chprio.c

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#include <xinu.h>

pri16 chprio(pid32 pid, pri16 newprio)
{
    intmask mask;          /* Saved interrupt mask      */
    struct procent *prptr; /* Ptr to process's table entry  */
    pri16 oldprio;         /* Priority to return        */

    mask = disable();
    if (isbadpid(pid))
    {
        restore(mask);
        return (pri16)SYSERR;
    }
    prptr = &proctab[pid];
    oldprio = prptr->prprio;
    prptr->prprio = newprio;
    restore(mask);
    return oldprio;
}