--- /dev/null
+/**
+ * \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 1.1 2008/08/06 23:21:19 andrewlxia Exp $
+ */
+
+#include <uip/clock.h>
+#include <uip/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_rester() 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 preioric 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;
+}
+/*---------------------------------------------------------------------------*/
+
+/** @} */
