Steve Karg
138 lines
3.5 KiB
C
138 lines
3.5 KiB
C
/**
|
|
* @file
|
|
* @author Steve Karg
|
|
* @date 2009
|
|
* @brief Millisecond timer library header file.
|
|
*
|
|
* @section DESCRIPTION
|
|
*
|
|
* The mstimer library provides functions for setting, resetting and
|
|
* restarting timers, and for checking if a timer has expired. An
|
|
* application must "manually" check if its timers have expired; this
|
|
* is not done automatically.
|
|
*
|
|
* A timer is declared as a \c struct \c mstimer and all access to the
|
|
* timer is made by a pointer to the declared timer.
|
|
*
|
|
* Adapted from the Contiki operating system.
|
|
* Original Authors: Adam Dunkels <adam@sics.se>, Nicolas Tsiftes <nvt@sics.se>
|
|
*/
|
|
#include <stdio.h>
|
|
#include <stdbool.h>
|
|
#include <stdint.h>
|
|
#include "bacnet/basic/sys/mstimer.h"
|
|
|
|
/**
|
|
* @brief Set a timer for a time sometime in the future
|
|
*
|
|
* This function is used to set a timer for a time sometime in the
|
|
* future. The function mstimer_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 mstimer_set(struct mstimer *t, unsigned long interval)
|
|
{
|
|
t->interval = interval;
|
|
t->start = mstimer_now();
|
|
}
|
|
|
|
/**
|
|
* @brief Reset the timer with the same interval.
|
|
*
|
|
* This function resets the timer with the same interval that was
|
|
* given to the mstimer_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
|
|
* mstimer_restart() function.
|
|
*
|
|
* @param t A pointer to the timer.
|
|
* @sa mstimer_restart()
|
|
*/
|
|
void mstimer_reset(struct mstimer *t)
|
|
{
|
|
t->start += t->interval;
|
|
}
|
|
|
|
/**
|
|
* @brief Restart the timer from the current point in time
|
|
*
|
|
* This function restarts a timer with the same interval that was
|
|
* given to the mstimer_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 mstimer_reset() function instead.
|
|
* @param t A pointer to the timer.
|
|
* @sa mstimer_reset()
|
|
*/
|
|
void mstimer_restart(struct mstimer *t)
|
|
{
|
|
t->start = mstimer_now();
|
|
}
|
|
|
|
/**
|
|
* @brief 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 mstimer_expired(struct mstimer *t)
|
|
{
|
|
if (t->interval) {
|
|
return ((unsigned long)((mstimer_now()) - (t->start + t->interval)) <
|
|
((unsigned long)(~((unsigned long)0)) >> 1));
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
/*---------------------------------------------------------------------------*/
|
|
/**
|
|
* The time until the timer expires
|
|
*
|
|
* This function returns the time until the timer expires.
|
|
*
|
|
* @param t A pointer to the timer
|
|
*
|
|
* @return The time until the timer expires
|
|
*
|
|
*/
|
|
unsigned long mstimer_remaining(struct mstimer *t)
|
|
{
|
|
return t->start + t->interval - mstimer_now();
|
|
}
|
|
|
|
/**
|
|
* The time elapsed since the timer started
|
|
*
|
|
* This function returns the time elapsed.
|
|
*
|
|
* @param t A pointer to the timer
|
|
*
|
|
* @return The time elapsed since the last start of the timer
|
|
*
|
|
*/
|
|
unsigned long mstimer_elapsed(struct mstimer *t)
|
|
{
|
|
return mstimer_now() - t->start;
|
|
}
|
|
|
|
/**
|
|
* The value of the interval
|
|
*
|
|
* This function returns the interval value
|
|
*
|
|
* @param t A pointer to the timer
|
|
*
|
|
* @return The interval value
|
|
*
|
|
*/
|
|
unsigned long mstimer_interval(struct mstimer *t)
|
|
{
|
|
return t->interval;
|
|
}
|