/** \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__ */
|
/** @} */
|
/** @} */
|
