unsleep.c

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/* unsleep.c - unsleep */

#include <xinu.h>

/*------------------------------------------------------------------------
 *  unsleep  -  Internal function to remove a process from the sleep
 *          queue prematurely.  The caller must adjust the delay
 *          of successive processes.
 *------------------------------------------------------------------------
 */
status  unsleep(
      pid32     pid     /* ID of process to remove  */
        )
{
    intmask mask;           /* Saved interrupt mask     */
        struct  procent *prptr;     /* Ptr to process's table entry */

        pid32   pidnext;        /* ID of process on sleep queue */
                    /*   that follows the process   */
                    /*   which is being removed */

    mask = disable();

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

    /* Verify that candidate process is on the sleep queue */

    prptr = &proctab[pid];
    if ((prptr->prstate!=PR_SLEEP) && (prptr->prstate!=PR_RECTIM)) {
        restore(mask);
        return SYSERR;
    }

    /* Increment delay of next process if such a process exists */

    pidnext = queuetab[pid].qnext;
    if (pidnext < NPROC) {
        queuetab[pidnext].qkey += queuetab[pid].qkey;
    }

    getitem(pid);           /* Unlink process from queue */
    restore(mask);
    return OK;
}