/*******************************************************************************
* 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.InputStream;
import java.io.PrintWriter;
import org.sat4j.specs.ContradictionException;
import org.sat4j.specs.IProblem;
import org.sat4j.specs.ISolver;
import org.sat4j.tools.GateTranslator;
/**
* Reader for the Binary And Inverter Graph format defined by Armin Biere.
*
* @author daniel
*
*/
public class AIGReader extends Reader {
private final static int FALSE = 0;
private final static int TRUE = 1;
private final GateTranslator solver;
private int maxvarid;
private int nbinputs;
AIGReader(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);
}
}
int parseInt(InputStream in, char expected) throws IOException,
ParseFormatException {
int res, ch;
ch = in.read();
if (ch < '0' || ch > '9')
throw new ParseFormatException("expected digit");
res = ch - '0';
while ((ch = in.read()) >= '0' && ch <= '9')
res = 10 * res + (ch - '0');
if (ch != expected)
throw new ParseFormatException("unexpected character");
return res;
}
/*
* (non-Javadoc)
*
* @see org.sat4j.reader.Reader#parseInstance(java.io.InputStream)
*/
@Override
public IProblem parseInstance(InputStream in) throws ParseFormatException,
ContradictionException, IOException {
if (in.read() != 'a' || in.read() != 'i' || in.read() != 'g'
|| in.read() != ' ') {
throw new ParseFormatException("AIG format only!");
}
maxvarid = parseInt(in, ' ');
nbinputs = parseInt(in, ' ');
int nblatches = parseInt(in, ' ');
if (nblatches > 0) {
throw new ParseFormatException(
"CNF conversion cannot handle latches!");
}
int nboutputs = parseInt(in, ' ');
if (nboutputs > 1) {
throw new ParseFormatException(
"CNF conversion allowed for single output circuit only!");
}
int nbands = parseInt(in, '\n');
solver.newVar(maxvarid + 1);
solver.setExpectedNumberOfClauses(3 * nbands + 2);
if (nboutputs > 0) {
assert nboutputs == 1;
int output0 = parseInt(in, '\n');
readAnd(nbands, output0, in, 2 * (nbinputs + 1));
}
return solver;
}
static int safeGet(InputStream in) throws IOException, ParseFormatException {
int ch = in.read();
if (ch == -1) {
throw new ParseFormatException("AIG Error, EOF met too early");
}
return ch;
}
static int decode(InputStream in) throws IOException, ParseFormatException {
int x = 0, i = 0;
int ch;
while (((ch = safeGet(in)) & 0x80) > 0) {
System.out.println("=>" + ch);
x |= (ch & 0x7f) << (7 * i++);
}
return x | (ch << (7 * i));
}
private void readAnd(int nbands, int output0, InputStream in, int startid)
throws ContradictionException, IOException, ParseFormatException {
int lhs = startid;
for (int i = 0; i < nbands; i++) {
int delta0 = decode(in);
int delta1 = decode(in);
int rhs0 = lhs - delta0;
int rhs1 = rhs0 - delta1;
solver.and(toDimacs(lhs), toDimacs(rhs0), toDimacs(rhs1));
lhs += 2;
}
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;
}
@Override
public IProblem parseInstance(java.io.Reader in)
throws ParseFormatException, ContradictionException, IOException {
throw new UnsupportedOperationException();
}
}