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

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

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

syscall signal(semaphore sem)
{
        irqmask ps;
        register struct sentry *psem;

        ps = disable();                /* disable interrupts                  */
        if ( isbadsem(sem) )           /* safety check                        */
        {
                restore(ps);
                return SYSERR;
        }
        psem = &semtab[sem];           /* retrieve semaphore entry            */
        if ( (psem->count++) < 0 )     /* release one process from wait queue */
        { ready(dequeue(psem->queue), RESCHED_YES); }
        restore(ps);                   /* restore interrupts                  */
        return OK;
}

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