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lufa-master/Projects/Webserver/Lib/uip/timer.c 3.95 KB
142ecdaf   rguillom   first commit
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  /**
   * \addtogroup timer
   * @{
   */
  
  /**
   * \file
   * Timer library implementation.
   * \author
   * Adam Dunkels <adam@sics.se>
   */
  
  /*
   * Copyright (c) 2004, Swedish Institute of Computer Science.
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. Neither the name of the Institute nor the names of its contributors
   *    may be used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   *
   * This file is part of the uIP TCP/IP stack
   *
   * Author: Adam Dunkels <adam@sics.se>
   *
   * $Id: timer.c,v 1.2 2006/06/12 08:00:30 adam Exp $
   */
  
  #include "clock.h"
  #include "timer.h"
  
  /*---------------------------------------------------------------------------*/
  /**
   * Set a timer.
   *
   * This function is used to set a timer for a time sometime in the
   * future. The function timer_expired() will evaluate to true after
   * the timer has expired.
   *
   * \param t A pointer to the timer
   * \param interval The interval before the timer expires.
   *
   */
  void
  timer_set(struct timer *t, clock_time_t interval)
  {
    t->interval = interval;
    t->start = clock_time();
  }
  /*---------------------------------------------------------------------------*/
  /**
   * Reset the timer with the same interval.
   *
   * This function resets the timer with the same interval that was
   * given to the timer_set() function. The start point of the interval
   * is the exact time that the timer last expired. Therefore, this
   * function will cause the timer to be stable over time, unlike the
   * timer_restart() function.
   *
   * \param t A pointer to the timer.
   *
   * \sa timer_restart()
   */
  void
  timer_reset(struct timer *t)
  {
    t->start += t->interval;
  }
  /*---------------------------------------------------------------------------*/
  /**
   * Restart the timer from the current point in time
   *
   * This function restarts a timer with the same interval that was
   * given to the timer_set() function. The timer will start at the
   * current time.
   *
   * \note A periodic timer will drift if this function is used to reset
   * it. For periodic timers, use the timer_reset() function instead.
   *
   * \param t A pointer to the timer.
   *
   * \sa timer_reset()
   */
  void
  timer_restart(struct timer *t)
  {
    t->start = clock_time();
  }
  /*---------------------------------------------------------------------------*/
  /**
   * Check if a timer has expired.
   *
   * This function tests if a timer has expired and returns true or
   * false depending on its status.
   *
   * \param t A pointer to the timer
   *
   * \return Non-zero if the timer has expired, zero otherwise.
   *
   */
  int
  timer_expired(struct timer *t)
  {
    return (clock_time_t)(clock_time() - t->start) >= (clock_time_t)t->interval;
  }
  /*---------------------------------------------------------------------------*/
  
  /** @} */