LOOKUPSWITCH.java :  » Code-Analyzer » javapathfinder » gov » nasa » jpf » jvm » bytecode » Java Open Source

//
// Copyright (C) 2005 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 gov.nasa.jpf.jvm.KernelState;
import gov.nasa.jpf.jvm.SystemState;
import gov.nasa.jpf.jvm.ThreadInfo;

import org.apache.bcel.classfile.ConstantPool;
import org.apache.bcel.generic.InstructionHandle;


/**
 * Access jump table by key match and jump
 * ..., key => ...
 */
public class LOOKUPSWITCH extends Instruction {
  private int   target;
  private int[] matches;
  private int[] targets;

  public void setPeer (org.apache.bcel.generic.Instruction i, ConstantPool cp) {
    target = ((org.apache.bcel.generic.LOOKUPSWITCH) i).getTarget()
                                                     .getPosition();
    matches = ((org.apache.bcel.generic.LOOKUPSWITCH) i).getMatchs();

    int length = matches.length;
    targets = new int[length];

    InstructionHandle[] ih = ((org.apache.bcel.generic.LOOKUPSWITCH) i).getTargets();

    for (int j = 0; j < length; j++) {
      targets[j] = ih[j].getPosition();
    }
  }

  public Instruction execute (SystemState ss, KernelState ks, ThreadInfo th) {
    int value = th.pop();

    for (int i = 0, l = matches.length; i < l; i++) {
      if (value == matches[i]) {
        return th.getMethod().getInstructionAt(targets[i]);
      }
    }

    return th.getMethod().getInstructionAt(target);
  }

  public int getByteCode () {
    return 0xAB;
  }
}