recvtime.c

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#include <xinu.h>

/*------------------------------------------------------------------------
 *  recvtime  -  Wait specified time to receive a message and return
 *------------------------------------------------------------------------
 */
umsg32 recvtime(
    int32 maxwait /* Ticks to wait before timeout */
)
{
    intmask mask;          /* Saved interrupt mask      */
    struct procent *prptr; /* Tbl entry of current process  */
    umsg32 msg;            /* Message to return     */

    if (maxwait < 0)
    {
        return SYSERR;
    }
    mask = disable();

    /* Schedule wakeup and place process in timed-receive state */

    prptr = &proctab[currpid];
    if (prptr->prhasmsg == FALSE)
    { /* Delay if no message waiting    */
        if (insertd(currpid, sleepq, maxwait) == SYSERR)
        {
            restore(mask);
            return SYSERR;
        }
        prptr->prstate = PR_RECTIM;
        resched();
    }

    /* Either message arrived or timer expired */

    if (prptr->prhasmsg)
    {
        msg = prptr->prmsg;      /* Retrieve message        */
        prptr->prhasmsg = FALSE; /* Reset message indicator */
    }
    else
    {
        msg = TIMEOUT;
    }
    restore(mask);
    return msg;
}