Event timers provides a way to generate timed events.

An event timer will post an event to the process that set the timer when the event timer expires.

An event timer is declared as a struct etimer and all access to the event timer is made by a pointer to the declared event timer.

See Also: Simple timer library; Clock library (used by the timer library)

Data Structures
struct	etimer
	A timer. More...

Files
file	etimer.c
	Event timer library implementation.

file	etimer.h
	Event timer header file.

Functions
static void	add_timer (struct etimer *timer)

	PROCESS (etimer_process,"Event timer")

	PROCESS_NAME (etimer_process)

	PROCESS_THREAD (etimer_process, ev, data)

static void	update_time (void)

Variables
static clock_time_t	next_expiration

static struct etimer *	timerlist

Functions called from application programs
void	etimer_set (struct etimer *et, clock_time_t interval)
	Set an event timer. More...

void	etimer_reset (struct etimer *et)
	Reset an event timer with the same interval as was previously set. More...

void	etimer_restart (struct etimer *et)
	Restart an event timer from the current point in time. More...

void	etimer_adjust (struct etimer *et, int td)
	Adjust the expiration time for an event timer. More...

int	etimer_expired (struct etimer *et)
	Check if an event timer has expired. More...

clock_time_t	etimer_expiration_time (struct etimer *et)
	Get the expiration time for the event timer. More...

clock_time_t	etimer_start_time (struct etimer *et)
	Get the start time for the event timer. More...

void	etimer_stop (struct etimer *et)
	Stop a pending event timer. More...

Functions called from timer interrupts, by the system
void	etimer_request_poll (void)
	Make the event timer aware that the clock has changed. More...

int	etimer_pending (void)
	Check if there are any non-expired event timers. More...

clock_time_t	etimer_next_expiration_time (void)
	Get next event timer expiration time. More...

static void add_timer ( struct etimer * timer )

static

References etimer_request_poll(), next, NULL, p, PROCESS_CURRENT, PROCESS_NONE, timer, timerlist, and update_time().

Referenced by etimer_reset(), etimer_restart(), and etimer_set().

void etimer_adjust	(	struct etimer *	et,
		int	td
	)

Adjust the expiration time for an event timer.

Parameters

et A pointer to the event timer.

td

The time difference to adjust the expiration time with.

        This function is used to adjust the time the event
        timer will expire. It can be used to synchronize
        periodic timers without the need to restart the timer
        or change the timer interval.

        \note This function should only be used for small
        adjustments. For large adjustments use etimer_set()
        instead.

        \note A periodic timer will drift unless the
        etimer_reset() function is used.

See Also: etimer_set(); etimer_reset()

References timer::start, timer, and update_time().

clock_time_t etimer_expiration_time ( struct etimer * et )

Get the expiration time for the event timer.

Parameters

et	A pointer to the event timer

Returns

The expiration time for the event timer.

        This function returns the expiration time for an event timer.

References timer::interval, timer::start, and timer.

Referenced by schedule_dao().

CCIF int etimer_expired ( struct etimer * et )

Check if an event timer has expired.

Parameters

et	A pointer to the event timer

Returns

Non-zero if the timer has expired, zero otherwise.

        This function tests if an event timer has expired and
        returns true or false depending on its status.

References p, and PROCESS_NONE.

Referenced by ctimer_expired(), eventhandler(), handle_dao_timer(), PROCESS_THREAD(), schedule_dao(), start_periodic_tcp_timer(), and while().

clock_time_t etimer_next_expiration_time ( void )

Get next event timer expiration time.

Returns

Next expiration time of all pending event timers. If there are no pending event timers this function returns 0.

This functions returns next expiration time of all
pending event timers.

References etimer_pending(), and next_expiration.

int etimer_pending ( void )

Check if there are any non-expired event timers.

Returns: True if there are active event timers, false if there are no active timers.

This function checks if there are any active event timers that have not expired.

References NULL.

Referenced by _TC3_Handler(), clock_irq_callback(), and etimer_next_expiration_time().

void etimer_request_poll ( void )

Make the event timer aware that the clock has changed.

This function is used to inform the event timer module that the system clock has been updated. Typically, this function would be called from the timer interrupt handler when the clock has ticked.

References etimer_process, and process_poll().

Referenced by _TC3_Handler(), add_timer(), clock_irq_callback(), and PROCESS_THREAD().

CCIF void etimer_reset ( struct etimer * et )

Reset an event timer with the same interval as was previously set.

Parameters

et

A pointer to the event timer.

        This function resets the event timer with the same
        interval that was given to the event timer with the
        etimer_set() function. The start point of the interval
        is the exact time that the event timer last
        expired. Therefore, this function will cause the timer
        to be stable over time, unlike the etimer_restart()
        function.

See Also: etimer_restart()

References add_timer(), timer, and timer_reset().

Referenced by ctimer_reset(), PROCESS_THREAD(), and uip_ds6_periodic().

void etimer_restart ( struct etimer * et )

Restart an event timer from the current point in time.

Parameters

et

A pointer to the event timer.

        This function restarts the event timer with the same
        interval that was given to the etimer_set()
        function. The event 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
        etimer_reset() function instead.

See Also: etimer_reset()

References add_timer(), timer, and timer_restart().

Referenced by ctimer_restart(), eventhandler(), PROCESS_THREAD(), and start_periodic_tcp_timer().

CCIF void etimer_set	(	struct etimer *	et,
		clock_time_t	interval
	)

Set an event timer.

Parameters

et A pointer to the event timer

interval

The interval before the timer expires.

        This function is used to set an event timer for a time
        sometime in the future. When the event timer expires,
        the event PROCESS_EVENT_TIMER will be posted to the
        process that called the etimer_set() function.

References add_timer(), timer, and timer_set().

Referenced by ctimer_set(), PROCESS_THREAD(), servreg_hack_register(), start_timeout_timer(), uip_ds6_init(), uip_ds6_send_rs(), and while().

clock_time_t etimer_start_time ( struct etimer * et )

Get the start time for the event timer.

Parameters

et	A pointer to the event timer

Returns

The start time for the event timer.

        This function returns the start time (when the timer
        was last set) for an event timer.

References timer::start, and timer.

void etimer_stop ( struct etimer * et )

Stop a pending event timer.

Parameters

et	A pointer to the pending event timer. This function stops an event timer that has previously been set with etimer_set() or etimer_reset(). After this function has been called, the event timer will not emit any event when it expires.

References next, NULL, p, PROCESS_NONE, and update_time().

Referenced by ctimer_stop(), removesocket(), and uip_ds6_send_rs().