Package jmri.jmrix.mrc

Class MrcPacketizer

java.lang.Object

jmri.jmrix.mrc.MrcTrafficController

jmri.jmrix.mrc.MrcPacketizer

All Implemented Interfaces:

MrcInterface

public class MrcPacketizer
extends MrcTrafficController

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

This is based upon the Packetizer used for LocoNet Connections due to its speed and efficiency to handle messages. This also takes some code from the AbstractMRTrafficController, when dealing with handling replies to messages sent. The MRC Command Station sends out a poll message to each handset which then has approximately 20ms to initially respond with a request. Otherwise the Command Station will poll the next handset.

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 MRC, 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 Mrc Inc for separate permission.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
(package private) static class	MrcPacketizer.Echo
(package private) static class	MrcPacketizer.Failed
(package private) class	MrcPacketizer.RcvHandler	Captive class to handle incoming characters.
(package private) class	MrcPacketizer.XmtHandler	Captive class to handle transmission

Field Summary

Fields

Modifier and Type	Field	Description
(package private) static final int	BADCOMMAND
(package private) static final int	CONFIRMATIONONLY
(package private) int	consecutiveMissedPolls
MrcPortController	controller
(package private) static final int	DOUBLELOCOCONTROL
protected boolean	echo	true if the external hardware is not echoing messages, so we must
(package private) static final int	IDLESTATE
DataInputStream	istream
(package private) int	mCurrentState
(package private) static final int	MISSEDPOLL
(package private) final MrcMessage	noData
(package private) final byte[]	noDataMsg
OutputStream	ostream
protected Runnable	rcvHandler	RcvHandler (a local class) object to implement the receive thread
(package private) static final Object	transmitLock
(package private) static final int	WAITFORCMDRECEIVED
protected Runnable	xmtHandler	XmtHandler (a local class) object to implement the transmit thread
LinkedList<MrcMessage>	xmtList	Synchronized list used as a transmit queue.

Fields inherited from class jmri.jmrix.mrc.MrcTrafficController

adaptermemo, cabAddress, receivedByteCount, receivedMsgCount, trafficListeners, transmittedMsgCount

Fields inherited from interface jmri.jmrix.mrc.MrcInterface

ALL, CLOCK, POLL, POWER, PROGRAMMING, SENSORS, THROTTLEINFO, TURNOUTS

Constructor Summary

Constructors

Constructor	Description
MrcPacketizer()

Method Summary

Modifier and Type	Method	Description
void	connectPort(MrcPortController p)	Make connection to existing MrcPortController object.
void	disconnectPort(MrcPortController p)	Break connection to existing MrcPortController object.
boolean	isXmtBusy()	Implement abstract method to signal if there's a backlog of information waiting to be sent.
protected void	messageFailed(MrcMessage m)
protected void	messageTransmitted(MrcMessage msg)	When a message is finally transmitted, forward it to listeners if echoing is needed.
protected byte	readByteProtected(DataInputStream istream)	Read a single byte, protecting against various timeouts, etc.
void	sendMrcMessage(MrcMessage m)	Forward a preformatted MrcMessage to the actual interface.
void	startThreads()	Invoked at startup to start the threads needed here.
boolean	status()
protected void	transmitWait(int waitTime, int state, String InterruptMessage, int x)

Methods inherited from class jmri.jmrix.mrc.MrcTrafficController

addTrafficListener, changeTrafficListener, getAdapterMemo, getCabNumber, getReceivedByteCount, getReceivedMsgCount, getSystemPrefix, getTransmittedMsgCount, getUserName, notifyRcv, notifyXmit, removeTrafficListener, resetStatistics, setAdapterMemo, setCabNumber

Methods inherited from class java.lang.Object

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

Field Details

echo

protected boolean echo

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

xmtList

public LinkedList<MrcMessage> 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 MrcPortController controller

istream

public DataInputStream istream

ostream

public OutputStream ostream

IDLESTATE

static final int IDLESTATE

See Also:

• Constant Field Values

WAITFORCMDRECEIVED

static final int WAITFORCMDRECEIVED

See Also:

• Constant Field Values

DOUBLELOCOCONTROL

static final int DOUBLELOCOCONTROL

See Also:

• Constant Field Values

MISSEDPOLL

static final int MISSEDPOLL

See Also:

• Constant Field Values

BADCOMMAND

static final int BADCOMMAND

See Also:

• Constant Field Values

CONFIRMATIONONLY

static final int CONFIRMATIONONLY

See Also:

• Constant Field Values

mCurrentState

int mCurrentState

consecutiveMissedPolls

int consecutiveMissedPolls

noData

final MrcMessage noData

noDataMsg

final byte[] noDataMsg

transmitLock

static final Object transmitLock

Constructor Details

MrcPacketizer

public MrcPacketizer()

Method Details

status

public boolean status()

Specified by:

status in interface MrcInterface

Specified by:

status in class MrcTrafficController

sendMrcMessage

public void sendMrcMessage(MrcMessage m)

Forward a preformatted MrcMessage to the actual interface. The message is converted to a byte array and queue for transmission

Specified by:

sendMrcMessage in interface MrcInterface

Specified by:

sendMrcMessage in class MrcTrafficController

Parameters:

m - Message to send;

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 MrcTrafficController

Returns:

true if busy, false if nothing waiting to send

connectPort

public void connectPort(MrcPortController p)

Make connection to existing MrcPortController object.

Parameters:

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

disconnectPort

public void disconnectPort(MrcPortController p)

Break connection to existing MrcPortController 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 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.

Parameters:

istream - data input stream from layout

Returns:

byte stream from interface

Throws:

IOException - from read errors

transmitWait

protected void transmitWait(int waitTime,
 int state,
 String InterruptMessage,
 int x)

messageFailed

protected void messageFailed(MrcMessage m)

messageTransmitted

protected void messageTransmitted(MrcMessage msg)

When a message is finally transmitted, forward it to listeners if echoing is needed.

Parameters:

msg - message to tag a transmitted message

startThreads

public void startThreads()

Invoked at startup to start the threads needed here.