jmri.jmrix.loconet
Class LnPacketizer

java.lang.Object
  jmri.jmrix.loconet.LnTrafficController
      jmri.jmrix.loconet.LnPacketizer

All Implemented Interfaces:

LocoNetInterface

Direct Known Subclasses:

IBLnPacketizer, LnOverTcpPacketizer, LnPacketizer

public class LnPacketizer
extends LnTrafficController

Converts Stream-based I/O to/from LocoNet messages. The "LocoNetInterface" side sends/receives LocoNetMessage objects. The connection to a LnPortController is via a pair of *Streams, which then carry sequences of characters for transmission.

Messages come to this via the main GUI thread, and are forwarded back to listeners in that same thread. Reception and transmission are handled in dedicated threads by RcvHandler and XmtHandler objects. Those are internal classes defined here. The thread priorities are:

• RcvHandler - at highest available priority
• XmtHandler - down one, which is assumed to be above the GUI
• (everything else)

Some of the message formats used in this class are Copyright Digitrax, Inc. and used with permission as part of the JMRI project. That permission does not extend to uses in other software products. If you wish to use this code, algorithm or these message formats outside of JMRI, please contact Digitrax Inc for separate permission.

Author:

Bob Jacobsen Copyright (C) 2001

Field Summary

LnPortController	controller
protected boolean	echo true if the external hardware is not echoing messages, so we must
DataInputStream	istream
OutputStream	ostream
protected Runnable	rcvHandler RcvHandler (a local class) object to implement the receive thread
protected Runnable	xmtHandler XmtHandler (a local class) object to implement the transmit thread
LinkedList	xmtList Synchronized list used as a transmit queue.

Fields inherited from class jmri.jmrix.loconet.LnTrafficController

listeners, receivedByteCount, receivedMsgCount, self, transmittedMsgCount

Fields inherited from interface jmri.jmrix.loconet.LocoNetInterface

ALL, POWER, PROGRAMMING, SENSORS, SLOTINFO, TURNOUTS

Constructor Summary

LnPacketizer()

Method Summary

void	connectPort(LnPortController p) Make connection to existing LnPortController object.
void	disconnectPort(LnPortController p) Break connection to existing LnPortController object.
boolean	isXmtBusy() Implement abstract method to signal if there's a backlog of information waiting to be sent.
protected byte	readByteProtected(DataInputStream istream) Read a single byte, protecting against various timeouts, etc.
void	run() Handle incoming characters.
void	sendLocoNetMessage(LocoNetMessage m) Forward a preformatted LocoNetMessage to the actual interface.
void	startThreads() Invoked at startup to start the threads needed here.
boolean	status()

Methods inherited from class jmri.jmrix.loconet.LnTrafficController

addLocoNetListener, getReceivedByteCount, getReceivedMsgCount, getTransmittedMsgCount, instance, notify, removeLocoNetListener, resetStatistics

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

echo

protected boolean echo

true if the external hardware is not echoing messages, so we must

xmtList

public LinkedList xmtList

Synchronized list used as a transmit queue.

This is public to allow access from the internal class(es) when compiling with Java 1.1

xmtHandler

protected Runnable xmtHandler

XmtHandler (a local class) object to implement the transmit thread

rcvHandler

protected Runnable rcvHandler

RcvHandler (a local class) object to implement the receive thread

controller

public LnPortController controller

istream

public DataInputStream istream

ostream

public OutputStream ostream

Constructor Detail

LnPacketizer

public LnPacketizer()

Method Detail

status

public boolean status()

Specified by:

status in interface LocoNetInterface

Specified by:

status in class LnTrafficController

sendLocoNetMessage

public void sendLocoNetMessage(LocoNetMessage m)

Forward a preformatted LocoNetMessage to the actual interface. Checksum is computed and overwritten here, then the message is converted to a byte array and queue for transmission

Specified by:

sendLocoNetMessage in interface LocoNetInterface

Specified by:

sendLocoNetMessage in class LnTrafficController

Parameters:

m - Message to send; will be updated with CRC

isXmtBusy

public boolean isXmtBusy()

Implement abstract method to signal if there's a backlog of information waiting to be sent.

Specified by:

isXmtBusy in class LnTrafficController

Returns:

true if busy, false if nothing waiting to send

connectPort

public void connectPort(LnPortController p)

Make connection to existing LnPortController object.

Parameters:

p - Port controller for connected. Save this for a later disconnect call

disconnectPort

public void disconnectPort(LnPortController p)

Break connection to existing LnPortController object. Once broken, attempts to send via "message" member will fail.

Parameters:

p - previously connected port

readByteProtected

protected byte readByteProtected(DataInputStream istream)
                          throws IOException

Read a single byte, protecting against various timeouts, etc.

When a javax.comm port is set to have a receive timeout (via the enableReceiveTimeout() method), some will return zero bytes or an EOFException at the end of the timeout. In that case, the read should be repeated to get the next real character.

Throws:

IOException

run

public void run()

Handle incoming characters. This is a permanent loop, looking for input messages in character form on the stream connected to the LnPortController via connectPort. Terminates with the input stream breaking out of the try block.

startThreads

public void startThreads()

Invoked at startup to start the threads needed here.