name.martingeisse.esdk.model.hdl.assembler.verilog.SignalDeclarationRequirementDetector.java Source code

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Here is the source code for name.martingeisse.esdk.model.hdl.assembler.verilog.SignalDeclarationRequirementDetector.java

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/**
 * Copyright (c) 2013 Martin Geisse
 *
 * This file is distributed under the terms of the MIT license.
 */

package name.martingeisse.esdk.model.hdl.assembler.verilog;

import java.util.HashSet;
import java.util.Set;
import org.apache.commons.collections.Bag;
import org.apache.commons.collections.bag.HashBag;
import name.martingeisse.esdk.model.hdl.core.BitSignal;
import name.martingeisse.esdk.model.hdl.core.Register;
import name.martingeisse.esdk.model.hdl.core.Signal;
import name.martingeisse.esdk.model.hdl.module.port.InputPort;
import name.martingeisse.esdk.model.hdl.util.RegisterBlockedRecursiveCommonHandlerSignalVisitor;

/**
 * This visitor checks which signals require top-level declaration.
 * This does not include registers.
 */
public class SignalDeclarationRequirementDetector extends RegisterBlockedRecursiveCommonHandlerSignalVisitor {

    /**
     * the result
     */
    private final Set<Signal> result;

    /**
     * the bag
     */
    private final Bag bag;

    /**
     * Constructor.
     */
    public SignalDeclarationRequirementDetector() {
        this.result = new HashSet<>();
        this.bag = new HashBag();
    }

    /* (non-Javadoc)
     * @see name.martingeisse.esdk.model.hdl.util.RecursiveCommonHandlerSignalVisitor#handleSignal(name.martingeisse.esdk.model.hdl.core.Signal)
     */
    @Override
    protected void handleSignal(final Signal signal) {

        // always declare the clock signal for registers, unless they are self-declaring
        if (signal instanceof Register<?, ?>) {
            final BitSignal clock = ((Register<?, ?>) signal).getClock();
            if (!isSelfDeclaring(clock)) {
                result.add(clock);
            }
            return;
        }

        // all non-self-declaring signals must be declared if used more than once
        if (!isSelfDeclaring(signal)) {
            if (!bag.add(signal)) {
                result.add(signal);
            }
        }

    }

    private boolean isSelfDeclaring(final Signal signal) {
        return ((signal instanceof InputPort<?>) || (signal instanceof Register<?, ?>));
    }

    /**
     * Getter method for the result.
     * @return the result
     */
    public Set<Signal> getResult() {
        return result;
    }

}