If timers are updated the elapsed time between their due time and the time they were actually updated is not considered. More...

Data Structures
struct	timer_base
	Timer management base structure. More...

Macros
#define	TIMER_ID_INVALID UINT32_MAX
	Timer id, that is always considered invalid by the timer functions.

Typedefs
typedef int	timer_cb (uint64_t elapsed, void *data)
	Format of a timer callback. More...

Enumerations
enum	timer_mode { TIMER_DEFAULT = 0, TIMER_SINGLESHOT = 1 }
	Mode for newly added timers. More...

Functions
static bool	timer_isvalid (struct timer_base *base, uint32_t id)

int	timer_base_init (struct timer_base *base, uint32_t num_timers)
	Initialize a timer base and allocate resources. More...

void	timer_base_clear (struct timer_base *base)
	Clear a timer base and free all its associated resources. More...

int	timer_add (struct timer_base base, uint32_t id, uint32_t ms, timer_cb cb, void *data, uint8_t mode)
	Initialize and activate an emtpy timer element in the base. More...

int	timer_remove (struct timer_base base, uint32_t id, void *data)
	Deactivate and remove a timer entry. More...

int	timer_activate (struct timer_base *base, uint32_t id)
	Activate the timer entry with `id`. More...

int	timer_deactivate (struct timer_base *base, uint32_t id)
	Deactivate the timer entry with `id`. More...

uint32_t	timer_update (struct timer_base *base)
	Find and shoot all due timers in the base. More...

uint64_t	timer_tickcount (void)
	Returns a monotonically increasing tickcount in milisecond resolution. More...

uint64_t	timer_tickdiff (uint64_t current, uint64_t last)
	Calculate the difference between two tickcounts. More...

Detailed Description

If timers are updated the elapsed time between their due time and the time they were actually updated is not considered.

So timers won't shoot at a constant frequency if update isn't called exactly at their due times, but they will always run for at least their configured interval.

A timer can be removed from inside the timer callback using one of the following options:

Create the timer with the singleshot option, it will be removed after the first shot automatically.
Return -1 in the timer callback.
Call the timer_remove() function.

Note: Each of these is a valid option, but do not combine them!

Typedef Documentation

typedef int timer_cb(uint64_t elapsed, void *data)

Format of a timer callback.

Parameters

elapsed	Actually elapesd time since the last callback in miliseconds.
data	The data that was added to the timer with timer_add.

Returns: Zero by default, -1 will remove the timer after the callback.

Enumeration Type Documentation

enum timer_mode

Mode for newly added timers.

See also: timer_add

Enumerator
TIMER_DEFAULT	Default: periodic timer.
TIMER_SINGLESHOT	Singleshot timer.

Function Documentation

int timer_activate	(	struct timer_base *	base,
		uint32_t	id
	)

Activate the timer entry with id.

The timer will resume shooting with the properties it was added. The timer will not shoot before ms time has past.

Parameters

base	The timer base holding the timer to activate.
id	The id of the timer to be activated.

Returns: Zero on success or errocode on failure.

int timer_add	(	struct timer_base *	base,
		uint32_t *	id,
		uint32_t	ms,
		timer_cb	cb,
		void *	data,
		uint8_t	mode
	)

Initialize and activate an emtpy timer element in the base.

Parameters

base	The timer base to add a new timer to.
id	Output parameter that contains the id of the new timer (may be NULL).
ms	The interval of the timer to shoot at in milliseconds. Zero is not allowed.
cb	The callback function to be called when the timer shoots.
data	The data passed to the callback function (may be NULL).
mode	Timer mode like TIMER_DEFAULT, see timer_mode.

Returns: Zero on success or errocode on failure.

void timer_base_clear ( struct timer_base * base )

Clear a timer base and free all its associated resources.

Parameters

base	The base to be cleared.

int timer_base_init	(	struct timer_base *	base,
		uint32_t	num_timers
	)

Initialize a timer base and allocate resources.

Parameters

base	The base to be initialized.
num_timers	The maximum number of timers the base can hold.

Returns: Zero on success or errocode on failure.

int timer_deactivate	(	struct timer_base *	base,
		uint32_t	id
	)

Deactivate the timer entry with id.

The timer will stop shooting, but its resources will still be allocated. Note: Calling deactivate and then activate is much faster than calling remove and add for a timer.

Parameters

base	The timer base holding the timer to deactivate.
id	The id of the timer to be deactivated.

Returns: Zero on success or errocode on failure.

int timer_remove	(	struct timer_base *	base,
		uint32_t	id,
		void **	data
	)

Deactivate and remove a timer entry.

Parameters

base	The timer base holding the timer to remove.
id	The id of the timer to be removed.
data	Output parameter that returns the data added with timer_add (may be NULL).

Returns: Zero on success or errocode on failure.

uint64_t timer_tickcount ( void )

Returns a monotonically increasing tickcount in milisecond resolution.

Depending on the platform this value may or may not overflow.

uint64_t timer_tickdiff	(	uint64_t	current,
		uint64_t	last
	)

Calculate the difference between two tickcounts.

This function handles a possible overflow between the tickcounts, but doesn't work correctly if more than one epoch elapsed between the tickcounts.

Parameters

current	The newer tickcount.
last	The older tickcount.

Returns: Difference between current and last in miliseconds.

uint32_t timer_update ( struct timer_base * base )

Find and shoot all due timers in the base.

Looks at every timer and calls the callback if its due time has passed.

Parameters

base	Timer base whose timers need to be updated

Returns: ms till the next timer is due, or UINT32_MAX if there is none.

Data Structures

Macros

Typedefs

Enumerations

Functions

Detailed Description

Typedef Documentation

Enumeration Type Documentation

Function Documentation