Zephyr API Documentation  3.7.0-rc3
A Scalable Open Source RTOS
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User mode semaphore APIs

Macros

#define SYS_SEM_DEFINE(_name, _initial_count, _count_limit)
 Statically define and initialize a sys_sem.
 

Functions

int sys_sem_init (struct sys_sem *sem, unsigned int initial_count, unsigned int limit)
 Initialize a semaphore.
 
int sys_sem_give (struct sys_sem *sem)
 Give a semaphore.
 
int sys_sem_take (struct sys_sem *sem, k_timeout_t timeout)
 Take a sys_sem.
 
unsigned int sys_sem_count_get (struct sys_sem *sem)
 Get sys_sem's value.
 

Detailed Description

Macro Definition Documentation

◆ SYS_SEM_DEFINE

#define SYS_SEM_DEFINE (   _name,
  _initial_count,
  _count_limit 
)

#include <zephyr/sys/sem.h>

Value:
struct sys_sem _name = { \
.futex = { _initial_count }, \
.limit = _count_limit \
}; \
BUILD_ASSERT(((_count_limit) != 0) && \
((_initial_count) <= (_count_limit)))
sys_sem structure
Definition: sem.h:34
struct k_futex futex
Definition: sem.h:36

Statically define and initialize a sys_sem.

The semaphore can be accessed outside the module where it is defined using:

extern struct sys_sem <name>;

Route this to memory domains using K_APP_DMEM().

Parameters
_nameName of the semaphore.
_initial_countInitial semaphore count.
_count_limitMaximum permitted semaphore count.

Function Documentation

◆ sys_sem_count_get()

unsigned int sys_sem_count_get ( struct sys_sem sem)

#include <zephyr/sys/sem.h>

Get sys_sem's value.

This routine returns the current value of sem.

Parameters
semAddress of the sys_sem.
Returns
Current value of sys_sem.

◆ sys_sem_give()

int sys_sem_give ( struct sys_sem sem)

#include <zephyr/sys/sem.h>

Give a semaphore.

This routine gives sem, unless the semaphore is already at its maximum permitted count.

Parameters
semAddress of the semaphore.
Return values
0Semaphore given.
-EINVALParameter address not recognized.
-EACCESCaller does not have enough access.
-EAGAINCount reached Maximum permitted count and try again.

◆ sys_sem_init()

int sys_sem_init ( struct sys_sem sem,
unsigned int  initial_count,
unsigned int  limit 
)

#include <zephyr/sys/sem.h>

Initialize a semaphore.

This routine initializes a semaphore instance, prior to its first use.

Parameters
semAddress of the semaphore.
initial_countInitial semaphore count.
limitMaximum permitted semaphore count.
Return values
0Initial success.
-EINVALBad parameters, the value of limit should be located in (0, INT_MAX] and initial_count shouldn't be greater than limit.

◆ sys_sem_take()

int sys_sem_take ( struct sys_sem sem,
k_timeout_t  timeout 
)

#include <zephyr/sys/sem.h>

Take a sys_sem.

This routine takes sem.

Parameters
semAddress of the sys_sem.
timeoutWaiting period to take the sys_sem, or one of the special values K_NO_WAIT and K_FOREVER.
Return values
0sys_sem taken.
-EINVALParameter address not recognized.
-ETIMEDOUTWaiting period timed out.
-EACCESCaller does not have enough access.