Event timers

Files
file	etimer.c
file	etimer.h

Classes
struct	etimer

Macros
#define	data   _data

Functions
	PROCESS (etimer_process, "Event timer")
static void	update_time (void)
	PROCESS_THREAD (etimer_process, ev, data)
static void	add_timer (struct etimer *timer)
	PROCESS_NAME (etimer_process)

Variables
static struct etimer *	timerlist
static clock_time_t	next_expiration

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...

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...

Detailed Description

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)

Macro Definition Documentation

data

#define data   _data

Function Documentation

add_timer()

static void add_timer ( struct etimer *  timer )

static

etimer_adjust()

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()

etimer_expiration_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.

etimer_expired()

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.

etimer_next_expiration_time()

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.

etimer_pending()

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.

etimer_request_poll()

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.

etimer_reset()

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()

etimer_restart()

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()

etimer_set()

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.

etimer_start_time()

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.

etimer_stop()

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.

PROCESS()

PROCESS	(	etimer_process	,
		"Event timer"
	)

PROCESS_NAME()

PROCESS_NAME

(

etimer_process

)

PROCESS_THREAD()

PROCESS_THREAD	(	etimer_process	,
		ev	,
		data
	)

update_time()

static void update_time ( void  )

static

Variable Documentation

next_expiration

clock_time_t next_expiration

static

timerlist

struct etimer* timerlist

static