Spinlock Handler

Data Structures
struct	CORE_spinlock_Attributes
struct	CORE_spinlock_Control
Defines
#define	CORE_SPINLOCK_STATUS_LAST   CORE_SPINLOCK_NOT_LOCKED
#define	CORE_SPINLOCK_UNLOCKED   0
#define	CORE_SPINLOCK_LOCKED   1
Enumerations
enum	CORE_spinlock_Status {   CORE_SPINLOCK_SUCCESSFUL, CORE_SPINLOCK_HOLDER_RELOCKING, CORE_SPINLOCK_NOT_HOLDER, CORE_SPINLOCK_TIMEOUT,   CORE_SPINLOCK_IS_BUSY, CORE_SPINLOCK_UNAVAILABLE, CORE_SPINLOCK_NOT_LOCKED }
Functions
void	_CORE_spinlock_Initialize (CORE_spinlock_Control *the_spinlock, CORE_spinlock_Attributes *the_spinlock_attributes)
CORE_spinlock_Status	_CORE_spinlock_Wait (CORE_spinlock_Control *the_spinlock, boolean wait, Watchdog_Interval timeout)
CORE_spinlock_Status	_CORE_spinlock_Release (CORE_spinlock_Control *the_spinlock)
RTEMS_INLINE_ROUTINE boolean	_CORE_spinlock_Is_busy (CORE_spinlock_Control *the_spinlock)

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Detailed Description

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

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Define Documentation

#define CORE_SPINLOCK_LOCKED   1

This indicates the lock is unavailable.

#define CORE_SPINLOCK_STATUS_LAST   CORE_SPINLOCK_NOT_LOCKED

This is a shorthand for the last status code.

#define CORE_SPINLOCK_UNLOCKED   0

This indicates the lock is available.

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Enumeration Type Documentation

enum CORE_spinlock_Status

Core Spinlock handler return statuses.

Enumerator:

CORE_SPINLOCK_SUCCESSFUL	This status indicates that the operation completed successfully.
CORE_SPINLOCK_HOLDER_RELOCKING	This status indicates that the current thread already holds the spinlock. An attempt to relock it will result in deadlock.
CORE_SPINLOCK_NOT_HOLDER	This status indicates that the current thread is attempting to unlock a spinlock that is held by another thread.
CORE_SPINLOCK_TIMEOUT	This status indicates that a thread reached the limit of time it was willing to wait on the spin lock.
CORE_SPINLOCK_IS_BUSY	This status indicates that a thread is currently waiting for this spin lock.
CORE_SPINLOCK_UNAVAILABLE	This status indicates that the spinlock is currently locked and thus unavailable.
CORE_SPINLOCK_NOT_LOCKED	This status indicates that the spinlock is not currently locked and thus should not be released.

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Function Documentation

void _CORE_spinlock_Initialize	(	CORE_spinlock_Control *	the_spinlock,
		CORE_spinlock_Attributes *	the_spinlock_attributes
	)

This routine initializes the spinlock based on the parameters passed.

Parameters:

[in]	the_spinlock	is the spinlock to initialize
[in]	the_spinlock_attributes	define the behavior of this instance

RTEMS_INLINE_ROUTINE boolean _CORE_spinlock_Is_busy

(

CORE_spinlock_Control *

the_spinlock

)

This method is used to determine if the spinlock is available or not.

Parameters:

[in]

the_spinlock

will be checked

Returns:

This method will return TRUE if the spinlock is busy and FALSE otherwise.

References CORE_spinlock_Control::users.

CORE_spinlock_Status _CORE_spinlock_Release

(

CORE_spinlock_Control *

the_spinlock

)

This routine manually releases the spinlock. All of the threads waiting for the spinlock will be readied.

Parameters:

[in]

the_spinlock

is the spinlock to surrender

CORE_spinlock_Status _CORE_spinlock_Wait	(	CORE_spinlock_Control *	the_spinlock,
		boolean	wait,
		Watchdog_Interval	timeout
	)

This routine wait for the spinlock to be released. If the spinlock is set to automatic and this is the appropriate thread, then it returns immediately. Otherwise, the calling thread is blocked until the spinlock is released.

Parameters:

[in]	the_spinlock	is the spinlock to wait for
[in]	wait	is true if willing to wait
[in]	timeout	is the maximum number of ticks to spin (0 is forever)

Returns:

A status is returned which indicates the success or failure of this operation.