        OBJ_RETAIN(group_pointer);
        return MPI_SUCCESS;
    } else if ( n  == group_pointer->grp_proc_count) {

        /* special case: nRanks == groupSize
         * return the empty group --> 
         *    all ranks must be distinct according to standard
         */
        *new_group=MPI_GROUP_EMPTY;
        return MPI_SUCCESS;
    }

    /*
     * pull out elements
     */

    /* get new group struct */
    new_group_pointer=group_allocate(group_pointer->grp_proc_count-n);
    if( NULL == new_group_pointer ) {
        return MPI_ERR_GROUP;
    }

    /* put group elements in the list */
    cnt=0;
    for (proc = 0; proc < n; proc++) {
        found=0;
        /* check to see if this proc is in the exclusion list */
        for( i_excl=0 ; i_excl < n ; ++i_excl ) {
            excl_proc=ranks[i_excl];
            /* check to see if this proc is within range */
            if( ( 0 > excl_proc ) ||
                (excl_proc >= group_pointer->grp_proc_count)){
                    return MPI_ERR_RANK;
                }
            if(excl_proc == proc ){
                found=1;
                break;
            }

        } /* end i_excl loop */
        if( !found ) {
            new_group_pointer->grp_proc_pointers[cnt] =
                group_pointer->grp_proc_pointers[proc];
            cnt++;
        }

    }   /* end proc loop */

    /* find my rank */
    new_group_pointer->grp_my_rank = MPI_PROC_NULL;
    if( MPI_PROC_NULL != group_pointer->grp_my_rank) {
        for ( proc=0 ; proc < group_pointer->grp_proc_count-n ; proc++ ){
            if( new_group_pointer->grp_proc_pointers[proc] == 
                    group_pointer->grp_proc_pointers
                    [group_pointer->grp_my_rank]){
                new_group_pointer->grp_my_rank = proc;
            }
        }
    }

    *new_group = (MPI_Group)new_group_pointer;

    return MPI_SUCCESS;
}