/*******************************************************************************
* Copyright 2012 Analog Devices, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
********************************************************************************/
package com.analog.lyric.dimple.factorfunctions;
import static java.util.Objects.*;
import com.analog.lyric.dimple.factorfunctions.core.FactorFunction;
import com.analog.lyric.dimple.model.domains.FiniteFieldNumber;
import com.analog.lyric.dimple.model.values.Value;
/**
* Deterministic finite field (GF(2^n)) addition. This is a deterministic directed factor.
* <p>
* The variables are ordered as follows in the argument list:
* <ol>
* <li>Output (FiniteFieldVariable; Output = input1 + input2)
* <li>Input1 (FiniteFieldVariable)
* <li>Input2 (FiniteFieldVariable)
* </ol>
* @since 0.05
*/
public class FiniteFieldAdd extends FactorFunction
{
@Override
public final double evalEnergy(Value[] arguments)
{
final int result = arguments[0].getInt();
final int input1 = arguments[1].getInt();
final int input2 = arguments[2].getInt();
final int computedResult = input1 ^ input2;
return (computedResult == result) ? 0 : Double.POSITIVE_INFINITY;
}
@Override
public final boolean isDirected() {return true;}
@Override
public final int[] getDirectedToIndices() {return new int[]{0};}
@Override
public final boolean isDeterministicDirected() {return true;}
@Override
public final void evalDeterministic(Value[] arguments)
{
// Allow one constant input
final Value arg1Value = arguments[1];
final Value arg2Value = arguments[2];
final Object arg1 = requireNonNull(arg1Value.getObject());
final Object arg2 = requireNonNull(arg2Value.getObject());
final FiniteFieldNumber input1 = (arg1 instanceof FiniteFieldNumber) ? (FiniteFieldNumber)arg1 : ((FiniteFieldNumber)arg2).cloneWithNewValue(arg1Value.getInt());
final FiniteFieldNumber input2 = (arg2 instanceof FiniteFieldNumber) ? (FiniteFieldNumber)arg2 : ((FiniteFieldNumber)arg1).cloneWithNewValue(arg2Value.getInt());
arguments[0].setFiniteField(input1.cloneWithNewValue(input1.intValue() ^ input2.intValue())); // Replace the output value
}
}