NeighborOnPathSelectionAlgorithm.java

/**
 * ****************************************************************************
 * Copyright (c) 2010-2016 by Min Cai (min.cai.china@gmail.com).
 * <p>
 * This file is part of the Archimulator multicore architectural simulator.
 * <p>
 * Archimulator is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * <p>
 * Archimulator is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * <p>
 * You should have received a copy of the GNU General Public License
 * along with Archimulator. If not, see <http://www.gnu.org/licenses/>.
 * ****************************************************************************
 */
package archimulator.uncore.noc.selection;

import archimulator.uncore.noc.Direction;
import archimulator.uncore.noc.Node;
import archimulator.uncore.noc.routers.Router;

import java.util.List;

/**
 * Neighbor-on-Path (NoP) selection algorithm.
 *
 * @author Min Cai
 */
public class NeighborOnPathSelectionAlgorithm extends AbstractSelectionAlgorithm {
    /**
     * Create a neighbor-on-Path (NoP) selection algorithm for the specified node.
     *
     * @param node the parent node
     */
    public NeighborOnPathSelectionAlgorithm(Node node) {
        super(node);
    }

    /**
     * Select the best output direction from a list of candidate output directions.
     *
     * @param src the source node ID
     * @param dest the destination node ID
     * @param ivc the input virtual channel ID
     * @param directions the list of candidate output directions
     * @return the best output direction selected from a list of candidate output directions
     */
    @Override
    public Direction select(int src, int dest, int ivc, List<Direction> directions) {
        double maxScore = -1.0;
        Direction directionWithMaxScore = null;

        for(Direction direction : directions) {
            Router neighborRouter = this.getNode().getNetwork().getNodes().get(this.getNode().getNeighbors().get(direction)).getRouter();

            if(neighborRouter.getNode().getId() == dest) {
                return direction;
            }

            double score = ((NeighborOnPathSelectionAlgorithm) (neighborRouter.getNode().getSelectionAlgorithm())).nopScore(
                    src, dest, this.getNode().getId(), ivc
            );
            if(score > maxScore) {
                maxScore = score;
                directionWithMaxScore = direction;
            }
        }

        return directionWithMaxScore;
    }

    /**
     * Get the NoP score.
     *
     * @param src the source node ID
     * @param dest the destination node ID
     * @param parent the parent node ID
     * @param ivc the input virtual channel ID
     * @return the NoP score
     */
    private double nopScore(int src, int dest, int parent, int ivc) {
        List<Direction> directions = this.getNode().getRoutingAlgorithm().nextHop(
                src, dest, parent
        );

        double score = 0.0;

        for(Direction direction : directions) {
            Router neighborRouter = this.getNode().getNetwork().getNodes().get(this.getNode().getNeighbors().get(direction)).getRouter();
            score += neighborRouter.getFreeSlots(direction.getReflexDirection(), ivc);
        }

        return score;
    }
}