/* * 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> * */ /** * \file * Timer library implementation. * \author * Adam Dunkels <adam@sics.se> */ /** * \addtogroup timer * @{ */ #include "contiki.h" #include "sys/clock.h" #include "sys/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_restart() function. * * \note Must not be executed before timer expired * * \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) { /* Note: Can not return diff >= t->interval so we add 1 to diff and return t->interval < diff - required to avoid an internal error in mspgcc. */ clock_time_t diff = (clock_time() - t->start) + 1; return t->interval < diff; } /*---------------------------------------------------------------------------*/ /** * The time until the timer expires * * This function returns the time until the timer expires. * * \param t A pointer to the timer * * \return The time until the timer expires * */ clock_time_t timer_remaining(struct timer *t) { return t->start + t->interval - clock_time(); } /*---------------------------------------------------------------------------*/ /** @} */