WIP - Updated P25 C4FM and LSM decoders to assemble dibits and push

reusable byte buffers out to the processing chain.  This enables the
processing chain to broadcast these buffers back to the decoder for
message assembly and to any running binary recorder.

Updated P25Decoder to be a reusable byte buffer listener.  The decoder
will now pass reusable byte buffers down to the message framer for
message processing.  This should make the code more efficient since it
can process byte arrays versus handling each individual dibit.

The P25MessageFramer has been updated to be a listener of reusable byte
buffers instead of Dibits, but the actual processing of byte arrays
has to be coded.

Added max recording size to the binary recorder so that it cycles at
500 kB max file size.

src/main/java/io/github/dsheirer/dsp/symbol/DibitToByteBufferAssembler.java

@@ -0,0 +1,125 @@
+/*******************************************************************************
+ * 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.symbol;
+
+import io.github.dsheirer.sample.Listener;
+import io.github.dsheirer.sample.buffer.IReusableByteBufferProvider;
+import io.github.dsheirer.sample.buffer.ReusableByteBuffer;
+import io.github.dsheirer.sample.buffer.ReusableByteBufferQueue;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Assembles reusable byte buffers from an incoming stream of Dibits.
+ */
+public class DibitToByteBufferAssembler implements Listener<Dibit>, IReusableByteBufferProvider
+{
+    private final static Logger mLog = LoggerFactory.getLogger(DibitToByteBufferAssembler.class);
+
+    private ReusableByteBufferQueue mBufferQueue = new ReusableByteBufferQueue("DibitToByteBufferAssembler");
+    private ReusableByteBuffer mCurrentBuffer;
+    private int mBufferPointer;
+    private int mBufferSize;
+    private byte mCurrentByte;
+    private int mDibitCount;
+    private Listener<ReusableByteBuffer> mBufferListener;
+
+    /**
+     * Constructs an assembler to produce reusable byte buffers of the specified size
+     *
+     * @param bufferSize
+     */
+    public DibitToByteBufferAssembler(int bufferSize)
+    {
+        mBufferSize = bufferSize;
+        getNextBuffer();
+    }
+
+    /**
+     * Broadcasts the current buffer to the registered listener and creates a new buffer, resetting
+     * the buffer pointer to zero so that new dibits can be loaded.
+     */
+    private void getNextBuffer()
+    {
+        if(mCurrentBuffer != null && mBufferListener != null)
+        {
+            mBufferListener.receive(mCurrentBuffer);
+        }
+
+        mCurrentBuffer = mBufferQueue.getBuffer(mBufferSize);
+        mBufferPointer = 0;
+    }
+
+    @Override
+    public void receive(Dibit dibit)
+    {
+        mCurrentByte <<= 2;
+
+        switch(dibit)
+        {
+            case D01_PLUS_3:
+                mCurrentByte |= 0x01;
+                break;
+            case D00_PLUS_1:
+                //no-op - value is already 00
+                break;
+            case D10_MINUS_1:
+                mCurrentByte |= 0x02;
+                break;
+            case D11_MINUS_3:
+                mCurrentByte |= 0x03;
+                break;
+        }
+
+        mDibitCount++;
+
+        if(mDibitCount >= 4)
+        {
+            mCurrentBuffer.getBytes()[mBufferPointer++] = mCurrentByte;
+            mCurrentByte = 0x00;
+            mDibitCount = 0;
+
+            if(mBufferPointer >= mBufferSize)
+            {
+                getNextBuffer();
+            }
+        }
+    }
+
+    /**
+     * Registers the listener to receive fully assembled byte buffers from this assembler.
+     */
+    @Override
+    public void setBufferListener(Listener<ReusableByteBuffer> listener)
+    {
+        mBufferListener = listener;
+    }
+
+    /**
+     * Removes the listener from receiving buffers from this assembler
+     */
+    @Override
+    public void removeBufferListener(Listener<ReusableByteBuffer> listener)
+    {
+        mBufferListener = null;
+    }
+
+    @Override
+    public boolean hasBufferListeners()
+    {
+        return mBufferListener != null;
+    }
+}