hdf5/examples/h5_vds-exc.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 example illustrates the concept of the virtual dataset.
  Excalibur use case with k=2 and m=3.
  This file is intended for use with HDF5 Library version 1.10

 ************************************************************/
/* EIP Add link to the picture */

#include "hdf5.h"
#include <stdio.h>
#include <stdlib.h>

#define FILE    "vds-exc.h5"
#define DATASET "VDS-Excalibur"
#define VDSDIM0 0
#define VDSDIM1 15
#define VDSDIM2 6
#define KDIM0   0
#define KDIM1   2
#define KDIM2   6
#define NDIM0   0
#define NDIM1   3
#define NDIM2   6
#define RANK    3

const char *SRC_FILE[] = {"a.h5", "b.h5", "c.h5", "d.h5", "e.h5", "f.h5"};

const char *SRC_DATASET[] = {"A", "B", "C", "D", "E", "F"};

int
main(void)
{
    hid_t   file, space, ksrc_space, nsrc_space, vspace, src_space, dset; /* Handles */
    hid_t   dcpl;
    herr_t  status;
    hsize_t vdsdims[3] = {VDSDIM0, VDSDIM1, VDSDIM2}, vdsdims_max[3] = {H5S_UNLIMITED, VDSDIM1, VDSDIM2},
            kdims[3] = {KDIM0, KDIM1, KDIM2}, kdims_max[3] = {H5S_UNLIMITED, KDIM1, KDIM2},
            ndims[3] = {NDIM0, NDIM1, NDIM2}, ndims_max[3] = {H5S_UNLIMITED, NDIM1, NDIM2},
            start[3], /* Hyperslab parameters */
        count[3], block[3];
    hsize_t      start_out[3], stride_out[3], count_out[3], block_out[3];
    int          k = 2;
    int          n = 3;
    int          i;
    H5D_layout_t layout;  /* Storage layout */
    size_t       num_map; /* Number of mappings */
    ssize_t      len;     /* Length of the string; also a return value */
    char        *filename;
    char        *dsetname;

    file = H5Fcreate(FILE, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);

    /* Create VDS dataspace.  */
    space = H5Screate_simple(RANK, vdsdims, vdsdims_max);
    /* Create dataspaces for A, C, and E datasets. */
    ksrc_space = H5Screate_simple(RANK, kdims, kdims_max);
    /* Create dataspaces for B, D, and F datasets. */
    nsrc_space = H5Screate_simple(RANK, ndims, ndims_max);

    /* Create VDS creation property */
    dcpl = H5Pcreate(H5P_DATASET_CREATE);

    /* Initialize hyperslab values */

    start[0] = 0;
    start[1] = 0;
    start[2] = 0;
    count[0] = H5S_UNLIMITED;
    count[1] = 1;
    count[2] = 1;
    block[0] = 1;
    block[1] = k;
    block[2] = VDSDIM2;

    /*
     * Build the mappings for A, C and E source datasets.
     * Unlimited hyperslab selection is the same in the source datasets.
     * Unlimited hyperslab selections in the virtual dataset have different offsets.
     */
    status = H5Sselect_hyperslab(ksrc_space, H5S_SELECT_SET, start, NULL, count, block);
    for (i = 0; i < 3; i++) {
        start[1] = (hsize_t)((k + n) * i);
        status   = H5Sselect_hyperslab(space, H5S_SELECT_SET, start, NULL, count, block);
        status   = H5Pset_virtual(dcpl, space, SRC_FILE[2 * i], SRC_DATASET[2 * i], ksrc_space);
    }

    /* Reinitialize start[1] and block[1] to build the second set of mappings. */
    start[1] = 0;
    block[1] = n;
    /*
     * Build the mappings for B, D and F source datasets.
     * Unlimited hyperslab selection is the same in the source datasets.
     * Unlimited hyperslab selections in the virtual dataset have different offsets.
     */
    status = H5Sselect_hyperslab(nsrc_space, H5S_SELECT_SET, start, NULL, count, block);
    for (i = 0; i < 3; i++) {
        start[1] = (hsize_t)(k + (k + n) * i);
        status   = H5Sselect_hyperslab(space, H5S_SELECT_SET, start, NULL, count, block);
        status   = H5Pset_virtual(dcpl, space, SRC_FILE[2 * i + 1], SRC_DATASET[2 * i + 1], nsrc_space);
    }

    /* Create a virtual dataset */
    dset   = H5Dcreate2(file, DATASET, H5T_NATIVE_INT, space, H5P_DEFAULT, dcpl, H5P_DEFAULT);
    status = H5Sclose(space);
    status = H5Sclose(nsrc_space);
    status = H5Sclose(ksrc_space);
    status = H5Dclose(dset);
    status = H5Fclose(file);

    /*
     * Now we begin the read section of this example.
     */

    /*
     * Open file and dataset using the default properties.
     */
    file = H5Fopen(FILE, H5F_ACC_RDONLY, H5P_DEFAULT);
    dset = H5Dopen2(file, DATASET, H5P_DEFAULT);

    /*
     * Get creation property list and mapping properties.
     */
    dcpl = H5Dget_create_plist(dset);

    /*
     * Get storage layout.
     */
    layout = H5Pget_layout(dcpl);

    if (H5D_VIRTUAL == layout)
        printf(" Dataset has a virtual layout \n");
    else
        printf("Wrong layout found \n");

    /*
     * Find number of mappings.
     */
    status = H5Pget_virtual_count(dcpl, &num_map);
    printf(" Number of mappings is %lu\n", (unsigned long)num_map);

    /*
     * Get mapping parameters for each mapping.
     */
    for (i = 0; i < (int)num_map; i++) {
        printf(" Mapping %d \n", i);
        printf("         Selection in the virtual dataset \n");
        /* Get selection in the virtual dataset */
        vspace = H5Pget_virtual_vspace(dcpl, (size_t)i);
        if (H5Sget_select_type(vspace) == H5S_SEL_HYPERSLABS) {
            if (H5Sis_regular_hyperslab(vspace)) {
                status = H5Sget_regular_hyperslab(vspace, start_out, stride_out, count_out, block_out);
                printf("         start  = [%llu, %llu, %llu] \n", (unsigned long long)start_out[0],
                       (unsigned long long)start_out[1], (unsigned long long)start_out[2]);
                printf("         stride = [%llu, %llu, %llu] \n", (unsigned long long)stride_out[0],
                       (unsigned long long)stride_out[1], (unsigned long long)stride_out[2]);
                printf("         count  = [%llu, %llu, %llu] \n", (unsigned long long)count_out[0],
                       (unsigned long long)count_out[1], (unsigned long long)count_out[2]);
                printf("         block  = [%llu, %llu, %llu] \n", (unsigned long long)block_out[0],
                       (unsigned long long)block_out[1], (unsigned long long)block_out[2]);
            }
        }
        /* Get source file name */
        len      = H5Pget_virtual_filename(dcpl, (size_t)i, NULL, 0);
        filename = (char *)malloc((size_t)len * sizeof(char) + 1);
        H5Pget_virtual_filename(dcpl, (size_t)i, filename, len + 1);
        printf("         Source filename %s\n", filename);

        /* Get source dataset name */
        len      = H5Pget_virtual_dsetname(dcpl, (size_t)i, NULL, 0);
        dsetname = (char *)malloc((size_t)len * sizeof(char) + 1);
        H5Pget_virtual_dsetname(dcpl, (size_t)i, dsetname, len + 1);
        printf("         Source dataset name %s\n", dsetname);

        /* Get selection in the source dataset */
        printf("         Selection in the source dataset \n");
        src_space = H5Pget_virtual_srcspace(dcpl, (size_t)i);
        if (H5Sget_select_type(src_space) == H5S_SEL_HYPERSLABS) {
            if (H5Sis_regular_hyperslab(vspace)) {
                status = H5Sget_regular_hyperslab(src_space, start_out, stride_out, count_out, block_out);
                printf("         start  = [%llu, %llu, %llu] \n", (unsigned long long)start_out[0],
                       (unsigned long long)start_out[1], (unsigned long long)start_out[2]);
                printf("         stride = [%llu, %llu, %llu] \n", (unsigned long long)stride_out[0],
                       (unsigned long long)stride_out[1], (unsigned long long)stride_out[2]);
                printf("         count  = [%llu, %llu, %llu] \n", (unsigned long long)count_out[0],
                       (unsigned long long)count_out[1], (unsigned long long)count_out[2]);
                printf("         block  = [%llu, %llu, %llu] \n", (unsigned long long)block_out[0],
                       (unsigned long long)block_out[1], (unsigned long long)block_out[2]);
            }
        }
        H5Sclose(vspace);
        H5Sclose(src_space);
        free(filename);
        free(dsetname);
    }
    /* EIP read data back */

    /*
     * Close and release resources.
     */
    status = H5Pclose(dcpl);
    status = H5Dclose(dset);
    status = H5Fclose(file);

    return 0;
}