Projects/Webserver/Lib/uip/timer.c

   1 /**
   2  * \addtogroup timer
   3  * @{
   4  */
   5
   6 /**
   7  * \file
   8  * Timer library implementation.
   9  * \author
  10  * Adam Dunkels <adam@sics.se>
  11  */
  12
  13 /*
  14  * Copyright (c) 2004, Swedish Institute of Computer Science.
  15  * All rights reserved.
  16  *
  17  * Redistribution and use in source and binary forms, with or without
  18  * modification, are permitted provided that the following conditions
  19  * are met:
  20  * 1. Redistributions of source code must retain the above copyright
  21  *    notice, this list of conditions and the following disclaimer.
  22  * 2. Redistributions in binary form must reproduce the above copyright
  23  *    notice, this list of conditions and the following disclaimer in the
  24  *    documentation and/or other materials provided with the distribution.
  25  * 3. Neither the name of the Institute nor the names of its contributors
  26  *    may be used to endorse or promote products derived from this software
  27  *    without specific prior written permission.
  28  *
  29  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  30  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  31  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  32  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  33  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  34  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  35  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  36  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  37  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  38  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  39  * SUCH DAMAGE.
  40  *
  41  * This file is part of the uIP TCP/IP stack
  42  *
  43  * Author: Adam Dunkels <adam@sics.se>
  44  *
  45  * $Id: timer.c,v 1.2 2006/06/12 08:00:30 adam Exp $
  46  */
  47
  48 #include "clock.h"
  49 #include "timer.h"
  50
  51 /*---------------------------------------------------------------------------*/
  52 /**
  53  * Set a timer.
  54  *
  55  * This function is used to set a timer for a time sometime in the
  56  * future. The function timer_expired() will evaluate to true after
  57  * the timer has expired.
  58  *
  59  * \param t A pointer to the timer
  60  * \param interval The interval before the timer expires.
  61  *
  62  */
  63 void
  64 timer_set(struct timer *t, clock_time_t interval)
  65 {
  66   t->interval = interval;
  67   t->start = clock_time();
  68 }
  69 /*---------------------------------------------------------------------------*/
  70 /**
  71  * Reset the timer with the same interval.
  72  *
  73  * This function resets the timer with the same interval that was
  74  * given to the timer_set() function. The start point of the interval
  75  * is the exact time that the timer last expired. Therefore, this
  76  * function will cause the timer to be stable over time, unlike the
  77  * timer_rester() function.
  78  *
  79  * \param t A pointer to the timer.
  80  *
  81  * \sa timer_restart()
  82  */
  83 void
  84 timer_reset(struct timer *t)
  85 {
  86   t->start += t->interval;
  87 }
  88 /*---------------------------------------------------------------------------*/
  89 /**
  90  * Restart the timer from the current point in time
  91  *
  92  * This function restarts a timer with the same interval that was
  93  * given to the timer_set() function. The timer will start at the
  94  * current time.
  95  *
  96  * \note A periodic timer will drift if this function is used to reset
  97  * it. For periodic timers, use the timer_reset() function instead.
  98  *
  99  * \param t A pointer to the timer.
 100  *
 101  * \sa timer_reset()
 102  */
 103 void
 104 timer_restart(struct timer *t)
 105 {
 106   t->start = clock_time();
 107 }
 108 /*---------------------------------------------------------------------------*/
 109 /**
 110  * Check if a timer has expired.
 111  *
 112  * This function tests if a timer has expired and returns true or
 113  * false depending on its status.
 114  *
 115  * \param t A pointer to the timer
 116  *
 117  * \return Non-zero if the timer has expired, zero otherwise.
 118  *
 119  */
 120 int
 121 timer_expired(struct timer *t)
 122 {
 123   return (clock_time_t)(clock_time() - t->start) >= (clock_time_t)t->interval;
 124 }
 125 /*---------------------------------------------------------------------------*/
 126
 127 /** @} */