h5testszip.c

/*! \file

Copyright 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002,
2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014,
2015, 2016, 2017, 2018
University Corporation for Atmospheric Research/Unidata.

See \ref copyright file for more info.

*/
/*
 * Example illustrates the use of SZIP compression in HDF5
 */

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

#define NX 500
#define NY 600
#define CH_NX 100
#define CH_NY 25

static void initialize(void);
static int compare(void);

static float buf[NX][NY];
static float buf_r[NX][NY];

static const char* filename = "test.h5";

static int
writeszip()
{
   hid_t file;
   hid_t dataset32;
   hid_t properties;
   hid_t lcpl_id, dapl_id;
   hid_t data_space;
   hsize_t dims[2], chunk_size[2];
   unsigned szip_options_mask;
   unsigned szip_pixels_per_block;

  /*
   * Create a new file using read/write access, default file
   * creation properties, and default file access properties.
   */
   file = H5Fcreate (filename, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);

   /* Describe the size of the array. */
   dims[0] = NX;
   dims[1] = NY;
   data_space = H5Screate_simple (2, dims, NULL);

  /*
   * Set the dataset creation property list to specify that
   * the raw data is to be partitioned into 100x100 element
   * chunks and that each chunk is to be compressed.
   */
   chunk_size[0] = CH_NX;
   chunk_size[1] = CH_NY;
   properties = H5Pcreate (H5P_DATASET_CREATE);
   H5Pset_chunk (properties, 2, chunk_size);

  /*
   * Set parameters for SZIP compression; check the description of
   * the H5Pset_szip function in the HDF5 Reference Manual for more
   * information.
   */
   szip_options_mask=H5_SZIP_NN_OPTION_MASK;
   szip_pixels_per_block=32;

   H5Pset_szip (properties, szip_options_mask, szip_pixels_per_block);

  /*
   * Create a new dataset within the file.  The datatype
   * and data space describe the data on disk, which may
   * be different from the format used in the application's
   * memory.
   */

   lcpl_id = H5Pcreate (H5P_LINK_CREATE);
   dapl_id = H5Pcreate (H5P_DATASET_ACCESS);

   dataset32 = H5Dcreate (file, "datasetF32", H5T_NATIVE_FLOAT, data_space, lcpl_id, properties, dapl_id);

  /*
   * Write the array to the file.  The datatype and dataspace
   * describe the format of the data in the `buf' buffer.
   * The raw data is translated to the format required on disk,
   * as defined above.  We use default raw data transfer properties.
   */

   H5Dwrite (dataset32, H5T_NATIVE_FLOAT, H5S_ALL, H5S_ALL,
            H5P_DEFAULT, buf);

   H5Sclose (data_space);
   H5Pclose(lcpl_id);
   H5Pclose(dapl_id);
   H5Pclose (properties);
   H5Dclose (dataset32);
   H5Fclose (file);

   return 1;
}

static int
readszip()
{
    hid_t file;
    hid_t dataset32;
    hid_t properties;
    int errcnt = 0;

    file = H5Fopen (filename, H5F_ACC_RDONLY, H5P_DEFAULT);
    properties = H5Pcreate(H5P_DATASET_ACCESS);
    dataset32 = H5Dopen(file, "datasetF32", properties);

    /*
     * Read the array.  This is similar to writing data,
     * except the data flows in the opposite direction.
     * Note: Decompression is automatic.
     */

    H5Dread(dataset32, H5T_NATIVE_FLOAT, H5S_ALL, H5S_ALL, H5P_DEFAULT, buf_r);

    errcnt = compare();

    H5Pclose(properties);
    H5Dclose (dataset32);
    H5Fclose (file);

    return (errcnt==0 ? 1 : 0);
}

static int
compare(void)
{
    int i,j;
    int errs = 0;

    /* Do comparison */
    for (i=0; i < NX; i++) {
	for (j=0; j < NY; j++) {
            if(buf[i][j] != buf_r[i][j]) {
		errs++;
	        printf("mismatch: [%d][%d]: write = %f read=%f\n",
		        i,j,buf[i][j],buf_r[i][j]);
	}
     }
   }
   return errs;
}

static void
initialize(void)
{
   int i, j;
   /* Initialize data buffer with some bogus data. */
   for(i=0; i < NX; i++) {
     for(j=0; j < NY; j++) {
       buf[i][j] = (float)(i + j);
     }
   }
}

int
main(int argc, char** argv)
{
    int extfile = 0;
    if(argc > 1) {
	filename = argv[1];
	extfile = 1;
    }

    initialize();
    if(!extfile) {
	if(!writeszip()) {
	    fprintf(stderr,"writeszip failed.\n");
	    goto fail;
	}
    }

    if(!readszip()) {
	fprintf(stderr,"openfile failed.\n");
	goto fail;
    }
    fprintf(stderr,"***PASS\n");
    return 0;
fail:
    fprintf(stderr,"***FAIL\n");
    return 1;
}