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