AAGReader.java

/*******************************************************************************
* SAT4J: a SATisfiability library for Java Copyright (C) 2004-2008 Daniel Le Berre
*
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU Lesser General Public License Version 2.1 or later (the
* "LGPL"), in which case the provisions of the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of the LGPL, and not to allow others to use your version of
* this file under the terms of the EPL, indicate your decision by deleting
* the provisions above and replace them with the notice and other provisions
* required by the LGPL. If you do not delete the provisions above, a recipient
* may use your version of this file under the terms of the EPL or the LGPL.
* 
* Based on the original MiniSat specification from:
* 
* An extensible SAT solver. Niklas Een and Niklas Sorensson. Proceedings of the
* Sixth International Conference on Theory and Applications of Satisfiability
* Testing, LNCS 2919, pp 502-518, 2003.
*
* See www.minisat.se for the original solver in C++.
* 
*******************************************************************************/
package org.sat4j.reader;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Scanner;

import org.sat4j.core.VecInt;
import org.sat4j.specs.ContradictionException;
import org.sat4j.specs.IProblem;
import org.sat4j.specs.ISolver;
import org.sat4j.specs.IVecInt;
import org.sat4j.tools.GateTranslator;

/**
 * Reader for the ASCII And Inverter Graph format defined by Armin Biere.
 * 
 * @author daniel
 *
 */
public class AAGReader extends Reader {

    private final static int FALSE = 0;

    private final static int TRUE = 1;

    private final GateTranslator solver;

    private int maxvarid;

    private int nbinputs;

    AAGReader(ISolver s) {
        solver = new GateTranslator(s);
    }

    @Override
    public String decode(int[] model) {
        StringBuffer stb = new StringBuffer();
        for (int i = 0; i < nbinputs; i++) {
            stb.append(model[i]>0?1:0);
        }
        return stb.toString();
    }

    @Override
    public void decode(int[] model, PrintWriter out) {
        for (int i = 0; i < nbinputs; i++) {
            out.print(model[i]>0?1:0);
        }
    }

    @Override
    public IProblem parseInstance(java.io.Reader in)
            throws ParseFormatException, ContradictionException, IOException {
        Scanner scanner = new Scanner(in);
        String prefix = scanner.next();
        if (!"aag".equals(prefix)) {
            throw new ParseFormatException("AAG format only!");
        }
        maxvarid = scanner.nextInt();
        nbinputs = scanner.nextInt();
        int nblatches = scanner.nextInt();
        int nboutputs = scanner.nextInt();
        if (nboutputs > 1) {
            throw new ParseFormatException(
                    "CNF conversion allowed for single output circuit only!");
        }
        int nbands = scanner.nextInt();
        solver.newVar(maxvarid + 1);
        solver.setExpectedNumberOfClauses(3 * nbands + 2);
        readInput(nbinputs, scanner);
        assert nblatches==0;
        if (nboutputs > 0) {
            int output0 = readOutput(nboutputs, scanner);
            readAnd(nbands, output0, scanner);
        }
        return solver;
    }

    private void readAnd(int nbands, int output0, Scanner scanner)
            throws ContradictionException {
        
        for (int i = 0; i < nbands; i++) {
            int lhs = scanner.nextInt();
            int rhs0 = scanner.nextInt();
            int rhs1 = scanner.nextInt();
            solver.and(toDimacs(lhs), toDimacs(rhs0), toDimacs(rhs1));
        }
        solver.gateTrue(maxvarid + 1);
        solver.gateTrue(toDimacs(output0));
    }

    private int toDimacs(int v) {
        if (v == FALSE) {
            return -(maxvarid + 1);
        }
        if (v == TRUE) {
            return maxvarid + 1;
        }
        int var = v >> 1;
        if ((v & 1) == 0) {
            return var;
        }
        return -var;
    }

    private int readOutput(int nboutputs, Scanner scanner) {
        IVecInt outputs = new VecInt(nboutputs);
        for (int i = 0; i < nboutputs; i++) {
            outputs.push(scanner.nextInt());
        }
        return outputs.get(0);
    }


    private IVecInt readInput(int numberOfInputs, Scanner scanner) {
        IVecInt inputs = new VecInt(numberOfInputs);
        for (int i = 0; i < numberOfInputs; i++) {
            inputs.push(scanner.nextInt());
        }
        return inputs;
    }

}