Semaphore

semaphores (binary, limited, counting) More...

Macros
#define	semDirect   ( 0U )
	direct semaphore (producer can't free the semaphore, it can post the semaphore only to the pending task)
#define	semBinary   ( 1U )
	binary semaphore
#define	semCounting   ( 0U-1 )
	counting semaphore
#define	semDefault   semCounting
	default semaphore type
#define	OS_SEM(sem, init, ...)
	define and initialize a semaphore object
#define	static_SEM(sem, init, ...)
	static alias of OS_SEM()
#define	SEM_INIT(init, ...)
	create and initialize a semaphore object
#define	SEM_CREATE(init, ...)
	create and initialize a semaphore object
#define	SEM_NEW   SEM_CREATE
	alias of SEM_CREATE()

Functions
void	sem_init (sem_t *sem, unsigned init, unsigned limit)
	initialize a semaphore object
void	sem_reset (sem_t *sem)
	reset the semaphore object and wake up all waiting tasks with 'E_STOPPED' event value
void	sem_kill (sem_t *sem)
	alias of sem_reset()
int	sem_take (sem_t *sem)
	try to lock the semaphore object, don't wait if the semaphore object can't be locked immediately
int	sem_tryWait (sem_t *sem)
	alias of sem_take()
int	sem_takeAsync (sem_t *sem)
	Async alias of sem_take().
int	sem_waitFor (sem_t *sem, cnt_t delay)
	try to lock the semaphore object, wait for given duration of time if the semaphore object can't be locked immediately
int	sem_waitUntil (sem_t *sem, cnt_t time)
	try to lock the semaphore object, wait until given timepoint if the semaphore object can't be locked immediately
int	sem_wait (sem_t *sem)
	try to lock the semaphore object, wait indefinitely if the semaphore object can't be locked immediately
int	sem_waitAsync (sem_t *sem)
	Async alias of sem_wait().
int	sem_give (sem_t *sem)
	try to unlock the semaphore object, don't wait if the semaphore object can't be unlocked immediately
int	sem_post (sem_t *sem)
	alias of sem_give()
int	sem_giveAsync (sem_t *sem)
	Async alias of sem_give().
int	sem_release (sem_t *sem, unsigned num)
	try to increment the internal semaphore counter by the value of num
unsigned	sem_getValue (sem_t *sem)
	return current value of semaphore

Detailed Description

semaphores (binary, limited, counting)

Macro Definition Documentation

OS_SEM

#define OS_SEM	(		sem,
			init,
			... )

Value:

sem_t sem[] = { _SEM_INIT( init, _VA_SEM(__VA_ARGS__) ) }

define and initialize a semaphore object

Parameters

sem	name of a pointer to semaphore object
init	initial value of semaphore counter
...	limit: (optional) maximum value of semaphore counter semDirect: direct semaphore semBinary: binary semaphore semCounting: counting semaphore (default) otherwise: limited semaphore

static_SEM

#define static_SEM	(		sem,
			init,
			... )

Value:

static sem_t sem[] = { _SEM_INIT( init, _VA_SEM(__VA_ARGS__) ) }

static alias of OS_SEM()

SEM_INIT

#define SEM_INIT	(		init,
			... )

Value:

_SEM_INIT( init, _VA_SEM(__VA_ARGS__) )

create and initialize a semaphore object

Parameters

init	initial value of semaphore counter
...	limit: (optional) maximum value of semaphore counter semDirect: direct semaphore semBinary: binary semaphore semCounting: counting semaphore (default) otherwise: limited semaphore

Returns

semaphore object

Note

use only in 'C' code

SEM_CREATE

#define SEM_CREATE	(		init,
			... )

Value:

{ SEM_INIT  ( init, _VA_SEM(__VA_ARGS__) ) }

create and initialize a semaphore object

Parameters

init	initial value of semaphore counter
...	limit: (optional) maximum value of semaphore counter semDirect: direct semaphore semBinary: binary semaphore semCounting: counting semaphore (default) otherwise: limited semaphore

Returns

semaphore object as array (id)

Note

use only in 'C' code

Function Documentation

sem_init()

void sem_init	(	sem_t *	sem,
		unsigned	init,
		unsigned	limit )

initialize a semaphore object

Parameters

sem	pointer to semaphore object
init	initial value of semaphore counter
limit	maximum value of semaphore counter semDirect: direct semaphore semBinary: binary semaphore semCounting: counting semaphore otherwise: limited semaphore

sem_reset()

void sem_reset

(

sem_t *

sem

)

reset the semaphore object and wake up all waiting tasks with 'E_STOPPED' event value

Parameters

sem	pointer to semaphore object

Note

use only in thread mode

sem_take()

int sem_take

(

sem_t *

sem

)

try to lock the semaphore object, don't wait if the semaphore object can't be locked immediately

Parameters

sem	pointer to semaphore object

Return values

E_SUCCESS	semaphore object was successfully locked
E_TIMEOUT	semaphore object can't be locked immediately, try again

Note

use Async alias for communication with unmasked interrupt handlers

sem_waitFor()

int sem_waitFor	(	sem_t *	sem,
		cnt_t	delay )

try to lock the semaphore object, wait for given duration of time if the semaphore object can't be locked immediately

Parameters

sem	pointer to semaphore object
delay	duration of time (maximum number of ticks to wait for lock the semaphore object) IMMEDIATE: don't wait if the semaphore object can't be locked immediately INFINITE: wait indefinitely until the semaphore object has been locked

Return values

E_SUCCESS	semaphore object was successfully locked
E_STOPPED	semaphore object was reseted before the specified timeout expired
E_TIMEOUT	semaphore object was not locked before the specified timeout expired

sem_waitUntil()

int sem_waitUntil	(	sem_t *	sem,
		cnt_t	time )

try to lock the semaphore object, wait until given timepoint if the semaphore object can't be locked immediately

Parameters

sem	pointer to semaphore object
time	timepoint value

Return values

E_SUCCESS	semaphore object was successfully locked
E_STOPPED	semaphore object was reseted before the specified timeout expired
E_TIMEOUT	semaphore object was not locked before the specified timeout expired

sem_wait()

int sem_wait ( sem_t * sem )

inline

try to lock the semaphore object, wait indefinitely if the semaphore object can't be locked immediately

Parameters

sem	pointer to semaphore object

Return values

E_SUCCESS	semaphore object was successfully locked
E_STOPPED	semaphore object was reseted (unavailable for async version)

Note

use Async alias for communication with unmasked interrupt handlers

sem_give()

int sem_give

(

sem_t *

sem

)

try to unlock the semaphore object, don't wait if the semaphore object can't be unlocked immediately

Parameters

sem	pointer to semaphore object

Return values

E_SUCCESS	semaphore object was successfully unlocked
E_TIMEOUT	semaphore object can't be unlocked immediately, try again

Note

use Async alias for communication with unmasked interrupt handlers

sem_release()

int sem_release	(	sem_t *	sem,
		unsigned	num )

try to increment the internal semaphore counter by the value of num

Parameters

sem	pointer to semaphore object
num	update value of semaphore counter

Return values

E_SUCCESS	semaphore counter was successfully updated
E_TIMEOUT	semaphore counter was updated to the limit value

sem_getValue()

unsigned sem_getValue

(

sem_t *

sem

)

return current value of semaphore

Parameters

sem	pointer to semaphore object

Returns

current value of semaphore