/*******************************************************************************
 * sdr-trunk
 * Copyright (C) 2014-2018 Dennis Sheirer
 *
 * This program 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.
 *
 * This program 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 this program.
 * If not, see <http://www.gnu.org/licenses/>
 *
 ******************************************************************************/
package io.github.dsheirer.dsp.psk;

import io.github.dsheirer.dsp.symbol.Dibit;
import io.github.dsheirer.sample.Broadcaster;
import io.github.dsheirer.sample.Listener;
import io.github.dsheirer.sample.complex.Complex;

public class QPSKSymbolDecoder implements Listener<Complex>, IQPSKSymbolDecoder
{
	private Broadcaster<Dibit> mBroadcaster = new Broadcaster<Dibit>();
	
	/**
	 * Slices a ComplexSample representing a phase shifted symbol according to
	 * the following constellation pattern:
	 * 
	 *    \ 00 /
	 *     \  /
	 *   01 \/ 10
	 *      /\
	 *     /  \
	 *    / 11 \
	 */
	public QPSKSymbolDecoder()
	{
	}
	
	public void dispose()
	{
		mBroadcaster.dispose();
		mBroadcaster = null;
	}

	public void addListener( Listener<Dibit> listener )
	{
		mBroadcaster.addListener( listener );
	}

	public void removeListener( Listener<Dibit> listener )
	{
		mBroadcaster.removeListener( listener );
	}

	@Override
	public void receive( Complex complex )
	{
		mBroadcaster.broadcast( decode( complex ) );
	}
	
	public Dibit decode(Complex complex )
	{
		if( Math.abs( complex.inphase() ) > Math.abs( complex.quadrature() ) )
		{
			if( complex.inphase() > 0 )
			{
				return Dibit.D10_MINUS_1;
			}
			else
			{
				return Dibit.D01_PLUS_3;
			}
		}
		else
		{
			if( complex.quadrature() > 0 )
			{
				return Dibit.D00_PLUS_1;
			}
			else
			{
				return Dibit.D11_MINUS_3;
			}
		}
	}
	
}