osal_semaphore

函数
int	osal_sem_init (osal_semaphore *sem, int val)
	Create a semaphore.
int	osal_sem_binary_sem_init (osal_semaphore *sem, int val)
	Create a binary semaphore.
int	osal_sem_down (osal_semaphore *sem)
	Request a semaphore.
int	osal_sem_down_timeout (osal_semaphore *sem, unsigned int timeout)
	Acquire the semaphore within a specified time that specifies the timeout period.
int	osal_sem_down_interruptible (osal_semaphore *sem)
	acquire the semaphore unless interrupted.
int	osal_sem_trydown (osal_semaphore *sem)
	try to acquire the semaphore, without waiting.
void	osal_sem_up (osal_semaphore *sem)
	Release a semaphore.
void	osal_sem_destroy (osal_semaphore *sem)
	Delete a semaphore.

详细描述

函数说明

osal_sem_binary_sem_init()

int osal_sem_binary_sem_init	(	osal_semaphore *	sem,
		int	val
	)

Create a binary semaphore.

Description:

This API is used to create a binary semaphore control structure according to the initial number of available semaphores specified by count

参数

val	[in] Initial number of available semaphores. The value range is [0, 1].
sem	[out] Pointer of semaphore control structure that is initialized.

返回

OSAL_SUCCESS/OSAL_FAILURE

Support System:

liteos freertos.

osal_sem_destroy()

void osal_sem_destroy

(

osal_semaphore *

sem

)

Delete a semaphore.

Description:

This API is used to destroy semaphore and release space.

注意

The specified sem must be created first before deleting it.

参数

sem	[in] The semaphore to destroyed.

Support System:

linux liteos freertos.

osal_sem_down()

int osal_sem_down

(

osal_semaphore *

sem

)

Request a semaphore.

Description:

This API is used to attempt to obtain the semaphore. Acquires the semaphore. If no more tasks are allowed to acquire the semaphore, calling this function will put the task to sleep until the semaphore is released.

注意

Do not pend sem during an interrupt. Do not pend sem in a system task, such as idle or swtmr task. The specified sem id must be created first. Do not recommend to use this API in software timer callback.

参数

sem	[in] The semaphore to be acquired.

返回

OSAL_SUCCESS/OSAL_FAILURE

Support System:

linux liteos freertos.

osal_sem_down_interruptible()

int osal_sem_down_interruptible

(

osal_semaphore *

sem

)

acquire the semaphore unless interrupted.

Description:

Acquire the semaphore unless interrupted. Attempts to acquire the semaphore. If no more tasks are allowed to acquire the semaphore, calling this function will put the task to sleep.

参数

sem	[in] The semaphore to be acquired.

返回

If the sleep is interrupted by a signal, this function will return OSAL_EINTR. If the semaphore is successfully acquired, this function returns OSAL_SUCCESS, failed return OSAL_FAILURE

Support System:

linux liteos freertos.

osal_sem_down_timeout()

int osal_sem_down_timeout	(	osal_semaphore *	sem,
		unsigned int	timeout
	)

Acquire the semaphore within a specified time that specifies the timeout period.

Description:

Acquire the semaphore within a specified time that specifies the timeout period.

注意

Do not pend sem during an interrupt. Do not pend sem in a system task, such as idle or swtmr task. The specified sem id must be created first. Do not recommend to use this API in software timer callback.

参数

sem	[in] The semaphore to be acquired.
timeout	[in] How long to wait before failing. (unit: ms)

返回

OSAL_SUCCESS/OSAL_FAILURE

Support System:

liteos freertos.

osal_sem_init()

int osal_sem_init	(	osal_semaphore *	sem,
		int	val
	)

Create a semaphore.

Description:

This API is used to create a semaphore control structure according to the initial number of available semaphores specified by count

参数

val	[in] Initial number of available semaphores.
sem	[out] Pointer of semaphore control structure that is initialized.

返回

OSAL_SUCCESS/OSAL_FAILURE

Support System:

linux liteos freertos.

osal_sem_trydown()

int osal_sem_trydown

(

osal_semaphore *

sem

)

try to acquire the semaphore, without waiting.

Description:

try to acquire the semaphore, without waiting.

注意

This return value is inverted from both spin_trylock and mutex_trylock! Be careful about this when converting code. Unlike mutex_trylock, this function can be used from interrupt context, and the semaphore can be released by any task or interrupt.

参数

sem	[in] The semaphore to be acquired.

返回

If the semaphore cannot be obtained, the system returns 1 instead of sleeping. If the value 0 is returned, the semaphore is obtained.

Support System:

linux liteos freertos.

osal_sem_up()

void osal_sem_up

(

osal_semaphore *

sem

)

Release a semaphore.

Description:

Release a semaphore.

注意

Unlike mutexes, osal_sem_up() may be called from any context and even by tasks which have never called osal_sem_down().

参数

sem	[in] The semaphore to release.

Support System:

linux liteos freertos.