ptolemy.actor.lib.comm
Class DeScrambler

java.lang.Object
  ptolemy.kernel.util.NamedObj
      ptolemy.kernel.InstantiableNamedObj
          ptolemy.kernel.Entity
              ptolemy.kernel.ComponentEntity
                  ptolemy.actor.AtomicActor
                      ptolemy.actor.TypedAtomicActor
                          ptolemy.actor.lib.Transformer
                              ptolemy.actor.lib.comm.DeScrambler

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable, Actor, Executable, FiringsRecordable, Initializable, TypedActor, Changeable, Debuggable, DebugListener, Derivable, Instantiable, ModelErrorHandler, MoMLExportable, Moveable, Nameable

public class DeScrambler
extends Transformer

Descramble the input bit sequence using a feedback shift register. The taps of the feedback shift register are given by the polynomial parameter. The initial state of the shift register is given by the initialState parameter. This is a self-synchronizing descrambler that will exactly reverse the operation of the Scrambler if the polynomials are the same. The low-order bit of the polynomial should always be set. For more information, see the documentation for the Scrambler actor and Lee and Messerschmitt, Digital Communication, Second Edition, Kluwer Academic Publishers, 1994, pp. 595-603.

Since:

Ptolemy II 3.0

Version:

$Id: DeScrambler.java 57040 2010-01-27 20:52:32Z cxh $

Author:

Edward A. Lee and Ye Zhou

See Also:

Serialized Form

Accepted Rating:

Red (cxh)

Proposed Rating:

Red (eal)

Nested Class Summary

Nested classes/interfaces inherited from class ptolemy.kernel.Entity

Entity.ContainedObjectsIterator

Field Summary

private int	_latestShiftReg
private int	_shiftReg
Parameter	initialState Integer defining the initial state of the shift register.
Parameter	polynomial Integer defining a polynomial with binary coefficients.

Fields inherited from class ptolemy.actor.lib.Transformer

input, output

Fields inherited from class ptolemy.actor.AtomicActor

_actorFiringListeners, _initializables, _notifyingActorFiring, _stopRequested

Fields inherited from class ptolemy.kernel.util.NamedObj

_changeListeners, _changeLock, _changeRequests, _debugging, _debugListeners, _elementName, _isPersistent, _verbose, _workspace, ATTRIBUTES, CLASSNAME, COMPLETE, CONTENTS, DEEP, FULLNAME, LINKS

Fields inherited from interface ptolemy.actor.Executable

COMPLETED, NOT_READY, STOP_ITERATING

Constructor Summary

DeScrambler(CompositeEntity container, java.lang.String name)
Construct an actor with the given container and name.

Method Summary

void	attributeChanged(Attribute attribute) If the attribute being changed is polynomial, then verify that is a positive integer and the lower-order bit is 1.
void	fire() Read bit from the input port and fill it into the shift register to descramble.
void	initialize() Initialize the actor by resetting the shift register state equal to the value of initialState.
boolean	postfire() Record the most recent shift register state as the new initial state for the next iteration.

Methods inherited from class ptolemy.actor.TypedAtomicActor

_addPort, _fireAt, _fireAt, attributeTypeChanged, clone, newPort, typeConstraintList, typeConstraints

Methods inherited from class ptolemy.actor.AtomicActor

_actorFiring, _actorFiring, addActorFiringListener, addInitializable, clone, connectionsChanged, createReceivers, declareDelayDependency, getCausalityInterface, getDirector, getExecutiveDirector, getManager, inputPortList, isFireFunctional, isStrict, iterate, newReceiver, outputPortList, prefire, preinitialize, pruneDependencies, recordFiring, removeActorFiringListener, removeDependency, removeInitializable, setContainer, stop, stopFire, terminate, wrapup

Methods inherited from class ptolemy.kernel.ComponentEntity

_adjustDeferrals, _checkContainer, _getContainedObject, _propagateExistence, getContainer, instantiate, isAtomic, isOpaque, moveDown, moveToFirst, moveToIndex, moveToLast, moveUp, propagateExistence, setName

Methods inherited from class ptolemy.kernel.Entity

_description, _exportMoMLContents, _removePort, _validateSettables, connectedPortList, connectedPorts, containedObjectsIterator, getAttribute, getPort, getPorts, linkedRelationList, linkedRelations, portList, removeAllPorts, setClassDefinition, uniqueName

Methods inherited from class ptolemy.kernel.InstantiableNamedObj

_setParent, exportMoML, getChildren, getElementName, getParent, getPrototypeList, isClassDefinition, isWithinClassDefinition

Methods inherited from class ptolemy.kernel.util.NamedObj

_addAttribute, _adjustOverride, _attachText, _cloneFixAttributeFields, _debug, _debug, _debug, _debug, _debug, _getIndentPrefix, _isMoMLSuppressed, _markContentsDerived, _propagateValue, _recordDecoratedAttributes, _removeAttribute, _splitName, _stripNumericSuffix, addChangeListener, addDebugListener, attributeList, attributeList, deepContains, depthInHierarchy, description, description, event, executeChangeRequests, exportMoML, exportMoML, exportMoML, exportMoML, exportMoMLPlain, getAttribute, getAttributes, getChangeListeners, getClassName, getDecoratorAttribute, getDecoratorAttributes, getDerivedLevel, getDerivedList, getDisplayName, getFullName, getModelErrorHandler, getName, getName, getSource, handleModelError, isDeferringChangeRequests, isOverridden, isPersistent, lazyContainedObjectsIterator, message, propagateValue, propagateValues, removeChangeListener, removeDebugListener, requestChange, setClassName, setDeferringChangeRequests, setDerivedLevel, setDisplayName, setModelErrorHandler, setPersistent, setSource, sortContainedObjects, toplevel, toString, validateSettables, workspace

Methods inherited from class java.lang.Object

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

Methods inherited from interface ptolemy.actor.Actor

createReceivers, getCausalityInterface, getDirector, getExecutiveDirector, getManager, inputPortList, newReceiver, outputPortList

Methods inherited from interface ptolemy.actor.Executable

isFireFunctional, isStrict, iterate, prefire, stop, stopFire, terminate

Methods inherited from interface ptolemy.actor.Initializable

addInitializable, preinitialize, removeInitializable, wrapup

Methods inherited from interface ptolemy.kernel.util.Nameable

description, getContainer, getDisplayName, getFullName, getName, getName, setName

Methods inherited from interface ptolemy.kernel.util.Derivable

getDerivedLevel, getDerivedList, propagateValue

Field Detail

polynomial

public Parameter polynomial

Integer defining a polynomial with binary coefficients. The coefficients indicate the presence (1) or absence (0) of a tap in a feedback shift register. This parameter should contain a positive integer with the lower-order bit being 1. Its default value is the integer 0440001.

initialState

public Parameter initialState

Integer defining the initial state of the shift register. The n-th bit of the integer indicates the value of the n-th register. This parameter should be a non-negative integer. Its default value is the integer 1.

_shiftReg

private int _shiftReg

_latestShiftReg

private int _latestShiftReg

Constructor Detail

DeScrambler

public DeScrambler(CompositeEntity container,
                   java.lang.String name)
            throws NameDuplicationException,
                   IllegalActionException

Construct an actor with the given container and name. The output and trigger ports are also constructed.

Parameters:

container - The container.

name - The name of this actor.

Throws:

IllegalActionException - If the entity cannot be contained by the proposed container.

NameDuplicationException - If the container already has an actor with this name.

Method Detail

attributeChanged

public void attributeChanged(Attribute attribute)
                      throws IllegalActionException

If the attribute being changed is polynomial, then verify that is a positive integer and the lower-order bit is 1.

Overrides:

attributeChanged in class NamedObj

Parameters:

attribute - The attribute that changed.

Throws:

IllegalActionException - If polynomial is non-positive or the lower-order bit is not 1.

fire

public void fire()
          throws IllegalActionException

Read bit from the input port and fill it into the shift register to descramble. Compute the parity and send it to the output port.

Specified by:

fire in interface Executable

Overrides:

fire in class AtomicActor

Throws:

IllegalActionException - Not thrown in this base class.

initialize

public void initialize()
                throws IllegalActionException

Initialize the actor by resetting the shift register state equal to the value of initialState.

Specified by:

initialize in interface Initializable

Overrides:

initialize in class AtomicActor

Throws:

IllegalActionException - If the parent class throws it.

postfire

public boolean postfire()
                 throws IllegalActionException

Record the most recent shift register state as the new initial state for the next iteration.

Specified by:

postfire in interface Executable

Overrides:

postfire in class AtomicActor

Returns:

True if execution can continue into the next iteration.

Throws:

IllegalActionException - If the base class throws it.