/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil ; -*- */
/*
 *
 *   Copyright (C) 1997 University of Chicago.
 *   See COPYRIGHT notice in top-level directory.
 */

#include "adio.h"
#include "adio_extern.h"

int ADIO_Type_create_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 = (MPI_Aint) array_of_sizes[0] * extent;
            for (i = 2; i < ndims; i++) {
                size *= (MPI_Aint) 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 *= (MPI_Aint) array_of_sizes[i - 1];
            disps[1] += size * (MPI_Aint) 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 = (MPI_Aint) array_of_sizes[ndims - 1] * extent;
            for (i = ndims - 3; i >= 0; i--) {
                size *= (MPI_Aint) 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 *= (MPI_Aint) array_of_sizes[i + 1];
            disps[1] += size * (MPI_Aint) array_of_starts[i];
        }
    }

    disps[1] *= extent;

    disps[2] = extent;
    for (i = 0; i < ndims; i++)
        disps[2] *= (MPI_Aint) 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;
}
