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 "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.  Note that we will only get here if
       rcount > 0 or rank == root. */

    if (rank != root) {
        err = MCA_PML_CALL(recv(rbuf, rcount, rdtype,
                                root, MCA_COLL_BASE_TAG_SCATTERV, 
                                comm, MPI_STATUS_IGNORE));
        return err;
    }

    /* 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) {
            if( 0 == scounts[i] ) {  /* simple optimization or a local operation */
                continue;
            }
            err = ompi_ddt_sndrcv(ptmp, scounts[i], sdtype, rbuf, rcount, rdtype);
        } else {
            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;
}