147 lines
4.5 KiB
C
147 lines
4.5 KiB
C
/**
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* \addtogroup stimer
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* @{
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*/
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/**
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* \file
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* Timer of seconds library implementation.
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* \author
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* Adam Dunkels <adam@sics.se>, Nicolas Tsiftes <nvt@sics.se>
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*/
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/*
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* Copyright (c) 2004, 2008, 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>, Nicolas Tsiftes <nvt@sics.se>
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*
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* $Id: stimer.c,v 1.1 2008/10/02 10:17:48 nvt-se 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/stimer.h"
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#define SCLOCK_LT(a, b) ((unsigned long)((a) - (b)) < \
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((unsigned long)(~((unsigned long)0)) >> 1))
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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 stimer_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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stimer_set(struct stimer *t, unsigned long interval)
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{
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t->interval = interval;
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t->start = clock_seconds();
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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 stimer_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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* stimer_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 stimer_restart()
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*/
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void
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stimer_reset(struct stimer *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 stimer_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 stimer_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 stimer_reset()
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*/
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void
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stimer_restart(struct stimer *t)
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{
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t->start = clock_seconds();
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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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stimer_expired(struct stimer *t)
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{
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return SCLOCK_LT(clock_seconds(), t->start + 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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unsigned long
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stimer_remaining(struct stimer *t)
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{
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return t->start + t->interval - clock_seconds();
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}
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/*---------------------------------------------------------------------------*/
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/** @} */
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