inverse Semaphores

Lightweight inverse semaphore implementation. More...

Detailed Description

Lightweight inverse semaphore implementation.

Files
file	sema_inv.h
	Inverse Semaphore definitions.

Data Structures
struct	sema_inv_t
	An Inverse Semaphore. More...

Functions
bool	sema_inv_post (sema_inv_t *s)
	Signal semaphore (counter mode).
bool	sema_inv_post_mask (sema_inv_t *s, uint32_t mask)
	Signal semaphore (mask mode).
static void	sema_inv_init (sema_inv_t *s, uint32_t value)
	Initialize an inverse semaphore.
static void	sema_inv_wait (sema_inv_t *s)
	Wait for the inverse semaphore value to reach zero.
static int	sema_inv_try_wait (sema_inv_t *s)
	Check if the inverse semaphore value has reached zero.
static int	sema_inv_wait_timeout (sema_inv_t *s, uint32_t us)
	Wait for the inverse semaphore value to reach zero or a timeout being reached.

Function Documentation

sema_inv_init()

static void sema_inv_init ( sema_inv_t *  s, uint32_t  value  )

inlinestatic

Initialize an inverse semaphore.

Parameters

s	an inverse semaphore
value	start value, either a counter or a bit mask

Definition at line 99 of file sema_inv.h.

sema_inv_post()

bool sema_inv_post

(

sema_inv_t *

s

)

Signal semaphore (counter mode).

     Decrements the semaphore counter by one.
     If the counter reaches zero, the waiting thread is woken.

Parameters

s	an inverse semaphore

Return values

`true`	the value of the semaphore has reached zero and the waiting thread has been woken
`false`	the semaphore has not reached zero yet

sema_inv_post_mask()

bool sema_inv_post_mask	(	sema_inv_t *	s,
		uint32_t	mask
	)

Signal semaphore (mask mode).

     Clears the bits specified by @p mask from the semaphore value.
     If the value reaches zero, the waiting thread is woken.

Parameters

s	an inverse semaphore
mask	bit mask to clear from the semaphore value

Return values

`true`	the value of the semaphore has reached zero and the waiting thread has been woken
`false`	the semaphore has not reached zero yet

sema_inv_try_wait()

static int sema_inv_try_wait ( sema_inv_t *  s )

inlinestatic

Check if the inverse semaphore value has reached zero.

Parameters

s	An inverse semaphore.

Returns

1 if the semaphore value has reached zero 0 otherwise

Definition at line 124 of file sema_inv.h.

sema_inv_wait()

static void sema_inv_wait ( sema_inv_t *  s )

inlinestatic

Wait for the inverse semaphore value to reach zero.

Parameters

s	An inverse semaphore.

Definition at line 111 of file sema_inv.h.

sema_inv_wait_timeout()

static int sema_inv_wait_timeout ( sema_inv_t *  s, uint32_t  us  )

inlinestatic

Wait for the inverse semaphore value to reach zero or a timeout being reached.

Parameters

s	An inverse semaphore.
us	Time in microseconds until the semaphore times out.

Returns

0 if the semaphore value has reached zero -1 when the timeout occurred

Definition at line 140 of file sema_inv.h.