//
// Copyright (C) 2006 United States Government as represented by the
// Administrator of the National Aeronautics and Space Administration
// (NASA).  All Rights Reserved.
// 
// This software is distributed under the NASA Open Source Agreement
// (NOSA), version 1.3.  The NOSA has been approved by the Open Source
// Initiative.  See the file NOSA-1.3-JPF at the top of the distribution
// directory tree for the complete NOSA document.
// 
// THE SUBJECT SOFTWARE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY OF ANY
// KIND, EITHER EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT
// LIMITED TO, ANY WARRANTY THAT THE SUBJECT SOFTWARE WILL CONFORM TO
// SPECIFICATIONS, ANY IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR
// A PARTICULAR PURPOSE, OR FREEDOM FROM INFRINGEMENT, ANY WARRANTY THAT
// THE SUBJECT SOFTWARE WILL BE ERROR FREE, OR ANY WARRANTY THAT
// DOCUMENTATION, IF PROVIDED, WILL CONFORM TO THE SUBJECT SOFTWARE.
//
package gov.nasa.jpf.jvm.bytecode;

import cmu.conditional.Conditional;
import de.fosd.typechef.featureexpr.FeatureExpr;
import gov.nasa.jpf.jvm.JVMInstruction;
import gov.nasa.jpf.vm.Instruction;
import gov.nasa.jpf.vm.StackFrame;
import gov.nasa.jpf.vm.ThreadInfo;

/**
 * Compare long ..., value1, value2 => ..., result
 */
public class LCMP extends JVMInstruction {

	@Override
	public Conditional<Instruction> execute(FeatureExpr ctx, ThreadInfo ti) {
		StackFrame frame = ti.getModifiableTopFrame();

		final Conditional<Long> v1 = frame.popLong(ctx);
		final Conditional<Long> v2 = frame.popLong(ctx);
		frame.push(ctx, v2.mapr(x2 -> v1.map(x1 -> instruction(x1, x2))).simplify());
		
		return getNext(ctx, ti);
	}

	private static int instruction(Long v1, Long v2) {
		if (v1.longValue() == v2.longValue()) {
			return 0;
		} else if (v2.longValue() > v1.longValue()) {
			return 1;
		} else {
			return -1;
		}
	}

	@Override
	public int getByteCode() {
		return 0x94;
	}

	@Override
	public void accept(InstructionVisitor insVisitor) {
		insVisitor.visit(this);
	}
}