alarm.nc

tinyos-2.x.rar

//$Id: Alarm.nc,v 1.4 2006/12/12 18:23:32 vlahan Exp $

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 * All rights reserved.
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 * IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR
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 * OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF THE UNIVERSITY
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#include "Timer.h"

/**
 * An Alarm is a low-level interface intended for precise timing.
 *
 * <p>An Alarm is parameterised by its "precision" (milliseconds,
 * microseconds, etc), identified by a type. This prevents, e.g.,
 * unintentionally mixing components expecting milliseconds with those
 * expecting microseconds as those interfaces have a different type.
 *
 * <p>An Alarm's second parameter is its "width", i.e., the number of
 * bits used to represent time values. Width is indicated by including
 * the appropriate size integer type as an Alarm parameter.
 *
 * <p>See TEP102 for more details.
 *
 * @param precision_tag A type indicating the precision of this Alarm.
 * @param size_type An integer type representing time values for this Alarm.
 *
 * @author Cory Sharp <[e-mail]>
 */

interface Alarm<precision_tag, size_type>
{
  // basic interface
  /**
   * Set a single-short alarm to some time units in the future. Replaces
   * any current alarm time. Equivalent to start(getNow(), dt). The
   * <code>fired</code> will be signaled when the alarm expires.
   *
   * @param dt Time until the alarm fires.
   */
  async command void start(size_type dt);

  /**
   * Cancel an alarm. Note that the <code>fired</code> event may have
   * already been signaled (even if your code has not yet started
   * executing).
   */
  async command void stop();

  /**
   * Signaled when the alarm expires.
   */
  async event void fired();

  // extended interface
  /**
   * Check if alarm is running. Note that a FALSE return does not indicate
   * that the <code>fired</code> event will not be signaled (it may have
   * already started executing, but not reached your code yet).
   *
   * @return TRUE if the alarm is still running.
   */
  async command bool isRunning();

  /**
   * Set a single-short alarm to time t0+dt. Replaces any current alarm
   * time. The <code>fired</code> will be signaled when the alarm expires.
   * Alarms set in the past will fire "soon".
   * 
   * <p>Because the current time may wrap around, it is possible to use
   * values of t0 greater than the <code>getNow</code>'s result. These
   * values represent times in the past, i.e., the time at which getNow()
   * would last of returned that value.
   *
   * @param t0 Base time for alarm.
   * @param dt Alarm time as offset from t0.
   */
  async command void startAt(size_type t0, size_type dt);

  /**
   * Return the current time.
   * @return Current time.
   */
  async command size_type getNow();

  /**
   * Return the time the currently running alarm will fire or the time that
   * the previously running alarm was set to fire.
   * @return Alarm time.
   */
  async command size_type getAlarm();
}