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+/************************************************************
+
+ This example illustrates the concept of virtual dataset I/O
+ The program creates 2-dim source dataset and writes
+ data to it. Then it creates 2-dim virtual dataset that has
+ the same dimesnion sizes and maps the all elements of the
+ virtual dataset to all elements of the source dataset.
+ Then VDS is read back.
+
+ 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-simpleIO.h5"
+#define DATASET "VDS"
+#define DIM1 6
+#define DIM0 4
+#define RANK 2
+
+#define SRC_FILE "a.h5"
+#define SRC_DATASET "/A"
+
+
+int
+main (void)
+{
+ hid_t file, space, src_space, vspace, dset; /* Handles */
+ hid_t dcpl;
+ herr_t status;
+ hsize_t vdsdims[2] = {DIM0, DIM1}, /* Virtual dataset dimension */
+ dims[2] = {DIM0, DIM1}; /* Source dataset dimensions */
+ int wdata[DIM0][DIM1], /* Write buffer for source dataset */
+ rdata[DIM0][DIM1], /* Read buffer for virtual dataset */
+ i, j;
+ 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;
+ /*
+ * Initialize data.
+ */
+ for (i = 0; i < DIM0; i++)
+ for (j = 0; j < DIM1; j++) wdata[i][j] = i+1;
+
+ /*
+ * Create the source file and the dataset. Write data to the source dataset
+ * and close all resources.
+ */
+
+ file = H5Fcreate (SRC_FILE, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
+ space = H5Screate_simple (RANK, dims, NULL);
+ dset = H5Dcreate2 (file, SRC_DATASET, H5T_NATIVE_INT, space, H5P_DEFAULT,
+ H5P_DEFAULT, H5P_DEFAULT);
+ status = H5Dwrite (dset, H5T_NATIVE_INT, H5S_ALL, H5S_ALL, H5P_DEFAULT,
+ wdata[0]);
+ status = H5Sclose (space);
+ status = H5Dclose (dset);
+ status = H5Fclose (file);
+
+ /* Create file in which virtual dataset will be stored. */
+ file = H5Fcreate (FILE, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
+
+ /* Create VDS dataspace. */
+ vspace = H5Screate_simple (RANK, vdsdims, NULL);
+
+ /* Set VDS creation property. */
+ dcpl = H5Pcreate (H5P_DATASET_CREATE);
+
+ /*
+ * Build the mappings.
+ * Selections in the source datasets are H5S_ALL.
+ * In the virtual dataset we select the first, the second and the third rows
+ * and map each row to the data in the corresponding source dataset.
+ */
+ src_space = H5Screate_simple (RANK, dims, NULL);
+ status = H5Pset_virtual (dcpl, vspace, SRC_FILE, SRC_DATASET, src_space);
+
+ /* Create a virtual dataset. */
+ dset = H5Dcreate2 (file, DATASET, H5T_NATIVE_INT, vspace, H5P_DEFAULT,
+ dcpl, H5P_DEFAULT);
+ status = H5Sclose (vspace);
+ status = H5Sclose (src_space);
+ status = H5Dclose (dset);
+ status = H5Fclose (file);
+
+ /*
+ * Now we begin the read section of this example.
+ */
+
+ /*
+ * Open the file and virtual dataset.
+ */
+ 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 the 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 ");
+ /* Get selection in the virttual dataset */
+ vspace = H5Pget_virtual_vspace (dcpl, (size_t)i);
+
+ /* Make sure it is ALL selection and then print selection. */
+ if(H5Sget_select_type(vspace) == H5S_SEL_ALL) {
+ printf("Selection is H5S_ALL \n");
+ }
+ /* 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 ");
+ src_space = H5Pget_virtual_srcspace (dcpl, (size_t)i);
+
+ /* Make sure it is ALL selection and then print selection. */
+ if(H5Sget_select_type(src_space) == H5S_SEL_ALL) {
+ printf("Selection is H5S_ALL \n");
+ }
+ H5Sclose(vspace);
+ H5Sclose(src_space);
+ free(filename);
+ free(dsetname);
+ }
+ /*
+ * Read the data using the default properties.
+ */
+ status = H5Dread (dset, H5T_NATIVE_INT, H5S_ALL, H5S_ALL, H5P_DEFAULT,
+ rdata[0]);
+
+ /*
+ * Output the data to the screen.
+ */
+ printf (" VDS Data:\n");
+ for (i=0; i<DIM0; i++) {
+ printf (" [");
+ for (j=0; j<DIM1; j++)
+ printf (" %3d", rdata[i][j]);
+ printf ("]\n");
+ }
+ /*
+ * Close and release resources.
+ */
+ status = H5Pclose (dcpl);
+ status = H5Dclose (dset);
+ status = H5Fclose (file);
+
+ return 0;
+}
+