Desktop/xinu_mips-1.0.2.tar/xinu_mips-1.0.2/system/freesem.c

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/* Embedded XINU, Copyright (C) 2007.  All rights reserved. */

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

syscall freesem(semaphore sem)
{
        irqmask ps;    
        struct sentry *sptr;
        int     pid;

        ps = disable();                 /* disable interrupts              */
        if ( isbadsem(sem) )            /* check sem validity              */
        {
                restore(ps);
                return SYSERR;
        }
        sptr = &semtab[sem];
        while ( nonempty(sptr->queue) ) /* release processes in wait queue */
        {
                pid = dequeue(sptr->queue);
                ready(pid, RESCHED_NO);
        }
        sptr->count = 0;                /* reset the semaphore count       */
        sptr->state = SFREE;            /* deallocate in semaphore table   */
        restore(ps);                    /* restore interrupts              */
        return OK;
}

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