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.monitors;
  
  import avrora.sim.Simulator;
  import avrora.sim.clock.MainClock;
  import cck.util.TimeUtil;
  
  /**
   * The <code>RealTimeMonitor</code> class slows down the simulation to real-time. This is
   * useful for simulations that run much faster than real time and for simulations that may
   * be connected to external device inputs.
   *
   * @author Ben L. Titzer
   */
  public class RealTimeMonitor extends MonitorFactory {
  
      private class ThrottleEvent implements Simulator.Event {
          boolean initialized;
          long beginMs;
          final long period;
          final MainClock clock;
  
          public ThrottleEvent(Simulator s) {
              clock = s.getClock();
              period = clock.getHZ() / 100;
          }
  
          public void fire() {
              if ( !initialized ) {
                  initialized = true;
                  beginMs = System.currentTimeMillis();
                  clock.insertEvent(this, period);
                  return;
              }
  
              long cycles = clock.getCount();
              long msGoal = (long)TimeUtil.cyclesToMillis(cycles, clock.getHZ());
              while ( (System.currentTimeMillis() - beginMs) < msGoal ) ;
  
              clock.insertEvent(this, period);
          }
      }
  
      public RealTimeMonitor() {
          super("The \"real-time\" monitor slows down the simulation so that it runs as close as possible " +
                  "to real-time.");
      }
  
      public Monitor newMonitor(Simulator s) {
          s.insertEvent(new ThrottleEvent(s), 1);
          return null;
      }
  }
  