| /** |
| * \defgroup timer Timer library |
| * @{ |
| * |
| * The Contiki kernel does not provide support for timed |
| * events. Rather, an application that wants to use timers needs to |
| * explicitly use the timer library. |
| * |
| * The timer library provides functions for setting, resetting and |
| * restarting timers, and for checking if a timer has expired. An |
| * application must "manually" check if its timers have expired; this |
| * is not done automatically. |
| * |
| * A timer is declared as a \c struct \c timer and all access to the |
| * timer is made by a pointer to the declared timer. |
| * |
| * Example: |
| \code |
| |
| static struct timer periodic; |
| |
| LOADER_INIT_FUNC(example_init, arg) { |
| timer_set(&periodic, CLOCK_SECOND); |
| } |
| |
| EK_POLLHANDLER(pollhandler) { |
| if(timer_expired(&periodic)) { |
| timer_restart(&periodic); |
| do_periodic_stuff(); |
| } |
| } |
| |
| \endcode |
| * |
| * \note The timer library uses the \ref clock "Clock library" to |
| * measure time. Intervals should be specified in the format used by |
| * the clock library. |
| * |
| * \sa \ref clock "Clock library" |
| */ |
| |
| /** |
| * \file |
| * Timer library implementation. |
| * \author |
| * Adam Dunkels <adam@sics.se> |
| */ |
| |
| /* |
| * Copyright (c) 2004, Swedish Institute of Computer Science. |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. 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. |
| * 3. Neither the name of the Institute 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 INSTITUTE 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 INSTITUTE 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. |
| * |
| * This file is part of the Contiki operating system. |
| * |
| * Author: Adam Dunkels <adam@sics.se> |
| * |
| * $Id: timer.c,v 1.5 2005/02/07 22:45:14 adamdunkels Exp $ |
| */ |
| #include "timer.h" |
| |
| /*---------------------------------------------------------------------------*/ |
| /** |
| * Set a timer. |
| * |
| * This function is used to set a timer for a time sometime in the |
| * future. The function timer_expired() will evaluate to true after |
| * the timer has expired. |
| * |
| * \param t A pointer to the timer |
| * \param interval The interval before the timer expires. |
| * |
| */ |
| void |
| timer_set(struct timer *t, clock_time_t interval) |
| { |
| t->interval = interval; |
| t->start = clock_time(); |
| } |
| /*---------------------------------------------------------------------------*/ |
| /** |
| * Reset the timer with the same interval. |
| * |
| * This function resets the timer with the same interval that was |
| * given to the timer_set() function. The start point of the interval |
| * is the exact time that the timer last expired. Therefore, this |
| * function will cause the timer to be stable over time, unlike the |
| * timer_rester() function. |
| * |
| * \param t A pointer to the timer. |
| * |
| * \sa timer_restart() |
| */ |
| void |
| timer_reset(struct timer *t) |
| { |
| t->start += t->interval; |
| } |
| /*---------------------------------------------------------------------------*/ |
| /** |
| * Restart the timer from the current point in time |
| * |
| * This function restarts a timer with the same interval that was |
| * given to the timer_set() function. The timer will start at the |
| * current time. |
| * |
| * \note A periodic timer will drift if this function is used to reset |
| * it. For preioric timers, use the timer_reset() function instead. |
| * |
| * \param t A pointer to the timer. |
| * |
| * \sa timer_reset() |
| */ |
| void |
| timer_restart(struct timer *t) |
| { |
| t->start = clock_time(); |
| } |
| /*---------------------------------------------------------------------------*/ |
| /** |
| * Check if a timer has expired. |
| * |
| * This function tests if a timer has expired and returns true or |
| * false depending on its status. |
| * |
| * \param t A pointer to the timer |
| * |
| * \return Non-zero if the timer has expired, zero otherwise. |
| * |
| */ |
| int |
| timer_expired(struct timer *t) |
| { |
| return (clock_time_t)(clock_time() - t->start) >= (clock_time_t)t->interval; |
| } |
| /*---------------------------------------------------------------------------*/ |
| |