ptolemy.domains.continuous.lib
Class PeriodicSampler

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.domains.continuous.lib.PeriodicSampler

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 PeriodicSampler
extends Transformer

This actor generates discrete events by periodically sampling the input signal. The sampling rate is given by parameter "samplePeriod", which has default value 0.1. Specifically, if the actor is initialized at time t and the sample period is T, then the output will have the value of the input at times t + nT, for all natural numbers n. This sampler will send to the output the first non-absent input event that occurs at a sample time. It produces it one microstep later than that input event. This ensures that the output at microstep 0 is always absent, thus ensuring continuity from the left. That is, the input is absent prior to the sample time, so continuity requires that it be absent at microstep 0 at the sample time. Moreover, this ensures that the sampler outputs the initial value of the input at the sample time.

This actor has multiport inputs and outputs. Signals in each input channel are sampled and produced to corresponding output channel. When there are multiple inputs, the first non-absent input from each channel is read, and the output is produced at the first microstep after the last of the inputs became non-absent.

Since:

Ptolemy II 8.0

Version:

$Id: PeriodicSampler.java 57046 2010-01-27 23:35:53Z cxh $

Author:

Edward A. Lee

See Also:

Serialized Form

Accepted Rating:

Red (cxh)

Proposed Rating:

Yellow (eal)

Nested Class Summary

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

Entity.ContainedObjectsIterator

Field Summary

private boolean	_inputIsComplete Flag indicating that the record of inputs is complete.
private Time	_nextSamplingTime The next sampling time.
private Token[]	_recordedInputs The recorded input data.
Parameter	samplePeriod The parameter for the sampling period.

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

PeriodicSampler(CompositeEntity container, java.lang.String name)
Construct an actor in the specified container with the specified name.

Method Summary

java.lang.Object	clone(Workspace workspace) Clone this actor into the specified workspace.
void	fire() Generate an output if the current time is one of the sampling times.
void	initialize() Set the next sampling time as the start time (i.e. the current time).
boolean	postfire() Set the next sampling time and return true.
void	preinitialize() Make sure the actor runs inside a Continuous domain.

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, connectionsChanged, createReceivers, declareDelayDependency, getCausalityInterface, getDirector, getExecutiveDirector, getManager, inputPortList, isFireFunctional, isStrict, iterate, newReceiver, outputPortList, prefire, 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, attributeChanged, 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, 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

samplePeriod

public Parameter samplePeriod

The parameter for the sampling period. This is a double whose default value is 0.1.

_inputIsComplete

private boolean _inputIsComplete

Flag indicating that the record of inputs is complete.

_nextSamplingTime

private Time _nextSamplingTime

The next sampling time.

_recordedInputs

private Token[] _recordedInputs

The recorded input data.

Constructor Detail

PeriodicSampler

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

Construct an actor in the specified container with the specified name. The name must be unique within the container or an exception is thrown. The container argument must not be null, or a NullPointerException will be thrown. The actor can be either dynamic, or not. It must be set at the construction time and can't be changed thereafter. A dynamic actor will produce a token at its initialization phase.

Parameters:

container - The container of this actor.

name - The actor's name

Throws:

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

NameDuplicationException - If name coincides with an entity already in the container.

Method Detail

clone

public java.lang.Object clone(Workspace workspace)
                       throws java.lang.CloneNotSupportedException

Clone this actor into the specified workspace. The new actor is not added to the directory of that workspace (you must do this yourself if you want it there). The result is a new actor with the same ports as the original, but no connections and no container. A container must be set before much can be done with this actor.

Overrides:

clone in class AtomicActor

Parameters:

workspace - The workspace for the cloned object.

Returns:

A new ComponentEntity.

Throws:

java.lang.CloneNotSupportedException - If cloned ports cannot have as their container the cloned entity (this should not occur), or if one of the attributes cannot be cloned.

See Also:

NamedObj.exportMoML(Writer, int, String), NamedObj.setDeferringChangeRequests(boolean)

fire

public void fire()
          throws IllegalActionException

Generate an output if the current time is one of the sampling times. The value of the event is the value of the input signal at the current time.

Specified by:

fire in interface Executable

Overrides:

fire in class AtomicActor

Throws:

IllegalActionException - If the transfer of tokens failed.

initialize

public void initialize()
                throws IllegalActionException

Set the next sampling time as the start time (i.e. the current time). We do not register the start time as a breakpoint, since the director will fire at the start time any way.

Specified by:

initialize in interface Initializable

Overrides:

initialize in class AtomicActor

Throws:

IllegalActionException - If thrown by the supper class.

postfire

public boolean postfire()
                 throws IllegalActionException

Set the next sampling time and return true.

Specified by:

postfire in interface Executable

Overrides:

postfire in class AtomicActor

Returns:

True.

Throws:

IllegalActionException - If the superclass throws it.

preinitialize

public void preinitialize()
                   throws IllegalActionException

Make sure the actor runs inside a Continuous domain.

Specified by:

preinitialize in interface Initializable

Overrides:

preinitialize in class AtomicActor

Throws:

IllegalActionException - If the director is not a ContinuousDirector or the parent class throws it.