39 - WIP - incorporates the latest P25 C4FM decoder from master and

updates the LSM decoder to follow the same design pattern.  Adds LSM
decoder support to the demodulator viewer application.  The current
symbol timing gain for LSM is set too high -- is using the C4FM gain
and causes too much fluctuation in the timing error.

src/main/java/io/github/dsheirer/dsp/gain/ComplexFeedForwardGainControl.java

@@ -19,6 +19,8 @@ import io.github.dsheirer.buffer.FloatCircularBuffer;
 import io.github.dsheirer.sample.complex.Complex;
 import io.github.dsheirer.sample.complex.ComplexBuffer;
 import io.github.dsheirer.sample.complex.ComplexSampleListener;
+import io.github.dsheirer.sample.complex.reusable.ReusableBufferQueue;
+import io.github.dsheirer.sample.complex.reusable.ReusableComplexBuffer;
 
 public class ComplexFeedForwardGainControl implements ComplexSampleListener
 {
@@ -26,8 +28,8 @@ public class ComplexFeedForwardGainControl implements ComplexSampleListener
     public static final float MINIMUM_ENVELOPE = 0.0001f;
 
     private ComplexSampleListener mListener;
-
     private FloatCircularBuffer mEnvelopeHistory;
+    private ReusableBufferQueue mReusableBufferQueue = new ReusableBufferQueue();
 
     private float mMaxEnvelope = 0.0f;
     private float mGain = 1.0f;
@@ -107,19 +109,59 @@ public class ComplexFeedForwardGainControl implements ComplexSampleListener
         mListener = listener;
     }
 
-    public ComplexBuffer filter(ComplexBuffer complexBuffer)
+    public float[] filter(float[] complesSamples)
     {
-        float[] samples = complexBuffer.getSamples();
-        float[] processed = new float[samples.length];
+        mMaxEnvelope = MINIMUM_ENVELOPE;
+        float currentEnvelope;
 
-        for(int x = 0; x < samples.length; x += 2)
+        for(int x = 0; x < complesSamples.length; x += 2)
         {
-            process(samples[x], samples[x + 1]);
+            currentEnvelope = Complex.envelope(complesSamples[x], complesSamples[x + 1]);
 
-            processed[x] = samples[x] * mGain;
-            processed[x + 1] = samples[x + 1] * mGain;
+            if(currentEnvelope > mMaxEnvelope)
+            {
+                mMaxEnvelope = currentEnvelope;
+            }
         }
 
-        return new ComplexBuffer(processed);
+        adjustGain();
+
+        float[] processed = new float[complesSamples.length];
+
+        for(int x = 0; x < complesSamples.length; x += 2)
+        {
+            processed[x] = complesSamples[x] * mGain;
+            processed[x + 1] = complesSamples[x + 1] * mGain;
+        }
+
+        return processed;
+    }
+
+    /**
+     * Applies gain to the complex sample buffer
+     * @param buffer to apply gain
+     * @return buffer with gain applied samples
+     */
+    public ComplexBuffer filter(ComplexBuffer buffer)
+    {
+        float[] filtered = filter(buffer.getSamples());
+        return new ComplexBuffer(filtered);
+    }
+
+    /**
+     * Applies gain to the complex sample buffer
+     * @param buffer to apply gain
+     * @return reusable buffer with the user count incremented to 1
+     */
+    public ReusableComplexBuffer filter(ReusableComplexBuffer buffer)
+    {
+        float[] filtered = filter(buffer.getSamples());
+
+        ReusableComplexBuffer filteredBuffer = mReusableBufferQueue.getBuffer(filtered.length);
+
+        filteredBuffer.reloadFrom(filtered, buffer.getTimestamp());
+        filteredBuffer.incrementUserCount();
+
+        return filteredBuffer;
     }
 }