code: /**
   * Copyright (c) 2004-2005, Regents of the University of California
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * Redistributions of source code must retain the above copyright notice,
   * this list of conditions and the following disclaimer.
   *
   * Redistributions in binary form must reproduce the above copyright
   * notice, this list of conditions and the following disclaimer in the
   * documentation and/or other materials provided with the distribution.
   *
   * Neither the name of the University of California, Los Angeles nor the
   * names of its contributors may be used to endorse or promote products
   * derived from this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
   * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  package avrora.sim.util;
  
  import avrora.sim.Simulator;
  import avrora.sim.State;
  
  /**
   * The <code>BranchCounter</code> class is a profiling probe that can be inserted at a branch instruction to
   * count the number of times the branch is taken and not taken. It demonstrates the ability to inspect the
   * state of the program after the execution of a program. It determines whether the branch was taken by
   * inspecting the program counter of the new state. If the program counter is not equal to the instruction
   * following the branch, then the branch was taken.
   *
   * @author Ben L. Titzer
   * @see Counter
   */
  public class BranchCounter extends Simulator.Probe.Empty {
  
      /**
       * This field tracks the number of times the branch is taken. It is incremented in the
       * <code>fireAfter</code> method if the branch was taken.
       */
      public int takenCount;
  
      /**
       * This field tracks the number of times the branch is not taken. It is incremented in the
       * <code>fireAfter</code> method if the branch was not taken.
       */
      public int nottakenCount;
  
      /**
       * The <code>fireAfter()</code> method is called after the probed instruction executes. In the
       * implementation of the branch counter, the counter determines whether the branch was taken by inspecting
       * the program counter of the new state. If the program counter is not equal to the instruction following
       * the branch, then the branch was taken.
       *
       * @param state   the state of the simulation
       * @param pc the address at which this instruction resides
       */
      public void fireAfter(State state, int pc) {
          int nextaddr = pc + state.getInstr(pc).getSize();
          if (state.getPC() == nextaddr)
              nottakenCount++;
          else
              takenCount++;
      }
  }
  