/**
* @file rtems/rtems/event.h
*
* @defgroup ClassicEvent Events
*
* @ingroup ClassicRTEMS
* @brief Information Related to Event Manager
*
* This include file contains the information pertaining to the Event
* Manager. This manager provides a high performance method of communication
* and synchronization.
*
* Directives provided are:
*
* - send an event set to a task
* - receive event condition
*
*/
/* COPYRIGHT (c) 1989-2008.
* On-Line Applications Research Corporation (OAR).
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.org/license/LICENSE.
*/
#ifndef _RTEMS_RTEMS_EVENT_H
#define _RTEMS_RTEMS_EVENT_H
#include <rtems/rtems/status.h>
#include <rtems/rtems/types.h>
#include <rtems/rtems/options.h>
#ifdef __cplusplus
extern "C" {
#endif
/**
* @defgroup ClassicEventSet Event Set
*
* @ingroup ClassicEvent
*
* @{
*/
/**
* @brief Integer type to hold an event set of up to 32 events represented as
* a bit field.
*/
typedef uint32_t rtems_event_set;
/**
* @brief Constant used to send or receive all events.
*/
#define RTEMS_ALL_EVENTS 0xFFFFFFFF
/** @brief Defines the bit in the event set associated with event 0. */
#define RTEMS_EVENT_0 0x00000001
/** @brief Defines the bit in the event set associated with event 1. */
#define RTEMS_EVENT_1 0x00000002
/** @brief Defines the bit in the event set associated with event 2. */
#define RTEMS_EVENT_2 0x00000004
/** @brief Defines the bit in the event set associated with event 3. */
#define RTEMS_EVENT_3 0x00000008
/** @brief Defines the bit in the event set associated with event 4. */
#define RTEMS_EVENT_4 0x00000010
/** @brief Defines the bit in the event set associated with event 5. */
#define RTEMS_EVENT_5 0x00000020
/** @brief Defines the bit in the event set associated with event 6. */
#define RTEMS_EVENT_6 0x00000040
/** @brief Defines the bit in the event set associated with event 7. */
#define RTEMS_EVENT_7 0x00000080
/** @brief Defines the bit in the event set associated with event 8. */
#define RTEMS_EVENT_8 0x00000100
/** @brief Defines the bit in the event set associated with event 9. */
#define RTEMS_EVENT_9 0x00000200
/** @brief Defines the bit in the event set associated with event 10. */
#define RTEMS_EVENT_10 0x00000400
/** @brief Defines the bit in the event set associated with event 11. */
#define RTEMS_EVENT_11 0x00000800
/** @brief Defines the bit in the event set associated with event 12. */
#define RTEMS_EVENT_12 0x00001000
/** @brief Defines the bit in the event set associated with event 13. */
#define RTEMS_EVENT_13 0x00002000
/** @brief Defines the bit in the event set associated with event 14. */
#define RTEMS_EVENT_14 0x00004000
/** @brief Defines the bit in the event set associated with event 15. */
#define RTEMS_EVENT_15 0x00008000
/** @brief Defines the bit in the event set associated with event 16. */
#define RTEMS_EVENT_16 0x00010000
/** @brief Defines the bit in the event set associated with event 17. */
#define RTEMS_EVENT_17 0x00020000
/** @brief Defines the bit in the event set associated with event 18. */
#define RTEMS_EVENT_18 0x00040000
/** @brief Defines the bit in the event set associated with event 19. */
#define RTEMS_EVENT_19 0x00080000
/** @brief Defines the bit in the event set associated with event 20. */
#define RTEMS_EVENT_20 0x00100000
/** @brief Defines the bit in the event set associated with event 21. */
#define RTEMS_EVENT_21 0x00200000
/** @brief Defines the bit in the event set associated with event 22. */
#define RTEMS_EVENT_22 0x00400000
/** @brief Defines the bit in the event set associated with event 23. */
#define RTEMS_EVENT_23 0x00800000
/** @brief Defines the bit in the event set associated with event 24. */
#define RTEMS_EVENT_24 0x01000000
/** @brief Defines the bit in the event set associated with event 25. */
#define RTEMS_EVENT_25 0x02000000
/** @brief Defines the bit in the event set associated with event 26. */
#define RTEMS_EVENT_26 0x04000000
/** @brief Defines the bit in the event set associated with event 27. */
#define RTEMS_EVENT_27 0x08000000
/** @brief Defines the bit in the event set associated with event 29. */
#define RTEMS_EVENT_28 0x10000000
/** @brief Defines the bit in the event set associated with event 29. */
#define RTEMS_EVENT_29 0x20000000
/** @brief Defines the bit in the event set associated with event 30. */
#define RTEMS_EVENT_30 0x40000000
/** @brief Defines the bit in the event set associated with event 31. */
#define RTEMS_EVENT_31 0x80000000
/** @} */
/**
* @defgroup ClassicEvent Events
*
* @ingroup ClassicRTEMS
*
* @brief The event manager provides a high performance method of intertask
* communication and synchronization.
*
* An event flag is used by a task (or ISR) to inform another task of the
* occurrence of a significant situation. Thirty-two event flags are
* associated with each task. A collection of one or more event flags is
* referred to as an event set. The data type rtems_event_set is used to
* manage event sets.
*
* The application developer should remember the following key characteristics
* of event operations when utilizing the event manager:
*
* - Events provide a simple synchronization facility.
* - Events are aimed at tasks.
* - Tasks can wait on more than one event simultaneously.
* - Events are independent of one another.
* - Events do not hold or transport data.
* - Events are not queued. In other words, if an event is sent more than once
* to a task before being received, the second and subsequent send
* operations to that same task have no effect.
*
* An event set is posted when it is directed (or sent) to a task. A pending
* event is an event that has been posted but not received. An event condition
* is used to specify the event set which the task desires to receive and the
* algorithm which will be used to determine when the request is satisfied. An
* event condition is satisfied based upon one of two algorithms which are
* selected by the user. The @ref RTEMS_EVENT_ANY algorithm states that an
* event condition is satisfied when at least a single requested event is
* posted. The @ref RTEMS_EVENT_ALL algorithm states that an event condition
* is satisfied when every requested event is posted.
*
* An event set or condition is built by a bitwise or of the desired events.
* The set of valid events is @ref RTEMS_EVENT_0 through @ref RTEMS_EVENT_31.
* If an event is not explicitly specified in the set or condition, then it is
* not present. Events are specifically designed to be mutually exclusive,
* therefore bitwise or and addition operations are equivalent as long as each
* event appears exactly once in the event set list.
*
* For example, when sending the event set consisting of @ref RTEMS_EVENT_6,
* @ref RTEMS_EVENT_15, and @ref RTEMS_EVENT_31, the event parameter to the
* rtems_event_send() directive should be @ref RTEMS_EVENT_6 |
* @ref RTEMS_EVENT_15 | @ref RTEMS_EVENT_31.
*
* @{
*/
/**
* @brief Constant used to receive the set of currently pending events in
* rtems_event_receive().
*/
#define RTEMS_PENDING_EVENTS 0
/**
* @brief Sends an Event Set to the Target Task
*
* This directive sends an event set @a event_in to the task specified by
* @a id.
*
* Based upon the state of the target task, one of the following situations
* applies. The target task is
* - blocked waiting for events.
* If the waiting task's input event condition is
* - satisfied, then the task is made ready for execution.
* - not satisfied, then the event set is posted but left pending and the
* task remains blocked.
* - not waiting for events.
* - The event set is posted and left pending.
*
* 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.
*
* @param[in] id Identifier of the target task. Specifying @ref RTEMS_SELF
* results in the event set being sent to the calling task.
* @param[in] event_in Event set sent to the target task.
*
* @retval RTEMS_SUCCESSFUL Successful operation.
* @retval RTEMS_INVALID_ID Invalid task identifier.
*/
rtems_status_code rtems_event_send (
rtems_id id,
rtems_event_set event_in
);
/**
* @brief Receives pending events.
*
* This directive attempts to receive the event condition specified in
* @a event_in. If @a event_in is set to @ref RTEMS_PENDING_EVENTS, then the
* current pending events are returned in @a event_out and left pending. The
* @ref RTEMS_WAIT and @ref RTEMS_NO_WAIT options in the @a option_set
* parameter are used to specify whether or not the task is willing to wait
* for the event condition to be satisfied. The @ref RTEMS_EVENT_ANY and @ref
* RTEMS_EVENT_ALL are used in the @a option_set parameter to specify whether
* at least a single event or the complete event set is necessary to satisfy
* the event condition. The @a event_out parameter is returned to the calling
* task with the value that corresponds to the events in @a event_in that were
* satisfied.
*
* A task can determine the pending event set by using a value of
* @ref RTEMS_PENDING_EVENTS for the input event set @a event_in. The pending
* events are returned to the calling task but the event set is left
* unaltered.
*
* A task can receive all of the currently pending events by using the a value
* of @ref RTEMS_ALL_EVENTS for the input event set @a event_in and
* @ref RTEMS_NO_WAIT | @ref RTEMS_EVENT_ANY for the option set @a option_set.
* The pending events are returned to the calling task and the event set is
* cleared. If no events are pending then the @ref RTEMS_UNSATISFIED status
* code will be returned.
*
* If pending events satisfy the event condition, then @a event_out is set to
* the satisfied events and the pending events in the event condition are
* cleared. If the event condition is not satisfied and @ref RTEMS_NO_WAIT is
* specified, then @a event_out is set to the currently satisfied events. If
* the calling task chooses to wait, then it will block waiting for the event
* condition.
*
* If the calling task must wait for the event condition to be satisfied, then
* the timeout parameter is used to specify the maximum interval to wait. If
* it is set to @ref RTEMS_NO_TIMEOUT, then the calling task will wait forever.
*
* This directive only affects the events specified in @a event_in. Any
* pending events that do not correspond to any of the events specified in
* @a event_in will be left pending.
*
* A clock tick is required to support the wait with time out functionality of
* this directive.
*
* @param[in] event_in Set of requested events (input events).
* @param[in] option_set Use a bitwise or of the following options
* - @ref RTEMS_WAIT - task will wait for event (default),
* - @ref RTEMS_NO_WAIT - task should not wait,
* - @ref RTEMS_EVENT_ALL - return after all events (default), and
* - @ref RTEMS_EVENT_ANY - return after any events.
* @param[in] ticks Time out in ticks. Use @ref RTEMS_NO_TIMEOUT to wait
* without a time out (potentially forever).
* @param[out] event_out Set of received events (output events).
*
* @retval RTEMS_SUCCESSFUL Successful operation.
* @retval RTEMS_UNSATISFIED Input events not satisfied (only with the
* @ref RTEMS_NO_WAIT option).
* @retval RTEMS_INVALID_ADDRESS The @a event_out pointer is @c NULL.
* @retval RTEMS_TIMEOUT Timed out waiting for events.
*/
rtems_status_code rtems_event_receive (
rtems_event_set event_in,
rtems_option option_set,
rtems_interval ticks,
rtems_event_set *event_out
);
/** @} */
/**
* @defgroup ClassicEventSystem System Events
*
* @ingroup ClassicEvent
*
* System events are similar to normal events. They offer a second set of
* events. These events are intended for internal RTEMS use and should not be
* used by applications (with the exception of the transient system event).
*
* The event @ref RTEMS_EVENT_SYSTEM_TRANSIENT is used for transient usage.
* See also @ref ClassicEventTransient. This event may be used by every entity
* that fulfils its usage pattern.
*/
/**@{**/
/**
* @brief Reserved system event for network SBWAIT usage.
*/
#define RTEMS_EVENT_SYSTEM_NETWORK_SBWAIT RTEMS_EVENT_24
/**
* @brief Reserved system event for network SOSLEEP usage.
*/
#define RTEMS_EVENT_SYSTEM_NETWORK_SOSLEEP RTEMS_EVENT_25
/**
* @brief Reserved system event for network socket close.
*/
#define RTEMS_EVENT_SYSTEM_NETWORK_CLOSE RTEMS_EVENT_26
/**
* @brief Reserved system event to resume server threads, e.g timer or
* interrupt server.
*/
#define RTEMS_EVENT_SYSTEM_SERVER_RESUME RTEMS_EVENT_29
/**
* @brief Reserved system event for the server threads, e.g timer or interrupt
* server.
*/
#define RTEMS_EVENT_SYSTEM_SERVER RTEMS_EVENT_30
/**
* @brief Reserved system event for transient usage.
*/
#define RTEMS_EVENT_SYSTEM_TRANSIENT RTEMS_EVENT_31
/**
* @brief See rtems_event_send().
*/
rtems_status_code rtems_event_system_send(
rtems_id id,
rtems_event_set event_in
);
/**
* @brief See rtems_event_receive().
*/
rtems_status_code rtems_event_system_receive(
rtems_event_set event_in,
rtems_option option_set,
rtems_interval ticks,
rtems_event_set *event_out
);
/** @} */
/**
* @defgroup ClassicEventTransient Transient Event
*
* @ingroup ClassicEvent
*
* The transient event can be used by a client task to issue a request to
* another task or interrupt service (server). The server can send the
* transient event to the client task to notify about a request completion, see
* rtems_event_transient_send(). The client task can wait for the transient
* event reception with rtems_event_transient_receive().
*
* The user of the transient event must ensure that this event is not pending
* once the request is finished or cancelled. A successful reception of the
* transient event with rtems_event_transient_receive() will clear the
* transient event. If a reception with timeout is used the transient event
* state is undefined after a timeout return status. The transient event can
* be cleared unconditionally with the non-blocking
* rtems_event_transient_clear().
*
* @msc
* hscale="1.6";
* M [label="Main Task"], IDLE [label="Idle Task"], S [label="Server"], TIME [label="System Tick Handler"];
* |||;
* --- [label="sequence with request completion"];
* M box M [label="prepare request\nissue request\nrtems_event_transient_receive()"];
* M=>>IDLE [label="blocking operation"];
* IDLE=>>S [label="request completion"];
* S box S [label="rtems_event_transient_send()"];
* S=>>M [label="task is ready again"];
* M box M [label="finish request"];
* |||;
* --- [label="sequence with early request completion"];
* M box M [label="prepare request\nissue request"];
* M=>>S [label="request completion"];
* S box S [label="rtems_event_transient_send()"];
* S=>>M [label="transient event is now pending"];
* M box M [label="rtems_event_transient_receive()\nfinish request"];
* |||;
* --- [label="sequence with timeout event"];
* M box M [label="prepare request\nissue request\nrtems_event_transient_receive()"];
* M=>>IDLE [label="blocking operation"];
* IDLE=>>TIME [label="timeout expired"];
* TIME box TIME [label="cancel blocking operation"];
* TIME=>>M [label="task is ready again"];
* M box M [label="cancel request\nrtems_event_transient_clear()"];
* @endmsc
*
* Suppose you have a task that wants to issue a certain request and then waits
* for request completion. It can create a request structure and store its
* task identifier there. Now it can place the request on a work queue of
* another task (or interrupt handler). Afterwards the task waits for the
* reception of the transient event. Once the server task is finished with the
* request it can send the transient event to the waiting task and wake it up.
*
* @code
* #include <assert.h>
* #include <rtems.h>
*
* typedef struct {
* rtems_id task_id;
* bool work_done;
* } request;
*
* void server(rtems_task_argument arg)
* {
* rtems_status_code sc;
* request *req = (request *) arg;
*
* req->work_done = true;
*
* sc = rtems_event_transient_send(req->task_id);
* assert(sc == RTEMS_SUCCESSFUL);
*
* sc = rtems_task_delete(RTEMS_SELF);
* assert(sc == RTEMS_SUCCESSFUL);
* }
*
* void issue_request_and_wait_for_completion(void)
* {
* rtems_status_code sc;
* rtems_id id;
* request req;
*
* req.task_id = rtems_task_self();
* req.work_done = false;
*
* sc = rtems_task_create(
* rtems_build_name('S', 'E', 'R', 'V'),
* 1,
* RTEMS_MINIMUM_STACK_SIZE,
* RTEMS_DEFAULT_MODES,
* RTEMS_DEFAULT_ATTRIBUTES,
* &id
* );
* assert(sc == RTEMS_SUCCESSFUL);
*
* sc = rtems_task_start(id, server, (rtems_task_argument) &req);
* assert(sc == RTEMS_SUCCESSFUL);
*
* sc = rtems_event_transient_receive(RTEMS_WAIT, RTEMS_NO_TIMEOUT);
* assert(sc == RTEMS_SUCCESSFUL);
*
* assert(req.work_done);
* }
* @endcode
*/
/**@{**/
/**
* @brief See rtems_event_system_send().
*
* The system event @ref RTEMS_EVENT_SYSTEM_TRANSIENT will be sent.
*/
RTEMS_INLINE_ROUTINE rtems_status_code rtems_event_transient_send(
rtems_id id
)
{
return rtems_event_system_send( id, RTEMS_EVENT_SYSTEM_TRANSIENT );
}
/**
* @brief See rtems_event_system_receive().
*
* The system event @ref RTEMS_EVENT_SYSTEM_TRANSIENT will be received.
*/
RTEMS_INLINE_ROUTINE rtems_status_code rtems_event_transient_receive(
rtems_option option_set,
rtems_interval ticks
)
{
rtems_event_set event_out;
return rtems_event_system_receive(
RTEMS_EVENT_SYSTEM_TRANSIENT,
RTEMS_EVENT_ALL | option_set,
ticks,
&event_out
);
}
/**
* @brief See rtems_event_system_receive().
*
* The system event @ref RTEMS_EVENT_SYSTEM_TRANSIENT will be cleared.
*/
RTEMS_INLINE_ROUTINE void rtems_event_transient_clear( void )
{
rtems_event_set event_out;
rtems_event_system_receive(
RTEMS_EVENT_SYSTEM_TRANSIENT,
RTEMS_EVENT_ALL | RTEMS_NO_WAIT,
0,
&event_out
);
}
/** @} */
typedef struct {
rtems_event_set pending_events;
} Event_Control;
#ifdef __cplusplus
}
#endif
#endif
/* end of include file */
