Semaphore Handler

Semaphore Handler. More...

Files
file	coresem.h
	Data Associated with the Counting Semaphore Handler.
file	coresemimpl.h
	Inlined Routines Associated with the SuperCore Semaphore.
file	semaphoreimpl.h
	Semaphore Implementation.
file	coresem.c
	Core Semaphore Initialize.

Data Structures
struct	CORE_semaphore_Control
struct	Sem_Control

Macros
#define	SEMAPHORE_TQ_OPERATIONS   &_Thread_queue_Operations_priority

Functions
void	_CORE_semaphore_Initialize (CORE_semaphore_Control *the_semaphore, uint32_t initial_value)
	Initializes the semaphore based on the parameters passed. More...
RTEMS_INLINE_ROUTINE void	_CORE_semaphore_Acquire_critical (CORE_semaphore_Control *the_semaphore, Thread_queue_Context *queue_context)
	Acquires the semaphore critical. More...
RTEMS_INLINE_ROUTINE void	_CORE_semaphore_Release (CORE_semaphore_Control *the_semaphore, Thread_queue_Context *queue_context)
	Releases the semaphore. More...
RTEMS_INLINE_ROUTINE void	_CORE_semaphore_Destroy (CORE_semaphore_Control *the_semaphore, const Thread_queue_Operations *operations, Thread_queue_Context *queue_context)
	Destroys the semaphore. More...
RTEMS_INLINE_ROUTINE Status_Control	_CORE_semaphore_Surrender (CORE_semaphore_Control *the_semaphore, const Thread_queue_Operations *operations, uint32_t maximum_count, Thread_queue_Context *queue_context)
	Surrenders a unit to the semaphore. More...
RTEMS_INLINE_ROUTINE uint32_t	_CORE_semaphore_Get_count (const CORE_semaphore_Control *the_semaphore)
	Returns the current count associated with the semaphore. More...
RTEMS_INLINE_ROUTINE Status_Control	_CORE_semaphore_Seize (CORE_semaphore_Control *the_semaphore, const Thread_queue_Operations *operations, Thread_Control *executing, bool wait, Thread_queue_Context *queue_context)
	Seizes the semaphore. More...

Detailed Description

Semaphore Handler.

This handler encapsulates functionality which provides the foundation Semaphore services used in all of the APIs supported by RTEMS.

Function Documentation

_CORE_semaphore_Acquire_critical()

RTEMS_INLINE_ROUTINE void _CORE_semaphore_Acquire_critical	(	CORE_semaphore_Control *	the_semaphore,
		Thread_queue_Context *	queue_context
	)

Acquires the semaphore critical.

This routine acquires the semaphore.

Parameters

[in,out]	the_semaphore	The semaphore to acquire.
	queue_context	The thread queue context.

_CORE_semaphore_Destroy()

RTEMS_INLINE_ROUTINE void _CORE_semaphore_Destroy	(	CORE_semaphore_Control *	the_semaphore,
		const Thread_queue_Operations *	operations,
		Thread_queue_Context *	queue_context
	)

Destroys the semaphore.

This routine destroys the semaphore.

Parameters

[out]	the_semaphore	The semaphore to destroy.
	operations	The thread queue operations.
	queue_context	The thread queue context.

_CORE_semaphore_Get_count()

RTEMS_INLINE_ROUTINE uint32_t _CORE_semaphore_Get_count

(

const CORE_semaphore_Control *

the_semaphore

)

Returns the current count associated with the semaphore.

Parameters

the_semaphore

The semaphore to obtain the count of.

Returns

the current count of this semaphore.

_CORE_semaphore_Initialize()

void _CORE_semaphore_Initialize	(	CORE_semaphore_Control *	the_semaphore,
		uint32_t	initial_value
	)

Initializes the semaphore based on the parameters passed.

This package is the implementation of the CORE Semaphore Handler. This core object utilizes standard Dijkstra counting semaphores to provide synchronization and mutual exclusion capabilities.

This routine initializes the semaphore based on the parameters passed.

Parameters

[out]	the_semaphore	The semaphore to initialize.
	initial_value	The initial count of the semaphore.

_CORE_semaphore_Release()

RTEMS_INLINE_ROUTINE void _CORE_semaphore_Release	(	CORE_semaphore_Control *	the_semaphore,
		Thread_queue_Context *	queue_context
	)

Releases the semaphore.

This routine releases the semaphore.

Parameters

[in,out]	the_semaphore	The semaphore to release.
	queue_context	The thread queue context.

_CORE_semaphore_Seize()

RTEMS_INLINE_ROUTINE Status_Control _CORE_semaphore_Seize	(	CORE_semaphore_Control *	the_semaphore,
		const Thread_queue_Operations *	operations,
		Thread_Control *	executing,
		bool	wait,
		Thread_queue_Context *	queue_context
	)

Seizes the semaphore.

This routine attempts to receive a unit from the_semaphore. If a unit is available or if the wait flag is false, then the routine returns. Otherwise, the calling task is blocked until a unit becomes available.

Parameters

[in,out]	the_semaphore	The semaphore to obtain.
	operations	The thread queue operations.
	executing	The currently executing thread.
	wait	Indicates whether the calling thread is willing to wait.
	queue_context	is a temporary variable used to contain the ISR disable level cookie.

Return values

STATUS_SUCCESSFUL	The semaphore was successfully seized.
STATUS_UNSATISFIED	The semaphore is currently not free and the calling thread not willing to wait.
STATUS_TIMEOUT	A timeout occured.

_CORE_semaphore_Surrender()

RTEMS_INLINE_ROUTINE Status_Control _CORE_semaphore_Surrender	(	CORE_semaphore_Control *	the_semaphore,
		const Thread_queue_Operations *	operations,
		uint32_t	maximum_count,
		Thread_queue_Context *	queue_context
	)

Surrenders a unit to the semaphore.

This routine frees a unit to the semaphore. If a task was blocked waiting for a unit from this semaphore, then that task will be readied and the unit given to that task. Otherwise, the unit will be returned to the semaphore.

Parameters

[in,out]	the_semaphore	is the semaphore to surrender
	operations	The thread queue operations.
	maximum_count	The maximum number of units in the semaphore.
	queue_context	is a temporary variable used to contain the ISR disable level cookie.

Return values

STATUS_SUCCESSFUL	The unit was successfully freed to the semaphore.
STATUS_MAXIMUM_COUNT_EXCEEDED	The maximum number of units was exceeded.