uip_timer.c

00001 /**
00002  * \addtogroup timer
00003  * @{
00004  */
00005 /**
00006  * \file
00007  * Timer library implementation.
00008  * \author
00009  * Adam Dunkels <adam@sics.se>
00010  */
00011 /*
00012  * Copyright (c) 2004, Swedish Institute of Computer Science.
00013  * All rights reserved.
00014  *
00015  * Redistribution and use in source and binary forms, with or without
00016  * modification, are permitted provided that the following conditions
00017  * are met:
00018  * 1. Redistributions of source code must retain the above copyright
00019  *    notice, this list of conditions and the following disclaimer.
00020  * 2. Redistributions in binary form must reproduce the above copyright
00021  *    notice, this list of conditions and the following disclaimer in the
00022  *    documentation and/or other materials provided with the distribution.
00023  * 3. Neither the name of the Institute nor the names of its contributors
00024  *    may be used to endorse or promote products derived from this software
00025  *    without specific prior written permission.
00026  *
00027  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
00028  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
00029  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
00030  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
00031  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
00032  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
00033  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
00034  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
00035  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
00036  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
00037  * SUCH DAMAGE.
00038  *
00039  * This file is part of the UIP TCP/IP stack
00040  *
00041  * Author: Adam Dunkels <adam@sics.se>
00042  *
00043  * $Id: timer.c,v 1.2 2006/06/12 08:00:30 adam Exp $
00044  */
00045 #include "uip_clock.h"
00046 #include "uip_timer.h"
00047 
00048 /*---------------------------------------------------------------------------*/
00049 
00050 /**
00051  * Set a timer.
00052  *
00053  * This function is used to set a timer for a time sometime in the
00054  * future. The function timer_expired() will evaluate to true after
00055  * the timer has expired.
00056  *
00057  * \param t A pointer to the timer
00058  * \param interval The interval before the timer expires.
00059  *
00060  */
00061 void uip_timer_set(struct uip_timer* t, clock_time_t interval) {
00062     t->interval = interval;
00063     t->start = clock_time();
00064 }
00065 
00066 /*---------------------------------------------------------------------------*/
00067 
00068 /**
00069  * Reset the timer with the same interval.
00070  *
00071  * This function resets the timer with the same interval that was
00072  * given to the timer_set() function. The start point of the interval
00073  * is the exact time that the timer last expired. Therefore, this
00074  * function will cause the timer to be stable over time, unlike the
00075  * timer_rester() function.
00076  *
00077  * \param t A pointer to the timer.
00078  *
00079  * \sa timer_restart()
00080  */
00081 void uip_timer_reset(struct uip_timer* t) {
00082     t->start += t->interval;
00083 }
00084 
00085 /*---------------------------------------------------------------------------*/
00086 
00087 /**
00088  * Restart the timer from the current point in time
00089  *
00090  * This function restarts a timer with the same interval that was
00091  * given to the timer_set() function. The timer will start at the
00092  * current time.
00093  *
00094  * \note A periodic timer will drift if this function is used to reset
00095  * it. For preioric timers, use the timer_reset() function instead.
00096  *
00097  * \param t A pointer to the timer.
00098  *
00099  * \sa timer_reset()
00100  */
00101 void uip_timer_restart(struct uip_timer* t) {
00102     t->start = clock_time();
00103 }
00104 
00105 /*---------------------------------------------------------------------------*/
00106 
00107 /**
00108  * Check if a timer has expired.
00109  *
00110  * This function tests if a timer has expired and returns true or
00111  * false depending on its status.
00112  *
00113  * \param t A pointer to the timer
00114  *
00115  * \return Non-zero if the timer has expired, zero otherwise.
00116  *
00117  */
00118 int uip_timer_expired(struct uip_timer* t) {
00119     return(clock_time_t) (clock_time() - t->start) >= (clock_time_t) t->interval;
00120 }
00121 
00122 /*---------------------------------------------------------------------------*/
00123 /** @} */