H5ObjectEx_T_Bit.java

/************************************************************
  This example shows how to read and write bitfield
  datatypes to a dataset.  The program first writes bit
  fields to a dataset with a dataspace of DIM0xDIM1, then
  closes the file.  Next, it reopens the file, reads back
  the data, and outputs it to the screen.
 ************************************************************/

package datatypes;

import hdf.object.FileFormat;
import hdf.object.Group;
import hdf.object.h5.H5File;
import hdf.object.h5.H5ScalarDS;

import hdf.hdf5lib.H5;
import hdf.hdf5lib.HDF5Constants;

public class H5ObjectEx_T_Bit {
    private static String FILENAME    = "H5ObjectEx_T_Bit.h5";
    private static String DATASETNAME = "DS1";
    private static final int DIM0     = 4;
    private static final int DIM1     = 7;
    private static final int RANK     = 2;

    private static void CreateDataset()
    {
        H5File file       = null;
        H5ScalarDS dset   = null;
        long file_id      = -1;
        long dataspace_id = -1;
        long dataset_id   = -1;
        long[] dims       = {DIM0, DIM1};
        int[][] dset_data = new int[DIM0][DIM1];
        /* H5Datatype typeBitField = new H5Datatype(Datatype.CLASS_BITFIELD, 8, Datatype.ORDER_BE,
         * Datatype.NATIVE); */

        // Initialize data.
        for (int indx = 0; indx < DIM0; indx++)
            for (int jndx = 0; jndx < DIM1; jndx++) {
                dset_data[indx][jndx] = 0;
                dset_data[indx][jndx] |= (indx * jndx - jndx) & 0x03; /* Field "A" */
                dset_data[indx][jndx] |= (indx & 0x03) << 2;          /* Field "B" */
                dset_data[indx][jndx] |= (jndx & 0x03) << 4;          /* Field "C" */
                dset_data[indx][jndx] |= ((indx + jndx) & 0x03) << 6; /* Field "D" */
            }

        // Create a new file using default properties.
        try {
            file    = new H5File(FILENAME, FileFormat.CREATE);
            file_id = file.open();
        }
        catch (Exception e) {
            e.printStackTrace();
        }

        // Create dataspace. Setting maximum size to NULL sets the maximum
        // size to be the current size.
        try {
            dataspace_id = H5.H5Screate_simple(RANK, dims, null);
        }
        catch (Exception e) {
            e.printStackTrace();
        }

        // Create the dataset.
        try {
            if ((file_id >= 0) && (dataspace_id >= 0))
                dataset_id = H5.H5Dcreate(file_id, DATASETNAME, HDF5Constants.H5T_STD_B8BE, dataspace_id,
                                          HDF5Constants.H5P_DEFAULT, HDF5Constants.H5P_DEFAULT,
                                          HDF5Constants.H5P_DEFAULT);
            dset         = new H5ScalarDS(file, DATASETNAME, "/");
            Group pgroup = (Group)file.get("/");
            pgroup.addToMemberList(dset);
        }
        catch (Exception e) {
            e.printStackTrace();
        }

        // Write the bitfield data to the dataset.
        try {
            if (dataset_id >= 0)
                H5.H5Dwrite(dataset_id, HDF5Constants.H5T_NATIVE_B8, HDF5Constants.H5S_ALL,
                            HDF5Constants.H5S_ALL, HDF5Constants.H5P_DEFAULT, dset_data);
        }
        catch (Exception e) {
            e.printStackTrace();
        }

        // End access to the dataset and release resources used by it.
        try {
            if (dataset_id >= 0)
                dset.close(dataset_id);
        }
        catch (Exception e) {
            e.printStackTrace();
        }

        // Terminate access to the data space.
        try {
            if (dataspace_id >= 0)
                H5.H5Sclose(dataspace_id);
        }
        catch (Exception e) {
            e.printStackTrace();
        }

        // Close the file.
        try {
            file.close();
        }
        catch (Exception e) {
            e.printStackTrace();
        }
    }

    private static void ReadDataset()
    {
        H5File file       = null;
        H5ScalarDS dset   = null;
        long dataset_id   = -1;
        long dataspace_id = -1;
        long[] dims       = {DIM0, DIM1};
        int[][] dset_data;

        // Open an existing file.
        try {
            file = new H5File(FILENAME, FileFormat.READ);
            file.open();
        }
        catch (Exception e) {
            e.printStackTrace();
        }

        // Open an existing dataset.
        try {
            dset       = (H5ScalarDS)file.get(DATASETNAME);
            dataset_id = dset.open();
        }
        catch (Exception e) {
            e.printStackTrace();
        }

        // Get dataspace and allocate memory for read buffer.
        try {
            if (dataset_id >= 0)
                dataspace_id = H5.H5Dget_space(dataset_id);
        }
        catch (Exception e) {
            e.printStackTrace();
        }

        try {
            if (dataspace_id >= 0)
                H5.H5Sget_simple_extent_dims(dataspace_id, dims, null);
        }
        catch (Exception e) {
            e.printStackTrace();
        }

        // Allocate array of pointers to two-dimensional arrays (the
        // elements of the dataset.
        dset_data = new int[(int)dims[0]][(int)(dims[1])];

        // Read data.
        try {
            if (dataset_id >= 0)
                H5.H5Dread(dataset_id, HDF5Constants.H5T_NATIVE_B8, HDF5Constants.H5S_ALL,
                           HDF5Constants.H5S_ALL, HDF5Constants.H5P_DEFAULT, dset_data);
        }
        catch (Exception e) {
            e.printStackTrace();
        }

        // Output the data to the screen.
        System.out.println(DATASETNAME + ":");
        for (int indx = 0; indx < dims[0]; indx++) {
            System.out.print(" [");
            for (int jndx = 0; jndx < dims[1]; jndx++) {
                System.out.print("{" + (dset_data[indx][jndx] & 0x03) + ", ");
                System.out.print(((dset_data[indx][jndx] >> 2) & 0x03) + ", ");
                System.out.print(((dset_data[indx][jndx] >> 4) & 0x03) + ", ");
                System.out.print(((dset_data[indx][jndx] >> 6) & 0x03) + "}");
            }
            System.out.println("]");
        }
        System.out.println();

        // End access to the dataset and release resources used by it.
        try {
            if (dataset_id >= 0)
                dset.close(dataset_id);
        }
        catch (Exception e) {
            e.printStackTrace();
        }

        // Terminate access to the data space.
        try {
            if (dataspace_id >= 0)
                H5.H5Sclose(dataspace_id);
        }
        catch (Exception e) {
            e.printStackTrace();
        }

        // Close the file.
        try {
            file.close();
        }
        catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args)
    {
        H5ObjectEx_T_Bit.CreateDataset();
        // Now we begin the read section of this example. Here we assume
        // the dataset and array have the same name and rank, but can have
        // any size. Therefore we must allocate a new array to read in
        // data using malloc().
        H5ObjectEx_T_Bit.ReadDataset();
    }
}