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Annotation of xinu/sys/sdelete.c, revision 1.1

1.1     ! root        1: /* sdelete.c - sdelete */
        !             2: 
        !             3: #include <conf.h>
        !             4: #include <kernel.h>
        !             5: #include <proc.h>
        !             6: #include <q.h>
        !             7: #include <sem.h>
        !             8: 
        !             9: /*------------------------------------------------------------------------
        !            10:  * sdelete  --  delete a semaphore by releasing its table entry
        !            11:  *------------------------------------------------------------------------
        !            12:  */
        !            13: SYSCALL sdelete(sem)
        !            14:        int     sem;
        !            15: {
        !            16:        PStype  ps;
        !            17:        int     pid;
        !            18:        struct  sentry  *sptr;          /* address of sem to free       */
        !            19: 
        !            20:        disable(ps);
        !            21:        if (isbadsem(sem) || semaph[sem].sstate==SFREE) {
        !            22:                restore(ps);
        !            23:                return(SYSERR);
        !            24:        }
        !            25:        sptr = &semaph[sem];
        !            26:        sptr->sstate = SFREE;
        !            27:        if (nonempty(sptr->sqhead)) {   /* free waiting processes       */
        !            28:                while( (pid=getfirst(sptr->sqhead)) != EMPTY)
        !            29:                        ready(pid,RESCHNO);
        !            30:                resched();
        !            31:        }
        !            32:        restore(ps);
        !            33:        return(OK);
        !            34: }

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