uIP 1.0: uip/timer.c Source File

00001 /**
+00002  * \addtogroup timer
+00003  * @{
+00004  */
+00005 
+00006 /**
+00007  * \file
+00008  * Timer library implementation.
+00009  * \author
+00010  * Adam Dunkels <adam@sics.se>
+00011  */
+00012 
+00013 /*
+00014  * Copyright (c) 2004, Swedish Institute of Computer Science.
+00015  * All rights reserved.
+00016  *
+00017  * Redistribution and use in source and binary forms, with or without
+00018  * modification, are permitted provided that the following conditions
+00019  * are met:
+00020  * 1. Redistributions of source code must retain the above copyright
+00021  *    notice, this list of conditions and the following disclaimer.
+00022  * 2. Redistributions in binary form must reproduce the above copyright
+00023  *    notice, this list of conditions and the following disclaimer in the
+00024  *    documentation and/or other materials provided with the distribution.
+00025  * 3. Neither the name of the Institute nor the names of its contributors
+00026  *    may be used to endorse or promote products derived from this software
+00027  *    without specific prior written permission.
+00028  *
+00029  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
+00030  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+00031  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+00032  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
+00033  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+00034  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+00035  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+00036  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+00037  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+00038  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+00039  * SUCH DAMAGE.
+00040  *
+00041  * This file is part of the uIP TCP/IP stack
+00042  *
+00043  * Author: Adam Dunkels <adam@sics.se>
+00044  *
+00045  * $Id: timer.c,v 1.2 2006/06/12 08:00:30 adam Exp $
+00046  */
+00047 
+00048 #include "clock.h"
+00049 #include "timer.h"
+00050 
+00051 /*---------------------------------------------------------------------------*/
+00052 /**
+00053  * Set a timer.
+00054  *
+00055  * This function is used to set a timer for a time sometime in the
+00056  * future. The function timer_expired() will evaluate to true after
+00057  * the timer has expired.
+00058  *
+00059  * \param t A pointer to the timer
+00060  * \param interval The interval before the timer expires.
+00061  *
+00062  */
+00063 void
+00064 timer_set(struct timer *t, clock_time_t interval)
+00065 {
+00066   t->interval = interval;
+00067   t->start = clock_time();
+00068 }
+00069 /*---------------------------------------------------------------------------*/
+00070 /**
+00071  * Reset the timer with the same interval.
+00072  *
+00073  * This function resets the timer with the same interval that was
+00074  * given to the timer_set() function. The start point of the interval
+00075  * is the exact time that the timer last expired. Therefore, this
+00076  * function will cause the timer to be stable over time, unlike the
+00077  * timer_rester() function.
+00078  *
+00079  * \param t A pointer to the timer.
+00080  *
+00081  * \sa timer_restart()
+00082  */
+00083 void
+00084 timer_reset(struct timer *t)
+00085 {
+00086   t->start += t->interval;
+00087 }
+00088 /*---------------------------------------------------------------------------*/
+00089 /**
+00090  * Restart the timer from the current point in time
+00091  *
+00092  * This function restarts a timer with the same interval that was
+00093  * given to the timer_set() function. The timer will start at the
+00094  * current time.
+00095  *
+00096  * \note A periodic timer will drift if this function is used to reset
+00097  * it. For preioric timers, use the timer_reset() function instead.
+00098  *
+00099  * \param t A pointer to the timer.
+00100  *
+00101  * \sa timer_reset()
+00102  */
+00103 void
+00104 timer_restart(struct timer *t)
+00105 {
+00106   t->start = clock_time();
+00107 }
+00108 /*---------------------------------------------------------------------------*/
+00109 /**
+00110  * Check if a timer has expired.
+00111  *
+00112  * This function tests if a timer has expired and returns true or
+00113  * false depending on its status.
+00114  *
+00115  * \param t A pointer to the timer
+00116  *
+00117  * \return Non-zero if the timer has expired, zero otherwise.
+00118  *
+00119  */
+00120 int
+00121 timer_expired(struct timer *t)
+00122 {
+00123   return (clock_time_t)(clock_time() - t->start) >= (clock_time_t)t->interval;
+00124 }
+00125 /*---------------------------------------------------------------------------*/
+00126 
+00127 /** @} */
+