Timer library

Data Structures
struct	timer
Files
file	timer.c
file	timer.h
Functions
void	timer_set (struct timer *t, clock_time_t interval)
void	timer_reset (struct timer *t)
void	timer_restart (struct timer *t)
int	timer_expired (struct timer *t)

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Detailed Description

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

Note:

The timer library uses the Clock library to measure time. Intervals should be specified in the format used by the clock library.

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Function Documentation

int timer_expired

(

struct timer *

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.

void timer_reset

(

struct timer *

t

)

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.

Parameters:

t

A pointer to the timer.

See also:

timer_restart()

void timer_restart

(

struct timer *

t

)

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.

Parameters:

t

A pointer to the timer.

See also:

timer_reset()

void timer_set	(	struct timer *	t,
		clock_time_t	interval
	)

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.

Parameters:

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