Timer library
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.
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:
-
- 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()
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. |
