send.c

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#include <xinu.h>

syscall send(pid32 pid, umsg32 msg)
{
    intmask mask;          /* Saved interrupt mask      */
    struct procent *prptr; /* Ptr to process's table entry  */

    mask = disable();
    if (isbadpid(pid))
    {
        restore(mask);
        return SYSERR;
    }

    prptr = &proctab[pid];
    if (prptr->prhasmsg)
    {
        restore(mask);
        return SYSERR;
    }
    prptr->prmsg = msg;     /* Deliver message      */
    prptr->prhasmsg = TRUE; /* Indicate message is waiting  */

    /* If recipient waiting or in timed-wait make it ready */

    if (prptr->prstate == PR_RECV)
    {
        ready(pid);
    }
    else if (prptr->prstate == PR_RECTIM)
    {
        unsleep(pid);
        ready(pid);
    }
    restore(mask); /* Restore interrupts */
    return OK;
}