Semaphore
[Application Candies]

Collaboration diagram for 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.

Data Structures
struct	_SEM
struct	_mutex
	Recursive mutex. More...
Typedefs
typedef _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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Function Documentation

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

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

void NutSemPost (  SEM *  sem  )

Unlock a sempahore. Note: : Should not be called from interrupt context

int NutSemDestroy (  SEM *  sem  )

Free resources allocated for a semaphore. Return zero, if successful, otherwise there are threads blocked on the sempahore

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