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>MemoryCounter</code> is the simplest example of memory profiling functionality. When inserted as
   * a watch at a particular memory location, it will simply count the number of reads and writes to that memory
   * location. It is analagous to the <code>Counter</code> probe which is used to count the execution frequency
   * of a particular instruction.
   *
   * @author Ben L. Titzer
   * @see Simulator.Watch
   * @see Counter
   */
  public class MemoryCounter extends Simulator.Watch.Empty {
  
      /**
       * The <code>rcount</code> field stores the number of reads encountered for this memory location.
       */
      public long rcount;
  
      /**
       * The <code>wcount</code> field stores the number of writes encountered for this memory location.
       */
      public long wcount;
  
      /**
       * The <code>fireBeforeRead()</code> method is called before the data address is read by the program. In
       * the implementation of <code>MemoryCounter</code>, it simply increments the count of reads by one.
       *
       * @param state     the state of the simulation
       * @param data_addr the address of the data being referenced
       */
      public void fireBeforeRead(State state, int data_addr) {
          rcount++;
      }
  
      /**
       * The <code>fireBeforeWrite()</code> method is called before the data address is written by the program.
       * In the implementation of <code>MemoryCounter</code>, it simply increments the count of writes by one.
       *
       * @param state     the state of the simulation
       * @param data_addr the address of the data being referenced
       * @param value     the value being written to the memory location
       */
      public void fireBeforeWrite(State state, int data_addr, byte value) {
          wcount++;
      }
  
  }
  