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

#include "mpiimpl.h"

static int MPII_Type_block(int *array_of_gsizes, int dim, int ndims,
                           int nprocs, int rank, int darg, int order, MPI_Aint orig_extent,
                           MPI_Datatype type_old, MPI_Datatype * type_new, MPI_Aint * st_offset);
static int MPII_Type_cyclic(int *array_of_gsizes, int dim, int ndims, int nprocs,
                            int rank, int darg, int order, MPI_Aint orig_extent,
                            MPI_Datatype type_old, MPI_Datatype * type_new, MPI_Aint * st_offset);


#undef FUNCNAME
#define FUNCNAME MPIDU_Type_convert_darray
#undef FCNAME
#define FCNAME MPL_QUOTE(FUNCNAME)
int MPIR_Type_convert_darray(int size,
                             int rank,
                             int ndims,
                             int *array_of_gsizes,
                             int *array_of_distribs,
                             int *array_of_dargs,
                             int *array_of_psizes,
                             int order, MPI_Datatype oldtype, MPI_Datatype * newtype)
{
    int mpi_errno = MPI_SUCCESS;
    MPI_Datatype type_old, type_new = MPI_DATATYPE_NULL, types[3];
    int procs, tmp_rank, i, tmp_size, blklens[3], *coords;
    MPI_Aint *st_offsets, orig_extent, disps[3];

    MPIR_Datatype_get_extent_macro(oldtype, orig_extent);

/* calculate position in Cartesian grid as MPI would (row-major
   ordering) */
    coords = (int *) DLOOP_Malloc(ndims * sizeof(int), MPL_MEM_DATATYPE);
    procs = size;
    tmp_rank = rank;
    for (i = 0; i < ndims; i++) {
        procs = procs / array_of_psizes[i];
        coords[i] = tmp_rank / procs;
        tmp_rank = tmp_rank % procs;
    }

    st_offsets = (MPI_Aint *) DLOOP_Malloc(ndims * sizeof(MPI_Aint), MPL_MEM_DATATYPE);
    type_old = oldtype;

    if (order == MPI_ORDER_FORTRAN) {
        /* dimension 0 changes fastest */
        for (i = 0; i < ndims; i++) {
            switch (array_of_distribs[i]) {
                case MPI_DISTRIBUTE_BLOCK:
                    mpi_errno = MPII_Type_block(array_of_gsizes, i, ndims,
                                                array_of_psizes[i],
                                                coords[i], array_of_dargs[i],
                                                order, orig_extent,
                                                type_old, &type_new, st_offsets + i);
                    if (mpi_errno)
                        MPIR_ERR_POP(mpi_errno);
                    break;
                case MPI_DISTRIBUTE_CYCLIC:
                    mpi_errno = MPII_Type_cyclic(array_of_gsizes, i, ndims,
                                                 array_of_psizes[i], coords[i],
                                                 array_of_dargs[i], order,
                                                 orig_extent, type_old, &type_new, st_offsets + i);
                    if (mpi_errno)
                        MPIR_ERR_POP(mpi_errno);
                    break;
                case MPI_DISTRIBUTE_NONE:
                    /* treat it as a block distribution on 1 process */
                    mpi_errno = MPII_Type_block(array_of_gsizes, i, ndims, 1, 0,
                                                MPI_DISTRIBUTE_DFLT_DARG, order,
                                                orig_extent, type_old, &type_new, st_offsets + i);
                    if (mpi_errno)
                        MPIR_ERR_POP(mpi_errno);
                    break;
            }
            if (i)
                MPIR_Type_free_impl(&type_old);
            type_old = type_new;
        }

        /* add displacement and UB */
        disps[1] = st_offsets[0];
        tmp_size = 1;
        for (i = 1; i < ndims; i++) {
            tmp_size *= array_of_gsizes[i - 1];
            disps[1] += ((MPI_Aint) tmp_size) * st_offsets[i];
        }
        /* rest done below for both Fortran and C order */
    }

    else {      /* order == MPI_ORDER_C */

        /* dimension ndims-1 changes fastest */
        for (i = ndims - 1; i >= 0; i--) {
            switch (array_of_distribs[i]) {
                case MPI_DISTRIBUTE_BLOCK:
                    mpi_errno = MPII_Type_block(array_of_gsizes, i, ndims, array_of_psizes[i],
                                                coords[i], array_of_dargs[i], order,
                                                orig_extent, type_old, &type_new, st_offsets + i);
                    if (mpi_errno)
                        MPIR_ERR_POP(mpi_errno);
                    break;
                case MPI_DISTRIBUTE_CYCLIC:
                    mpi_errno = MPII_Type_cyclic(array_of_gsizes, i, ndims,
                                                 array_of_psizes[i], coords[i],
                                                 array_of_dargs[i], order,
                                                 orig_extent, type_old, &type_new, st_offsets + i);
                    if (mpi_errno)
                        MPIR_ERR_POP(mpi_errno);
                    break;
                case MPI_DISTRIBUTE_NONE:
                    /* treat it as a block distribution on 1 process */
                    mpi_errno = MPII_Type_block(array_of_gsizes, i, ndims, array_of_psizes[i],
                                                coords[i], MPI_DISTRIBUTE_DFLT_DARG, order,
                                                orig_extent, type_old, &type_new, st_offsets + i);
                    if (mpi_errno)
                        MPIR_ERR_POP(mpi_errno);
                    break;
            }
            if (i != ndims - 1)
                MPIR_Type_free_impl(&type_old);
            type_old = type_new;
        }

        /* add displacement and UB */
        disps[1] = st_offsets[ndims - 1];
        tmp_size = 1;
        for (i = ndims - 2; i >= 0; i--) {
            tmp_size *= array_of_gsizes[i + 1];
            disps[1] += ((MPI_Aint) tmp_size) * st_offsets[i];
        }
    }

    disps[1] *= orig_extent;

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

    disps[0] = 0;
    blklens[0] = blklens[1] = blklens[2] = 1;
    types[0] = MPI_LB;
    types[1] = type_new;
    types[2] = MPI_UB;

    DLOOP_Free(st_offsets);
    DLOOP_Free(coords);

    mpi_errno = MPIR_Type_struct_impl(3, blklens, disps, types, newtype);
    if (mpi_errno)
        MPIR_ERR_POP(mpi_errno);

    MPIR_Type_free_impl(&type_new);


  fn_exit:
    return mpi_errno;
  fn_fail:
    goto fn_exit;
}


/* Returns MPI_SUCCESS on success, an MPI error code on failure.  Code above
 * needs to call MPIO_Err_return_xxx.
 */
#undef FUNCNAME
#define FUNCNAME MPII_Type_block
#undef FCNAME
#define FCNAME MPL_QUOTE(FUNCNAME)
static int MPII_Type_block(int *array_of_gsizes, int dim, int ndims, int nprocs,
                           int rank, int darg, int order, MPI_Aint orig_extent,
                           MPI_Datatype type_old, MPI_Datatype * type_new, MPI_Aint * st_offset)
{
/* nprocs = no. of processes in dimension dim of grid
   rank = coordinate of this process in dimension dim */
    int mpi_errno = MPI_SUCCESS;
    int blksize, global_size, mysize, i, j;
    MPI_Aint stride;

    global_size = array_of_gsizes[dim];

    if (darg == MPI_DISTRIBUTE_DFLT_DARG)
        blksize = (global_size + nprocs - 1) / nprocs;
    else {
        blksize = darg;

        MPIR_ERR_CHKINTERNAL(blksize <= 0, mpi_errno, "blksize must be > 0");
        MPIR_ERR_CHKINTERNAL(blksize * nprocs < global_size, mpi_errno,
                             "blksize * nprocs must be >= global size");
    }

    j = global_size - blksize * rank;
    mysize = (blksize < j) ? blksize : j;
    if (mysize < 0)
        mysize = 0;

    stride = orig_extent;
    if (order == MPI_ORDER_FORTRAN) {
        if (dim == 0) {
            mpi_errno = MPIR_Type_contiguous_impl(mysize, type_old, type_new);
            if (mpi_errno)
                MPIR_ERR_POP(mpi_errno);
        } else {
            for (i = 0; i < dim; i++)
                stride *= (MPI_Aint) (array_of_gsizes[i]);
            mpi_errno = MPIR_Type_hvector_impl(mysize, 1, stride, type_old, type_new);
            if (mpi_errno)
                MPIR_ERR_POP(mpi_errno);
        }
    } else {
        if (dim == ndims - 1) {
            mpi_errno = MPIR_Type_contiguous_impl(mysize, type_old, type_new);
            if (mpi_errno)
                MPIR_ERR_POP(mpi_errno);
        } else {
            for (i = ndims - 1; i > dim; i--)
                stride *= (MPI_Aint) (array_of_gsizes[i]);
            mpi_errno = MPIR_Type_hvector_impl(mysize, 1, stride, type_old, type_new);
            if (mpi_errno)
                MPIR_ERR_POP(mpi_errno);
        }
    }

    *st_offset = blksize * rank;
    /* in terms of no. of elements of type oldtype in this dimension */
    if (mysize == 0)
        *st_offset = 0;

  fn_exit:
    return mpi_errno;
  fn_fail:
    goto fn_exit;
}


/* Returns MPI_SUCCESS on success, an MPI error code on failure.  Code above
 * needs to call MPIO_Err_return_xxx.
 */
static int MPII_Type_cyclic(int *array_of_gsizes, int dim, int ndims, int nprocs,
                            int rank, int darg, int order, MPI_Aint orig_extent,
                            MPI_Datatype type_old, MPI_Datatype * type_new, MPI_Aint * st_offset)
{
/* nprocs = no. of processes in dimension dim of grid
   rank = coordinate of this process in dimension dim */
    int mpi_errno = MPI_SUCCESS;
    int blksize, i, blklens[3], st_index, end_index, local_size, rem, count;
    MPI_Aint stride, disps[3];
    MPI_Datatype type_tmp, types[3];

    if (darg == MPI_DISTRIBUTE_DFLT_DARG)
        blksize = 1;
    else
        blksize = darg;

    MPIR_ERR_CHKINTERNAL(blksize <= 0, mpi_errno, "blksize must be > 0");

    st_index = rank * blksize;
    end_index = array_of_gsizes[dim] - 1;

    if (end_index < st_index)
        local_size = 0;
    else {
        local_size = ((end_index - st_index + 1) / (nprocs * blksize)) * blksize;
        rem = (end_index - st_index + 1) % (nprocs * blksize);
        local_size += (rem < blksize) ? rem : blksize;
    }

    count = local_size / blksize;
    rem = local_size % blksize;

    stride = ((MPI_Aint) nprocs) * ((MPI_Aint) blksize) * orig_extent;
    if (order == MPI_ORDER_FORTRAN)
        for (i = 0; i < dim; i++)
            stride *= (MPI_Aint) (array_of_gsizes[i]);
    else
        for (i = ndims - 1; i > dim; i--)
            stride *= (MPI_Aint) (array_of_gsizes[i]);

    mpi_errno = MPIR_Type_hvector_impl(count, blksize, stride, type_old, type_new);
    if (mpi_errno)
        MPIR_ERR_POP(mpi_errno);

    if (rem) {
        /* if the last block is of size less than blksize, include
         * it separately using MPI_Type_struct */

        types[0] = *type_new;
        types[1] = type_old;
        disps[0] = 0;
        disps[1] = ((MPI_Aint) count) * stride;
        blklens[0] = 1;
        blklens[1] = rem;

        mpi_errno = MPIR_Type_struct_impl(2, blklens, disps, types, &type_tmp);
        if (mpi_errno)
            MPIR_ERR_POP(mpi_errno);

        MPIR_Type_free_impl(type_new);
        *type_new = type_tmp;
    }

    /* In the first iteration, we need to set the displacement in that
     * dimension correctly. */
    if (((order == MPI_ORDER_FORTRAN) && (dim == 0)) ||
        ((order == MPI_ORDER_C) && (dim == ndims - 1))) {
        types[0] = MPI_LB;
        disps[0] = 0;
        types[1] = *type_new;
        disps[1] = ((MPI_Aint) rank) * ((MPI_Aint) blksize) * orig_extent;
        types[2] = MPI_UB;
        disps[2] = orig_extent * ((MPI_Aint) (array_of_gsizes[dim]));
        blklens[0] = blklens[1] = blklens[2] = 1;

        mpi_errno = MPIR_Type_struct_impl(3, blklens, disps, types, &type_tmp);
        if (mpi_errno)
            MPIR_ERR_POP(mpi_errno);

        MPIR_Type_free_impl(type_new);
        *type_new = type_tmp;

        *st_offset = 0; /* set it to 0 because it is taken care of in
                         * the struct above */
    } else {
        *st_offset = ((MPI_Aint) rank) * ((MPI_Aint) blksize);
        /* st_offset is in terms of no. of elements of type oldtype in
         * this dimension */
    }

    if (local_size == 0)
        *st_offset = 0;

  fn_exit:
    return mpi_errno;
  fn_fail:
    goto fn_exit;
}
