001/* Output true if the input is present, false otherwise.
002
003 Copyright (c) 1997-2014 The Regents of the University of California.
004 All rights reserved.
005 Permission is hereby granted, without written agreement and without
006 license or royalty fees, to use, copy, modify, and distribute this
007 software and its documentation for any purpose, provided that the above
008 copyright notice and the following two paragraphs appear in all copies
009 of this software.
010
011 IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY
012 FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
013 ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF
014 THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF
015 SUCH DAMAGE.
016
017 THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
018 INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
019 MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE
020 PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND THE UNIVERSITY OF
021 CALIFORNIA HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES,
022 ENHANCEMENTS, OR MODIFICATIONS.
023
024 PT_COPYRIGHT_VERSION_2
025 COPYRIGHTENDKEY
026
027 */
028package ptolemy.actor.lib.logic;
029
030import ptolemy.actor.lib.Transformer;
031import ptolemy.data.BooleanToken;
032import ptolemy.data.type.BaseType;
033import ptolemy.kernel.CompositeEntity;
034import ptolemy.kernel.util.IllegalActionException;
035import ptolemy.kernel.util.NameDuplicationException;
036
037///////////////////////////////////////////////////////////////////
038//// IsPresent
039
040/**
041 On each firing, output true if the input is present and false otherwise.
042 The type of the output port is boolean, and the input is general.
043 The width of the input is expected to match the width of the output.
044 Note that the utility of this actor varies by domain.  In PN, for
045 example, the input is always present (by definition). In SDF, it is
046 expected to be always present, but may not be.  In DE, the actor is
047 only triggered if one of the input channels has data.  The actor is
048 probably most useful in synchronous domains like SR and Giotto.
049
050 @author Edward A. Lee
051 @version $Id$
052 @since Ptolemy II 2.0
053 @Pt.ProposedRating Yellow (eal)
054 @Pt.AcceptedRating Red (eal)
055 */
056public class IsPresent extends Transformer {
057    /** Construct an actor in the specified container with the specified
058     *  name.
059     *  @param container The container.
060     *  @param name The name of this actor within the container.
061     *  @exception IllegalActionException If the actor cannot be contained
062     *   by the proposed container.
063     *  @exception NameDuplicationException If the name coincides with
064     *   an actor already in the container.
065     */
066    public IsPresent(CompositeEntity container, String name)
067            throws IllegalActionException, NameDuplicationException {
068        super(container, name);
069        input.setTypeEquals(BaseType.GENERAL);
070        input.setMultiport(true);
071        output.setTypeEquals(BaseType.BOOLEAN);
072        output.setMultiport(true);
073
074        input.setWidthEquals(output, true);
075
076        _attachText("_iconDescription",
077                "<svg>\n" + "<rect x=\"-15\" y=\"-15\" "
078                        + "width=\"30\" height=\"30\" "
079                        + "style=\"fill:white\"/>\n" + "<text x=\"-4\" y=\"8\""
080                        + "style=\"font-size:24\">?</text>\n" + "</svg>\n");
081    }
082
083    ///////////////////////////////////////////////////////////////////
084    ////                         public methods                    ////
085
086    /** Consume at most one token from each input channel, and output
087     *  a boolean on the corresponding output channel (if there is one).
088     *  The value of the boolean is true if the input is present and
089     *  false otherwise.
090     */
091    @Override
092    public void fire() throws IllegalActionException {
093        super.fire();
094        int outputWidth = output.getWidth();
095
096        for (int i = 0; i < input.getWidth(); i++) {
097            if (input.hasToken(i)) {
098                // Consume the token.
099                input.get(i);
100
101                if (i < outputWidth) {
102                    output.send(i, BooleanToken.TRUE);
103                }
104            } else {
105                if (i < outputWidth) {
106                    output.send(i, BooleanToken.FALSE);
107                }
108            }
109        }
110    }
111}