The Event Manager provides a high performance method of inter-task communication and synchronization. More...

Macros
#define	RTEMS_ALL_EVENTS 0xffffffff
	This event set constant represents all events of an event set.

#define	RTEMS_EVENT_0 0x00000001
	This event set constant represents the bit in the event set associated with event 0.

#define	RTEMS_EVENT_1 0x00000002
	This event set constant represents the bit in the event set associated with event 1.

#define	RTEMS_EVENT_2 0x00000004
	This event set constant represents the bit in the event set associated with event 2.

#define	RTEMS_EVENT_3 0x00000008
	This event set constant represents the bit in the event set associated with event 3.

#define	RTEMS_EVENT_4 0x00000010
	This event set constant represents the bit in the event set associated with event 4.

#define	RTEMS_EVENT_5 0x00000020
	This event set constant represents the bit in the event set associated with event 5.

#define	RTEMS_EVENT_6 0x00000040
	This event set constant represents the bit in the event set associated with event 6.

#define	RTEMS_EVENT_7 0x00000080
	This event set constant represents the bit in the event set associated with event 7.

#define	RTEMS_EVENT_8 0x00000100
	This event set constant represents the bit in the event set associated with event 8.

#define	RTEMS_EVENT_9 0x00000200
	This event set constant represents the bit in the event set associated with event 9.

#define	RTEMS_EVENT_10 0x00000400
	This event set constant represents the bit in the event set associated with event 10.

#define	RTEMS_EVENT_11 0x00000800
	This event set constant represents the bit in the event set associated with event 11.

#define	RTEMS_EVENT_12 0x00001000
	This event set constant represents the bit in the event set associated with event 12.

#define	RTEMS_EVENT_13 0x00002000
	This event set constant represents the bit in the event set associated with event 13.

#define	RTEMS_EVENT_14 0x00004000
	This event set constant represents the bit in the event set associated with event 14.

#define	RTEMS_EVENT_15 0x00008000
	This event set constant represents the bit in the event set associated with event 15.

#define	RTEMS_EVENT_16 0x00010000
	This event set constant represents the bit in the event set associated with event 16.

#define	RTEMS_EVENT_17 0x00020000
	This event set constant represents the bit in the event set associated with event 17.

#define	RTEMS_EVENT_18 0x00040000
	This event set constant represents the bit in the event set associated with event 18.

#define	RTEMS_EVENT_19 0x00080000
	This event set constant represents the bit in the event set associated with event 19.

#define	RTEMS_EVENT_20 0x00100000
	This event set constant represents the bit in the event set associated with event 20.

#define	RTEMS_EVENT_21 0x00200000
	This event set constant represents the bit in the event set associated with event 21.

#define	RTEMS_EVENT_22 0x00400000
	This event set constant represents the bit in the event set associated with event 22.

#define	RTEMS_EVENT_23 0x00800000
	This event set constant represents the bit in the event set associated with event 23.

#define	RTEMS_EVENT_24 0x01000000
	This event set constant represents the bit in the event set associated with event 24.

#define	RTEMS_EVENT_25 0x02000000
	This event set constant represents the bit in the event set associated with event 25.

#define	RTEMS_EVENT_26 0x04000000
	This event set constant represents the bit in the event set associated with event 26.

#define	RTEMS_EVENT_27 0x08000000
	This event set constant represents the bit in the event set associated with event 27.

#define	RTEMS_EVENT_28 0x10000000
	This event set constant represents the bit in the event set associated with event 28.

#define	RTEMS_EVENT_29 0x20000000
	This event set constant represents the bit in the event set associated with event 29.

#define	RTEMS_EVENT_30 0x40000000
	This event set constant represents the bit in the event set associated with event 30.

#define	RTEMS_EVENT_31 0x80000000
	This event set constant represents the bit in the event set associated with event 31.

#define	RTEMS_PENDING_EVENTS 0
	This event set constant indicates that rtems_event_receive() shall return the set of pending events.

Typedefs
typedef uint32_t	rtems_event_set
	This integer type represents a bit field which can hold exactly 32 individual events.

Functions
rtems_status_code	rtems_event_send (rtems_id id, rtems_event_set event_in)
	Sends the event set to the task.

rtems_status_code	rtems_event_receive (rtems_event_set event_in, rtems_option option_set, rtems_interval ticks, rtems_event_set *event_out)
	Receives or gets an event set from the calling task.

Detailed Description

The Event Manager provides a high performance method of inter-task communication and synchronization.

Macro Definition Documentation

◆ RTEMS_ALL_EVENTS

#define RTEMS_ALL_EVENTS 0xffffffff

This event set constant represents all events of an event set.

This event set constant is equal to the bitwise or of RTEMS_EVENT_0, RTEMS_EVENT_1, RTEMS_EVENT_2, RTEMS_EVENT_3, RTEMS_EVENT_4, RTEMS_EVENT_5, RTEMS_EVENT_6, RTEMS_EVENT_7, RTEMS_EVENT_8, RTEMS_EVENT_9, RTEMS_EVENT_10, RTEMS_EVENT_11, RTEMS_EVENT_12, RTEMS_EVENT_13, RTEMS_EVENT_14, RTEMS_EVENT_15, RTEMS_EVENT_16, RTEMS_EVENT_17, RTEMS_EVENT_18, RTEMS_EVENT_19, RTEMS_EVENT_20, RTEMS_EVENT_21, RTEMS_EVENT_22, RTEMS_EVENT_23, RTEMS_EVENT_24, RTEMS_EVENT_25, RTEMS_EVENT_26, RTEMS_EVENT_27, RTEMS_EVENT_28, RTEMS_EVENT_29, RTEMS_EVENT_30, and RTEMS_EVENT_31.

Function Documentation

◆ rtems_event_receive()

rtems_status_code rtems_event_receive	(	rtems_event_set	event_in,
		rtems_option	option_set,
		rtems_interval	ticks,
		rtems_event_set *	event_out
	)

Receives or gets an event set from the calling task.

Parameters

event_in	is the event set of interest. Use RTEMS_PENDING_EVENTS to get the pending events.
option_set	is the option set.
ticks	is the timeout in clock ticks if the RTEMS_WAIT option is set. Use RTEMS_NO_TIMEOUT to wait potentially forever.
event_out	is the pointer to an event set. The received or pending events are stored in the referenced event set if the operation was successful.

This directive can be used to

get the pending events of the calling task, or
receive events.

To get the pending events use the constant RTEMS_PENDING_EVENTS for the event_in parameter. The pending events are returned to the calling task but the event set of the calling task is left unaltered. The option_set and ticks parameters are ignored in this case. The directive returns immediately and does not block.

To receive events you have to define an input event condition and some options.

The option set specified in option_set is built through a bitwise or of the option constants described below. Not all combinations of options are allowed. Some options are mutually exclusive. If mutually exclusive options are combined, the behaviour is undefined. Options not mentioned below are not evaluated by this directive and have no effect. Default options can be selected by using the RTEMS_DEFAULT_OPTIONS constant. The option set defines

if the calling task will wait or poll for the events, and
if the calling task wants to receive all or any of the input events.

The calling task can wait or poll for the events.

Waiting for events is the default and can be emphasized through the use of the RTEMS_WAIT option. The ticks parameter defines how long the calling task is willing to wait. Use RTEMS_NO_TIMEOUT to wait potentially forever, otherwise set a timeout interval in clock ticks.
Not waiting for events (polling) is selected by the RTEMS_NO_WAIT option. If this option is defined, then the ticks parameter is ignored.

The calling task can receive all or any of the input events specified in event_in.

Receiving all input events is the default and can be emphasized through the use of the RTEMS_EVENT_ALL option.
Receiving any of the input events is selected by the RTEMS_EVENT_ANY option.

Return values

RTEMS_SUCCESSFUL	The requested operation was successful.
RTEMS_INVALID_ADDRESS	The `event_out` parameter was NULL.
RTEMS_UNSATISFIED	The events of interest were not immediately available.
RTEMS_TIMEOUT	The events of interest were not available within the specified timeout interval.

Notes

This directive only affects the events specified in event_in. Any pending events that do not correspond to any of the events specified in event_in will be left pending.

To receive all events use the event set constant RTEMS_ALL_EVENTS for the event_in parameter. Do not confuse this event set constant with the directive option RTEMS_EVENT_ALL.

A task can receive all of the pending events by calling the directive with a value of RTEMS_ALL_EVENTS for the event_in parameter and the bitwise or of the RTEMS_NO_WAIT and RTEMS_EVENT_ANY options for the option_set parameter. The pending events are returned and the event set of the task is cleared. If no events are pending then the RTEMS_UNSATISFIED status code will be returned.

Constraints

The following constraints apply to this directive:

The directive may be called from within device driver initialization context.
The directive may be called from within task context.
The timeout functionality of the directive requires a clock tick.

◆ rtems_event_send()

rtems_status_code rtems_event_send	(	rtems_id	id,
		rtems_event_set	event_in
	)

Sends the event set to the task.

Parameters

id	is the identifier of the target task to receive the event set.
event_in	is the event set to send.

This directive sends the event set, event_in, to the target task identified by id. Based upon the state of the target task, one of the following situations applies:

The target task is blocked waiting for events, then
- if the waiting task's input event condition is satisfied, then the task is made ready for execution, or
- otherwise, the event set is posted but left pending and the task remains blocked.
The target task is not waiting for events, then the event set is posted and left pending.

Return values

RTEMS_SUCCESSFUL	The requested operation was successful.
RTEMS_INVALID_ID	There was no task associated with the identifier specified by `id`.

Notes

Events can be sent by tasks or an ISR.

Specifying RTEMS_SELF for id results in the event set being sent to the calling task.

The event set to send shall be built by a bitwise or of the desired events. The set of valid events is RTEMS_EVENT_0 through RTEMS_EVENT_31. If an event is not explicitly specified in the set, then it is not present.

Identical events sent to a task are not queued. In other words, the second, and subsequent, posting of an event to a task before it can perform an rtems_event_receive() has no effect.

The calling task will be preempted if it has preemption enabled and a higher priority task is unblocked as the result of this directive.

Sending an event set to a global task which does not reside on the local node will generate a request telling the remote node to send the event set to the appropriate task.