Task Services
[Driver Development API]

Task Priority Range
Maximum and minimum task priorities
#define	RTDM_TASK_LOWEST_PRIORITY   XNCORE_LOW_PRIO
#define	RTDM_TASK_HIGHEST_PRIORITY   XNCORE_HIGH_PRIO
Task Priority Modification
Raise or lower task priorities by one level
#define	RTDM_TASK_RAISE_PRIORITY   (+1)
#define	RTDM_TASK_LOWER_PRIORITY   (-1)
Typedefs
typedef void(*	rtdm_task_proc_t )(void *arg)
	Real-time task procedure.
Functions
int	rtdm_task_init (rtdm_task_t *task, const char *name, rtdm_task_proc_t task_proc, void *arg, int priority, nanosecs_rel_t period)
	Intialise and start a real-time task.
void	rtdm_task_destroy (rtdm_task_t *task)
	Destroy a real-time task.
void	rtdm_task_set_priority (rtdm_task_t *task, int priority)
	Adjust real-time task priority.
int	rtdm_task_set_period (rtdm_task_t *task, nanosecs_rel_t period)
	Adjust real-time task period.
int	rtdm_task_wait_period (void)
	Wait on next real-time task period.
int	rtdm_task_unblock (rtdm_task_t *task)
	Activate a blocked real-time task.
rtdm_task_t *	rtdm_task_current (void)
	Get current real-time task.
void	rtdm_task_join_nrt (rtdm_task_t *task, unsigned int poll_delay)
	Wait on a real-time task to terminate.
int	rtdm_task_sleep (nanosecs_rel_t delay)
	Sleep a specified amount of time.
int	rtdm_task_sleep_until (nanosecs_abs_t wakeup_time)
	Sleep until a specified absolute time.
void	rtdm_task_busy_sleep (nanosecs_rel_t delay)
	Busy-wait a specified amount of time.

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Typedef Documentation

typedef void(* rtdm_task_proc_t)(void *arg)

Real-time task procedure. Parameters: [in,out]  arg  argument as passed to rtdm_task_init()

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Function Documentation

void rtdm_task_busy_sleep (  nanosecs_rel_t  delay  )

Busy-wait a specified amount of time. Parameters: [in]  delay  Delay in nanoseconds. Note that a zero delay does not have the meaning of RTDM_TIMEOUT_INFINITE here. Note: The caller must not be migratable to different CPUs while executing this service. Otherwise, the actual delay will be undefined. Environments: This service can be called from: Kernel module initialization/cleanup code Interrupt service routine (should be avoided or kept short) Kernel-based task User-space task (RT, non-RT) Rescheduling: never (except due to external interruptions).

rtdm_task_t* rtdm_task_current (  void   )

Get current real-time task. Returns: Pointer to task handle Environments: This service can be called from: Kernel-based task User-space task (RT, non-RT) Rescheduling: never.

void rtdm_task_destroy (  rtdm_task_t *  task  )

Destroy a real-time task. Parameters: [in,out]  task  Task handle as returned by rtdm_task_init() Note: Passing the same task handle to RTDM services after the completion of this function is not allowed. Environments: This service can be called from: Kernel module initialization/cleanup code Kernel-based task User-space task (RT, non-RT) Rescheduling: never.

int rtdm_task_init (  rtdm_task_t *  task, const char *  name, rtdm_task_proc_t  task_proc, void *  arg, int  priority, nanosecs_rel_t  period )

Intialise and start a real-time task. After initialising a task, the task handle remains valid and can be passed to RTDM services until either rtdm_task_destroy() or rtdm_task_join_nrt() was invoked. Parameters: [in,out]  task  Task handle [in]  name  Optional task name [in]  task_proc  Procedure to be executed by the task [in]  arg  Custom argument passed to task_proc() on entry [in]  priority  Priority of the task, see also Task Priority Range [in]  period  Period in nanosecons of a cyclic task, 0 for non-cyclic mode Returns: 0 on success, otherwise negative error code Environments: This service can be called from: Kernel module initialization/cleanup code Kernel-based task User-space task (RT, non-RT) Rescheduling: possible.

void rtdm_task_join_nrt (  rtdm_task_t *  task, unsigned int  poll_delay )

Wait on a real-time task to terminate. Parameters: [in,out]  task  Task handle as returned by rtdm_task_init() [in]  poll_delay  Polling delay in milliseconds Note: Passing the same task handle to RTDM services after the completion of this function is not allowed. This service does not trigger the termination of the targeted task. The user has to take of this, otherwise rtdm_task_join_nrt() will never return. Environments: This service can be called from: Kernel module initialization/cleanup code User-space task (non-RT) Rescheduling: possible.

int rtdm_task_set_period (  rtdm_task_t *  task, nanosecs_rel_t  period )

Adjust real-time task period. Parameters: [in,out]  task  Task handle as returned by rtdm_task_init() [in]  period  New period in nanosecons of a cyclic task, 0 for non-cyclic mode Environments: This service can be called from: Kernel module initialization/cleanup code Interrupt service routine Kernel-based task User-space task (RT, non-RT) Rescheduling: possible.

void rtdm_task_set_priority (  rtdm_task_t *  task, int  priority )

Adjust real-time task priority. Parameters: [in,out]  task  Task handle as returned by rtdm_task_init() [in]  priority  New priority of the task, see also Task Priority Range Environments: This service can be called from: Kernel module initialization/cleanup code Interrupt service routine Kernel-based task User-space task (RT, non-RT) Rescheduling: possible.

int rtdm_task_sleep (  nanosecs_rel_t  delay  )

Sleep a specified amount of time. Parameters: [in]  delay  Delay in nanoseconds, see RTDM_TIMEOUT_xxx for special values. Returns: 0 on success, otherwise: -EINTR is returned if calling task has been unblock by a signal or explicitely via rtdm_task_unblock(). -EPERM may be returned if an illegal invocation environment is detected. Environments: This service can be called from: Kernel-based task User-space task (RT) Rescheduling: always.

int rtdm_task_sleep_until (  nanosecs_abs_t  wakeup_time  )

Sleep until a specified absolute time. Parameters: [in]  wakeup_time  Absolute timeout in nanoseconds Returns: 0 on success, otherwise: -EINTR is returned if calling task has been unblock by a signal or explicitely via rtdm_task_unblock(). -EPERM may be returned if an illegal invocation environment is detected. Environments: This service can be called from: Kernel-based task User-space task (RT) Rescheduling: always, unless the specified time already passed.

int rtdm_task_unblock (  rtdm_task_t *  task  )

Activate a blocked real-time task. Returns: Non-zero is returned if the task was actually unblocked from a pending wait state, 0 otherwise. Environments: This service can be called from: Kernel module initialization/cleanup code Interrupt service routine Kernel-based task User-space task (RT, non-RT) Rescheduling: possible.

int rtdm_task_wait_period (  void   )

Wait on next real-time task period. Returns: 0 on success, otherwise: -EINVAL is returned if calling task is not in periodic mode. -ETIMEDOUT is returned if a timer overrun occurred, which indicates that a previous release point has been missed by the calling task. Environments: This service can be called from: Kernel-based task User-space task (RT) Rescheduling: always, unless a timer overrun occured.

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