/*
 * $HEADER$
 */
#include "ompi_config.h"
#include <stdio.h>

#include "mpi.h"
#include "mpi/c/bindings.h"
#include "mca/coll/coll.h"
#include "errhandler/errhandler.h"
#include "communicator/communicator.h"
#include "op/op.h"

#if OMPI_HAVE_WEAK_SYMBOLS && OMPI_PROFILING_DEFINES
#pragma weak MPI_Reduce_scatter = PMPI_Reduce_scatter
#endif

#if OMPI_PROFILING_DEFINES
#include "mpi/c/profile/defines.h"
#endif

static const char FUNC_NAME[] = "MPI_Reduce_scatter";


int MPI_Reduce_scatter(void *sendbuf, void *recvbuf, int *recvcounts,
                       MPI_Datatype datatype, MPI_Op op, MPI_Comm comm) 
{
    int i, err, size;

    if (MPI_PARAM_CHECK) {
        err = MPI_SUCCESS;
        OMPI_ERR_INIT_FINALIZE(FUNC_NAME);
        if (ompi_comm_invalid(comm)) {
	    return OMPI_ERRHANDLER_INVOKE(MPI_COMM_WORLD, MPI_ERR_COMM, 
                                          FUNC_NAME);
	}

        /* Unrooted operation; same checks for all ranks on both
           intracommunicators and intercommunicators */
	
        else if (MPI_OP_NULL == op) {
          err = MPI_ERR_OP;
        } else if (ompi_op_is_intrinsic(op) && 
                   datatype->id < DT_MAX_PREDEFINED &&
                   -1 == ompi_op_ddt_map[datatype->id]) {
          err = MPI_ERR_OP;
        } else if (NULL == recvcounts) {
          err = MPI_ERR_COUNT;
        }
        OMPI_ERRHANDLER_CHECK(err, comm, err, FUNC_NAME);

      /* We always define the remote group to be the same as the local
         group in the case of an intracommunicator, so it's safe to
         get the size of the remote group here for both intra- and
         intercommunicators */

        size = ompi_comm_remote_size(comm);
        for (i = 0; i < size; ++i) {
          OMPI_CHECK_DATATYPE_FOR_SEND(err, datatype, recvcounts[i]);
          OMPI_ERRHANDLER_CHECK(err, comm, err, FUNC_NAME);
        }
    }

    /* Invoke the coll component to perform the back-end operation */

    err = comm->c_coll.coll_reduce_scatter(sendbuf, recvbuf, recvcounts,
                                           datatype, op, comm);
    OMPI_ERRHANDLER_RETURN(err, comm, err, FUNC_NAME);
}