/************************************************************

  This example shows how to read and write integer datatypes
  to an attribute.  The program first writes integers to an
  attribute with a dataspace of DIM0xDIM1, then closes the
  file.  Next, it reopens the file, reads back the data, and
  outputs it to the screen.

  This file is intended for use with HDF5 Library version 1.6

 ************************************************************/

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

#define FILE      "h5ex_t_intatt.h5"
#define DATASET   "DS1"
#define ATTRIBUTE "A1"
#define DIM0      4
#define DIM1      7

int
main(void)
{
    hid_t   file, space, dset, attr; /* Handles */
    herr_t  status;
    hsize_t dims[2] = {DIM0, DIM1};
    int     wdata[DIM0][DIM1], /* Write buffer */
        **rdata,               /* Read buffer */
        ndims, i, j;

    /*
     * Initialize data.
     */
    for (i = 0; i < DIM0; i++)
        for (j = 0; j < DIM1; j++)
            wdata[i][j] = i * j - j;

    /*
     * Create a new file using the default properties.
     */
    file = H5Fcreate(FILE, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);

    /*
     * Create dataset with a scalar dataspace.
     */
    space  = H5Screate(H5S_SCALAR);
    dset   = H5Dcreate(file, DATASET, H5T_STD_I32LE, space, H5P_DEFAULT);
    status = H5Sclose(space);

    /*
     * Create dataspace.  Setting maximum size to NULL sets the maximum
     * size to be the current size.
     */
    space = H5Screate_simple(2, dims, NULL);

    /*
     * Create the attribute and write the integer data to it.  In this
     * example we will save the data as 64 bit big endian integers,
     * regardless of the native integer type.  The HDF5 library
     * automatically converts between different integer types.
     */
    attr   = H5Acreate(dset, ATTRIBUTE, H5T_STD_I64BE, space, H5P_DEFAULT);
    status = H5Awrite(attr, H5T_NATIVE_INT, wdata[0]);

    /*
     * Close and release resources.
     */
    status = H5Aclose(attr);
    status = H5Dclose(dset);
    status = H5Sclose(space);
    status = H5Fclose(file);

    /*
     * Now we begin the read section of this example.  Here we assume
     * the attribute has the same name and rank, but can have any size.
     * Therefore we must allocate a new array to read in data using
     * malloc().
     */

    /*
     * Open file, dataset, and attribute.
     */
    file = H5Fopen(FILE, H5F_ACC_RDONLY, H5P_DEFAULT);
    dset = H5Dopen(file, DATASET);
    attr = H5Aopen_name(dset, ATTRIBUTE);

    /*
     * Get dataspace and allocate memory for read buffer.  This is a
     * two dimensional attribute so the dynamic allocation must be done
     * in steps.
     */
    space = H5Aget_space(attr);
    ndims = H5Sget_simple_extent_dims(space, dims, NULL);

    /*
     * Allocate array of pointers to rows.
     */
    rdata = (int **)malloc(dims[0] * sizeof(int *));

    /*
     * Allocate space for integer data.
     */
    rdata[0] = (int *)malloc(dims[0] * dims[1] * sizeof(int));

    /*
     * Set the rest of the pointers to rows to the correct addresses.
     */
    for (i = 1; i < dims[0]; i++)
        rdata[i] = rdata[0] + i * dims[1];

    /*
     * Read the data.
     */
    status = H5Aread(attr, H5T_NATIVE_INT, rdata[0]);

    /*
     * Output the data to the screen.
     */
    printf("%s:\n", ATTRIBUTE);
    for (i = 0; i < dims[0]; i++) {
        printf(" [");
        for (j = 0; j < dims[1]; j++)
            printf(" %3d", rdata[i][j]);
        printf("]\n");
    }

    /*
     * Close and release resources.
     */
    free(rdata[0]);
    free(rdata);
    status = H5Aclose(attr);
    status = H5Dclose(dset);
    status = H5Sclose(space);
    status = H5Fclose(file);

    return 0;
}