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/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* Copyright by The HDF Group. *
* All rights reserved. *
* *
* This file is part of the HDF5 LZ4 filter plugin source. The full *
* copyright notice, including terms governing use, modification, and *
* terms governing use, modification, and redistribution, is contained in *
* the file COPYING, which can be found at the root of the LZ4 source code *
* distribution tree. If you do not have access to this file, you may *
* request a copy from help@hdfgroup.org. *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/************************************************************
This example shows how to write data and read it from a dataset
using lz4 compression.
lz4 filter is not available in HDF5.
The example uses a new feature available in HDF5 version 1.8.11
to discover, load and register filters at run time.
************************************************************/
#include "hdf5.h"
#include <stdio.h>
#include <stdlib.h>
#define FILE "h5ex_d_lz4.h5"
#define DATASET "DS1"
#define DIM0 32
#define DIM1 64
#define CHUNK0 4
#define CHUNK1 8
#define H5Z_FILTER_LZ4 32004
int
main(void)
{
hid_t file_id = H5I_INVALID_HID; /* Handles */
hid_t space_id = H5I_INVALID_HID; /* Handles */
hid_t dset_id = H5I_INVALID_HID; /* Handles */
hid_t dcpl_id = H5I_INVALID_HID; /* Handles */
herr_t status;
htri_t avail;
H5Z_filter_t filter_id = 0;
char filter_name[80];
hsize_t dims[2] = {DIM0, DIM1}, chunk[2] = {CHUNK0, CHUNK1};
size_t nelmts = 1; /* number of elements in cd_values */
unsigned int flags;
unsigned filter_config;
const unsigned int cd_values[1] = {3}; /* lz4 default is 3 */
unsigned int values_out[1] = {99};
int wdata[DIM0][DIM1], /* Write buffer */
rdata[DIM0][DIM1], /* Read buffer */
max;
hsize_t i, j;
int ret_value = 1;
/*
* 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_id = H5Fcreate(FILE, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
if (file_id < 0)
goto done;
/*
* Create dataspace. Setting maximum size to NULL sets the maximum
* size to be the current size.
*/
space_id = H5Screate_simple(2, dims, NULL);
if (space_id < 0)
goto done;
/*
* Create the dataset creation property list, add the gzip
* compression filter and set the chunk size.
*/
dcpl_id = H5Pcreate(H5P_DATASET_CREATE);
if (dcpl_id < 0)
goto done;
status = H5Pset_filter(dcpl_id, H5Z_FILTER_LZ4, H5Z_FLAG_MANDATORY, nelmts, cd_values);
if (status < 0)
goto done;
/*
* Check that filter is registered with the library now.
* If it is registered, retrieve filter's configuration.
*/
avail = H5Zfilter_avail(H5Z_FILTER_LZ4);
if (avail) {
status = H5Zget_filter_info(H5Z_FILTER_LZ4, &filter_config);
if ((filter_config & H5Z_FILTER_CONFIG_ENCODE_ENABLED) &&
(filter_config & H5Z_FILTER_CONFIG_DECODE_ENABLED))
printf("lz4 filter is available for encoding and decoding.\n");
}
else {
printf("H5Zfilter_avail - not found.\n");
goto done;
}
status = H5Pset_chunk(dcpl_id, 2, chunk);
if (status < 0)
printf("failed to set chunk.\n");
/*
* Create the dataset.
*/
printf("....Create dataset ................\n");
dset_id = H5Dcreate(file_id, DATASET, H5T_STD_I32LE, space_id, H5P_DEFAULT, dcpl_id, H5P_DEFAULT);
if (dset_id < 0) {
printf("failed to create dataset.\n");
goto done;
}
/*
* Write the data to the dataset.
*/
printf("....Writing lz4 compressed data ................\n");
status = H5Dwrite(dset_id, H5T_NATIVE_INT, H5S_ALL, H5S_ALL, H5P_DEFAULT, wdata[0]);
if (status < 0)
printf("failed to write data.\n");
/*
* Close and release resources.
*/
H5Dclose(dset_id);
dset_id = -1;
H5Pclose(dcpl_id);
dcpl_id = -1;
H5Sclose(space_id);
space_id = -1;
H5Fclose(file_id);
file_id = -1;
status = H5close();
if (status < 0) {
printf("/nFAILED to close library/n");
goto done;
}
printf("....Close the file and reopen for reading ........\n");
/*
* Now we begin the read section of this example.
*/
/*
* Open file and dataset using the default properties.
*/
file_id = H5Fopen(FILE, H5F_ACC_RDONLY, H5P_DEFAULT);
if (file_id < 0)
goto done;
dset_id = H5Dopen(file_id, DATASET, H5P_DEFAULT);
if (dset_id < 0)
goto done;
/*
* Retrieve dataset creation property list.
*/
dcpl_id = H5Dget_create_plist(dset_id);
if (dcpl_id < 0)
goto done;
/*
* Retrieve and print the filter id, compression level and filter's name for lz4.
*/
filter_id = H5Pget_filter2(dcpl_id, (unsigned)0, &flags, &nelmts, values_out, sizeof(filter_name),
filter_name, NULL);
printf("Filter info is available from the dataset creation property \n ");
printf(" Filter identifier is ");
switch (filter_id) {
case H5Z_FILTER_LZ4:
printf("%d\n", filter_id);
printf(" Number of parameters is %ld with the value %u\n", nelmts, values_out[0]);
printf(" To find more about the filter check %s\n", filter_name);
break;
default:
printf("Not expected filter\n");
break;
}
/*
* Read the data using the default properties.
*/
printf("....Reading lz4 compressed data ................\n");
status = H5Dread(dset_id, H5T_NATIVE_INT, H5S_ALL, H5S_ALL, H5P_DEFAULT, rdata[0]);
if (status < 0)
printf("failed to read data.\n");
/*
* Find the maximum value in the dataset, to verify that it was
* read correctly.
*/
max = rdata[0][0];
for (i = 0; i < DIM0; i++)
for (j = 0; j < DIM1; j++) {
/*printf("%d \n", rdata[i][j]); */
if (max < rdata[i][j])
max = rdata[i][j];
}
/*
* Print the maximum value.
*/
printf("Maximum value in %s is %d\n", DATASET, max);
/*
* Check that filter is registered with the library now.
*/
avail = H5Zfilter_avail(H5Z_FILTER_LZ4);
if (avail)
printf("lz4 filter is available now since H5Dread triggered loading of the filter.\n");
ret_value = 0;
done:
/*
* Close and release resources.
*/
if (dcpl_id >= 0)
H5Pclose(dcpl_id);
if (dset_id >= 0)
H5Dclose(dset_id);
if (space_id >= 0)
H5Sclose(space_id);
if (file_id >= 0)
H5Fclose(file_id);
return ret_value;
}
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