path: root/testpar/t_span_tree.c

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * Copyright by The HDF Group.                                               *
 * All rights reserved.                                                      *
 *                                                                           *
 * This file is part of HDF5.  The full HDF5 copyright notice, including     *
 * terms governing use, modification, and redistribution, is contained in    *
 * the COPYING file, which can be found at the root of the source code       *
 * distribution tree, or in https://www.hdfgroup.org/licenses.               *
 * If you do not have access to either file, you may request a copy from     *
 * help@hdfgroup.org.                                                        *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/*
   This program will test irregular hyperslab selections with collective write and read.
   The way to test whether collective write and read works is to use independent IO
   output to verify the collective output.

   1) We will write two datasets with the same hyperslab selection settings;
   one in independent mode,
   one in collective mode,
   2) We will read two datasets with the same hyperslab selection settings,
      1.  independent read to read independent output,
          independent read to read collective output,
    Compare the result,
    If the result is the same, then collective write succeeds.
      2.  collective read to read independent output,
          independent read to read independent output,
    Compare the result,
    If the result is the same, then collective read succeeds.

 */

#include "H5private.h"
#include "testphdf5.h"

#define LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG 0

static void coll_write_test(int chunk_factor);
static void coll_read_test(void);

/*-------------------------------------------------------------------------
 * Function:    coll_irregular_cont_write
 *
 * Purpose:    Wrapper to test the collectively irregular hyperslab write in
 *             contiguous storage
 *
 * Return:    Success:    0
 *
 *        Failure:    -1
 *
 *-------------------------------------------------------------------------
 */
void
coll_irregular_cont_write(void)
{
    int mpi_rank;

    MPI_Comm_rank(MPI_COMM_WORLD, &mpi_rank);

    /* Make sure the connector supports the API functions being tested */
    if (!(vol_cap_flags_g & H5VL_CAP_FLAG_FILE_BASIC) || !(vol_cap_flags_g & H5VL_CAP_FLAG_DATASET_BASIC) ||
        !(vol_cap_flags_g & H5VL_CAP_FLAG_DATASET_MORE)) {
        if (MAINPROCESS) {
            puts("SKIPPED");
            printf("    API functions for basic file dataset, or dataset more aren't supported with this "
                   "connector\n");
            fflush(stdout);
        }

        return;
    }

    coll_write_test(0);
}

/*-------------------------------------------------------------------------
 * Function:    coll_irregular_cont_read
 *
 * Purpose:    Wrapper to test the collectively irregular hyperslab read in
 *             contiguous storage
 *
 * Return:    Success:    0
 *
 *        Failure:    -1
 *
 *-------------------------------------------------------------------------
 */
void
coll_irregular_cont_read(void)
{
    int mpi_rank;

    MPI_Comm_rank(MPI_COMM_WORLD, &mpi_rank);

    /* Make sure the connector supports the API functions being tested */
    if (!(vol_cap_flags_g & H5VL_CAP_FLAG_FILE_BASIC) || !(vol_cap_flags_g & H5VL_CAP_FLAG_DATASET_BASIC) ||
        !(vol_cap_flags_g & H5VL_CAP_FLAG_DATASET_MORE)) {
        if (MAINPROCESS) {
            puts("SKIPPED");
            printf("    API functions for basic file dataset, or dataset more aren't supported with this "
                   "connector\n");
            fflush(stdout);
        }

        return;
    }

    coll_read_test();
}

/*-------------------------------------------------------------------------
 * Function:    coll_irregular_simple_chunk_write
 *
 * Purpose:    Wrapper to test the collectively irregular hyperslab write in
 *             chunk storage(1 chunk)
 *
 * Return:    Success:    0
 *
 *        Failure:    -1
 *
 *-------------------------------------------------------------------------
 */
void
coll_irregular_simple_chunk_write(void)
{
    int mpi_rank;

    MPI_Comm_rank(MPI_COMM_WORLD, &mpi_rank);

    /* Make sure the connector supports the API functions being tested */
    if (!(vol_cap_flags_g & H5VL_CAP_FLAG_FILE_BASIC) || !(vol_cap_flags_g & H5VL_CAP_FLAG_DATASET_BASIC) ||
        !(vol_cap_flags_g & H5VL_CAP_FLAG_DATASET_MORE)) {
        if (MAINPROCESS) {
            puts("SKIPPED");
            printf("    API functions for basic file dataset, or dataset more aren't supported with this "
                   "connector\n");
            fflush(stdout);
        }

        return;
    }

    coll_write_test(1);
}

/*-------------------------------------------------------------------------
 * Function:    coll_irregular_simple_chunk_read
 *
 * Purpose:    Wrapper to test the collectively irregular hyperslab read in chunk
 *             storage(1 chunk)
 *
 * Return:    Success:    0
 *
 *        Failure:    -1
 *
 *-------------------------------------------------------------------------
 */
void
coll_irregular_simple_chunk_read(void)
{
    int mpi_rank;

    MPI_Comm_rank(MPI_COMM_WORLD, &mpi_rank);

    /* Make sure the connector supports the API functions being tested */
    if (!(vol_cap_flags_g & H5VL_CAP_FLAG_FILE_BASIC) || !(vol_cap_flags_g & H5VL_CAP_FLAG_DATASET_BASIC) ||
        !(vol_cap_flags_g & H5VL_CAP_FLAG_DATASET_MORE)) {
        if (MAINPROCESS) {
            puts("SKIPPED");
            printf("    API functions for basic file dataset, or dataset more aren't supported with this "
                   "connector\n");
            fflush(stdout);
        }

        return;
    }

    coll_read_test();
}

/*-------------------------------------------------------------------------
 * Function:    coll_irregular_complex_chunk_write
 *
 * Purpose:    Wrapper to test the collectively irregular hyperslab write in chunk
 *             storage(4 chunks)
 *
 * Return:    Success:    0
 *
 *        Failure:    -1
 *
 *-------------------------------------------------------------------------
 */
void
coll_irregular_complex_chunk_write(void)
{
    int mpi_rank;

    MPI_Comm_rank(MPI_COMM_WORLD, &mpi_rank);

    /* Make sure the connector supports the API functions being tested */
    if (!(vol_cap_flags_g & H5VL_CAP_FLAG_FILE_BASIC) || !(vol_cap_flags_g & H5VL_CAP_FLAG_DATASET_BASIC) ||
        !(vol_cap_flags_g & H5VL_CAP_FLAG_DATASET_MORE)) {
        if (MAINPROCESS) {
            puts("SKIPPED");
            printf("    API functions for basic file dataset, or dataset more aren't supported with this "
                   "connector\n");
            fflush(stdout);
        }

        return;
    }

    coll_write_test(4);
}

/*-------------------------------------------------------------------------
 * Function:    coll_irregular_complex_chunk_read
 *
 * Purpose:    Wrapper to test the collectively irregular hyperslab read in chunk
 *             storage(1 chunk)
 *
 * Return:    Success:    0
 *
 *        Failure:    -1
 *
 *-------------------------------------------------------------------------
 */
void
coll_irregular_complex_chunk_read(void)
{
    int mpi_rank;

    MPI_Comm_rank(MPI_COMM_WORLD, &mpi_rank);

    /* Make sure the connector supports the API functions being tested */
    if (!(vol_cap_flags_g & H5VL_CAP_FLAG_FILE_BASIC) || !(vol_cap_flags_g & H5VL_CAP_FLAG_DATASET_BASIC) ||
        !(vol_cap_flags_g & H5VL_CAP_FLAG_DATASET_MORE)) {
        if (MAINPROCESS) {
            puts("SKIPPED");
            printf("    API functions for basic file dataset, or dataset more aren't supported with this "
                   "connector\n");
            fflush(stdout);
        }

        return;
    }

    coll_read_test();
}

/*-------------------------------------------------------------------------
 * Function:    coll_write_test
 *
 * Purpose:    To test the collectively irregular hyperslab write in chunk
 *              storage
 *  Input:      number of chunks on each dimension
 *              if number is equal to 0, contiguous storage
 * Return:    Success:    0
 *
 *        Failure:    -1
 *
 *-------------------------------------------------------------------------
 */
void
coll_write_test(int chunk_factor)
{

    const char *filename;
    hid_t       facc_plist, dxfer_plist, dcrt_plist;
    hid_t       file, datasetc, dataseti;                 /* File and dataset identifiers */
    hid_t       mspaceid1, mspaceid, fspaceid, fspaceid1; /* Dataspace identifiers */

    hsize_t mdim1[1]; /* Dimension size of the first dataset (in memory) */
    hsize_t fsdim[2]; /* Dimension sizes of the dataset (on disk) */
    hsize_t mdim[2];  /* Dimension sizes of the dataset in memory when we
                       * read selection from the dataset on the disk
                       */

    hsize_t start[2];  /* Start of hyperslab */
    hsize_t stride[2]; /* Stride of hyperslab */
    hsize_t count[2];  /* Block count */
    hsize_t block[2];  /* Block sizes */
    hsize_t chunk_dims[2];

    herr_t ret;
    int    i;
    int    fillvalue = 0; /* Fill value for the dataset */

    int *matrix_out  = NULL;
    int *matrix_out1 = NULL; /* Buffer to read from the dataset */
    int *vector      = NULL;

    int mpi_size, mpi_rank;

    MPI_Comm comm = MPI_COMM_WORLD;
    MPI_Info info = MPI_INFO_NULL;

    /*set up MPI parameters */
    MPI_Comm_size(comm, &mpi_size);
    MPI_Comm_rank(comm, &mpi_rank);

    /* Obtain file name */
    filename = GetTestParameters();

    /*
     * Buffers' initialization.
     */

    mdim1[0] = (hsize_t)(MSPACE1_DIM * mpi_size);
    mdim[0]  = MSPACE_DIM1;
    mdim[1]  = (hsize_t)(MSPACE_DIM2 * mpi_size);
    fsdim[0] = FSPACE_DIM1;
    fsdim[1] = (hsize_t)(FSPACE_DIM2 * mpi_size);

    vector      = (int *)malloc(sizeof(int) * (size_t)mdim1[0] * (size_t)mpi_size);
    matrix_out  = (int *)malloc(sizeof(int) * (size_t)mdim[0] * (size_t)mdim[1] * (size_t)mpi_size);
    matrix_out1 = (int *)malloc(sizeof(int) * (size_t)mdim[0] * (size_t)mdim[1] * (size_t)mpi_size);

    memset(vector, 0, sizeof(int) * (size_t)mdim1[0] * (size_t)mpi_size);
    vector[0] = vector[MSPACE1_DIM * mpi_size - 1] = -1;
    for (i = 1; i < MSPACE1_DIM * mpi_size - 1; i++)
        H5_CHECKED_ASSIGN(vector[i], int, i, unsigned);

    /* Grab file access property list */
    facc_plist = create_faccess_plist(comm, info, facc_type);
    VRFY((facc_plist >= 0), "");

    /*
     * Create a file.
     */
    file = H5Fcreate(filename, H5F_ACC_TRUNC, H5P_DEFAULT, facc_plist);
    VRFY((file >= 0), "H5Fcreate succeeded");

    /*
     * Create property list for a dataset and set up fill values.
     */
    dcrt_plist = H5Pcreate(H5P_DATASET_CREATE);
    VRFY((dcrt_plist >= 0), "");

    ret = H5Pset_fill_value(dcrt_plist, H5T_NATIVE_INT, &fillvalue);
    VRFY((ret >= 0), "Fill value creation property list succeeded");

    if (chunk_factor != 0) {
        chunk_dims[0] = fsdim[0] / (hsize_t)chunk_factor;
        chunk_dims[1] = fsdim[1] / (hsize_t)chunk_factor;
        ret           = H5Pset_chunk(dcrt_plist, 2, chunk_dims);
        VRFY((ret >= 0), "chunk creation property list succeeded");
    }

    /*
     *
     * Create dataspace for the first dataset in the disk.
     * dim1 = 9
     * dim2 = 3600
     *
     *
     */
    fspaceid = H5Screate_simple(FSPACE_RANK, fsdim, NULL);
    VRFY((fspaceid >= 0), "file dataspace created succeeded");

    /*
     * Create dataset in the file. Notice that creation
     * property list dcrt_plist is used.
     */
    datasetc =
        H5Dcreate2(file, "collect_write", H5T_NATIVE_INT, fspaceid, H5P_DEFAULT, dcrt_plist, H5P_DEFAULT);
    VRFY((datasetc >= 0), "dataset created succeeded");

    dataseti =
        H5Dcreate2(file, "independ_write", H5T_NATIVE_INT, fspaceid, H5P_DEFAULT, dcrt_plist, H5P_DEFAULT);
    VRFY((dataseti >= 0), "dataset created succeeded");

    /* The First selection for FILE
     *
     *  block (3,2)
     *  stride(4,3)
     *  count (1,768/mpi_size)
     *  start (0,1+768*3*mpi_rank/mpi_size)
     *
     */

    start[0]  = FHSTART0;
    start[1]  = (hsize_t)(FHSTART1 + mpi_rank * FHSTRIDE1 * FHCOUNT1);
    stride[0] = FHSTRIDE0;
    stride[1] = FHSTRIDE1;
    count[0]  = FHCOUNT0;
    count[1]  = FHCOUNT1;
    block[0]  = FHBLOCK0;
    block[1]  = FHBLOCK1;

    ret = H5Sselect_hyperslab(fspaceid, H5S_SELECT_SET, start, stride, count, block);
    VRFY((ret >= 0), "hyperslab selection succeeded");

    /* The Second selection for FILE
     *
     *  block  (3,768)
     *  stride (1,1)
     *  count  (1,1)
     *  start  (4,768*mpi_rank/mpi_size)
     *
     */

    start[0]  = SHSTART0;
    start[1]  = (hsize_t)(SHSTART1 + SHCOUNT1 * SHBLOCK1 * mpi_rank);
    stride[0] = SHSTRIDE0;
    stride[1] = SHSTRIDE1;
    count[0]  = SHCOUNT0;
    count[1]  = SHCOUNT1;
    block[0]  = SHBLOCK0;
    block[1]  = SHBLOCK1;

    ret = H5Sselect_hyperslab(fspaceid, H5S_SELECT_OR, start, stride, count, block);
    VRFY((ret >= 0), "hyperslab selection succeeded");

    /*
     * Create dataspace for the first dataset in the memory
     * dim1 = 27000
     *
     */
    mspaceid1 = H5Screate_simple(MSPACE1_RANK, mdim1, NULL);
    VRFY((mspaceid1 >= 0), "memory dataspace created succeeded");

    /*
     * Memory space is 1-D, this is a good test to check
     * whether a span-tree derived datatype needs to be built.
     * block  1
     * stride 1
     * count  6912/mpi_size
     * start  1
     *
     */
    start[0]  = MHSTART0;
    stride[0] = MHSTRIDE0;
    count[0]  = MHCOUNT0;
    block[0]  = MHBLOCK0;

    ret = H5Sselect_hyperslab(mspaceid1, H5S_SELECT_SET, start, stride, count, block);
    VRFY((ret >= 0), "hyperslab selection succeeded");

    /* independent write */
    ret = H5Dwrite(dataseti, H5T_NATIVE_INT, mspaceid1, fspaceid, H5P_DEFAULT, vector);
    VRFY((ret >= 0), "dataset independent write succeed");

    dxfer_plist = H5Pcreate(H5P_DATASET_XFER);
    VRFY((dxfer_plist >= 0), "");

    ret = H5Pset_dxpl_mpio(dxfer_plist, H5FD_MPIO_COLLECTIVE);
    VRFY((ret >= 0), "MPIO data transfer property list succeed");
    if (dxfer_coll_type == DXFER_INDEPENDENT_IO) {
        ret = H5Pset_dxpl_mpio_collective_opt(dxfer_plist, H5FD_MPIO_INDIVIDUAL_IO);
        VRFY((ret >= 0), "set independent IO collectively succeeded");
    }

    /* collective write */
    ret = H5Dwrite(datasetc, H5T_NATIVE_INT, mspaceid1, fspaceid, dxfer_plist, vector);
    VRFY((ret >= 0), "dataset collective write succeed");

    ret = H5Sclose(mspaceid1);
    VRFY((ret >= 0), "");

    ret = H5Sclose(fspaceid);
    VRFY((ret >= 0), "");

    /*
     * Close dataset.
     */
    ret = H5Dclose(datasetc);
    VRFY((ret >= 0), "");

    ret = H5Dclose(dataseti);
    VRFY((ret >= 0), "");

    /*
     * Close the file.
     */
    ret = H5Fclose(file);
    VRFY((ret >= 0), "");
    /*
     * Close property list
     */

    ret = H5Pclose(facc_plist);
    VRFY((ret >= 0), "");
    ret = H5Pclose(dxfer_plist);
    VRFY((ret >= 0), "");
    ret = H5Pclose(dcrt_plist);
    VRFY((ret >= 0), "");

    /*
     * Open the file.
     */

    /***

         For testing collective hyperslab selection write
         In this test, we are using independent read to check
         the correctness of collective write compared with
         independent write,

         In order to thoroughly test this feature, we choose
         a different selection set for reading the data out.


    ***/

    /* Obtain file access property list with MPI-IO driver */
    facc_plist = create_faccess_plist(comm, info, facc_type);
    VRFY((facc_plist >= 0), "");

    file = H5Fopen(filename, H5F_ACC_RDONLY, facc_plist);
    VRFY((file >= 0), "H5Fopen succeeded");

    /*
     * Open the dataset.
     */
    datasetc = H5Dopen2(file, "collect_write", H5P_DEFAULT);
    VRFY((datasetc >= 0), "H5Dopen2 succeeded");

    dataseti = H5Dopen2(file, "independ_write", H5P_DEFAULT);
    VRFY((dataseti >= 0), "H5Dopen2 succeeded");

    /*
     * Get dataspace of the open dataset.
     */
    fspaceid = H5Dget_space(datasetc);
    VRFY((fspaceid >= 0), "file dataspace obtained succeeded");

    fspaceid1 = H5Dget_space(dataseti);
    VRFY((fspaceid1 >= 0), "file dataspace obtained succeeded");

    /* The First selection for FILE to read
     *
     *  block (1,1)
     *  stride(1.1)
     *  count (3,768/mpi_size)
     *  start (1,2+768*mpi_rank/mpi_size)
     *
     */
    start[0]  = RFFHSTART0;
    start[1]  = (hsize_t)(RFFHSTART1 + mpi_rank * RFFHCOUNT1);
    block[0]  = RFFHBLOCK0;
    block[1]  = RFFHBLOCK1;
    stride[0] = RFFHSTRIDE0;
    stride[1] = RFFHSTRIDE1;
    count[0]  = RFFHCOUNT0;
    count[1]  = RFFHCOUNT1;

    /* The first selection of the dataset generated by collective write */
    ret = H5Sselect_hyperslab(fspaceid, H5S_SELECT_SET, start, stride, count, block);
    VRFY((ret >= 0), "hyperslab selection succeeded");

    /* The first selection of the dataset generated by independent write */
    ret = H5Sselect_hyperslab(fspaceid1, H5S_SELECT_SET, start, stride, count, block);
    VRFY((ret >= 0), "hyperslab selection succeeded");

    /* The Second selection for FILE to read
     *
     *  block (1,1)
     *  stride(1.1)
     *  count (3,1536/mpi_size)
     *  start (2,4+1536*mpi_rank/mpi_size)
     *
     */

    start[0]  = RFSHSTART0;
    start[1]  = (hsize_t)(RFSHSTART1 + RFSHCOUNT1 * mpi_rank);
    block[0]  = RFSHBLOCK0;
    block[1]  = RFSHBLOCK1;
    stride[0] = RFSHSTRIDE0;
    stride[1] = RFSHSTRIDE0;
    count[0]  = RFSHCOUNT0;
    count[1]  = RFSHCOUNT1;

    /* The second selection of the dataset generated by collective write */
    ret = H5Sselect_hyperslab(fspaceid, H5S_SELECT_OR, start, stride, count, block);
    VRFY((ret >= 0), "hyperslab selection succeeded");

    /* The second selection of the dataset generated by independent write */
    ret = H5Sselect_hyperslab(fspaceid1, H5S_SELECT_OR, start, stride, count, block);
    VRFY((ret >= 0), "hyperslab selection succeeded");

    /*
     * Create memory dataspace.
     * rank  = 2
     * mdim1 = 9
     * mdim2 = 3600
     *
     */
    mspaceid = H5Screate_simple(MSPACE_RANK, mdim, NULL);

    /*
     * Select two hyperslabs in memory. Hyperslabs have the same
     * size and shape as the selected hyperslabs for the file dataspace
     * Only the starting point is different.
     * The first selection
     *  block (1,1)
     *  stride(1.1)
     *  count (3,768/mpi_size)
     *  start (0,768*mpi_rank/mpi_size)
     *
     */

    start[0]  = RMFHSTART0;
    start[1]  = (hsize_t)(RMFHSTART1 + mpi_rank * RMFHCOUNT1);
    block[0]  = RMFHBLOCK0;
    block[1]  = RMFHBLOCK1;
    stride[0] = RMFHSTRIDE0;
    stride[1] = RMFHSTRIDE1;
    count[0]  = RMFHCOUNT0;
    count[1]  = RMFHCOUNT1;

    ret = H5Sselect_hyperslab(mspaceid, H5S_SELECT_SET, start, stride, count, block);
    VRFY((ret >= 0), "hyperslab selection succeeded");

    /*
     * Select two hyperslabs in memory. Hyperslabs has the same
     * size and shape as the selected hyperslabs for the file dataspace
     * Only the starting point is different.
     * The second selection
     *  block (1,1)
     *  stride(1,1)
     *  count (3,1536/mpi_size)
     *  start (1,2+1536*mpi_rank/mpi_size)
     *
     */
    start[0]  = RMSHSTART0;
    start[1]  = (hsize_t)(RMSHSTART1 + mpi_rank * RMSHCOUNT1);
    block[0]  = RMSHBLOCK0;
    block[1]  = RMSHBLOCK1;
    stride[0] = RMSHSTRIDE0;
    stride[1] = RMSHSTRIDE1;
    count[0]  = RMSHCOUNT0;
    count[1]  = RMSHCOUNT1;

    ret = H5Sselect_hyperslab(mspaceid, H5S_SELECT_OR, start, stride, count, block);
    VRFY((ret >= 0), "hyperslab selection succeeded");

    /*
     * Initialize data buffer.
     */

    memset(matrix_out, 0, sizeof(int) * (size_t)MSPACE_DIM1 * (size_t)MSPACE_DIM2 * (size_t)mpi_size);
    memset(matrix_out1, 0, sizeof(int) * (size_t)MSPACE_DIM1 * (size_t)MSPACE_DIM2 * (size_t)mpi_size);
    /*
     * Read data back to the buffer matrix_out.
     */

    ret = H5Dread(datasetc, H5T_NATIVE_INT, mspaceid, fspaceid, H5P_DEFAULT, matrix_out);
    VRFY((ret >= 0), "H5D independent read succeed");

    ret = H5Dread(dataseti, H5T_NATIVE_INT, mspaceid, fspaceid, H5P_DEFAULT, matrix_out1);
    VRFY((ret >= 0), "H5D independent read succeed");

    ret = 0;

    for (i = 0; i < MSPACE_DIM1 * MSPACE_DIM2 * mpi_size; i++) {
        if (matrix_out[i] != matrix_out1[i])
            ret = -1;
        if (ret < 0)
            break;
    }

    VRFY((ret >= 0), "H5D irregular collective write succeed");

    /*
     * Close memory file and memory dataspaces.
     */
    ret = H5Sclose(mspaceid);
    VRFY((ret >= 0), "");
    ret = H5Sclose(fspaceid);
    VRFY((ret >= 0), "");

    /*
     * Close dataset.
     */
    ret = H5Dclose(dataseti);
    VRFY((ret >= 0), "");

    ret = H5Dclose(datasetc);
    VRFY((ret >= 0), "");

    /*
     * Close property list
     */

    ret = H5Pclose(facc_plist);
    VRFY((ret >= 0), "");

    /*
     * Close the file.
     */
    ret = H5Fclose(file);
    VRFY((ret >= 0), "");

    if (vector)
        free(vector);
    if (matrix_out)
        free(matrix_out);
    if (matrix_out1)
        free(matrix_out1);

    return;
}

/*-------------------------------------------------------------------------
 * Function:    coll_read_test
 *
 * Purpose:    To test the collectively irregular hyperslab read in chunk
 *              storage
 * Input:       number of chunks on each dimension
 *              if number is equal to 0, contiguous storage
 * Return:    Success:    0
 *
 *        Failure:    -1
 *
 *-------------------------------------------------------------------------
 */
static void
coll_read_test(void)
{

    const char *filename;
    hid_t       facc_plist, dxfer_plist;
    hid_t       file, dataseti;      /* File and dataset identifiers */
    hid_t       mspaceid, fspaceid1; /* Dataspace identifiers */

    /* Dimension sizes of the dataset (on disk) */
    hsize_t mdim[2]; /* Dimension sizes of the dataset in memory when we
                      * read selection from the dataset on the disk
                      */

    hsize_t start[2];  /* Start of hyperslab */
    hsize_t stride[2]; /* Stride of hyperslab */
    hsize_t count[2];  /* Block count */
    hsize_t block[2];  /* Block sizes */
    herr_t  ret;

    int i;

    int *matrix_out;
    int *matrix_out1; /* Buffer to read from the dataset */

    int mpi_size, mpi_rank;

    MPI_Comm comm = MPI_COMM_WORLD;
    MPI_Info info = MPI_INFO_NULL;

    /*set up MPI parameters */
    MPI_Comm_size(comm, &mpi_size);
    MPI_Comm_rank(comm, &mpi_rank);

    /* Obtain file name */
    filename = GetTestParameters();

    /* Initialize the buffer */

    mdim[0]     = MSPACE_DIM1;
    mdim[1]     = (hsize_t)(MSPACE_DIM2 * mpi_size);
    matrix_out  = (int *)malloc(sizeof(int) * (size_t)MSPACE_DIM1 * (size_t)MSPACE_DIM2 * (size_t)mpi_size);
    matrix_out1 = (int *)malloc(sizeof(int) * (size_t)MSPACE_DIM1 * (size_t)MSPACE_DIM2 * (size_t)mpi_size);

    /*** For testing collective hyperslab selection read ***/

    /* Obtain file access property list */
    facc_plist = create_faccess_plist(comm, info, facc_type);
    VRFY((facc_plist >= 0), "");

    /*
     * Open the file.
     */
    file = H5Fopen(filename, H5F_ACC_RDONLY, facc_plist);
    VRFY((file >= 0), "H5Fopen succeeded");

    /*
     * Open the dataset.
     */
    dataseti = H5Dopen2(file, "independ_write", H5P_DEFAULT);
    VRFY((dataseti >= 0), "H5Dopen2 succeeded");

    /*
     * Get dataspace of the open dataset.
     */
    fspaceid1 = H5Dget_space(dataseti);
    VRFY((fspaceid1 >= 0), "file dataspace obtained succeeded");

    /* The First selection for FILE to read
     *
     *  block (1,1)
     *  stride(1.1)
     *  count (3,768/mpi_size)
     *  start (1,2+768*mpi_rank/mpi_size)
     *
     */
    start[0]  = RFFHSTART0;
    start[1]  = (hsize_t)(RFFHSTART1 + mpi_rank * RFFHCOUNT1);
    block[0]  = RFFHBLOCK0;
    block[1]  = RFFHBLOCK1;
    stride[0] = RFFHSTRIDE0;
    stride[1] = RFFHSTRIDE1;
    count[0]  = RFFHCOUNT0;
    count[1]  = RFFHCOUNT1;

    ret = H5Sselect_hyperslab(fspaceid1, H5S_SELECT_SET, start, stride, count, block);
    VRFY((ret >= 0), "hyperslab selection succeeded");

    /* The Second selection for FILE to read
     *
     *  block (1,1)
     *  stride(1.1)
     *  count (3,1536/mpi_size)
     *  start (2,4+1536*mpi_rank/mpi_size)
     *
     */
    start[0]  = RFSHSTART0;
    start[1]  = (hsize_t)(RFSHSTART1 + RFSHCOUNT1 * mpi_rank);
    block[0]  = RFSHBLOCK0;
    block[1]  = RFSHBLOCK1;
    stride[0] = RFSHSTRIDE0;
    stride[1] = RFSHSTRIDE0;
    count[0]  = RFSHCOUNT0;
    count[1]  = RFSHCOUNT1;

    ret = H5Sselect_hyperslab(fspaceid1, H5S_SELECT_OR, start, stride, count, block);
    VRFY((ret >= 0), "hyperslab selection succeeded");

    /*
     * Create memory dataspace.
     */
    mspaceid = H5Screate_simple(MSPACE_RANK, mdim, NULL);

    /*
     * Select two hyperslabs in memory. Hyperslabs have the same
     * size and shape as the selected hyperslabs for the file dataspace.
     * Only the starting point is different.
     * The first selection
     *  block (1,1)
     *  stride(1.1)
     *  count (3,768/mpi_size)
     *  start (0,768*mpi_rank/mpi_size)
     *
     */

    start[0]  = RMFHSTART0;
    start[1]  = (hsize_t)(RMFHSTART1 + mpi_rank * RMFHCOUNT1);
    block[0]  = RMFHBLOCK0;
    block[1]  = RMFHBLOCK1;
    stride[0] = RMFHSTRIDE0;
    stride[1] = RMFHSTRIDE1;
    count[0]  = RMFHCOUNT0;
    count[1]  = RMFHCOUNT1;
    ret       = H5Sselect_hyperslab(mspaceid, H5S_SELECT_SET, start, stride, count, block);
    VRFY((ret >= 0), "hyperslab selection succeeded");

    /*
     * Select two hyperslabs in memory. Hyperslabs has the same
     * size and shape as the selected hyperslabs for the file dataspace
     * Only the starting point is different.
     * The second selection
     *  block (1,1)
     *  stride(1,1)
     *  count (3,1536/mpi_size)
     *  start (1,2+1536*mpi_rank/mpi_size)
     *
     */
    start[0]  = RMSHSTART0;
    start[1]  = (hsize_t)(RMSHSTART1 + mpi_rank * RMSHCOUNT1);
    block[0]  = RMSHBLOCK0;
    block[1]  = RMSHBLOCK1;
    stride[0] = RMSHSTRIDE0;
    stride[1] = RMSHSTRIDE1;
    count[0]  = RMSHCOUNT0;
    count[1]  = RMSHCOUNT1;
    ret       = H5Sselect_hyperslab(mspaceid, H5S_SELECT_OR, start, stride, count, block);
    VRFY((ret >= 0), "hyperslab selection succeeded");

    /*
     * Initialize data buffer.
     */

    memset(matrix_out, 0, sizeof(int) * (size_t)MSPACE_DIM1 * (size_t)MSPACE_DIM2 * (size_t)mpi_size);
    memset(matrix_out1, 0, sizeof(int) * (size_t)MSPACE_DIM1 * (size_t)MSPACE_DIM2 * (size_t)mpi_size);

    /*
     * Read data back to the buffer matrix_out.
     */

    dxfer_plist = H5Pcreate(H5P_DATASET_XFER);
    VRFY((dxfer_plist >= 0), "");

    ret = H5Pset_dxpl_mpio(dxfer_plist, H5FD_MPIO_COLLECTIVE);
    VRFY((ret >= 0), "MPIO data transfer property list succeed");
    if (dxfer_coll_type == DXFER_INDEPENDENT_IO) {
        ret = H5Pset_dxpl_mpio_collective_opt(dxfer_plist, H5FD_MPIO_INDIVIDUAL_IO);
        VRFY((ret >= 0), "set independent IO collectively succeeded");
    }

    /* Collective read */
    ret = H5Dread(dataseti, H5T_NATIVE_INT, mspaceid, fspaceid1, dxfer_plist, matrix_out);
    VRFY((ret >= 0), "H5D collecive read succeed");

    ret = H5Pclose(dxfer_plist);
    VRFY((ret >= 0), "");

    /* Independent read */
    ret = H5Dread(dataseti, H5T_NATIVE_INT, mspaceid, fspaceid1, H5P_DEFAULT, matrix_out1);
    VRFY((ret >= 0), "H5D independent read succeed");

    ret = 0;
    for (i = 0; i < MSPACE_DIM1 * MSPACE_DIM2 * mpi_size; i++) {
        if (matrix_out[i] != matrix_out1[i])
            ret = -1;
        if (ret < 0)
            break;
    }
    VRFY((ret >= 0), "H5D contiguous irregular collective read succeed");

    /*
     * Free read buffers.
     */
    free(matrix_out);
    free(matrix_out1);

    /*
     * Close memory file and memory dataspaces.
     */
    ret = H5Sclose(mspaceid);
    VRFY((ret >= 0), "");
    ret = H5Sclose(fspaceid1);
    VRFY((ret >= 0), "");

    /*
     * Close dataset.
     */
    ret = H5Dclose(dataseti);
    VRFY((ret >= 0), "");

    /*
     * Close property list
     */
    ret = H5Pclose(facc_plist);
    VRFY((ret >= 0), "");

    /*
     * Close the file.
     */
    ret = H5Fclose(file);
    VRFY((ret >= 0), "");

    return;
}

/****************************************************************
**
**  lower_dim_size_comp_test__select_checker_board():
**
**    Given a dataspace of tgt_rank, and dimensions:
**
**        (mpi_size + 1), edge_size, ... , edge_size
**
**    edge_size, and a checker_edge_size, select a checker
**    board selection of a sel_rank (sel_rank < tgt_rank)
**    dimensional slice through the dataspace parallel to the
**      sel_rank fastest changing indices, with origin (in the
**    higher indices) as indicated by the start array.
**
**    Note that this function is hard-coded to presume a
**    maximum dataspace rank of 5.
**
**    While this maximum is declared as a constant, increasing
**    it will require extensive coding in addition to changing
**      the value of the constant.
**
**                    JRM -- 11/11/09
**
****************************************************************/

#define LDSCT_DS_RANK 5
#if LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG
#define LOWER_DIM_SIZE_COMP_TEST_DEBUG_TARGET_RANK 0
#endif

#define LOWER_DIM_SIZE_COMP_TEST__SELECT_CHECKER_BOARD__DEBUG 0

static void
lower_dim_size_comp_test__select_checker_board(const int mpi_rank, const hid_t tgt_sid, const int tgt_rank,
                                               const hsize_t dims[LDSCT_DS_RANK], const int checker_edge_size,
                                               const int sel_rank, hsize_t sel_start[])
{
#if LOWER_DIM_SIZE_COMP_TEST__SELECT_CHECKER_BOARD__DEBUG
    const char *fcnName = "lower_dim_size_comp_test__select_checker_board():";
#endif
    bool      first_selection = true;
    int       i, j, k, l, m;
    int       ds_offset;
    int       sel_offset;
    const int test_max_rank = LDSCT_DS_RANK; /* must update code if */
                                             /* this changes        */
    hsize_t base_count;
    hsize_t offset_count;
    hsize_t start[LDSCT_DS_RANK];
    hsize_t stride[LDSCT_DS_RANK];
    hsize_t count[LDSCT_DS_RANK];
    hsize_t block[LDSCT_DS_RANK];
    herr_t  ret; /* Generic return value */

#if LOWER_DIM_SIZE_COMP_TEST__SELECT_CHECKER_BOARD__DEBUG
    if (mpi_rank == LOWER_DIM_SIZE_COMP_TEST_DEBUG_TARGET_RANK) {
        fprintf(stdout, "%s:%d: dims/checker_edge_size = %d %d %d %d %d / %d\n", fcnName, mpi_rank,
                (int)dims[0], (int)dims[1], (int)dims[2], (int)dims[3], (int)dims[4], checker_edge_size);
    }
#endif /* LOWER_DIM_SIZE_COMP_TEST__SELECT_CHECKER_BOARD__DEBUG */

    assert(0 < checker_edge_size);
    assert(0 < sel_rank);
    assert(sel_rank <= tgt_rank);
    assert(tgt_rank <= test_max_rank);
    assert(test_max_rank <= LDSCT_DS_RANK);

    sel_offset = test_max_rank - sel_rank;
    assert(sel_offset >= 0);

    ds_offset = test_max_rank - tgt_rank;
    assert(ds_offset >= 0);
    assert(ds_offset <= sel_offset);

    assert((hsize_t)checker_edge_size <= dims[sel_offset]);
    assert(dims[sel_offset] == 10);

#if LOWER_DIM_SIZE_COMP_TEST__SELECT_CHECKER_BOARD__DEBUG
    if (mpi_rank == LOWER_DIM_SIZE_COMP_TEST_DEBUG_TARGET_RANK) {
        fprintf(stdout, "%s:%d: sel_rank/sel_offset = %d/%d.\n", fcnName, mpi_rank, sel_rank, sel_offset);
        fprintf(stdout, "%s:%d: tgt_rank/ds_offset = %d/%d.\n", fcnName, mpi_rank, tgt_rank, ds_offset);
    }
#endif /* LOWER_DIM_SIZE_COMP_TEST__SELECT_CHECKER_BOARD__DEBUG */

    /* First, compute the base count (which assumes start == 0
     * for the associated offset) and offset_count (which
     * assumes start == checker_edge_size for the associated
     * offset).
     *
     * Note that the following computation depends on the C99
     * requirement that integer division discard any fraction
     * (truncation towards zero) to function correctly. As we
     * now require C99, this shouldn't be a problem, but note
     * it may save us some pain if we are ever obliged to support
     * pre-C99 compilers again.
     */

    base_count = dims[sel_offset] / (hsize_t)(checker_edge_size * 2);

    if ((dims[sel_rank] % (hsize_t)(checker_edge_size * 2)) > 0) {

        base_count++;
    }

    offset_count =
        (hsize_t)((dims[sel_offset] - (hsize_t)checker_edge_size) / ((hsize_t)(checker_edge_size * 2)));

    if (((dims[sel_rank] - (hsize_t)checker_edge_size) % ((hsize_t)(checker_edge_size * 2))) > 0) {

        offset_count++;
    }

#if LOWER_DIM_SIZE_COMP_TEST__SELECT_CHECKER_BOARD__DEBUG
    if (mpi_rank == LOWER_DIM_SIZE_COMP_TEST_DEBUG_TARGET_RANK) {
        fprintf(stdout, "%s:%d: base_count/offset_count = %d/%d.\n", fcnName, mpi_rank, base_count,
                offset_count);
    }
#endif /* LOWER_DIM_SIZE_COMP_TEST__SELECT_CHECKER_BOARD__DEBUG */

    /* Now set up the stride and block arrays, and portions of the start
     * and count arrays that will not be altered during the selection of
     * the checkerboard.
     */
    i = 0;
    while (i < ds_offset) {

        /* these values should never be used */
        start[i]  = 0;
        stride[i] = 0;
        count[i]  = 0;
        block[i]  = 0;

        i++;
    }

    while (i < sel_offset) {

        start[i]  = sel_start[i];
        stride[i] = 2 * dims[i];
        count[i]  = 1;
        block[i]  = 1;

        i++;
    }

    while (i < test_max_rank) {

        stride[i] = (hsize_t)(2 * checker_edge_size);
        block[i]  = (hsize_t)checker_edge_size;

        i++;
    }

    i = 0;
    do {
        if (0 >= sel_offset) {

            if (i == 0) {

                start[0] = 0;
                count[0] = base_count;
            }
            else {

                start[0] = (hsize_t)checker_edge_size;
                count[0] = offset_count;
            }
        }

        j = 0;
        do {
            if (1 >= sel_offset) {

                if (j == 0) {

                    start[1] = 0;
                    count[1] = base_count;
                }
                else {

                    start[1] = (hsize_t)checker_edge_size;
                    count[1] = offset_count;
                }
            }

            k = 0;
            do {
                if (2 >= sel_offset) {

                    if (k == 0) {

                        start[2] = 0;
                        count[2] = base_count;
                    }
                    else {

                        start[2] = (hsize_t)checker_edge_size;
                        count[2] = offset_count;
                    }
                }

                l = 0;
                do {
                    if (3 >= sel_offset) {

                        if (l == 0) {

                            start[3] = 0;
                            count[3] = base_count;
                        }
                        else {

                            start[3] = (hsize_t)checker_edge_size;
                            count[3] = offset_count;
                        }
                    }

                    m = 0;
                    do {
                        if (4 >= sel_offset) {

                            if (m == 0) {

                                start[4] = 0;
                                count[4] = base_count;
                            }
                            else {

                                start[4] = (hsize_t)checker_edge_size;
                                count[4] = offset_count;
                            }
                        }

                        if (((i + j + k + l + m) % 2) == 0) {

#if LOWER_DIM_SIZE_COMP_TEST__SELECT_CHECKER_BOARD__DEBUG
                            if (mpi_rank == LOWER_DIM_SIZE_COMP_TEST_DEBUG_TARGET_RANK) {

                                fprintf(stdout, "%s%d: *** first_selection = %d ***\n", fcnName, mpi_rank,
                                        (int)first_selection);
                                fprintf(stdout, "%s:%d: i/j/k/l/m = %d/%d/%d/%d/%d\n", fcnName, mpi_rank, i,
                                        j, k, l, m);
                                fprintf(stdout, "%s:%d: start = %d %d %d %d %d.\n", fcnName, mpi_rank,
                                        (int)start[0], (int)start[1], (int)start[2], (int)start[3],
                                        (int)start[4]);
                                fprintf(stdout, "%s:%d: stride = %d %d %d %d %d.\n", fcnName, mpi_rank,
                                        (int)stride[0], (int)stride[1], (int)stride[2], (int)stride[3],
                                        (int)stride[4]);
                                fprintf(stdout, "%s:%d: count = %d %d %d %d %d.\n", fcnName, mpi_rank,
                                        (int)count[0], (int)count[1], (int)count[2], (int)count[3],
                                        (int)count[4]);
                                fprintf(stdout, "%s:%d: block = %d %d %d %d %d.\n", fcnName, mpi_rank,
                                        (int)block[0], (int)block[1], (int)block[2], (int)block[3],
                                        (int)block[4]);
                                fprintf(stdout, "%s:%d: n-cube extent dims = %d.\n", fcnName, mpi_rank,
                                        H5Sget_simple_extent_ndims(tgt_sid));
                                fprintf(stdout, "%s:%d: selection rank = %d.\n", fcnName, mpi_rank, sel_rank);
                            }
#endif

                            if (first_selection) {

                                first_selection = false;

                                ret = H5Sselect_hyperslab(tgt_sid, H5S_SELECT_SET, &(start[ds_offset]),
                                                          &(stride[ds_offset]), &(count[ds_offset]),
                                                          &(block[ds_offset]));

                                VRFY((ret != FAIL), "H5Sselect_hyperslab(SET) succeeded");
                            }
                            else {

                                ret = H5Sselect_hyperslab(tgt_sid, H5S_SELECT_OR, &(start[ds_offset]),
                                                          &(stride[ds_offset]), &(count[ds_offset]),
                                                          &(block[ds_offset]));

                                VRFY((ret != FAIL), "H5Sselect_hyperslab(OR) succeeded");
                            }
                        }

                        m++;

                    } while ((m <= 1) && (4 >= sel_offset));

                    l++;

                } while ((l <= 1) && (3 >= sel_offset));

                k++;

            } while ((k <= 1) && (2 >= sel_offset));

            j++;

        } while ((j <= 1) && (1 >= sel_offset));

        i++;

    } while ((i <= 1) && (0 >= sel_offset));

#if LOWER_DIM_SIZE_COMP_TEST__SELECT_CHECKER_BOARD__DEBUG
    if (mpi_rank == LOWER_DIM_SIZE_COMP_TEST_DEBUG_TARGET_RANK) {
        fprintf(stdout, "%s%d: H5Sget_select_npoints(tgt_sid) = %d.\n", fcnName, mpi_rank,
                (int)H5Sget_select_npoints(tgt_sid));
    }
#endif /* LOWER_DIM_SIZE_COMP_TEST__SELECT_CHECKER_BOARD__DEBUG */

    /* Clip the selection back to the dataspace proper. */

    for (i = 0; i < test_max_rank; i++) {

        start[i]  = 0;
        stride[i] = dims[i];
        count[i]  = 1;
        block[i]  = dims[i];
    }

    ret = H5Sselect_hyperslab(tgt_sid, H5S_SELECT_AND, start, stride, count, block);

    VRFY((ret != FAIL), "H5Sselect_hyperslab(AND) succeeded");

#if LOWER_DIM_SIZE_COMP_TEST__SELECT_CHECKER_BOARD__DEBUG
    if (mpi_rank == LOWER_DIM_SIZE_COMP_TEST_DEBUG_TARGET_RANK) {
        fprintf(stdout, "%s%d: H5Sget_select_npoints(tgt_sid) = %d.\n", fcnName, mpi_rank,
                (int)H5Sget_select_npoints(tgt_sid));
        fprintf(stdout, "%s%d: done.\n", fcnName, mpi_rank);
    }
#endif /* LOWER_DIM_SIZE_COMP_TEST__SELECT_CHECKER_BOARD__DEBUG */

    return;

} /* lower_dim_size_comp_test__select_checker_board() */

/****************************************************************
**
**  lower_dim_size_comp_test__verify_data():
**
**    Examine the supplied buffer to see if it contains the
**    expected data.  Return true if it does, and false
**      otherwise.
**
**    The supplied buffer is presumed to be this process's slice
**    of the target data set.  Each such slice will be an
**    n-cube of rank (rank -1) and the supplied edge_size with
**    origin (mpi_rank, 0, ... , 0) in the target data set.
**
**    Further, the buffer is presumed to be the result of reading
**    or writing a checkerboard selection of an m (1 <= m <
**      rank) dimensional slice through this processes slice
**    of the target data set.  Also, this slice must be parallel
**    to the fastest changing indices.
**
**    It is further presumed that the buffer was zeroed before
**    the read/write, and that the full target data set (i.e.
**    the buffer/data set for all processes) was initialized
**      with the natural numbers listed in order from the origin
**    along the fastest changing axis.
**
**      Thus for a 20x10x10 dataset, the value stored in location
**    (x, y, z) (assuming that z is the fastest changing index
**    and x the slowest) is assumed to be:
**
**        (10 * 10 * x) + (10 * y) + z
**
**    Further, supposing that this is process 10, this process's
**    slice of the dataset would be a 10 x 10 2-cube with origin
**    (10, 0, 0) in the data set, and would be initialized (prior
**    to the checkerboard selection) as follows:
**
**        1000, 1001, 1002, ... 1008, 1009
**        1010, 1011, 1012, ... 1018, 1019
**          .     .     .         .     .
**          .     .     .         .     .
**          .     .     .         .     .
**        1090, 1091, 1092, ... 1098, 1099
**
**    In the case of a read from the processors slice of another
**    data set of different rank, the values expected will have
**    to be adjusted accordingly.  This is done via the
**    first_expected_val parameter.
**
**    Finally, the function presumes that the first element
**    of the buffer resides either at the origin of either
**    a selected or an unselected checker.  (Translation:
**    if partial checkers appear in the buffer, they will
**    intersect the edges of the n-cube opposite the origin.)
**
****************************************************************/

#define LOWER_DIM_SIZE_COMP_TEST__VERIFY_DATA__DEBUG 0

static bool
lower_dim_size_comp_test__verify_data(uint32_t *buf_ptr,
#if LOWER_DIM_SIZE_COMP_TEST__VERIFY_DATA__DEBUG
                                      const int mpi_rank,
#endif /* LOWER_DIM_SIZE_COMP_TEST__VERIFY_DATA__DEBUG */
                                      const int rank, const int edge_size, const int checker_edge_size,
                                      uint32_t first_expected_val, bool buf_starts_in_checker)
{
#if LOWER_DIM_SIZE_COMP_TEST__VERIFY_DATA__DEBUG
    const char *fcnName = "lower_dim_size_comp_test__verify_data():";
#endif
    bool      good_data = true;
    bool      in_checker;
    bool      start_in_checker[5];
    uint32_t  expected_value;
    uint32_t *val_ptr;
    int       i, j, k, l, m;     /* to track position in n-cube */
    int       v, w, x, y, z;     /* to track position in checker */
    const int test_max_rank = 5; /* code changes needed if this is increased */

    assert(buf_ptr != NULL);
    assert(0 < rank);
    assert(rank <= test_max_rank);
    assert(edge_size >= 6);
    assert(0 < checker_edge_size);
    assert(checker_edge_size <= edge_size);
    assert(test_max_rank <= LDSCT_DS_RANK);

#if LOWER_DIM_SIZE_COMP_TEST__VERIFY_DATA__DEBUG
    if (mpi_rank == LOWER_DIM_SIZE_COMP_TEST_DEBUG_TARGET_RANK) {
        fprintf(stdout, "%s mpi_rank = %d.\n", fcnName, mpi_rank);
        fprintf(stdout, "%s rank = %d.\n", fcnName, rank);
        fprintf(stdout, "%s edge_size = %d.\n", fcnName, edge_size);
        fprintf(stdout, "%s checker_edge_size = %d.\n", fcnName, checker_edge_size);
        fprintf(stdout, "%s first_expected_val = %d.\n", fcnName, (int)first_expected_val);
        fprintf(stdout, "%s starts_in_checker = %d.\n", fcnName, (int)buf_starts_in_checker);
    }
#endif

    val_ptr        = buf_ptr;
    expected_value = first_expected_val;

    i                   = 0;
    v                   = 0;
    start_in_checker[0] = buf_starts_in_checker;
    do {
        if (v >= checker_edge_size) {

            start_in_checker[0] = !start_in_checker[0];
            v                   = 0;
        }

        j                   = 0;
        w                   = 0;
        start_in_checker[1] = start_in_checker[0];
        do {
            if (w >= checker_edge_size) {

                start_in_checker[1] = !start_in_checker[1];
                w                   = 0;
            }

            k                   = 0;
            x                   = 0;
            start_in_checker[2] = start_in_checker[1];
            do {
                if (x >= checker_edge_size) {

                    start_in_checker[2] = !start_in_checker[2];
                    x                   = 0;
                }

                l                   = 0;
                y                   = 0;
                start_in_checker[3] = start_in_checker[2];
                do {
                    if (y >= checker_edge_size) {

                        start_in_checker[3] = !start_in_checker[3];
                        y                   = 0;
                    }

                    m = 0;
                    z = 0;
#if LOWER_DIM_SIZE_COMP_TEST__VERIFY_DATA__DEBUG
                    if (mpi_rank == LOWER_DIM_SIZE_COMP_TEST_DEBUG_TARGET_RANK) {
                        fprintf(stdout, "%d, %d, %d, %d, %d:", i, j, k, l, m);
                    }
#endif
                    in_checker = start_in_checker[3];
                    do {
#if LOWER_DIM_SIZE_COMP_TEST__VERIFY_DATA__DEBUG
                        if (mpi_rank == LOWER_DIM_SIZE_COMP_TEST_DEBUG_TARGET_RANK) {
                            fprintf(stdout, " %d", (int)(*val_ptr));
                        }
#endif
                        if (z >= checker_edge_size) {

                            in_checker = !in_checker;
                            z          = 0;
                        }

                        if (in_checker) {

                            if (*val_ptr != expected_value) {

                                good_data = false;
                            }

                            /* zero out buffer for reuse */
                            *val_ptr = 0;
                        }
                        else if (*val_ptr != 0) {

                            good_data = false;

                            /* zero out buffer for reuse */
                            *val_ptr = 0;
                        }

                        val_ptr++;
                        expected_value++;
                        m++;
                        z++;

                    } while ((rank >= (test_max_rank - 4)) && (m < edge_size));
#if LOWER_DIM_SIZE_COMP_TEST__VERIFY_DATA__DEBUG
                    if (mpi_rank == LOWER_DIM_SIZE_COMP_TEST_DEBUG_TARGET_RANK) {
                        fprintf(stdout, "\n");
                    }
#endif
                    l++;
                    y++;
                } while ((rank >= (test_max_rank - 3)) && (l < edge_size));
                k++;
                x++;
            } while ((rank >= (test_max_rank - 2)) && (k < edge_size));
            j++;
            w++;
        } while ((rank >= (test_max_rank - 1)) && (j < edge_size));
        i++;
        v++;
    } while ((rank >= test_max_rank) && (i < edge_size));

    return (good_data);

} /* lower_dim_size_comp_test__verify_data() */

/*-------------------------------------------------------------------------
 * Function:    lower_dim_size_comp_test__run_test()
 *
 * Purpose:    Verify that a bug in the computation of the size of the
 *        lower dimensions of a dataspace in H5S_obtain_datatype()
 *        has been corrected.
 *
 * Return:    void
 *
 *-------------------------------------------------------------------------
 */

#define LDSCT_DS_RANK 5

static void
lower_dim_size_comp_test__run_test(const int chunk_edge_size, const bool use_collective_io,
                                   const hid_t dset_type)
{
#if LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG
    const char *fcnName = "lower_dim_size_comp_test__run_test()";
    int         rank;
    hsize_t     dims[32];
    hsize_t     max_dims[32];
#endif /* LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG */
    const char *filename;
    bool        data_ok   = false;
    bool        mis_match = false;
    int         i;
    int         start_index;
    int         stop_index;
    int         mrc;
    int         mpi_rank;
    int         mpi_size;
    MPI_Comm    mpi_comm = MPI_COMM_NULL;
    MPI_Info    mpi_info = MPI_INFO_NULL;
    hid_t       fid;     /* HDF5 file ID */
    hid_t       acc_tpl; /* File access templates */
    hid_t       xfer_plist = H5P_DEFAULT;
    size_t      small_ds_size;
    size_t      small_ds_slice_size;
    size_t      large_ds_size;
#if LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG
    size_t large_ds_slice_size;
#endif
    uint32_t  expected_value;
    uint32_t *small_ds_buf_0 = NULL;
    uint32_t *small_ds_buf_1 = NULL;
    uint32_t *large_ds_buf_0 = NULL;
    uint32_t *large_ds_buf_1 = NULL;
    uint32_t *ptr_0;
    uint32_t *ptr_1;
    hsize_t   small_chunk_dims[LDSCT_DS_RANK];
    hsize_t   large_chunk_dims[LDSCT_DS_RANK];
    hsize_t   small_dims[LDSCT_DS_RANK];
    hsize_t   large_dims[LDSCT_DS_RANK];
    hsize_t   start[LDSCT_DS_RANK];
    hsize_t   stride[LDSCT_DS_RANK];
    hsize_t   count[LDSCT_DS_RANK];
    hsize_t   block[LDSCT_DS_RANK];
    hsize_t   small_sel_start[LDSCT_DS_RANK];
    hsize_t   large_sel_start[LDSCT_DS_RANK];
    hid_t     full_mem_small_ds_sid;
    hid_t     full_file_small_ds_sid;
    hid_t     mem_small_ds_sid;
    hid_t     file_small_ds_sid;
    hid_t     full_mem_large_ds_sid;
    hid_t     full_file_large_ds_sid;
    hid_t     mem_large_ds_sid;
    hid_t     file_large_ds_sid;
    hid_t     small_ds_dcpl_id = H5P_DEFAULT;
    hid_t     large_ds_dcpl_id = H5P_DEFAULT;
    hid_t     small_dataset; /* Dataset ID                   */
    hid_t     large_dataset; /* Dataset ID                   */
    htri_t    check;         /* Shape comparison return value */
    herr_t    ret;           /* Generic return value */

    MPI_Comm_size(MPI_COMM_WORLD, &mpi_size);
    MPI_Comm_rank(MPI_COMM_WORLD, &mpi_rank);

    assert(mpi_size >= 1);

    mpi_comm = MPI_COMM_WORLD;
    mpi_info = MPI_INFO_NULL;

#if LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG
    if (mpi_rank == LOWER_DIM_SIZE_COMP_TEST_DEBUG_TARGET_RANK) {
        fprintf(stdout, "%s:%d: chunk_edge_size = %d.\n", fcnName, mpi_rank, (int)chunk_edge_size);
        fprintf(stdout, "%s:%d: use_collective_io = %d.\n", fcnName, mpi_rank, (int)use_collective_io);
    }
#endif /* LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG */

    small_ds_size       = (size_t)((mpi_size + 1) * 1 * 1 * 10 * 10);
    small_ds_slice_size = (size_t)(1 * 1 * 10 * 10);
    large_ds_size       = (size_t)((mpi_size + 1) * 10 * 10 * 10 * 10);

#if LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG
    large_ds_slice_size = (size_t)(10 * 10 * 10 * 10);

    if (mpi_rank == LOWER_DIM_SIZE_COMP_TEST_DEBUG_TARGET_RANK) {
        fprintf(stdout, "%s:%d: small ds size / slice size = %d / %d.\n", fcnName, mpi_rank,
                (int)small_ds_size, (int)small_ds_slice_size);
        fprintf(stdout, "%s:%d: large ds size / slice size = %d / %d.\n", fcnName, mpi_rank,
                (int)large_ds_size, (int)large_ds_slice_size);
    }
#endif /* LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG */

    /* Allocate buffers */
    small_ds_buf_0 = (uint32_t *)malloc(sizeof(uint32_t) * small_ds_size);
    VRFY((small_ds_buf_0 != NULL), "malloc of small_ds_buf_0 succeeded");

    small_ds_buf_1 = (uint32_t *)malloc(sizeof(uint32_t) * small_ds_size);
    VRFY((small_ds_buf_1 != NULL), "malloc of small_ds_buf_1 succeeded");

    large_ds_buf_0 = (uint32_t *)malloc(sizeof(uint32_t) * large_ds_size);
    VRFY((large_ds_buf_0 != NULL), "malloc of large_ds_buf_0 succeeded");

    large_ds_buf_1 = (uint32_t *)malloc(sizeof(uint32_t) * large_ds_size);
    VRFY((large_ds_buf_1 != NULL), "malloc of large_ds_buf_1 succeeded");

    /* initialize the buffers */

    ptr_0 = small_ds_buf_0;
    ptr_1 = small_ds_buf_1;

    for (i = 0; i < (int)small_ds_size; i++) {

        *ptr_0 = (uint32_t)i;
        *ptr_1 = 0;

        ptr_0++;
        ptr_1++;
    }

    ptr_0 = large_ds_buf_0;
    ptr_1 = large_ds_buf_1;

    for (i = 0; i < (int)large_ds_size; i++) {

        *ptr_0 = (uint32_t)i;
        *ptr_1 = 0;

        ptr_0++;
        ptr_1++;
    }

    /* get the file name */

    filename = (const char *)GetTestParameters();
    assert(filename != NULL);

    /* ----------------------------------------
     * CREATE AN HDF5 FILE WITH PARALLEL ACCESS
     * ---------------------------------------*/
    /* setup file access template */
    acc_tpl = create_faccess_plist(mpi_comm, mpi_info, facc_type);
    VRFY((acc_tpl >= 0), "create_faccess_plist() succeeded");

    /* create the file collectively */
    fid = H5Fcreate(filename, H5F_ACC_TRUNC, H5P_DEFAULT, acc_tpl);
    VRFY((fid >= 0), "H5Fcreate succeeded");

    MESG("File opened.");

    /* Release file-access template */
    ret = H5Pclose(acc_tpl);
    VRFY((ret >= 0), "H5Pclose(acc_tpl) succeeded");

    /* setup dims: */
    small_dims[0] = (hsize_t)(mpi_size + 1);
    small_dims[1] = 1;
    small_dims[2] = 1;
    small_dims[3] = 10;
    small_dims[4] = 10;

    large_dims[0] = (hsize_t)(mpi_size + 1);
    large_dims[1] = 10;
    large_dims[2] = 10;
    large_dims[3] = 10;
    large_dims[4] = 10;

#if LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG
    if (mpi_rank == LOWER_DIM_SIZE_COMP_TEST_DEBUG_TARGET_RANK) {
        fprintf(stdout, "%s:%d: small_dims[] = %d %d %d %d %d\n", fcnName, mpi_rank, (int)small_dims[0],
                (int)small_dims[1], (int)small_dims[2], (int)small_dims[3], (int)small_dims[4]);
        fprintf(stdout, "%s:%d: large_dims[] = %d %d %d %d %d\n", fcnName, mpi_rank, (int)large_dims[0],
                (int)large_dims[1], (int)large_dims[2], (int)large_dims[3], (int)large_dims[4]);
    }
#endif

    /* create dataspaces */

    full_mem_small_ds_sid = H5Screate_simple(5, small_dims, NULL);
    VRFY((full_mem_small_ds_sid != 0), "H5Screate_simple() full_mem_small_ds_sid succeeded");

    full_file_small_ds_sid = H5Screate_simple(5, small_dims, NULL);
    VRFY((full_file_small_ds_sid != 0), "H5Screate_simple() full_file_small_ds_sid succeeded");

    mem_small_ds_sid = H5Screate_simple(5, small_dims, NULL);
    VRFY((mem_small_ds_sid != 0), "H5Screate_simple() mem_small_ds_sid succeeded");

    file_small_ds_sid = H5Screate_simple(5, small_dims, NULL);
    VRFY((file_small_ds_sid != 0), "H5Screate_simple() file_small_ds_sid succeeded");

    full_mem_large_ds_sid = H5Screate_simple(5, large_dims, NULL);
    VRFY((full_mem_large_ds_sid != 0), "H5Screate_simple() full_mem_large_ds_sid succeeded");

    full_file_large_ds_sid = H5Screate_simple(5, large_dims, NULL);
    VRFY((full_file_large_ds_sid != 0), "H5Screate_simple() full_file_large_ds_sid succeeded");

    mem_large_ds_sid = H5Screate_simple(5, large_dims, NULL);
    VRFY((mem_large_ds_sid != 0), "H5Screate_simple() mem_large_ds_sid succeeded");

    file_large_ds_sid = H5Screate_simple(5, large_dims, NULL);
    VRFY((file_large_ds_sid != 0), "H5Screate_simple() file_large_ds_sid succeeded");

    /* Select the entire extent of the full small ds dataspaces */
    ret = H5Sselect_all(full_mem_small_ds_sid);
    VRFY((ret != FAIL), "H5Sselect_all(full_mem_small_ds_sid) succeeded");

    ret = H5Sselect_all(full_file_small_ds_sid);
    VRFY((ret != FAIL), "H5Sselect_all(full_file_small_ds_sid) succeeded");

    /* Select the entire extent of the full large ds dataspaces */
    ret = H5Sselect_all(full_mem_large_ds_sid);
    VRFY((ret != FAIL), "H5Sselect_all(full_mem_large_ds_sid) succeeded");

    ret = H5Sselect_all(full_file_large_ds_sid);
    VRFY((ret != FAIL), "H5Sselect_all(full_file_large_ds_sid) succeeded");

    /* if chunk edge size is greater than zero, set up the small and
     * large data set creation property lists to specify chunked
     * datasets.
     */
    if (chunk_edge_size > 0) {

        small_chunk_dims[0] = (hsize_t)(1);
        small_chunk_dims[1] = small_chunk_dims[2] = (hsize_t)1;
        small_chunk_dims[3] = small_chunk_dims[4] = (hsize_t)chunk_edge_size;

#if LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG
        if (mpi_rank == LOWER_DIM_SIZE_COMP_TEST_DEBUG_TARGET_RANK) {
            fprintf(stdout, "%s:%d: small chunk dims[] = %d %d %d %d %d\n", fcnName, mpi_rank,
                    (int)small_chunk_dims[0], (int)small_chunk_dims[1], (int)small_chunk_dims[2],
                    (int)small_chunk_dims[3], (int)small_chunk_dims[4]);
        }
#endif

        small_ds_dcpl_id = H5Pcreate(H5P_DATASET_CREATE);
        VRFY((ret != FAIL), "H5Pcreate() small_ds_dcpl_id succeeded");

        ret = H5Pset_layout(small_ds_dcpl_id, H5D_CHUNKED);
        VRFY((ret != FAIL), "H5Pset_layout() small_ds_dcpl_id succeeded");

        ret = H5Pset_chunk(small_ds_dcpl_id, 5, small_chunk_dims);
        VRFY((ret != FAIL), "H5Pset_chunk() small_ds_dcpl_id succeeded");

        large_chunk_dims[0] = (hsize_t)(1);
        large_chunk_dims[1] = large_chunk_dims[2] = large_chunk_dims[3] = large_chunk_dims[4] =
            (hsize_t)chunk_edge_size;

#if LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG
        if (mpi_rank == LOWER_DIM_SIZE_COMP_TEST_DEBUG_TARGET_RANK) {
            fprintf(stdout, "%s:%d: large chunk dims[] = %d %d %d %d %d\n", fcnName, mpi_rank,
                    (int)large_chunk_dims[0], (int)large_chunk_dims[1], (int)large_chunk_dims[2],
                    (int)large_chunk_dims[3], (int)large_chunk_dims[4]);
        }
#endif

        large_ds_dcpl_id = H5Pcreate(H5P_DATASET_CREATE);
        VRFY((ret != FAIL), "H5Pcreate() large_ds_dcpl_id succeeded");

        ret = H5Pset_layout(large_ds_dcpl_id, H5D_CHUNKED);
        VRFY((ret != FAIL), "H5Pset_layout() large_ds_dcpl_id succeeded");

        ret = H5Pset_chunk(large_ds_dcpl_id, 5, large_chunk_dims);
        VRFY((ret != FAIL), "H5Pset_chunk() large_ds_dcpl_id succeeded");
    }

    /* create the small dataset */
    small_dataset = H5Dcreate2(fid, "small_dataset", dset_type, file_small_ds_sid, H5P_DEFAULT,
                               small_ds_dcpl_id, H5P_DEFAULT);
    VRFY((ret >= 0), "H5Dcreate2() small_dataset succeeded");

    /* create the large dataset */
    large_dataset = H5Dcreate2(fid, "large_dataset", dset_type, file_large_ds_sid, H5P_DEFAULT,
                               large_ds_dcpl_id, H5P_DEFAULT);
    VRFY((ret >= 0), "H5Dcreate2() large_dataset succeeded");

#if LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG
    if (mpi_rank == LOWER_DIM_SIZE_COMP_TEST_DEBUG_TARGET_RANK) {
        fprintf(stdout, "%s:%d: small/large ds id = %d / %d.\n", fcnName, mpi_rank, (int)small_dataset,
                (int)large_dataset);
    }
#endif /* LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG */

    /* setup xfer property list */
    xfer_plist = H5Pcreate(H5P_DATASET_XFER);
    VRFY((xfer_plist >= 0), "H5Pcreate(H5P_DATASET_XFER) succeeded");

    ret = H5Pset_dxpl_mpio(xfer_plist, H5FD_MPIO_COLLECTIVE);
    VRFY((ret >= 0), "H5Pset_dxpl_mpio succeeded");

    if (!use_collective_io) {

        ret = H5Pset_dxpl_mpio_collective_opt(xfer_plist, H5FD_MPIO_INDIVIDUAL_IO);
        VRFY((ret >= 0), "H5Pset_dxpl_mpio_collective_opt() succeeded");
    }

    /* setup selection to write initial data to the small data sets */
    start[0] = (hsize_t)(mpi_rank + 1);
    start[1] = start[2] = start[3] = start[4] = 0;

    stride[0] = (hsize_t)(2 * (mpi_size + 1));
    stride[1] = stride[2] = 2;
    stride[3] = stride[4] = 2 * 10;

    count[0] = count[1] = count[2] = count[3] = count[4] = 1;

    block[0] = block[1] = block[2] = 1;
    block[3] = block[4] = 10;

#if LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG
    if (mpi_rank == LOWER_DIM_SIZE_COMP_TEST_DEBUG_TARGET_RANK) {
        fprintf(stdout, "%s:%d: settings for small data set initialization.\n", fcnName, mpi_rank);
        fprintf(stdout, "%s:%d: start[]  = %d %d %d %d %d\n", fcnName, mpi_rank, (int)start[0], (int)start[1],
                (int)start[2], (int)start[3], (int)start[4]);
        fprintf(stdout, "%s:%d: stride[] = %d %d %d %d %d\n", fcnName, mpi_rank, (int)stride[0],
                (int)stride[1], (int)stride[2], (int)stride[3], (int)stride[4]);
        fprintf(stdout, "%s:%d: count[]  = %d %d %d %d %d\n", fcnName, mpi_rank, (int)count[0], (int)count[1],
                (int)count[2], (int)count[3], (int)count[4]);
        fprintf(stdout, "%s:%d: block[]  = %d %d %d %d %d\n", fcnName, mpi_rank, (int)block[0], (int)block[1],
                (int)block[2], (int)block[3], (int)block[4]);
    }
#endif /* LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG */

    /* setup selections for writing initial data to the small data set */
    ret = H5Sselect_hyperslab(mem_small_ds_sid, H5S_SELECT_SET, start, stride, count, block);
    VRFY((ret >= 0), "H5Sselect_hyperslab(mem_small_ds_sid, set) succeeded");

    ret = H5Sselect_hyperslab(file_small_ds_sid, H5S_SELECT_SET, start, stride, count, block);
    VRFY((ret >= 0), "H5Sselect_hyperslab(file_small_ds_sid, set) succeeded");

    if (MAINPROCESS) { /* add an additional slice to the selections */

        start[0] = 0;

#if LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG
        if (mpi_rank == LOWER_DIM_SIZE_COMP_TEST_DEBUG_TARGET_RANK) {
            fprintf(stdout, "%s:%d: added settings for main process.\n", fcnName, mpi_rank);
            fprintf(stdout, "%s:%d: start[]  = %d %d %d %d %d\n", fcnName, mpi_rank, (int)start[0],
                    (int)start[1], (int)start[2], (int)start[3], (int)start[4]);
            fprintf(stdout, "%s:%d: stride[] = %d %d %d %d %d\n", fcnName, mpi_rank, (int)stride[0],
                    (int)stride[1], (int)stride[2], (int)stride[3], (int)stride[4]);
            fprintf(stdout, "%s:%d: count[]  = %d %d %d %d %d\n", fcnName, mpi_rank, (int)count[0],
                    (int)count[1], (int)count[2], (int)count[3], (int)count[4]);
            fprintf(stdout, "%s:%d: block[]  = %d %d %d %d %d\n", fcnName, mpi_rank, (int)block[0],
                    (int)block[1], (int)block[2], (int)block[3], (int)block[4]);
        }
#endif /* LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG */

        ret = H5Sselect_hyperslab(mem_small_ds_sid, H5S_SELECT_OR, start, stride, count, block);
        VRFY((ret >= 0), "H5Sselect_hyperslab(mem_small_ds_sid, or) succeeded");

        ret = H5Sselect_hyperslab(file_small_ds_sid, H5S_SELECT_OR, start, stride, count, block);
        VRFY((ret >= 0), "H5Sselect_hyperslab(file_small_ds_sid, or) succeeded");
    }

    check = H5Sselect_valid(mem_small_ds_sid);
    VRFY((check == true), "H5Sselect_valid(mem_small_ds_sid) returns true");

    check = H5Sselect_valid(file_small_ds_sid);
    VRFY((check == true), "H5Sselect_valid(file_small_ds_sid) returns true");

    /* write the initial value of the small data set to file */
#if LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG
    if (mpi_rank == LOWER_DIM_SIZE_COMP_TEST_DEBUG_TARGET_RANK) {
        fprintf(stdout, "%s:%d: writing init value of small ds to file.\n", fcnName, mpi_rank);
    }
#endif /* LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG */
    ret = H5Dwrite(small_dataset, dset_type, mem_small_ds_sid, file_small_ds_sid, xfer_plist, small_ds_buf_0);
    VRFY((ret >= 0), "H5Dwrite() small_dataset initial write succeeded");

    /* sync with the other processes before reading data */
    mrc = MPI_Barrier(MPI_COMM_WORLD);
    VRFY((mrc == MPI_SUCCESS), "Sync after small dataset writes");

    /* read the small data set back to verify that it contains the
     * expected data.  Note that each process reads in the entire
     * data set and verifies it.
     */
    ret = H5Dread(small_dataset, H5T_NATIVE_UINT32, full_mem_small_ds_sid, full_file_small_ds_sid, xfer_plist,
                  small_ds_buf_1);
    VRFY((ret >= 0), "H5Dread() small_dataset initial read succeeded");

    /* sync with the other processes before checking data */
    mrc = MPI_Barrier(MPI_COMM_WORLD);
    VRFY((mrc == MPI_SUCCESS), "Sync after small dataset writes");

    /* verify that the correct data was written to the small data set,
     * and reset the buffer to zero in passing.
     */
    expected_value = 0;
    mis_match      = false;
    ptr_1          = small_ds_buf_1;

    i = 0;
    for (i = 0; i < (int)small_ds_size; i++) {

        if (*ptr_1 != expected_value) {

            mis_match = true;
        }

        *ptr_1 = (uint32_t)0;

        ptr_1++;
        expected_value++;
    }
    VRFY((mis_match == false), "small ds init data good.");

    /* setup selections for writing initial data to the large data set */
    start[0] = (hsize_t)(mpi_rank + 1);
    start[1] = start[2] = start[3] = start[4] = (hsize_t)0;

    stride[0] = (hsize_t)(2 * (mpi_size + 1));
    stride[1] = stride[2] = stride[3] = stride[4] = (hsize_t)(2 * 10);

    count[0] = count[1] = count[2] = count[3] = count[4] = (hsize_t)1;

    block[0] = (hsize_t)1;
    block[1] = block[2] = block[3] = block[4] = (hsize_t)10;

#if LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG
    if (mpi_rank == LOWER_DIM_SIZE_COMP_TEST_DEBUG_TARGET_RANK) {
        fprintf(stdout, "%s:%d: settings for large data set initialization.\n", fcnName, mpi_rank);
        fprintf(stdout, "%s:%d: start[]  = %d %d %d %d %d\n", fcnName, mpi_rank, (int)start[0], (int)start[1],
                (int)start[2], (int)start[3], (int)start[4]);
        fprintf(stdout, "%s:%d: stride[] = %d %d %d %d %d\n", fcnName, mpi_rank, (int)stride[0],
                (int)stride[1], (int)stride[2], (int)stride[3], (int)stride[4]);
        fprintf(stdout, "%s:%d: count[]  = %d %d %d %d %d\n", fcnName, mpi_rank, (int)count[0], (int)count[1],
                (int)count[2], (int)count[3], (int)count[4]);
        fprintf(stdout, "%s:%d: block[]  = %d %d %d %d %d\n", fcnName, mpi_rank, (int)block[0], (int)block[1],
                (int)block[2], (int)block[3], (int)block[4]);
    }
#endif /* LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG */

    ret = H5Sselect_hyperslab(mem_large_ds_sid, H5S_SELECT_SET, start, stride, count, block);
    VRFY((ret >= 0), "H5Sselect_hyperslab(mem_large_ds_sid, set) succeeded");

    ret = H5Sselect_hyperslab(file_large_ds_sid, H5S_SELECT_SET, start, stride, count, block);
    VRFY((ret >= 0), "H5Sselect_hyperslab(file_large_ds_sid, set) succeeded");

#if LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG
    if (mpi_rank == LOWER_DIM_SIZE_COMP_TEST_DEBUG_TARGET_RANK) {
        fprintf(stdout, "%s%d: H5Sget_select_npoints(mem_large_ds_sid) = %d.\n", fcnName, mpi_rank,
                (int)H5Sget_select_npoints(mem_large_ds_sid));
        fprintf(stdout, "%s%d: H5Sget_select_npoints(file_large_ds_sid) = %d.\n", fcnName, mpi_rank,
                (int)H5Sget_select_npoints(file_large_ds_sid));
    }
#endif /* LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG */

    if (MAINPROCESS) { /* add an additional slice to the selections */

        start[0] = (hsize_t)0;

#if LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG
        if (mpi_rank == LOWER_DIM_SIZE_COMP_TEST_DEBUG_TARGET_RANK) {
            fprintf(stdout, "%s:%d: added settings for main process.\n", fcnName, mpi_rank);
            fprintf(stdout, "%s:%d: start[]  = %d %d %d %d %d\n", fcnName, mpi_rank, (int)start[0],
                    (int)start[1], (int)start[2], (int)start[3], (int)start[4]);
            fprintf(stdout, "%s:%d: stride[] = %d %d %d %d %d\n", fcnName, mpi_rank, (int)stride[0],
                    (int)stride[1], (int)stride[2], (int)stride[3], (int)stride[4]);
            fprintf(stdout, "%s:%d: count[]  = %d %d %d %d %d\n", fcnName, mpi_rank, (int)count[0],
                    (int)count[1], (int)count[2], (int)count[3], (int)count[4]);
            fprintf(stdout, "%s:%d: block[]  = %d %d %d %d %d\n", fcnName, mpi_rank, (int)block[0],
                    (int)block[1], (int)block[2], (int)block[3], (int)block[4]);
        }
#endif /* LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG */

        ret = H5Sselect_hyperslab(mem_large_ds_sid, H5S_SELECT_OR, start, stride, count, block);
        VRFY((ret >= 0), "H5Sselect_hyperslab(mem_large_ds_sid, or) succeeded");

        ret = H5Sselect_hyperslab(file_large_ds_sid, H5S_SELECT_OR, start, stride, count, block);
        VRFY((ret >= 0), "H5Sselect_hyperslab(file_large_ds_sid, or) succeeded");

#if LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG
        if (mpi_rank == LOWER_DIM_SIZE_COMP_TEST_DEBUG_TARGET_RANK) {
            fprintf(stdout, "%s%d: H5Sget_select_npoints(mem_large_ds_sid) = %d.\n", fcnName, mpi_rank,
                    (int)H5Sget_select_npoints(mem_large_ds_sid));
            fprintf(stdout, "%s%d: H5Sget_select_npoints(file_large_ds_sid) = %d.\n", fcnName, mpi_rank,
                    (int)H5Sget_select_npoints(file_large_ds_sid));
        }
#endif /* LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG */
    }

    /* try clipping the selection back to the large dataspace proper */
    start[0] = start[1] = start[2] = start[3] = start[4] = (hsize_t)0;

    stride[0] = (hsize_t)(2 * (mpi_size + 1));
    stride[1] = stride[2] = stride[3] = stride[4] = (hsize_t)(2 * 10);

    count[0] = count[1] = count[2] = count[3] = count[4] = (hsize_t)1;

    block[0] = (hsize_t)(mpi_size + 1);
    block[1] = block[2] = block[3] = block[4] = (hsize_t)10;

    ret = H5Sselect_hyperslab(mem_large_ds_sid, H5S_SELECT_AND, start, stride, count, block);
    VRFY((ret != FAIL), "H5Sselect_hyperslab(mem_large_ds_sid, and) succeeded");

    ret = H5Sselect_hyperslab(file_large_ds_sid, H5S_SELECT_AND, start, stride, count, block);
    VRFY((ret != FAIL), "H5Sselect_hyperslab(file_large_ds_sid, and) succeeded");

#if LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG
    if (mpi_rank == LOWER_DIM_SIZE_COMP_TEST_DEBUG_TARGET_RANK) {

        rank = H5Sget_simple_extent_dims(mem_large_ds_sid, dims, max_dims);
        fprintf(stdout, "%s:%d: mem_large_ds_sid dims[%d] = %d %d %d %d %d\n", fcnName, mpi_rank, rank,
                (int)dims[0], (int)dims[1], (int)dims[2], (int)dims[3], (int)dims[4]);

        rank = H5Sget_simple_extent_dims(file_large_ds_sid, dims, max_dims);
        fprintf(stdout, "%s:%d: file_large_ds_sid dims[%d] = %d %d %d %d %d\n", fcnName, mpi_rank, rank,
                (int)dims[0], (int)dims[1], (int)dims[2], (int)dims[3], (int)dims[4]);
    }
#endif /* LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG */

    check = H5Sselect_valid(mem_large_ds_sid);
    VRFY((check == true), "H5Sselect_valid(mem_large_ds_sid) returns true");

    check = H5Sselect_valid(file_large_ds_sid);
    VRFY((check == true), "H5Sselect_valid(file_large_ds_sid) returns true");

    /* write the initial value of the large data set to file */
#if LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG
    if (mpi_rank == LOWER_DIM_SIZE_COMP_TEST_DEBUG_TARGET_RANK) {
        fprintf(stdout, "%s:%d: writing init value of large ds to file.\n", fcnName, mpi_rank);
        fprintf(stdout, "%s:%d: large_dataset = %d.\n", fcnName, mpi_rank, (int)large_dataset);
        fprintf(stdout, "%s:%d: mem_large_ds_sid = %d, file_large_ds_sid = %d.\n", fcnName, mpi_rank,
                (int)mem_large_ds_sid, (int)file_large_ds_sid);
    }
#endif /* LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG */

    ret = H5Dwrite(large_dataset, dset_type, mem_large_ds_sid, file_large_ds_sid, xfer_plist, large_ds_buf_0);

    if (ret < 0)
        H5Eprint2(H5E_DEFAULT, stderr);
    VRFY((ret >= 0), "H5Dwrite() large_dataset initial write succeeded");

    /* sync with the other processes before checking data */
    mrc = MPI_Barrier(MPI_COMM_WORLD);
    VRFY((mrc == MPI_SUCCESS), "Sync after large dataset writes");

    /* read the large data set back to verify that it contains the
     * expected data.  Note that each process reads in the entire
     * data set.
     */
    ret = H5Dread(large_dataset, H5T_NATIVE_UINT32, full_mem_large_ds_sid, full_file_large_ds_sid, xfer_plist,
                  large_ds_buf_1);
    VRFY((ret >= 0), "H5Dread() large_dataset initial read succeeded");

    /* verify that the correct data was written to the large data set.
     * in passing, reset the buffer to zeros
     */
    expected_value = 0;
    mis_match      = false;
    ptr_1          = large_ds_buf_1;

    i = 0;
    for (i = 0; i < (int)large_ds_size; i++) {

        if (*ptr_1 != expected_value) {

            mis_match = true;
        }

        *ptr_1 = (uint32_t)0;

        ptr_1++;
        expected_value++;
    }
    VRFY((mis_match == false), "large ds init data good.");

    /***********************************/
    /***** INITIALIZATION COMPLETE *****/
    /***********************************/

    /* read a checkerboard selection of the process slice of the
     * small on disk data set into the process slice of the large
     * in memory data set, and verify the data read.
     */

    small_sel_start[0] = (hsize_t)(mpi_rank + 1);
    small_sel_start[1] = small_sel_start[2] = small_sel_start[3] = small_sel_start[4] = 0;

    lower_dim_size_comp_test__select_checker_board(mpi_rank, file_small_ds_sid,
                                                   /* tgt_rank          = */ 5, small_dims,
                                                   /* checker_edge_size = */ 3,
                                                   /* sel_rank */ 2, small_sel_start);

    expected_value =
        (uint32_t)((small_sel_start[0] * small_dims[1] * small_dims[2] * small_dims[3] * small_dims[4]) +
                   (small_sel_start[1] * small_dims[2] * small_dims[3] * small_dims[4]) +
                   (small_sel_start[2] * small_dims[3] * small_dims[4]) +
                   (small_sel_start[3] * small_dims[4]) + (small_sel_start[4]));

    large_sel_start[0] = (hsize_t)(mpi_rank + 1);
    large_sel_start[1] = 5;
    large_sel_start[2] = large_sel_start[3] = large_sel_start[4] = 0;

    lower_dim_size_comp_test__select_checker_board(mpi_rank, mem_large_ds_sid,
                                                   /* tgt_rank          = */ 5, large_dims,
                                                   /* checker_edge_size = */ 3,
                                                   /* sel_rank          = */ 2, large_sel_start);

    /* verify that H5Sselect_shape_same() reports the two
     * selections as having the same shape.
     */
    check = H5Sselect_shape_same(mem_large_ds_sid, file_small_ds_sid);
    VRFY((check == true), "H5Sselect_shape_same passed (1)");

    ret = H5Dread(small_dataset, H5T_NATIVE_UINT32, mem_large_ds_sid, file_small_ds_sid, xfer_plist,
                  large_ds_buf_1);

    VRFY((ret >= 0), "H5Sread() slice from small ds succeeded.");

#if LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG
    if (mpi_rank == LOWER_DIM_SIZE_COMP_TEST_DEBUG_TARGET_RANK) {
        fprintf(stdout, "%s:%d: H5Dread() returns.\n", fcnName, mpi_rank);
    }
#endif /* LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG */

    /* verify that expected data is retrieved */

    data_ok = true;

    start_index = (int)((large_sel_start[0] * large_dims[1] * large_dims[2] * large_dims[3] * large_dims[4]) +
                        (large_sel_start[1] * large_dims[2] * large_dims[3] * large_dims[4]) +
                        (large_sel_start[2] * large_dims[3] * large_dims[4]) +
                        (large_sel_start[3] * large_dims[4]) + (large_sel_start[4]));

    stop_index = start_index + (int)small_ds_slice_size;

    assert(0 <= start_index);
    assert(start_index < stop_index);
    assert(stop_index <= (int)large_ds_size);

    ptr_1 = large_ds_buf_1;

    for (i = 0; i < start_index; i++) {

        if (*ptr_1 != (uint32_t)0) {

            data_ok = false;
            *ptr_1  = (uint32_t)0;
        }

        ptr_1++;
    }

    VRFY((data_ok == true), "slice read from small ds data good(1).");

    data_ok = lower_dim_size_comp_test__verify_data(ptr_1,
#if LOWER_DIM_SIZE_COMP_TEST__VERIFY_DATA__DEBUG
                                                    mpi_rank,
#endif /* LOWER_DIM_SIZE_COMP_TEST__VERIFY_DATA__DEBUG */
                                                    /* rank */ 2,
                                                    /* edge_size */ 10,
                                                    /*  checker_edge_size */ 3, expected_value,
                                                    /* buf_starts_in_checker */ true);

    VRFY((data_ok == true), "slice read from small ds data good(2).");

    data_ok = true;

    ptr_1 += small_ds_slice_size;

    for (i = stop_index; i < (int)large_ds_size; i++) {

        if (*ptr_1 != (uint32_t)0) {

            data_ok = false;
            *ptr_1  = (uint32_t)0;
        }

        ptr_1++;
    }

    VRFY((data_ok == true), "slice read from small ds data good(3).");

    /* read a checkerboard selection of a slice of the process slice of
     * the large on disk data set into the process slice of the small
     * in memory data set, and verify the data read.
     */

    small_sel_start[0] = (hsize_t)(mpi_rank + 1);
    small_sel_start[1] = small_sel_start[2] = small_sel_start[3] = small_sel_start[4] = 0;

    lower_dim_size_comp_test__select_checker_board(mpi_rank, mem_small_ds_sid,
                                                   /* tgt_rank          = */ 5, small_dims,
                                                   /* checker_edge_size = */ 3,
                                                   /* sel_rank */ 2, small_sel_start);

    large_sel_start[0] = (hsize_t)(mpi_rank + 1);
    large_sel_start[1] = 5;
    large_sel_start[2] = large_sel_start[3] = large_sel_start[4] = 0;

    lower_dim_size_comp_test__select_checker_board(mpi_rank, file_large_ds_sid,
                                                   /* tgt_rank          = */ 5, large_dims,
                                                   /* checker_edge_size = */ 3,
                                                   /* sel_rank          = */ 2, large_sel_start);

    /* verify that H5Sselect_shape_same() reports the two
     * selections as having the same shape.
     */
    check = H5Sselect_shape_same(mem_small_ds_sid, file_large_ds_sid);
    VRFY((check == true), "H5Sselect_shape_same passed (2)");

    ret = H5Dread(large_dataset, H5T_NATIVE_UINT32, mem_small_ds_sid, file_large_ds_sid, xfer_plist,
                  small_ds_buf_1);

    VRFY((ret >= 0), "H5Sread() slice from large ds succeeded.");

#if LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG
    if (mpi_rank == LOWER_DIM_SIZE_COMP_TEST_DEBUG_TARGET_RANK) {
        fprintf(stdout, "%s:%d: H5Dread() returns.\n", fcnName, mpi_rank);
    }
#endif /* LOWER_DIM_SIZE_COMP_TEST__RUN_TEST__DEBUG */

    /* verify that expected data is retrieved */

    data_ok = true;

    expected_value =
        (uint32_t)((large_sel_start[0] * large_dims[1] * large_dims[2] * large_dims[3] * large_dims[4]) +
                   (large_sel_start[1] * large_dims[2] * large_dims[3] * large_dims[4]) +
                   (large_sel_start[2] * large_dims[3] * large_dims[4]) +
                   (large_sel_start[3] * large_dims[4]) + (large_sel_start[4]));

    start_index = (int)(mpi_rank + 1) * (int)small_ds_slice_size;

    stop_index = start_index + (int)small_ds_slice_size;

    assert(0 <= start_index);
    assert(start_index < stop_index);
    assert(stop_index <= (int)small_ds_size);

    ptr_1 = small_ds_buf_1;

    for (i = 0; i < start_index; i++) {

        if (*ptr_1 != (uint32_t)0) {

            data_ok = false;
            *ptr_1  = (uint32_t)0;
        }

        ptr_1++;
    }

    VRFY((data_ok == true), "slice read from large ds data good(1).");

    data_ok = lower_dim_size_comp_test__verify_data(ptr_1,
#if LOWER_DIM_SIZE_COMP_TEST__VERIFY_DATA__DEBUG
                                                    mpi_rank,
#endif /* LOWER_DIM_SIZE_COMP_TEST__VERIFY_DATA__DEBUG */
                                                    /* rank */ 2,
                                                    /* edge_size */ 10,
                                                    /*  checker_edge_size */ 3, expected_value,
                                                    /* buf_starts_in_checker */ true);

    VRFY((data_ok == true), "slice read from large ds data good(2).");

    data_ok = true;

    ptr_1 += small_ds_slice_size;

    for (i = stop_index; i < (int)small_ds_size; i++) {

        if (*ptr_1 != (uint32_t)0) {

#if LOWER_DIM_SIZE_COMP_TEST__VERIFY_DATA__DEBUG
            if (mpi_rank == LOWER_DIM_SIZE_COMP_TEST_DEBUG_TARGET_RANK) {
                fprintf(stdout, "%s:%d: unexpected value at index %d: %d.\n", fcnName, mpi_rank, (int)i,
                        (int)(*ptr_1));
            }
#endif /* LOWER_DIM_SIZE_COMP_TEST__VERIFY_DATA__DEBUG */

            data_ok = false;
            *ptr_1  = (uint32_t)0;
        }

        ptr_1++;
    }

    VRFY((data_ok == true), "slice read from large ds data good(3).");

    /* Close dataspaces */
    ret = H5Sclose(full_mem_small_ds_sid);
    VRFY((ret != FAIL), "H5Sclose(full_mem_small_ds_sid) succeeded");

    ret = H5Sclose(full_file_small_ds_sid);
    VRFY((ret != FAIL), "H5Sclose(full_file_small_ds_sid) succeeded");

    ret = H5Sclose(mem_small_ds_sid);
    VRFY((ret != FAIL), "H5Sclose(mem_small_ds_sid) succeeded");

    ret = H5Sclose(file_small_ds_sid);
    VRFY((ret != FAIL), "H5Sclose(file_small_ds_sid) succeeded");

    ret = H5Sclose(full_mem_large_ds_sid);
    VRFY((ret != FAIL), "H5Sclose(full_mem_large_ds_sid) succeeded");

    ret = H5Sclose(full_file_large_ds_sid);
    VRFY((ret != FAIL), "H5Sclose(full_file_large_ds_sid) succeeded");

    ret = H5Sclose(mem_large_ds_sid);
    VRFY((ret != FAIL), "H5Sclose(mem_large_ds_sid) succeeded");

    ret = H5Sclose(file_large_ds_sid);
    VRFY((ret != FAIL), "H5Sclose(file_large_ds_sid) succeeded");

    /* Close Datasets */
    ret = H5Dclose(small_dataset);
    VRFY((ret != FAIL), "H5Dclose(small_dataset) succeeded");

    ret = H5Dclose(large_dataset);
    VRFY((ret != FAIL), "H5Dclose(large_dataset) succeeded");

    /* close the file collectively */
    MESG("about to close file.");
    ret = H5Fclose(fid);
    VRFY((ret != FAIL), "file close succeeded");

    /* Free memory buffers */
    if (small_ds_buf_0 != NULL)
        free(small_ds_buf_0);
    if (small_ds_buf_1 != NULL)
        free(small_ds_buf_1);

    if (large_ds_buf_0 != NULL)
        free(large_ds_buf_0);
    if (large_ds_buf_1 != NULL)
        free(large_ds_buf_1);

    return;

} /* lower_dim_size_comp_test__run_test() */

/*-------------------------------------------------------------------------
 * Function:    lower_dim_size_comp_test()
 *
 * Purpose:    Test to see if an error in the computation of the size
 *        of the lower dimensions in H5S_obtain_datatype() has
 *        been corrected.
 *
 * Return:    void
 *
 *-------------------------------------------------------------------------
 */

void
lower_dim_size_comp_test(void)
{
    /* const char *fcnName = "lower_dim_size_comp_test()"; */
    int chunk_edge_size = 0;
    int use_collective_io;
    int mpi_rank;

    MPI_Comm_rank(MPI_COMM_WORLD, &mpi_rank);

    /* Make sure the connector supports the API functions being tested */
    if (!(vol_cap_flags_g & H5VL_CAP_FLAG_FILE_BASIC) || !(vol_cap_flags_g & H5VL_CAP_FLAG_DATASET_BASIC)) {
        if (MAINPROCESS) {
            puts("SKIPPED");
            printf("    API functions for basic file or dataset aren't supported with this connector\n");
            fflush(stdout);
        }

        return;
    }

    HDcompile_assert(sizeof(uint32_t) == sizeof(unsigned));
    for (use_collective_io = 0; use_collective_io <= 1; use_collective_io++) {
        chunk_edge_size = 0;
        lower_dim_size_comp_test__run_test(chunk_edge_size, (bool)use_collective_io, H5T_NATIVE_UINT);

        chunk_edge_size = 5;
        lower_dim_size_comp_test__run_test(chunk_edge_size, (bool)use_collective_io, H5T_NATIVE_UINT);
    } /* end for */

    return;
} /* lower_dim_size_comp_test() */

/*-------------------------------------------------------------------------
 * Function:    link_chunk_collective_io_test()
 *
 * Purpose:    Test to verify that an error in MPI type management in
 *        H5D_link_chunk_collective_io() has been corrected.
 *        In this bug, we used to free MPI types regardless of
 *        whether they were basic or derived.
 *
 *        This test is based on a bug report kindly provided by
 *        Rob Latham of the MPICH team and ANL.
 *
 *        The basic thrust of the test is to cause a process
 *        to participate in a collective I/O in which it:
 *
 *        1) Reads or writes exactly one chunk,
 *
 *        2) Has no in memory buffer for any other chunk.
 *
 *        The test differs from Rob Latham's bug report in
 *        that it runs with an arbitrary number of processes,
 *        and uses a 1-dimensional dataset.
 *
 * Return:    void
 *
 *-------------------------------------------------------------------------
 */

#define LINK_CHUNK_COLLECTIVE_IO_TEST_CHUNK_SIZE 16

void
link_chunk_collective_io_test(void)
{
    /* const char *fcnName = "link_chunk_collective_io_test()"; */
    const char *filename;
    bool        mis_match = false;
    int         i;
    int         mrc;
    int         mpi_rank;
    int         mpi_size;
    MPI_Comm    mpi_comm  = MPI_COMM_WORLD;
    MPI_Info    mpi_info  = MPI_INFO_NULL;
    hsize_t     count[1]  = {1};
    hsize_t     stride[1] = {2 * LINK_CHUNK_COLLECTIVE_IO_TEST_CHUNK_SIZE};
    hsize_t     block[1]  = {LINK_CHUNK_COLLECTIVE_IO_TEST_CHUNK_SIZE};
    hsize_t     start[1];
    hsize_t     dims[1];
    hsize_t     chunk_dims[1] = {LINK_CHUNK_COLLECTIVE_IO_TEST_CHUNK_SIZE};
    herr_t      ret; /* Generic return value */
    hid_t       file_id;
    hid_t       acc_tpl;
    hid_t       dset_id;
    hid_t       file_ds_sid;
    hid_t       write_mem_ds_sid;
    hid_t       read_mem_ds_sid;
    hid_t       ds_dcpl_id;
    hid_t       xfer_plist;
    double      diff;
    double      expected_value;
    double      local_data_written[LINK_CHUNK_COLLECTIVE_IO_TEST_CHUNK_SIZE];
    double      local_data_read[LINK_CHUNK_COLLECTIVE_IO_TEST_CHUNK_SIZE];

    MPI_Comm_size(MPI_COMM_WORLD, &mpi_size);
    MPI_Comm_rank(MPI_COMM_WORLD, &mpi_rank);

    /* Make sure the connector supports the API functions being tested */
    if (!(vol_cap_flags_g & H5VL_CAP_FLAG_FILE_BASIC) || !(vol_cap_flags_g & H5VL_CAP_FLAG_DATASET_BASIC)) {
        if (MAINPROCESS) {
            puts("SKIPPED");
            printf("    API functions for basic file or dataset aren't supported with this connector\n");
            fflush(stdout);
        }

        return;
    }

    assert(mpi_size > 0);

    /* get the file name */
    filename = (const char *)GetTestParameters();
    assert(filename != NULL);

    /* setup file access template */
    acc_tpl = create_faccess_plist(mpi_comm, mpi_info, facc_type);
    VRFY((acc_tpl >= 0), "create_faccess_plist() succeeded");

    /* create the file collectively */
    file_id = H5Fcreate(filename, H5F_ACC_TRUNC, H5P_DEFAULT, acc_tpl);
    VRFY((file_id >= 0), "H5Fcreate succeeded");

    MESG("File opened.");

    /* Release file-access template */
    ret = H5Pclose(acc_tpl);
    VRFY((ret >= 0), "H5Pclose(acc_tpl) succeeded");

    /* setup dims */
    dims[0] = ((hsize_t)mpi_size) * ((hsize_t)(LINK_CHUNK_COLLECTIVE_IO_TEST_CHUNK_SIZE));

    /* setup mem and file dataspaces */
    write_mem_ds_sid = H5Screate_simple(1, chunk_dims, NULL);
    VRFY((write_mem_ds_sid != 0), "H5Screate_simple() write_mem_ds_sid succeeded");

    read_mem_ds_sid = H5Screate_simple(1, chunk_dims, NULL);
    VRFY((read_mem_ds_sid != 0), "H5Screate_simple() read_mem_ds_sid succeeded");

    file_ds_sid = H5Screate_simple(1, dims, NULL);
    VRFY((file_ds_sid != 0), "H5Screate_simple() file_ds_sid succeeded");

    /* setup data set creation property list */
    ds_dcpl_id = H5Pcreate(H5P_DATASET_CREATE);
    VRFY((ds_dcpl_id != FAIL), "H5Pcreate() ds_dcpl_id succeeded");

    ret = H5Pset_layout(ds_dcpl_id, H5D_CHUNKED);
    VRFY((ret != FAIL), "H5Pset_layout() ds_dcpl_id succeeded");

    ret = H5Pset_chunk(ds_dcpl_id, 1, chunk_dims);
    VRFY((ret != FAIL), "H5Pset_chunk() small_ds_dcpl_id succeeded");

    /* create the data set */
    dset_id =
        H5Dcreate2(file_id, "dataset", H5T_NATIVE_DOUBLE, file_ds_sid, H5P_DEFAULT, ds_dcpl_id, H5P_DEFAULT);
    VRFY((dset_id >= 0), "H5Dcreate2() dataset succeeded");

    /* close the dataset creation property list */
    ret = H5Pclose(ds_dcpl_id);
    VRFY((ret >= 0), "H5Pclose(ds_dcpl_id) succeeded");

    /* setup local data */
    expected_value = (double)(LINK_CHUNK_COLLECTIVE_IO_TEST_CHUNK_SIZE) * (double)(mpi_rank);
    for (i = 0; i < LINK_CHUNK_COLLECTIVE_IO_TEST_CHUNK_SIZE; i++) {

        local_data_written[i] = expected_value;
        local_data_read[i]    = 0.0;
        expected_value += 1.0;
    }

    /* select the file and mem spaces */
    start[0] = (hsize_t)(mpi_rank * LINK_CHUNK_COLLECTIVE_IO_TEST_CHUNK_SIZE);
    ret      = H5Sselect_hyperslab(file_ds_sid, H5S_SELECT_SET, start, stride, count, block);
    VRFY((ret >= 0), "H5Sselect_hyperslab(file_ds_sid, set) succeeded");

    ret = H5Sselect_all(write_mem_ds_sid);
    VRFY((ret != FAIL), "H5Sselect_all(mem_ds_sid) succeeded");

    /* Note that we use NO SELECTION on the read memory dataspace */

    /* setup xfer property list */
    xfer_plist = H5Pcreate(H5P_DATASET_XFER);
    VRFY((xfer_plist >= 0), "H5Pcreate(H5P_DATASET_XFER) succeeded");

    ret = H5Pset_dxpl_mpio(xfer_plist, H5FD_MPIO_COLLECTIVE);
    VRFY((ret >= 0), "H5Pset_dxpl_mpio succeeded");

    /* write the data set */
    ret = H5Dwrite(dset_id, H5T_NATIVE_DOUBLE, write_mem_ds_sid, file_ds_sid, xfer_plist, local_data_written);

    VRFY((ret >= 0), "H5Dwrite() dataset initial write succeeded");

    /* sync with the other processes before checking data */
    mrc = MPI_Barrier(MPI_COMM_WORLD);
    VRFY((mrc == MPI_SUCCESS), "Sync after dataset write");

    /* read this processes slice of the dataset back in */
    ret = H5Dread(dset_id, H5T_NATIVE_DOUBLE, read_mem_ds_sid, file_ds_sid, xfer_plist, local_data_read);
    VRFY((ret >= 0), "H5Dread() dataset read succeeded");

    /* close the xfer property list */
    ret = H5Pclose(xfer_plist);
    VRFY((ret >= 0), "H5Pclose(xfer_plist) succeeded");

    /* verify the data */
    mis_match = false;
    for (i = 0; i < LINK_CHUNK_COLLECTIVE_IO_TEST_CHUNK_SIZE; i++) {

        diff = local_data_written[i] - local_data_read[i];
        diff = fabs(diff);

        if (diff >= 0.001) {

            mis_match = true;
        }
    }
    VRFY((mis_match == false), "dataset data good.");

    /* Close dataspaces */
    ret = H5Sclose(write_mem_ds_sid);
    VRFY((ret != FAIL), "H5Sclose(write_mem_ds_sid) succeeded");

    ret = H5Sclose(read_mem_ds_sid);
    VRFY((ret != FAIL), "H5Sclose(read_mem_ds_sid) succeeded");

    ret = H5Sclose(file_ds_sid);
    VRFY((ret != FAIL), "H5Sclose(file_ds_sid) succeeded");

    /* Close Dataset */
    ret = H5Dclose(dset_id);
    VRFY((ret != FAIL), "H5Dclose(dset_id) succeeded");

    /* close the file collectively */
    ret = H5Fclose(file_id);
    VRFY((ret != FAIL), "file close succeeded");

    return;

} /* link_chunk_collective_io_test() */