/* An abstract ancestor for filter actors acting on shared buffers

 Copyright (c) 1998-2015 The Regents of the University of California.
 All rights reserved.
 Permission is hereby granted, without written agreement and without
 license or royalty fees, to use, copy, modify, and distribute this
 software and its documentation for any purpose, provided that the above
 copyright notice and the following two paragraphs appear in all copies
 of this software.

 IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY
 FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
 ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF
 THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF
 SUCH DAMAGE.

 THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
 INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE
 PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND THE UNIVERSITY OF
 CALIFORNIA HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES,
 ENHANCEMENTS, OR MODIFICATIONS.

 PT_COPYRIGHT_VERSION_2
 COPYRIGHTENDKEY

 */

package ptolemy.domains.sdf.optimize;

import ptolemy.actor.lib.Transformer;
import ptolemy.kernel.CompositeEntity;
import ptolemy.kernel.util.IllegalActionException;
import ptolemy.kernel.util.NameDuplicationException;

///////////////////////////////////////////////////////////////////
////SharedBufferTransformer

/**
An abstract ancestor class to be used for filters
using references to shared data frames.
It implements a default version of the BufferingProfile interface.
<p>
See {@link ptolemy.domains.sdf.optimize.OptimizingSDFDirector} and
{@link ptolemy.domains.sdf.optimize.BufferingProfile} for more information.
</p>
@see ptolemy.domains.sdf.optimize.OptimizingSDFDirector
@see ptolemy.domains.sdf.optimize.BufferingProfile

@author Marc Geilen
@version $Id$
@since Ptolemy II 10.0
@Pt.ProposedRating Red (mgeilen)
@Pt.AcceptedRating Red ()
 */

public abstract class SharedBufferTransformer extends Transformer
        implements BufferingProfile {

    /**
     * Construct an instance of a SharedBufferTransformer. Should not be used
     * because this in an abstract class.
     * TODO Is there a way to avoid defining a constructor for this abstract class?
     *  @param container The container.
     *  @param name The name of this actor.
     *  @exception IllegalActionException If the actor cannot be contained
     *   by the proposed container.
     *  @exception NameDuplicationException If the container already has an
     *   actor with this name.
     */
    public SharedBufferTransformer(CompositeEntity container, String name)
            throws NameDuplicationException, IllegalActionException {
        super(container, name);
    }

    /**
     * initialize. Set the default firing to non exclusive.
     */
    @Override
    public void initialize() throws IllegalActionException {
        // default to copying firing
        _nextIterationExclusive = false;
        super.initialize();
    }

    /**
     * Fire according to the value _nextIterationExclusive in shared or exclusive
     * firing mode.
     */
    @Override
    public void fire() throws IllegalActionException {
        if (_nextIterationExclusive) {
            _fireExclusive();
        } else {
            _fireCopying();
        }
    }

    /**
     * Default value for number of frame buffers required for shared firing.
     * @return the number of buffers required for a shared buffer firing
     */
    @Override
    public int sharedBuffers() {
        return 1;
    }

    /**
     * Default value for number of frame buffers required for exclusive firing.
     * @return the number of buffers required for an exclusive buffer firing
     */
    @Override
    public int exclusiveBuffers() {
        return 0;
    }

    /**
     * Default value for execution time for shared firing.
     * @return execution time of a shared buffer firing
     */
    @Override
    public int sharedExecutionTime() {
        return 1;
    }

    /**
     * Default value for execution time for exclusive firing.
     * @return execution time of an exclusive buffer firing
     */
    @Override
    public int exclusiveExecutionTime() {
        return 2;
    }

    /**
     * Invoke a specified number of iterations of the actor in either shared or
     * exclusive mode as indicated by the fireExclusive argument.
     * @param iterationCount The number of iterations to perform.
     * @param fireExclusive whether to fire exclusive or not.
     * @return NOT_READY, STOP_ITERATING, or COMPLETED.
     * @exception IllegalActionException If iterating is not
     *  permitted, or if prefire(), fire(), or postfire() throw it.
     **/
    @Override
    public int iterate(int iterationCount, boolean fireExclusive)
            throws IllegalActionException {
        _nextIterationExclusive = fireExclusive;
        int result = super.iterate(iterationCount);
        // default to copying firing
        _nextIterationExclusive = false;
        return result;
    }

    ///////////////////////////////////////////////////////////////////
    ////                         protected methods                 ////

    /**
     * Fire the actor in shared firing mode.
     * Shared firing method to be implemented in subclasses.
     * @exception IllegalActionException If thrown while writing to the port.
     */
    protected abstract void _fireCopying() throws IllegalActionException;

    /**
     * Fire the actor in exclusive firing mode.
     * Exclusive firing method to be implemented in subclasses.
     * @exception IllegalActionException If thrown while writing to the port.
     */
    protected abstract void _fireExclusive() throws IllegalActionException;

    //// private fields
    /**
     * determines whether the next firing will be exclusive or shared
     */
    private boolean _nextIterationExclusive;

}