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

Go to the documentation of this file.

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

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

syscall signaln(semaphore sem, short count)
{
        irqmask ps;
        register struct sentry *psem;

/* 
 * The implementation of signaln() is essentially like
 * signal(), but with a loop to make ready 'n' processes
 * instead of one.  Signaln() should be non-blocking, that is,
 * it should not call resched() or otherwise yield the processor.
 */

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

---