P25 - Automatic Gain Control for P25 decoder

src/dsp/gain/DirectGainControl.java

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+/*******************************************************************************
+ *     SDR Trunk 
+ *     Copyright (C) 2014 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 dsp.gain;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import sample.real.RealSampleListener;
+
+public class DirectGainControl implements GainController, RealSampleListener
+{
+	private final static Logger mLog = 
+			LoggerFactory.getLogger( DirectGainControl.class );
+
+	private float mGain;
+	private float mMinimum;
+	private float mMaximum;
+	private float mIncrement;
+	
+	private RealSampleListener mListener;
+
+	/**
+	 * Gain Control.
+	 * 
+	 * Note: does not perform null checking on output listener in order to 
+	 * streamline sample processing.
+	 * 
+	 * @param gain - initial value
+	 * @param minimum - minimum value greater than 0
+	 * @param maximum - maximum permitted value
+	 * @param increment - amount gain is adjusted when increase() or decrease()
+	 * is invoked
+	 */
+	public DirectGainControl( float gain, float minimum, float maximum, float increment )
+	{
+		assert( minimum > 0 );
+		
+		mGain = gain;
+		mMinimum = minimum;
+		mMaximum = maximum;
+		mIncrement = increment;
+	}
+
+	@Override
+    public void receive( float sample )
+    {
+		mListener.receive( (float)( sample * mGain ) );
+    }
+
+	@Override
+	public void increase()
+	{
+		mGain += mIncrement;
+		
+		if( mGain > mMaximum )
+		{
+			mGain = mMaximum;
+		}
+		
+		mLog.debug( "Gain Increased: " + mGain );
+	}
+	
+	@Override
+	public void decrease()
+	{
+		mGain -= mIncrement;
+		
+		if( mGain < mMinimum )
+		{
+			mGain = mMinimum;
+		}
+		
+		mLog.debug( "Gain Decreased: " + mGain );
+	}
+	
+    public void setListener( RealSampleListener listener )
+    {
+		mListener = listener;
+    }
+}