/*
 * This example opens a file, and extracts
 * the bit field from a subset of a dataset. 
 * The values are returned as a base-10 integer.
 * Main illustrative function: H5LTread_bitfield_value
 */

#include <stdlib.h>
#include "hdf5.h"
#include "hdf5_hl.h"
#include "h5hl_region.h"

#define FILENAME "SVI01-GIMFG_NPP_d2003125_t101038_e10116_b9_c2005829153351_dev.h5"
#define DATASET "/All_Data/VIIRS-I1-SDR_All/QF_VIIRSI1SDR_Array"
#define num_flags 1 

int main(void)
{
  int qf_data[5][6][1];  /* Read buffer */
  unsigned int offset[1] = {1};  /* Starting bits to be extracted from element */
  unsigned int length[1] = {2};  /* Number of bits to be extracted for each value */
  hid_t file, space; /* Handles */
  hid_t qf_dset;
  herr_t status;
  hsize_t start[3] =  {0,0,0}; 
  hsize_t count[3] =  {5,6,1}; 
  int i, j;
  
  /*
   * Open file.
   */
  file = H5Fopen (FILENAME, H5F_ACC_RDONLY, H5P_DEFAULT);
  /* 
   * Open the data set
   */
  qf_dset = H5Dopen (file, DATASET, H5P_DEFAULT);
  /*
   * Get dataspace and allocate memory for read buffer. Quality flags dataset
   * has the same dimensionality as corresponding product dataset;
   * we are using its dimensions for illustration purposes only.
   */
  space = H5Dget_space (qf_dset);
  status = H5Sselect_hyperslab(space, H5S_SELECT_SET, start, NULL, count, NULL); 
  /*
   * For each element read the value that takes first two bits and 
   * store it in a char buffer. This selects all the elements (H5S_ALL)
   */
  status = H5LTread_bitfield_value(qf_dset, num_flags, offset, length, space, (int *)qf_data);
  status = H5Sclose (space);

  /* Print out the bit field */
  printf("Bit Field:\n");
  for (i = 0; i<5; i++) {
    printf (" [");
    for (j = 0; j<6; j++) {
	printf(" %d ", qf_data[i][j][0]);
    }
    printf("]\n");
  }

  return 0;
  
}