code: 
  /*******************************************************************************
   * Copyright (c) 2015 Attila Kovacs <attila[AT]sigmyne.com>.
   * All rights reserved. 
   * 
   * This file is part of crush.
   * 
   *     crush is free software: you can redistribute it and/or modify
   *     it under the terms of the GNU General Public License as published by
   *     the Free Software Foundation, either version 3 of the License, or
   *     (at your option) any later version.
   * 
   *     crush is distributed in the hope that it will be useful,
   *     but WITHOUT ANY WARRANTY; without even the implied warranty of
   *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   *     GNU General Public License for more details.
   * 
   *     You should have received a copy of the GNU General Public License
   *     along with crush.  If not, see <http://www.gnu.org/licenses/>.
   * 
   * Contributors:
   *     Attila Kovacs <attila[AT]sigmyne.com> - initial API and implementation
   ******************************************************************************/
  package crush.fits;
  
  import java.io.IOException;
  
  import crush.CRUSH;
  import jnum.data.ArrayUtil;
  import jnum.parallel.ParallelTask;
  import nom.tam.fits.*;
  import nom.tam.util.*;
  
  // TODO does not work with gzipped FITS...
  
  public abstract class HDURowReader {	
  	protected BinaryTableHDU hdu;
  	protected BinaryTable table;
  	protected ArrayDataInput in;
  	
  	private Object[] modelRow;
      private int nextRow = 0;
  
  	
  	public HDURowReader(BinaryTableHDU hdu, ArrayDataInput in) throws FitsException { 
  		this.hdu = hdu;
  		this.table = hdu.getData();
  		this.in = in;
  	}
  
  	public abstract Reader getReader() throws FitsException;
  	
  	public void read() throws Exception {
  	    read(CRUSH.maxThreads);
  	}
  
  	public void read(int threadCount) throws Exception {   
  	    modelRow = table.getModelRow();
  	    if(!table.reset()) throw new FitsException("Cannot locate beginning of FITS binary table.");	// Go to the beginning
  	
  		nextRow = 0;		
  		if(CRUSH.executor != null) getReader().process(threadCount, CRUSH.executor);
  		else getReader().process(threadCount);
  	}
  	
  	private synchronized int readNextRow(Object[] data) throws IOException {  
  		if(nextRow >= table.getNRows()) return -1;		
  		long bytes = in.readLArray(data);
  		if(bytes == 0) return -1;
  		return nextRow++;
  	}
  	
  	public abstract class Reader extends ParallelTask<Void> {
  		private Object[] row;
  		
  		@Override
  		public void init() { 
  			super.init();		
  			try { row = (Object[]) ArrayUtil.copyOf(modelRow); } 
  			catch (Exception e) { CRUSH.error(this, e); }
  		}
  		
  		@Override
  		public void processChunk(int i, int threadCount) throws Exception {
  			int index;
  			while((index = readNextRow(row)) >= 0) {
  				if(isInterrupted()) return;				
  				processRow(index, row);
  			}
  		}
  		
  		public abstract void processRow(int index, Object[] row) throws Exception;
  		
  	}
  	
  }
  