netcdf-c/nc_test4/h5testszip.c

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/*
* Example illustrates the use of SZIP compression in HDF5
*/
#include <stdio.h>
#include "hdf5.h"
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#define NX 500
#define NY 600
#define CH_NX 100
#define CH_NY 25
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static void initialize(void);
static int compare(void);
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static float buf[NX][NY];
static float buf_r[NX][NY];
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static const char* filename = "test.h5";
static int
writeszip()
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{
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hid_t file;
hid_t dataset32;
hid_t properties;
hid_t lcpl_id, dapl_id;
hid_t data_space;
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hsize_t dims[2], chunk_size[2];
unsigned szip_options_mask;
unsigned szip_pixels_per_block;
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/*
* 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);
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/* 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);
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H5Sclose (data_space);
H5Pclose(lcpl_id);
H5Pclose(dapl_id);
H5Pclose (properties);
H5Dclose (dataset32);
H5Fclose (file);
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return 1;
}
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static int
readszip()
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{
hid_t file;
hid_t dataset32;
hid_t properties;
int errcnt = 0;
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file = H5Fopen (filename, H5F_ACC_RDONLY, H5P_DEFAULT);
properties = H5Pcreate(H5P_DATASET_ACCESS);
dataset32 = H5Dopen(file, "datasetF32", properties);
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/*
* Read the array. This is similar to writing data,
* except the data flows in the opposite direction.
* Note: Decompression is automatic.
*/
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H5Dread(dataset32, H5T_NATIVE_FLOAT, H5S_ALL, H5S_ALL, H5P_DEFAULT, buf_r);
errcnt = compare();
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H5Pclose(properties);
H5Dclose (dataset32);
H5Fclose (file);
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return (errcnt==0 ? 1 : 0);
}
static int
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compare(void)
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{
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]);
}
}
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}
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return errs;
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}
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);
}
}
}
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int
main(int argc, char** argv)
{
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int extfile = 0;
if(argc > 1) {
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filename = argv[1];
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extfile = 1;
}
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initialize();
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if(!extfile) {
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if(!writeszip()) {
fprintf(stderr,"writeszip failed.\n");
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goto fail;
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}
}
if(!readszip()) {
fprintf(stderr,"openfile failed.\n");
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goto fail;
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}
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fprintf(stderr,"***PASS\n");
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return 0;
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fail:
fprintf(stderr,"***FAIL\n");
return 1;
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}