Seconds timer library

The stimer 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 struct stimer and all access to the timer is made by a pointer to the declared timer.

Note

The stimer library is not able to post events when a timer expires. The Event timers should be used for this purpose.

The stimer library uses the Clock library to measure time. Intervals should be specified in the seconds.

See Also

Event timers

Data Structures
struct	stimer
	A timer. More...

Files
file	stimer.c
	Timer of seconds library implementation.
file	stimer.h
	Second timer library header file.

Macros
#define	SCLOCK_GEQ(a, b)

Functions
unsigned long	stimer_elapsed (struct stimer *t)
	The time elapsed since the timer started. More...
int	stimer_expired (struct stimer *t)
	Check if a timer has expired. More...
unsigned long	stimer_remaining (struct stimer *t)
	The time until the timer expires. More...
void	stimer_reset (struct stimer *t)
	Reset the timer with the same interval. More...
void	stimer_restart (struct stimer *t)
	Restart the timer from the current point in time. More...
void	stimer_set (struct stimer *t, unsigned long interval)
	Set a timer. More...

#define SCLOCK_GEQ	(		a,
			b
	)

Value:

((unsigned long)((a) - (b)) < \
                ((unsigned long)(~((unsigned long)0)) >> 1))

Referenced by stimer_expired().

unsigned long stimer_elapsed

(

struct stimer *

t

)

The time elapsed since the timer started.

This function returns the time elapsed.

Parameters

t	A pointer to the timer

Returns

The time elapsed since the last start of the timer

References clock_seconds(), and start.

int stimer_expired

(

struct stimer *

t

)

Check if a timer has expired.

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

Parameters

t	A pointer to the timer

Returns

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

References clock_seconds(), interval, SCLOCK_GEQ, and start.

Referenced by uip_ds6_defrt_periodic(), uip_ds6_neighbor_periodic(), and uip_ds6_periodic().

unsigned long stimer_remaining

(

struct stimer *

t

)

The time until the timer expires.

This function returns the time until the timer expires.

Parameters

t	A pointer to the timer

Returns

The time until the timer expires

References clock_seconds(), interval, and start.

Referenced by ra_input(), and uip_ds6_get_least_lifetime_neighbor().

void stimer_reset

(

struct stimer *

t

)

Reset the timer with the same interval.

This function resets the timer with the same interval that was given to the stimer_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 stimer_restart() function.

Parameters

t	A pointer to the timer.

See Also

stimer_restart()

References interval, and start.

void stimer_restart

(

struct stimer *

t

)

Restart the timer from the current point in time.

This function restarts a timer with the same interval that was given to the stimer_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 stimer_reset() function instead.

Parameters

t	A pointer to the timer.

See Also

stimer_reset()

References clock_seconds(), and start.

void stimer_set	(	struct stimer *	t,
		unsigned long	interval
	)

Set a timer.

This function is used to set a timer for a time sometime in the future. The function stimer_expired() will evaluate to true after the timer has expired.

Parameters

t	A pointer to the timer
interval	The interval before the timer expires.

References clock_seconds(), interval, and start.

Referenced by dao_input(), dio_input(), na_input(), ra_input(), tcpip_ipv6_output(), uip_ds6_addr_add(), uip_ds6_defrt_add(), uip_ds6_init(), uip_ds6_link_neighbor_callback(), uip_ds6_nbr_add(), uip_ds6_neighbor_periodic(), and uip_ds6_prefix_add().