/** \addtogroup sys * @{ */ /** * \defgroup etimer Event timers * * Event timers provides a way to generate timed events. An event * timer will post an event to the process that set the timer when the * event timer expires. * * An event timer is declared as a \c struct \c etimer and all access * to the event timer is made by a pointer to the declared event * timer. * * \sa \ref timer "Simple timer library" * \sa \ref clock "Clock library" (used by the timer library) * * @{ */ /** * \file * Event timer header file. * \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> * */ #ifndef __ETIMER_H__ #define __ETIMER_H__ #include "sys/timer.h" #include "sys/process.h" /** * A timer. * * This structure is used for declaring a timer. The timer must be set * with etimer_set() before it can be used. * * \hideinitializer */ struct etimer { struct timer timer; struct etimer *next; struct process *p; }; /** * \name Functions called from application programs * @{ */ /** * \brief Set an event timer. * \param et A pointer to the event timer * \param interval The interval before the timer expires. * * This function is used to set an event timer for a time * sometime in the future. When the event timer expires, * the event PROCESS_EVENT_TIMER will be posted to the * process that called the etimer_set() function. * */ CCIF void etimer_set(struct etimer *et, clock_time_t interval); /** * \brief Reset an event timer with the same interval as was * previously set. * \param et A pointer to the event timer. * * This function resets the event timer with the same * interval that was given to the event timer with the * etimer_set() function. The start point of the interval * is the exact time that the event timer last * expired. Therefore, this function will cause the timer * to be stable over time, unlike the etimer_restart() * function. * * \sa etimer_restart() */ CCIF void etimer_reset(struct etimer *et); /** * \brief Restart an event timer from the current point in time * \param et A pointer to the event timer. * * This function restarts the event timer with the same * interval that was given to the etimer_set() * function. The event timer will start at the current * time. * * \note A periodic timer will drift if this function is * used to reset it. For periodic timers, use the * etimer_reset() function instead. * * \sa etimer_reset() */ void etimer_restart(struct etimer *et); /** * \brief Adjust the expiration time for an event timer * \param et A pointer to the event timer. * \param td The time difference to adjust the expiration time with. * * This function is used to adjust the time the event * timer will expire. It can be used to synchronize * periodic timers without the need to restart the timer * or change the timer interval. * * \note This function should only be used for small * adjustments. For large adjustments use etimer_set() * instead. * * \note A periodic timer will drift unless the * etimer_reset() function is used. * * \sa etimer_set() * \sa etimer_reset() */ void etimer_adjust(struct etimer *et, int td); /** * \brief Get the expiration time for the event timer. * \param et A pointer to the event timer * \return The expiration time for the event timer. * * This function returns the expiration time for an event timer. */ clock_time_t etimer_expiration_time(struct etimer *et); /** * \brief Get the start time for the event timer. * \param et A pointer to the event timer * \return The start time for the event timer. * * This function returns the start time (when the timer * was last set) for an event timer. */ clock_time_t etimer_start_time(struct etimer *et); /** * \brief Check if an event timer has expired. * \param et A pointer to the event timer * \return Non-zero if the timer has expired, zero otherwise. * * This function tests if an event timer has expired and * returns true or false depending on its status. */ CCIF int etimer_expired(struct etimer *et); /** * \brief Stop a pending event timer. * \param et A pointer to the pending event timer. * * This function stops an event timer that has previously * been set with etimer_set() or etimer_reset(). After * this function has been called, the event timer will not * emit any event when it expires. * */ void etimer_stop(struct etimer *et); /** @} */ /** * \name Functions called from timer interrupts, by the system * @{ */ /** * \brief Make the event timer aware that the clock has changed * * This function is used to inform the event timer module * that the system clock has been updated. Typically, this * function would be called from the timer interrupt * handler when the clock has ticked. */ void etimer_request_poll(void); /** * \brief Check if there are any non-expired event timers. * \return True if there are active event timers, false if there are * no active timers. * * This function checks if there are any active event * timers that have not expired. */ int etimer_pending(void); /** * \brief Get next event timer expiration time. * \return Next expiration time of all pending event timers. * If there are no pending event timers this function * returns 0. * * This functions returns next expiration time of all * pending event timers. */ clock_time_t etimer_next_expiration_time(void); /** @} */ PROCESS_NAME(etimer_process); #endif /* __ETIMER_H__ */ /** @} */ /** @} */