1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
|
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* Copyright by The HDF Group. *
* Copyright by the Board of Trustees of the University of Illinois. *
* All rights reserved. *
* *
* This file is part of HDF5. The full HDF5 copyright notice, including *
* terms governing use, modification, and redistribution, is contained in *
* the COPYING file, which can be found at the root of the source code *
* distribution tree, or in https://www.hdfgroup.org/licenses. *
* If you do not have access to either file, you may request a copy from *
* help@hdfgroup.org. *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*
* This example illustrates how to create a compressed dataset.
* It is used in the HDF5 Tutorial.
*/
#include "hdf5.h"
#define FILE "cmprss.h5"
#define RANK 2
#define DIM0 100
#define DIM1 20
int
main()
{
hid_t file_id, dataset_id, dataspace_id; /* identifiers */
hid_t plist_id;
size_t nelmts;
unsigned flags, filter_info;
H5Z_filter_t filter_type;
herr_t status;
hsize_t dims[2];
hsize_t cdims[2];
int i, j, numfilt;
int buf[DIM0][DIM1];
int rbuf[DIM0][DIM1];
/* Uncomment these variables to use SZIP compression
unsigned szip_options_mask;
unsigned szip_pixels_per_block;
*/
/* Create a file. */
file_id = H5Fcreate(FILE, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
/* Create dataset "Compressed Data" in the group using absolute name. */
dims[0] = DIM0;
dims[1] = DIM1;
dataspace_id = H5Screate_simple(RANK, dims, NULL);
plist_id = H5Pcreate(H5P_DATASET_CREATE);
/* Dataset must be chunked for compression */
cdims[0] = 20;
cdims[1] = 20;
status = H5Pset_chunk(plist_id, 2, cdims);
/* Set ZLIB / DEFLATE Compression using compression level 6.
* To use SZIP Compression comment out these lines.
*/
status = H5Pset_deflate(plist_id, 6);
/* Uncomment these lines to set SZIP Compression
szip_options_mask = H5_SZIP_NN_OPTION_MASK;
szip_pixels_per_block = 16;
status = H5Pset_szip (plist_id, szip_options_mask, szip_pixels_per_block);
*/
dataset_id = H5Dcreate2(file_id, "Compressed_Data", H5T_STD_I32BE, dataspace_id, H5P_DEFAULT, plist_id,
H5P_DEFAULT);
for (i = 0; i < DIM0; i++)
for (j = 0; j < DIM1; j++)
buf[i][j] = i + j;
status = H5Dwrite(dataset_id, H5T_NATIVE_INT, H5S_ALL, H5S_ALL, H5P_DEFAULT, buf);
status = H5Sclose(dataspace_id);
status = H5Dclose(dataset_id);
status = H5Pclose(plist_id);
status = H5Fclose(file_id);
/* Now reopen the file and dataset in the file. */
file_id = H5Fopen(FILE, H5F_ACC_RDWR, H5P_DEFAULT);
dataset_id = H5Dopen2(file_id, "Compressed_Data", H5P_DEFAULT);
/* Retrieve filter information. */
plist_id = H5Dget_create_plist(dataset_id);
numfilt = H5Pget_nfilters(plist_id);
printf("Number of filters associated with dataset: %i\n", numfilt);
for (i = 0; i < numfilt; i++) {
nelmts = 0;
filter_type = H5Pget_filter2(plist_id, i, &flags, &nelmts, NULL, 0, NULL, &filter_info);
printf("Filter Type: ");
switch (filter_type) {
case H5Z_FILTER_DEFLATE:
printf("H5Z_FILTER_DEFLATE\n");
break;
case H5Z_FILTER_SZIP:
printf("H5Z_FILTER_SZIP\n");
break;
default:
printf("Other filter type included.\n");
}
}
status = H5Dread(dataset_id, H5T_NATIVE_INT, H5S_ALL, H5S_ALL, H5P_DEFAULT, rbuf);
status = H5Dclose(dataset_id);
status = H5Pclose(plist_id);
status = H5Fclose(file_id);
}
|
