Package ptolemy.domains.sdf.lib

Class VariableFIR

  • All Implemented Interfaces:
    java.lang.Cloneable, Actor, Executable, FiringsRecordable, Initializable, SequenceActor, TypedActor, Changeable, Debuggable, DebugListener, Derivable, Instantiable, ModelErrorHandler, MoMLExportable, Moveable, Nameable
    public class VariableFIR
extends FIR
    This actor implements a type polymorphic finite-impulse response filter with multirate capability, where the impulse response of the filter is provided by an input. Since this filter operates on Tokens, it is polymorphic in the type of data it operates on.

    If the decimation parameter is unity (the default), then the blockSize parameter specifies the number of inputs of the filter that are processed per coefficient set provided on the newTaps input. Otherwise, if decimation is greater than unity, then the number of tokens consumed is the product of decimation and blockSize, and all these inputs are processed using the filter coefficients provided on newTaps. In all other respects, the behavior of this actor is the same as that of the base class.

    Note that when a new set of filter coefficients arrives on newTaps, if the new set has more coefficients than the old set, then a transient will occur that may be unexpected. The delay line containing previously consumed data has to be increased in length to match the number of new coefficients. However, the extended part of the delay line cannot possibly be initialized with previously consumed data because that data has not been saved. Unless this actor were to save all previously consumed data (which would be hopelessly inefficient), there is no way it can be assured of always having the requisite data. Thus, the actor initializes the extended part of the delay line with zeros of the same type as the input data.

    Since:
    Ptolemy II 1.0
    Version:
    $Id$
    Author:
    Edward A. Lee, Yuhong Xiong
    See Also:
    Token
    Pt.AcceptedRating:
    Yellow (neuendor)
    Pt.ProposedRating:
    Yellow (neuendor)

    • Field Detail

      • blockSize

        public Parameter blockSize
        The number of inputs that use each each coefficient set is the value of this parameter multiplied by the value of the decimation parameter. This is an integer that defaults to 1.

      • newTaps

        public TypedIOPort newTaps
        The input for new tap values. This is an array.

    • Method Detail

      • attributeChanged

        public void attributeChanged​(Attribute attribute)
                      throws IllegalActionException
        Set a flag that causes recalculation of various local variables that are used in execution on the next invocation of fire().
        Overrides:
        attributeChanged in class FIR
        Parameters:
        attribute - The attribute that changed.
        Throws:
        IllegalActionException - If the attribute contains an invalid value or if the super method throws it.

      • clone

        public java.lang.Object clone​(Workspace workspace)
                       throws java.lang.CloneNotSupportedException
        Clone the actor into the specified workspace. This calls the base class and then resets the type constraints.
        Overrides:
        clone in class FIR
        Parameters:
        workspace - The workspace for the new object.
        Returns:
        A new actor.
        Throws:
        java.lang.CloneNotSupportedException - If a derived class contains an attribute that cannot be cloned.
        See Also:
        NamedObj.exportMoML(Writer, int, String), NamedObj.setDeferringChangeRequests(boolean)

      • fire

        public void fire()
          throws IllegalActionException
        Consume the inputs and produce the outputs of the FIR filter.
        Specified by:
        fire in interface Executable
        Overrides:
        fire in class FIR
        Throws:
        IllegalActionException - If parameter values are invalid, or if there is no director, or if runtime type conflicts occur.

      • prefire

        public boolean prefire()
                throws IllegalActionException
        Return false if the input does not have enough tokens to fire. Otherwise, return true.
        Specified by:
        prefire in interface Executable
        Overrides:
        prefire in class FIR
        Returns:
        False if the number of input tokens available is not at least equal to the decimation parameter multiplied by the blockSize parameter.
        Throws:
        IllegalActionException - If the superclass throws it.