Semaphore

Thread synchronization support. More...

Collaboration diagram for Semaphore:

Data Structures
struct	_SEM
	Semaphore. More...
Typedefs
typedef struct _SEM	SEM
	Sempahore type.
Functions
void	NutSemInit (SEM *sem, short value)
	Initialize an unnamed semaphore to value.
void	NutSemWait (SEM *sem)
	Lock a semaphore.
int	NutSemTryWait (SEM *sem)
	Attempt to lock a semaphore without blocking.
void	NutSemPost (SEM *sem)
	Unlock a sempahore.
int	NutSemDestroy (SEM *sem)
	Free resources allocated for a semaphore.

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Detailed Description

Thread synchronization support.

In addition to posting and waiting for events, Threads can use the provided semaphore funxtions to handle a pool of shared resources.

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Typedef Documentation

typedef struct _SEM SEM

Sempahore type.

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Function Documentation

void NutSemInit	(	SEM *	sem,
		short	value
	)

Initialize an unnamed semaphore to value.

References NULL, NUTASSERT, _SEM::qhp, and _SEM::value.

Referenced by CANBufferInit().

void NutSemWait

(

SEM *

sem

)

Lock a semaphore.

If the semaphore value is currently zero, then the calling thread will not return from the call to sem_wait() the semaphore becomes available

Note:

: Should not be called from interrupt context

Referenced by CANBufferGetMutex(), CANBufferPutMutex(), and NutSemTryWait().

int NutSemTryWait

(

SEM *

sem

)

Attempt to lock a semaphore without blocking.

Return zero, if successful, otherwise the sempahore is already locked

Note:

: Should not be called from interrupt context

References NULL, NUTASSERT, NutSemWait(), and _SEM::value.

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void NutSemPost

(

SEM *

sem

)

Unlock a sempahore.

Note:

: Should not be called from interrupt context

References NULL, NUTASSERT, NutEventPost(), _SEM::qhp, and _SEM::value.

Referenced by CANBufferGetMutex(), and CANBufferPutMutex().

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int NutSemDestroy

(

SEM *

sem

)

Free resources allocated for a semaphore.

Return zero, if successful, otherwise there are threads blocked on the sempahore

References NULL, NUTASSERT, _SEM::qhp, and SIGNALED.