Desktop/xinu_mips-1.0.2.tar/xinu_mips-1.0.2/include/semaphore.h File Reference

#include <kernel.h>
#include <queue.h>

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Data Structures
struct	sentry
Defines
#define	SFREE   0x01
#define	SUSED   0x02
#define	isbadsem(s)   (((ushort)(s) >= NSEM) || (SFREE == semtab[s].state))
Typedefs
typedef ulong	semaphore
Functions
syscall	wait (semaphore)
syscall	signal (semaphore)
syscall	signaln (semaphore, short)
semaphore	newsem (short)
syscall	freesem (semaphore)
syscall	scount (semaphore)
Variables
struct sentry	semtab []

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Detailed Description

isbadsem

Id

semaphore.h 226 2007-07-12 01:18:27Z mschul

Definition in file semaphore.h.

---

Define Documentation

#define isbadsem

(

s

)

(((ushort)(s) >= NSEM) || (SFREE == semtab[s].state))

isbadsem - check validity of reqested semaphore id and state

Parameters:

s

id number to test

Definition at line 36 of file semaphore.h.

Referenced by freesem(), scount(), signal(), signaln(), test_deltaQueue(), test_procQueue(), test_semaphore(), test_semaphore2(), test_semaphore3(), test_semaphore4(), and wait().

#define SFREE   0x01

< queue.h must define # of sem queues this semaphore is free

Definition at line 16 of file semaphore.h.

Referenced by allocsem(), freesem(), and sysinit().

#define SUSED   0x02

this semaphore is used

Definition at line 17 of file semaphore.h.

Referenced by allocsem().

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Typedef Documentation

typedef ulong semaphore

Definition at line 20 of file semaphore.h.

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Function Documentation

syscall freesem

(

semaphore

sem

)

freesem - deallocate a semaphore. Reset the semaphore count, releasing any processes in the waiting queue. Deallocate entry in global semaphore table.

Parameters:

sem

id of semaphore to be released

Returns:

OK on success, SYSERR on failure

Definition at line 21 of file freesem.c.

References sentry::count, dequeue(), disable(), isbadsem, nonempty, OK, sentry::queue, ready(), RESCHED_NO, restore(), semtab, SFREE, sentry::state, and SYSERR.

Referenced by test_deltaQueue(), test_procQueue(), test_semaphore(), test_semaphore2(), test_semaphore3(), and test_semaphore4().

semaphore newsem

(

short

count

)

newsem - allocate and initialize a new semaphore.

Parameters:

count

- number of resources available without waiting. example: count = 1 for mutual exclusion lock

Returns:

new semaphore id on success, SYSERR on failure

Definition at line 20 of file newsem.c.

References allocsem(), sentry::count, disable(), restore(), semtab, and SYSERR.

Referenced by test_deltaQueue(), test_procQueue(), test_semaphore(), test_semaphore2(), test_semaphore3(), test_semaphore4(), and uartInit().

syscall scount

(

semaphore

sem

)

scount - return a semaphore count

Parameters:

sem

id of semaphore to query

Returns:

count from semtab entry on success, SYSERR on failure

Definition at line 17 of file scount.c.

References isbadsem, semtab, and SYSERR.

Referenced by uartRead(), and uartWrite().

syscall signal

(

semaphore

sem

)

signal - signal a semaphore, releasing one waiting process, and block

Parameters:

sem

id of semaphore to signal

Returns:

OK on success, SYSERR on failure

Definition at line 18 of file signal.c.

References sentry::count, dequeue(), disable(), isbadsem, OK, sentry::queue, ready(), RESCHED_YES, restore(), semtab, and SYSERR.

Referenced by test_semaphore(), test_semaphore2(), and test_semaphore3().

syscall signaln	(	semaphore	sem,
		short	count
	)

signaln - signal a semaphore n times, releasing n waiting processes, non-blocking

Parameters:

	sem	id of semaphore to signal
	count	number of times to signal

Returns:

OK on success, SYSERR on failure

Definition at line 20 of file signaln.c.

References sentry::count, dequeue(), disable(), isbadsem, OK, sentry::queue, ready(), RESCHED_NO, restore(), semtab, and SYSERR.

Referenced by uartIntr().

syscall wait

(

semaphore

sem

)

wait - make current process wait on a semaphore

Parameters:

sem

semaphore for which to wait

Returns:

OK on success, SYSERR on failure

Definition at line 19 of file wait.c.

References sentry::count, currpid, disable(), enqueue(), isbadsem, OK, proctab, PRWAIT, sentry::queue, resched(), restore(), pentry::sem, semtab, pentry::state, and SYSERR.

Referenced by test_semWaiter(), uartRead(), and uartWrite().

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Variable Documentation

struct sentry semtab[]

Definition at line 40 of file initialize.c.

Referenced by allocsem(), freesem(), kill(), newsem(), scount(), signal(), signaln(), sysinit(), test_checkSemCount(), test_deltaQueue(), test_procQueue(), and wait().