X-Git-Url: https://codewiz.org/gitweb?a=blobdiff_plain;f=kern%2Fsem.c;h=3c645e957ae0723f2b863fb6a0c395eab64a7f17;hb=HEAD;hp=2262cb081d8306693cc13036903c1d0a4f92f69f;hpb=e05dacc96872c22d234af216d0728e46e8e222e0;p=bertos.git diff --git a/kern/sem.c b/kern/sem.c deleted file mode 100755 index 2262cb08..00000000 --- a/kern/sem.c +++ /dev/null @@ -1,168 +0,0 @@ -/*! - * \file - * - * - * \brief Semaphore based synchronization services. - * - * \version $Id$ - * - * \author Bernardo Innocenti - */ - -/*#* - *#* $Log$ - *#* Revision 1.5 2004/10/21 10:48:57 bernie - *#* sem_release(): Simplify (made by rasky on scfirm). - *#* - *#* Revision 1.4 2004/08/25 14:12:09 rasky - *#* Aggiornato il comment block dei log RCS - *#* - *#* Revision 1.3 2004/08/08 05:53:23 bernie - *#* Use DISABLE_IRQSAVE/ENABLE_IRQRESTORE; Cleanup documentation. - *#* - *#* Revision 1.2 2004/06/03 11:27:09 bernie - *#* Add dual-license information. - *#* - *#* Revision 1.1 2004/05/23 17:27:00 bernie - *#* Import kern/ subdirectory. - *#* - *#*/ - -#include "sem.h" -#include "proc.h" -#include "proc_p.h" -#include "signal.h" -#include "hw.h" - - -/*! - * \brief Initialize a Semaphore structure - */ -void sem_init(struct Semaphore *s) -{ - INITLIST(&s->wait_queue); - s->owner = NULL; - s->nest_count = 0; -} - - -/*! - * \brief Attempt to lock a semaphore without waiting. - * - * \return true in case of success, false if the semaphore - * was already locked by someone else. - * - * \note each call to sem_attempt() must be matched by a - * call to sem_release(). - * - * \see sem_obtain() sem_release() - */ -bool sem_attempt(struct Semaphore *s) -{ - cpuflags_t flags; - DISABLE_IRQSAVE(flags); - - if ((!s->owner) || (s->owner == CurrentProcess)) - { - s->owner = CurrentProcess; - s->nest_count++; - ENABLE_INTS; - return true; - } - - ENABLE_IRQRESTORE(flags); - return false; -} - - -/*! - * \brief Lock a semaphore. - * - * If the semaphore is already owned by another process, the caller - * process will be enqueued into the waiting list and sleep until - * the semaphore is available. - * - * \note Each call to sem_obtain() must be matched by a - * call to sem_release(). - * - * \note This routine is optimized for highest speed in - * the most common case: the semaphore is free or locked - * by the calling process itself. Rearranging this code - * is probably a bad idea. - * - * \sa sem_release() sem_attempt() - */ -void sem_obtain(struct Semaphore *s) -{ - cpuflags_t flags; - DISABLE_IRQSAVE(flags); - - /* Is the semaphore already locked by another process? */ - if (UNLIKELY(s->owner && (s->owner != CurrentProcess))) - { - /* Append calling process to the wait queue */ - ADDTAIL(&s->wait_queue, (Node *)CurrentProcess); - ENABLE_IRQRESTORE(flags); - - /* - * We will wake up only when the current owner calls - * sem_release(). Then, the semaphore will already - * be locked for us. - */ - proc_schedule(); - } - else - { - /* The semaphore was free: lock it */ - s->owner = CurrentProcess; - s->nest_count++; - ENABLE_IRQRESTORE(flags); - } -} - - -/*! - * \brief Releases a lock on a previously locked semaphore. - * - * If the nesting count of the semaphore reaches zero, - * the next process waiting for it will be awaken. - * - * \note This routine is optimized for highest speed in - * the most common case: the semaphore has been locked just - * once and nobody else was waiting for it. Rearranging - * this code is probably a bad idea. - * - * \sa sem_obtain() sem_attempt() - */ -void sem_release(struct Semaphore *s) -{ - cpuflags_t flags; - DISABLE_IRQSAVE(flags); - - /* - * Decrement nesting count and check if the semaphore - * has been fully unlocked - */ - if (--s->nest_count == 0) - { - Process *proc; - - /* Disown semaphore */ - s->owner = NULL; - - /* Give semaphore to the first applicant, if any */ - if ((proc = (Process*)REMHEAD(&s->wait_queue))) - { - s->nest_count = 1; - s->owner = proc; - SCHED_ENQUEUE(proc); - } - } - - ENABLE_IRQRESTORE(flags); -} -