semext

System-V Semaphore module. More...

Files
file	semext.h
	System-V Semaphore module.

Macros
#define	semup(semid, index)
#define	semdown(semid, index)
#define	semdown2(semid, index1, index2)
#define	semupdown(semid, up_index, down_index)
#define	semsetval(semid, index, value)

Detailed Description

System-V Semaphore module.

This module adds (very frequent!) useful operations to System-V library semaphores.

group of semext

Author

Miguel Oliveira e Silva

Date

2026

Version

1.0

Macro Definition Documentation

semup

#define semup	(		semid,
			index
	)

Increment a semaphore (uses semop()).

Parameters

[in]	semid	[int] System-V semaphore id
[in]	index	[int] semaphore index in array

semdown

#define semdown	(		semid,
			index
	)

Decrement a semaphore (uses semop()).

Parameters

[in]	semid	[int] System-V semaphore id
[in]	index	[int] semaphore index in array

semdown2

#define semdown2	(		semid,
			index1,
			index2
	)

Decrements atomically two (different) semaphores in a semaphore array (uses semop()).

Parameters

[in]	semid	[int] System-V semaphore id
[in]	index1	[int] semaphore index in array
[in]	index2	[int] semaphore index in array

Precondition:

index1 != index2

semupdown

#define semupdown	(		semid,
			up_index,
			down_index
	)

Atomically, increment and decrement two (different) semaphores in a System V semaphore array (uses semop()).

Parameters

[in]	semid	[int] System-V semaphore id
[in]	up_index	[int] semaphore index in array
[in]	down_index	[int] semaphore index in array

Precondition:

up_index != down_index

semsetval

#define semsetval	(		semid,
			index,
			value
	)

Sets the value of the semaphore (uses semctl()).

Parameters

[in]	semid	[int] System-V semaphore id
[in]	index	[int] semaphore index in array
[in]	value	[int] desired semaphore value