X-Git-Url: https://codewiz.org/gitweb?a=blobdiff_plain;f=kern%2Fsem.c;h=cc9234aa64a020531a6c1e354d93bd595fd80f6d;hb=HEAD;hp=25cf79e636c0be5704888cedb339b2be5f0ff445;hpb=96f0ef786b54356c56cc3d4e4f0838df2505cfcc;p=bertos.git diff --git a/kern/sem.c b/kern/sem.c deleted file mode 100755 index 25cf79e6..00000000 --- a/kern/sem.c +++ /dev/null @@ -1,147 +0,0 @@ -/*! - * \file - * - * - * \brief Semaphore based synchronization services. - * - * \version $Id$ - * - * \author Bernardo Innocenti - */ - -/* - * $Log$ - * 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(). - */ -bool sem_attempt(struct Semaphore *s) -{ - DISABLE_INTS; - if ((!s->owner) || (s->owner == CurrentProcess)) - { - s->owner = CurrentProcess; - s->nest_count++; - ENABLE_INTS; - return true; - } - ENABLE_INTS; - 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. - */ -void sem_obtain(struct Semaphore *s) -{ - DISABLE_INTS; - - /* Is the semaphore already locked by another process? */ - if (s->owner && (s->owner != CurrentProcess)) - { - /* Append calling process to the wait queue */ - ADDTAIL(&s->wait_queue, (Node *)CurrentProcess); - ENABLE_INTS; - - /* We will awake only when the current owner calls - * ReleaseSemaphore(). Then, the semaphore will already - * be locked for us. - */ - proc_schedule(); - } - else - { - /* The semaphore is free: lock it */ - s->owner = CurrentProcess; - s->nest_count++; - ENABLE_INTS; - } -} - - -/*! - * \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. - */ -void sem_release(struct Semaphore *s) -{ - DISABLE_INTS; - - /* Decremement nesting count and check if the semaphore - * has been fully unlocked - */ - if (--s->nest_count == 0) - { - /* Disown semaphore */ - s->owner = NULL; - - /* Anybody still waiting for this semaphore? */ - if (!ISLISTEMPTY(&s->wait_queue)) - { - /* Give semaphore to the first applicant */ - Process *proc = (Process *)s->wait_queue.head; - REMOVE((Node *)proc); - s->nest_count = 1; - s->owner = proc; - SCHED_ENQUEUE(proc); - } - } - - ENABLE_INTS; -} -