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libs/ck-libs/ampi/romio/common/dataloop/subarray_support.c

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/* -*- Mode: C; c-basic-offset:4 ; -*- */
/* 
 *
 *   Copyright (C) 1997 University of Chicago. 
 *   See COPYRIGHT notice in top-level directory.
 *
 * Note: This code originally appeared in ROMIO.
 */

#include "dataloop.h"

int PREPEND_PREFIX(Type_convert_subarray)(int ndims,
                      int *array_of_sizes, 
                      int *array_of_subsizes,
                      int *array_of_starts,
                      int order,
                      MPI_Datatype oldtype, 
                      MPI_Datatype *newtype)
{
    MPI_Aint extent, disps[3], size;
    int i, blklens[3];
    MPI_Datatype tmp1, tmp2, types[3];

    MPI_Type_extent(oldtype, &extent);

    if (order == MPI_ORDER_FORTRAN) {
    /* dimension 0 changes fastest */
    if (ndims == 1) {
        MPI_Type_contiguous(array_of_subsizes[0], oldtype, &tmp1);
    }
    else {
        MPI_Type_vector(array_of_subsizes[1],
                 array_of_subsizes[0],
                 array_of_sizes[0], oldtype, &tmp1);
        
        size = array_of_sizes[0]*extent;
        for (i=2; i<ndims; i++) {
        size *= array_of_sizes[i-1];
        MPI_Type_hvector(array_of_subsizes[i], 1, size, tmp1, &tmp2);
        MPI_Type_free(&tmp1);
        tmp1 = tmp2;
        }
    }
    
    /* add displacement and UB */
    disps[1] = array_of_starts[0];
    size = 1;
    for (i=1; i<ndims; i++) {
        size *= array_of_sizes[i-1];
        disps[1] += size*array_of_starts[i];
    }  
        /* rest done below for both Fortran and C order */
    }

    else /* order == MPI_ORDER_C */ {
    /* dimension ndims-1 changes fastest */
    if (ndims == 1) {
        MPI_Type_contiguous(array_of_subsizes[0], oldtype, &tmp1);
    }
    else {
        MPI_Type_vector(array_of_subsizes[ndims-2],
                 array_of_subsizes[ndims-1],
                 array_of_sizes[ndims-1], oldtype, &tmp1);
        
        size = array_of_sizes[ndims-1]*extent;
        for (i=ndims-3; i>=0; i--) {
        size *= array_of_sizes[i+1];
        MPI_Type_hvector(array_of_subsizes[i], 1, size, tmp1, &tmp2);
        MPI_Type_free(&tmp1);
        tmp1 = tmp2;
        }
    }
    
    /* add displacement and UB */
    disps[1] = array_of_starts[ndims-1];
    size = 1;
    for (i=ndims-2; i>=0; i--) {
        size *= array_of_sizes[i+1];
        disps[1] += size*array_of_starts[i];
    }
    }
    
    disps[1] *= extent;
    
    disps[2] = extent;
    for (i=0; i<ndims; i++) disps[2] *= array_of_sizes[i];
    
    disps[0] = 0;
    blklens[0] = blklens[1] = blklens[2] = 1;
    types[0] = MPI_LB;
    types[1] = tmp1;
    types[2] = MPI_UB;
    
    MPI_Type_struct(3, blklens, disps, types, newtype);

    MPI_Type_free(&tmp1);

    return MPI_SUCCESS;
}

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