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