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.clock;
  
  import cck.text.StringUtil;
  import java.util.HashMap;
  import java.util.NoSuchElementException;
  
  /**
   * The <code>ClockDomain</code> class represents a collection of clocks for a device or platform,
   * including the main clock used for the microcontroller.
   *
   * @author Ben L. Titzer
   */
  public class ClockDomain {
  
      protected final HashMap<String, Clock> clockMap;
      protected final MainClock mainClock;
  
      /**
       * The constructor for the <code>ClockDomain</code> class constructs the main clock (from which
       * all other clocks are derived). It accepts as a parameter the speed of the main clock.
       * @param mainHz the speed of the main clock in cycles per second
       */
      public ClockDomain(long mainHz) {
          clockMap = new HashMap<String, Clock>();
          mainClock = new MainClock("main", mainHz);
          clockMap.put("main", mainClock);
      }
  
      /**
       * The <code>getMainClock()</code> method returns the main clock for this clock domain.
       * @return an instance of the <code>MainClock</code> class that contains the main clock for
       * this clock domain.
       */
      public MainClock getMainClock() {
          return mainClock;
      }
  
      /**
       * The <code>getClock()</code> method looks for a clock with the specified name in this clock
       * domain.
       * @param name the name of the clock as a string
       * @return an instance of the <code>Clock</code> interface for the specified clock name
       * @throws NoSuchElementException if no clock with the specified name exists in this domain
       */
      public Clock getClock(String name) {
          Clock clock = (Clock)clockMap.get(name);
          if ( clock == null )
              throw new NoSuchElementException(StringUtil.quote(name)+" clock not found");
          return clock;
      }
  
      /**
       * The <code>addClock()</code> method adds a clock to this clock domain. It will be indexed
       * by the name returned by the clock's <code>getName()</code> method. If there is a clock
       * already in this domain with the name specified, the new clock will be returned for subsequent
       * calls to <code>getClock()</code>, and the old clock will no longer be accessible.
       * @param c the clock to add to this domain
       */
      public void addClock(Clock c) {
          clockMap.put(c.getName(), c);
      }
  
      /**
       * The <code>newClock()</code> method creates a new clock derived from the main clock of
       * this clock domain with the given name and clockspeed. The clock will automatically be
       * added to this clock domain with the specified name.
       * @param name the name of the new clock
       * @param hz the clockspeed of the new clock in cycles per second
       * @return a new <code>Clock</code> instance with the specified properties
       */
      public Clock newClock(String name, long hz) {
          if ( hz == mainClock.getHZ() ) {
              clockMap.put(name, mainClock);
              return mainClock;
          }
          DerivedClock c = new DerivedClock(name, mainClock, hz);
          addClock(c);
          return c;
      }
  
      /**
       * The <code>hasClock()</code> method queries the clock domain whether it contains a particular
       * named clock.
       * @param name the name of the clock to check for
       * @return true if a clock in this domain exists with the specified name; false otherwise
       */
      public boolean hasClock(String name) {
          return clockMap.get(name) != null;
      }
  }
  