function status = h5_ref2reg
%H5_REF2REG This example shows how to create, store and dereference
%references to the dataset regions.
% 
%   It creates a file and writes a two dimensional integer dataset to it.
%   Then it creates a dataset to store region references in. It stores
%   references to a hyperslab and 3 points selected (for the integer
%   dataset previously created). 
% 
%   It then reopens the references dataset, reads and dereferences the
%   region references, and then reads and displays the selected hyperslab
%   and selected elements data from the integer dataset.
% 
%   status is returned to indicate whether the example ran successfully

%   Copyright 2006 The MathWorks, Inc. 
%   $Revision: 1.1.4.1 $  $Date: 2006/05/23 23:21:44 $

% Initialize status to false
status = false;

fname     = qeTempFile('h5');
filename  = fname.fullpath;      
dsetnamev = 'MATRIX';
dsetnamer = 'REGION_REFERENCES';

dims  = [2,9];
dimsr = [2];
rank  = 2;
rankr = 1;

data     = int32([1,1,2,3,3,4,5,5,6,  1,2,2,3,4,4,5,6,6]);
coord    = [0, 0, 1 6, 0, 8];

% Create file with default file access and file creation properties.
file_id = H5F.create(filename, 'H5F_ACC_TRUNC', 'H5P_DEFAULT', 'H5P_DEFAULT');

% Create dataspace for datasets.
space_id = H5S.create_simple(rank, dims, []);
spacer_id = H5S.create_simple(rankr, dimsr, []);

% Create integer dataset. 
dsetv_id = H5D.create(file_id, dsetnamev, 'H5T_NATIVE_INT', space_id, ...
                      'H5P_DEFAULT');

% Write data to the dataset.
H5D.write(dsetv_id, 'H5T_NATIVE_INT', 'H5S_ALL' , 'H5S_ALL', 'H5P_DEFAULT', ...
          data);
H5D.close(dsetv_id);

% Dataset with references.
dsetr_id = H5D.create(file_id, dsetnamer, 'H5T_STD_REF_DSETREG', spacer_id, ...
                      'H5P_DEFAULT');

% Create a reference to the hyperslab.
start = [0 3];
count = [2 3];
H5S.select_hyperslab(space_id,'H5S_SELECT_SET',start,[],count,[]);
ref1 = H5R.create(file_id, dsetnamev, 'H5R_DATASET_REGION', space_id);

% Create a reference to elements selection.
H5S.select_none(space_id);
H5S.select_elements(space_id, 'H5S_SELECT_SET', coord);
ref2 = H5R.create(file_id, dsetnamev, 'H5R_DATASET_REGION', space_id);

% Write dataset with the references.
H5D.write(dsetr_id, 'H5T_STD_REF_DSETREG', 'H5S_ALL', 'H5S_ALL', ...
          'H5P_DEFAULT', [ref1 ref2]);

% Close all objects.
H5S.close(space_id);
H5S.close(spacer_id);
H5D.close(dsetr_id);
H5F.close(file_id);

% Reopen the file to read selections back.
file_id = H5F.open(filename, 'H5F_ACC_RDWR', 'H5P_DEFAULT');

% Reopen the dataset with object references and read references to the buffer.
dsetr_id = H5D.open( file_id, dsetnamer);

ref_out = H5D.read(dsetr_id, 'H5T_STD_REF_DSETREG', 'H5S_ALL', 'H5S_ALL', ...
                   'H5P_DEFAULT');

% Dereference the first reference.
dsetv_id = H5R.dereference(dsetr_id, 'H5R_DATASET_REGION', ref_out(:,1));
space_id = H5R.get_region(dsetr_id, 'H5R_DATASET_REGION', ref_out(:,1));

% Read and display hyperslab selection from the dataset.
data_out = H5D.read(dsetv_id, 'H5T_NATIVE_INT', 'H5S_ALL', space_id, ...
                    'H5P_DEFAULT');
                
% Close dataspace and the dataset.
H5S.close(space_id);
H5D.close(dsetv_id);

% Initialize data_out array again to get point selection.
data_out = zeros(8,1,'uint32');

% Dereference the second reference.
dsetv_id = H5R.dereference(dsetr_id, 'H5R_DATASET_REGION', ref_out(:,2));
space_id = H5R.get_region(dsetv_id, 'H5R_DATASET_REGION',ref_out(:,2));

% Read selected data from the dataset.
data_out = H5D.read(dsetv_id, 'H5T_NATIVE_INT', 'H5S_ALL', space_id,...
                   'H5P_DEFAULT');
               
% Close dataspace and the dataset.
H5S.close(space_id);
H5D.close(dsetv_id);
H5D.close(dsetr_id);
H5F.close(file_id);
               
% Example is successful if we did not error out in the statements above
status = true;