openmpi/ompi/mca/coll/base/coll_base_util.c

/*
 * Copyright (c) 2004-2005 The Trustees of Indiana University and Indiana
 *                         University Research and Technology
 *                         Corporation.  All rights reserved.
 * Copyright (c) 2004-2016 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 (c) 2014-2017 Research Organization for Information Science
 *                         and Technology (RIST). All rights reserved.
 * $COPYRIGHT$
 *
 * Additional copyrights may follow
 *
 * $HEADER$
 */

#include "ompi_config.h"

#include "mpi.h"
#include "ompi/constants.h"
#include "ompi/datatype/ompi_datatype.h"
#include "ompi/communicator/communicator.h"
#include "ompi/mca/coll/base/coll_tags.h"
#include "ompi/mca/coll/base/coll_base_functions.h"
#include "ompi/mca/pml/pml.h"
#include "coll_base_util.h"

int ompi_coll_base_sendrecv_actual( const void* sendbuf, size_t scount,
                                    ompi_datatype_t* sdatatype,
                                    int dest, int stag,
                                    void* recvbuf, size_t rcount,
                                    ompi_datatype_t* rdatatype,
                                    int source, int rtag,
                                    struct ompi_communicator_t* comm,
                                    ompi_status_public_t* status )

{ /* post receive first, then send, then wait... should be fast (I hope) */
    int err, line = 0;
    size_t rtypesize, stypesize;
    ompi_request_t *req = MPI_REQUEST_NULL;
    ompi_status_public_t rstatus;

    /* post new irecv */
    ompi_datatype_type_size(rdatatype, &rtypesize);
    err = MCA_PML_CALL(irecv( recvbuf, rcount, rdatatype, source, rtag,
                              comm, &req));
    if (err != MPI_SUCCESS) { line = __LINE__; goto error_handler; }

    /* send data to children */
    ompi_datatype_type_size(sdatatype, &stypesize);
    err = MCA_PML_CALL(send( sendbuf, scount, sdatatype, dest, stag,
                             MCA_PML_BASE_SEND_STANDARD, comm));
    if (err != MPI_SUCCESS) { line = __LINE__; goto error_handler; }

    err = ompi_request_wait( &req, &rstatus);
    if (err != MPI_SUCCESS) { line = __LINE__; goto error_handler; }

    if (MPI_STATUS_IGNORE != status) {
        *status = rstatus;
    }

    return (MPI_SUCCESS);

 error_handler:
    /* Error discovered during the posting of the irecv or send,
     * and no status is available.
     */
    OPAL_OUTPUT ((ompi_coll_base_framework.framework_output, "%s:%d: Error %d occurred\n",
                  __FILE__, line, err));
    (void)line;  // silence compiler warning
    if (MPI_STATUS_IGNORE != status) {
        status->MPI_ERROR = err;
    }
    return (err);
}

/*
 * ompi_mirror_perm: Returns mirror permutation of nbits low-order bits
 *                   of x [*].
 * [*] Warren Jr., Henry S. Hacker's Delight (2ed). 2013.
 *     Chapter 7. Rearranging Bits and Bytes.
 */
unsigned int ompi_mirror_perm(unsigned int x, int nbits)
{
    x = (((x & 0xaaaaaaaa) >> 1) | ((x & 0x55555555) << 1));
    x = (((x & 0xcccccccc) >> 2) | ((x & 0x33333333) << 2));
    x = (((x & 0xf0f0f0f0) >> 4) | ((x & 0x0f0f0f0f) << 4));
    x = (((x & 0xff00ff00) >> 8) | ((x & 0x00ff00ff) << 8));
    x = ((x >> 16) | (x << 16));
    return x >> (sizeof(x) * CHAR_BIT - nbits);
}

/*
 * ompi_rounddown: Rounds a number down to nearest multiple.
 *     rounddown(10,4) = 8, rounddown(6,3) = 6, rounddown(14,3) = 12
 */
int ompi_rounddown(int num, int factor)
{
    num /= factor;
    return num * factor;    /* floor(num / factor) * factor */
}