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/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* 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 files COPYING and Copyright.html. COPYING can be found at the root *
* of the source code distribution tree; Copyright.html can be found at the *
* root level of an installed copy of the electronic HDF5 document set and *
* is linked from the top-level documents page. It can also be found at *
* http://hdfgroup.org/HDF5/doc/Copyright.html. If you do not have *
* access to either file, you may request a copy from help@hdfgroup.org. *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*
* This program illustrates how references to objects can be used.
* Program creates a dataset and a group in a file. It also creates
* second dataset, and references to the first dataset and the group
* are stored in it.
* Program reopens the file and reads dataset with the references.
* References are used to open the objects. Information about the
* objects is displayed.
*/
#include <stdlib.h>
#include "hdf5.h"
#define H5FILE_NAME "refere.h5"
int
main(void) {
hid_t fid; /* File, group, datasets, datatypes */
hid_t gid_a; /* and dataspaces identifiers */
hid_t did_b, sid_b, tid_b;
hid_t did_r, tid_r, sid_r;
hid_t dapl_id; /* Dataset access property list */
H5O_type_t obj_type;
herr_t status;
hobj_ref_t *wbuf; /* buffer to write to disk */
hobj_ref_t *rbuf; /* buffer to read from disk */
hsize_t dim_r[1];
hsize_t dim_b[2];
/*
* Create a file using default properties.
*/
fid = H5Fcreate(H5FILE_NAME, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
/*
* Create group "A" in the file.
*/
gid_a = H5Gcreate2(fid, "A", H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
/*
* Create dataset access property list
*/
dapl_id = H5Pcreate(H5P_DATASET_ACCESS);
/*
* Create dataset "B" in the file.
*/
dim_b[0] = 2;
dim_b[1] = 6;
sid_b = H5Screate_simple(2, dim_b, NULL);
did_b = H5Dcreate2(fid, "B", H5T_NATIVE_FLOAT, sid_b, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
/*
* Create dataset "R" to store references to the objects "A" and "B".
*/
dim_r[0] = 2;
sid_r = H5Screate_simple(1, dim_r, NULL);
tid_r = H5Tcopy(H5T_STD_REF_OBJ);
did_r = H5Dcreate2(fid, "R", tid_r, sid_r, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
/*
* Allocate write and read buffers.
*/
wbuf = (hobj_ref_t *)malloc(sizeof(hobj_ref_t) * 2);
rbuf = (hobj_ref_t *)malloc(sizeof(hobj_ref_t) * 2);
/*
* Create references to the group "A" and dataset "B"
* and store them in the wbuf.
*/
H5Rcreate(&wbuf[0], fid, "A", H5R_OBJECT, -1);
H5Rcreate(&wbuf[1], fid, "B", H5R_OBJECT, -1);
/*
* Write dataset R using default transfer properties.
*/
status = H5Dwrite(did_r, H5T_STD_REF_OBJ, H5S_ALL, H5S_ALL, H5P_DEFAULT, wbuf);
/*
* Close all objects.
*/
H5Gclose(gid_a);
H5Sclose(sid_b);
H5Dclose(did_b);
H5Tclose(tid_r);
H5Sclose(sid_r);
H5Dclose(did_r);
H5Fclose(fid);
/*
* Reopen the file.
*/
fid = H5Fopen(H5FILE_NAME, H5F_ACC_RDWR, H5P_DEFAULT);
/*
* Open and read dataset "R".
*/
did_r = H5Dopen2(fid, "R", H5P_DEFAULT);
status = H5Dread(did_r, H5T_STD_REF_OBJ, H5S_ALL, H5S_ALL, H5P_DEFAULT, rbuf);
/*
* Find the type of referenced objects.
*/
status = H5Rget_obj_type2(did_r, H5R_OBJECT, &rbuf[0], &obj_type);
if(obj_type == H5O_TYPE_GROUP)
printf("First dereferenced object is a group. \n");
status = H5Rget_obj_type2(did_r, H5R_OBJECT, &rbuf[1], &obj_type);
if(obj_type == H5O_TYPE_DATASET)
printf("Second dereferenced object is a dataset. \n");
/*
* Get datatype of the dataset "B"
*/
did_b = H5Rdereference(did_r, dapl_id, H5R_OBJECT, &rbuf[1]);
tid_b = H5Dget_type(did_b);
if(H5Tequal(tid_b, H5T_NATIVE_FLOAT))
printf("Datatype of the dataset is H5T_NATIVE_FLOAT.\n");
printf("\n");
/*
* Close all objects and free memory buffers.
*/
H5Pclose(dapl_id);
H5Dclose(did_r);
H5Dclose(did_b);
H5Tclose(tid_b);
H5Fclose(fid);
free(rbuf);
free(wbuf);
return 0;
}
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