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P25 Work-in-progress check-in.
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dennis.sheirer
374
src/dsp/fsk/P25MessageFramer.java
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374
src/dsp/fsk/P25MessageFramer.java
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package dsp.fsk;
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import java.util.ArrayList;
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import java.util.BitSet;
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import message.Message;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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import sample.Listener;
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import bits.BitSetBuffer;
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import bits.BitSetFullException;
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import bits.SyncPatternMatcher;
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import decode.p25.P25Interleave;
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import decode.p25.TrellisHalfRate;
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import decode.p25.message.P25Message;
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import decode.p25.message.PDUMessage;
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import decode.p25.message.TSBKMessage;
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import decode.p25.message.TSBKMessageFactory;
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import decode.p25.reference.DataUnitID;
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public class P25MessageFramer implements Listener<C4FMSymbol>
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{
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private final static Logger mLog =
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LoggerFactory.getLogger( P25MessageFramer.class );
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private static final int[] STATUS_BITS =
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new int[] { 22,92,162,232,302,372,442,512,582,652,722,792,862,932 };
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private ArrayList<P25MessageAssembler> mAssemblers =
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new ArrayList<P25MessageAssembler>();
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public static final int TSBK_BEGIN = 64;
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public static final int TSBK_END = 260;
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public static final int TSBK_DECODED_END = 162;
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private Listener<Message> mListener;
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private SyncPatternMatcher mMatcher;
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private boolean mInverted = false;
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private TrellisHalfRate mHalfRate = new TrellisHalfRate();
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/**
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* Constructs a C4FM message framer to receive a stream of C4FM symbols and
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* detect the sync pattern then capture the following stream of symbols up
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* to the message length, and then broadcast that bit buffer to the registered
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* listener.
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*
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* @param sync - sync pattern (maximum of 63 bits)
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* @param messageLength - in bits
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* @param inverted - optional flag to indicate the symbol stream should be
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* uninverted prior to processing
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*/
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public P25MessageFramer( long sync, int messageLength, boolean inverted )
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{
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mMatcher = new SyncPatternMatcher( sync );
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mInverted = inverted;
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/**
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* We use two message assemblers to catch any sync detections, so that
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* if we have a false trigger then we still have a chance to catch the
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* valid message. If we have two false triggers before the arrival of
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* the actual message sync, then the third or subsequent real or false
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* sync pattern will produce a debug message indicating no assemblers
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* are available..
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*/
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mAssemblers.add( new P25MessageAssembler() );
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mAssemblers.add( new P25MessageAssembler() );
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}
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private void dispatch( Message message )
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{
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if( mListener != null )
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{
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mListener.receive( message );
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}
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}
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@Override
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public void receive( C4FMSymbol symbol )
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{
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C4FMSymbol correctedSymbol = symbol;
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mMatcher.receive( correctedSymbol.getBit1() );
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mMatcher.receive( correctedSymbol.getBit2() );
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for( P25MessageAssembler assembler: mAssemblers )
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{
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if( assembler.isActive() )
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{
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assembler.receive( correctedSymbol );
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if( assembler.complete() )
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{
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assembler.reset();
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}
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}
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}
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/* Check for sync match and activate a message assembler, if we can
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* find an inactive assembler. Otherwise, ignore and log the issue */
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if( mMatcher.matches() )
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{
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boolean found = false;
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for( P25MessageAssembler assembler: mAssemblers )
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{
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if( !assembler.isActive() )
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{
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assembler.setActive( true );
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found = true;
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break;
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}
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}
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if( !found )
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{
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mLog.debug( "no inactive C4FM message assemblers available" );
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}
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}
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}
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public void setListener( Listener<Message> listener )
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{
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mListener = listener;
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}
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public void removeListener( Listener<Message> listener )
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{
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mListener = null;
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}
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private class P25MessageAssembler
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{
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private int mStatusIndicatorPointer = 0;
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private BitSetBuffer mMessage;
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private int mMessageLength;
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private boolean mComplete = false;
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private boolean mActive = false;
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private DataUnitID mDUID = DataUnitID.NID;
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public P25MessageAssembler()
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{
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mMessageLength = mDUID.getMessageLength();
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mMessage = new BitSetBuffer( mMessageLength );
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reset();
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}
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public void receive( C4FMSymbol symbol )
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{
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if( mActive )
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{
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/* Throw away status bits that are injected every 70 bits */
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if( mMessage.pointer() == STATUS_BITS[ mStatusIndicatorPointer ] )
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{
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mStatusIndicatorPointer++;
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}
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else
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{
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try
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{
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mMessage.add( symbol.getBit1() );
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mMessage.add( symbol.getBit2() );
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}
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catch( BitSetFullException e )
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{
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mComplete = true;
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}
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/* Check the message for complete */
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if( mMessage.isFull() )
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{
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checkComplete();
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}
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}
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}
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}
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public void reset()
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{
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mDUID = DataUnitID.NID;
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mMessage.setSize( mDUID.getMessageLength() );
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mMessage.clear();
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mStatusIndicatorPointer = 0;
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mComplete = false;
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mActive = false;
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}
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public void setActive( boolean active )
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{
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mActive = active;
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}
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private void setDUID( DataUnitID id )
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{
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mDUID = id;
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mMessageLength = id.getMessageLength();
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mMessage.setSize( mMessageLength );
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}
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private void checkComplete()
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{
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switch( mDUID )
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{
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case NID:
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int value = mMessage.getInt( P25Message.DUID );
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DataUnitID duid = DataUnitID.fromValue( value );
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if( duid != DataUnitID.UNKN )
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{
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setDUID( duid );
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}
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else
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{
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mComplete = true;
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}
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break;
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case HDU:
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mComplete = true;
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dispatch( new P25Message( mMessage.copy(), mDUID ) );
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break;
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case LDU1:
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mComplete = true;
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dispatch( new P25Message( mMessage.copy(), mDUID ) );
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break;
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case LDU2:
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mComplete = true;
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dispatch( new P25Message( mMessage.copy(), mDUID ) );
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break;
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case PDU1:
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int blocks = mMessage.getInt(
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PDUMessage.PDU_HEADER_BLOCKS_TO_FOLLOW );
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int padBlocks = mMessage.getInt( PDUMessage.PDU_HEADER_PAD_BLOCKS );
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int blockCount = blocks + padBlocks;
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if( blockCount == 24 || blockCount == 32 )
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{
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setDUID( DataUnitID.PDU2 );
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}
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else if( blockCount == 36 || blockCount == 48 )
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{
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setDUID( DataUnitID.PDU3 );
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}
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else
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{
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dispatch( new PDUMessage( mMessage.copy(), mDUID ) );
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mComplete = true;
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}
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break;
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case PDU2:
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case PDU3:
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mComplete = true;
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dispatch( new P25Message( mMessage.copy(), mDUID ) );
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break;
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case TDU:
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mComplete = true;
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dispatch( new P25Message( mMessage.copy(), mDUID ) );
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break;
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case TDULC:
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mComplete = true;
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dispatch( new P25Message( mMessage.copy(), mDUID ) );
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break;
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case TSBK1:
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/* Remove interleaving */
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P25Interleave.deinterleave( mMessage, TSBK_BEGIN, TSBK_END );
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/* Remove trellis encoding */
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mHalfRate.decode( mMessage, TSBK_BEGIN, TSBK_END );
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/* Construct the message */
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int tsbkSystem1 = mMessage.getInt( P25Message.NAC );
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BitSetBuffer tsbkBuffer1 = new BitSetBuffer( mMessage.get(
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TSBK_BEGIN, TSBK_DECODED_END ), 96 );
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TSBKMessage tsbkMessage1 =
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TSBKMessageFactory.getMessage( tsbkSystem1, tsbkBuffer1 );
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if( tsbkMessage1.isLastBlock() )
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{
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mComplete = true;
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}
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else
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{
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setDUID( DataUnitID.TSBK2 );
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mMessage.setPointer( TSBK_BEGIN );
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}
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dispatch( tsbkMessage1 );
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break;
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case TSBK2:
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/* Remove interleaving */
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P25Interleave.deinterleave( mMessage, TSBK_BEGIN, TSBK_END );
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/* Remove trellis encoding */
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mHalfRate.decode( mMessage, TSBK_BEGIN, TSBK_END );
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/* Construct the message */
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int tsbkSystem2 = mMessage.getInt( P25Message.NAC );
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BitSetBuffer tsbkBuffer2 = new BitSetBuffer( mMessage.get(
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TSBK_BEGIN, TSBK_DECODED_END ), 98 );
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TSBKMessage tsbkMessage2 =
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TSBKMessageFactory.getMessage( tsbkSystem2, tsbkBuffer2 );
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if( tsbkMessage2.isLastBlock() )
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{
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mComplete = true;
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}
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else
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{
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setDUID( DataUnitID.TSBK3 );
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mMessage.setPointer( TSBK_BEGIN );
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}
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dispatch( tsbkMessage2 );
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break;
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case TSBK3:
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/* Remove interleaving */
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P25Interleave.deinterleave( mMessage, TSBK_BEGIN, TSBK_END );
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/* Remove trellis encoding */
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mHalfRate.decode( mMessage, TSBK_BEGIN, TSBK_END );
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/* Construct the message */
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int tsbkSystem3 = mMessage.getInt( P25Message.NAC );
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BitSetBuffer tsbkBuffer3 = new BitSetBuffer( mMessage.get(
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TSBK_BEGIN, TSBK_DECODED_END ), 96 );
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TSBKMessage tsbkMessage3 =
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TSBKMessageFactory.getMessage( tsbkSystem3, tsbkBuffer3 );
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mComplete = true;
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dispatch( tsbkMessage3 );
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break;
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case UNKN:
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mComplete = true;
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dispatch( new P25Message( mMessage.copy(), mDUID ) );
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break;
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default:
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mComplete = true;
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break;
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}
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}
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public void dispose()
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{
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mMessage = null;
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mHalfRate.dispose();
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}
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/**
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* Flag to indicate when this assembler has received all of the bits it
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* is looking for (ie message length), and should then be removed from
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* receiving any more bits
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*/
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public boolean complete()
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{
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return mComplete;
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}
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public boolean isActive()
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{
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return mActive;
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}
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}
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}
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