a timer of seconds
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nvt-se
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147
core/sys/stimer.c
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147
core/sys/stimer.c
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/**
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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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99
core/sys/stimer.h
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99
core/sys/stimer.h
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@ -0,0 +1,99 @@
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/** \addtogroup sys
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* @{ */
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/**
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* \defgroup timer Seconds timer library
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*
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* The stimer library provides functions for setting, resetting and
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* restarting timers, and for checking if a timer has expired. An
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* application must "manually" check if its timers have expired; this
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* is not done automatically.
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*
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* A timer is declared as a \c struct \c stimer and all access to the
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* timer is made by a pointer to the declared timer.
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*
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* \note The stimer library is not able to post events when a timer
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* expires. The \ref etimer "Event timers" should be used for this
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* purpose.
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*
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* \note The stimer library uses the \ref clock "Clock library" to
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* measure time. Intervals should be specified in the seconds.
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*
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* \sa \ref etimer "Event timers"
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*
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* @{
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*/
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/**
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* \file
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* Second timer library header file.
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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.h,v 1.1 2008/10/02 10:17:48 nvt-se Exp $
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*/
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#ifndef __STIMER_H__
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#define __STIMER_H__
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#include "sys/clock.h"
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typedef unsigned long clock_second_t;
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/**
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* A timer.
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*
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* This structure is used for declaring a timer. The timer must be set
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* with stimer_set() before it can be used.
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*
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* \hideinitializer
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*/
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struct stimer {
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clock_second_t start;
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clock_second_t interval;
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};
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void stimer_set(struct stimer *t, clock_second_t interval);
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void stimer_reset(struct stimer *t);
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void stimer_restart(struct stimer *t);
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int stimer_expired(struct stimer *t);
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clock_second_t stimer_remaining(struct stimer *t);
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#endif /* __STIMER_H__ */
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/** @} */
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/** @} */
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