148 lines
4.5 KiB
C
148 lines
4.5 KiB
C
/**
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* \addtogroup timer
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* @{
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*/
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/**
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* \file
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* Timer library implementation.
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* \author
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* Adam Dunkels <adam@sics.se>
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*/
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/*
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* Copyright (c) 2004, Swedish Institute of Computer Science.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* This file is part of the Contiki operating system.
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*
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* Author: Adam Dunkels <adam@sics.se>
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*
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* $Id: timer.c,v 1.6 2010/02/23 18:40:08 adamdunkels Exp $
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*/
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#include "contiki-conf.h"
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#include "sys/clock.h"
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#include "sys/timer.h"
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/*---------------------------------------------------------------------------*/
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/**
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* Set a timer.
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*
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* This function is used to set a timer for a time sometime in the
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* future. The function timer_expired() will evaluate to true after
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* the timer has expired.
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*
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* \param t A pointer to the timer
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* \param interval The interval before the timer expires.
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*
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*/
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void
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timer_set(struct timer *t, clock_time_t interval)
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{
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t->interval = interval;
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t->start = clock_time();
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}
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/*---------------------------------------------------------------------------*/
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/**
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* Reset the timer with the same interval.
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*
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* This function resets the timer with the same interval that was
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* given to the timer_set() function. The start point of the interval
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* is the exact time that the timer last expired. Therefore, this
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* function will cause the timer to be stable over time, unlike the
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* timer_restart() function.
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*
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* \param t A pointer to the timer.
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*
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* \sa timer_restart()
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*/
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void
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timer_reset(struct timer *t)
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{
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t->start += t->interval;
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}
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/*---------------------------------------------------------------------------*/
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/**
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* Restart the timer from the current point in time
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*
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* This function restarts a timer with the same interval that was
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* given to the timer_set() function. The timer will start at the
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* current time.
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*
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* \note A periodic timer will drift if this function is used to reset
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* it. For preioric timers, use the timer_reset() function instead.
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*
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* \param t A pointer to the timer.
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*
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* \sa timer_reset()
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*/
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void
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timer_restart(struct timer *t)
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{
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t->start = clock_time();
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}
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/*---------------------------------------------------------------------------*/
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/**
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* Check if a timer has expired.
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*
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* This function tests if a timer has expired and returns true or
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* false depending on its status.
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*
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* \param t A pointer to the timer
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*
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* \return Non-zero if the timer has expired, zero otherwise.
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*
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*/
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int
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timer_expired(struct timer *t)
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{
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clock_time_t diff = clock_time() - t->start;
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/* This somewhat ugly way of returning (diff >= t->interval) is
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required to avoid an internal error in mspgcc. */
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return diff > t->interval || diff == t->interval;
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}
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/*---------------------------------------------------------------------------*/
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/**
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* The time until the timer expires
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*
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* This function returns the time until the timer expires.
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*
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* \param t A pointer to the timer
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*
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* \return The time until the timer expires
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*
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*/
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clock_time_t
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timer_remaining(struct timer *t)
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{
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return t->start + t->interval - clock_time();
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}
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/*---------------------------------------------------------------------------*/
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/** @} */
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