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

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

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

short insertd(short pid, queue q, short key)
{
        short next;         /* runs through list                  */
        short prev;         /* follows next through list          */
        short head, tail;

        if (isbadqueue(q) || isbadpid(pid))
        { return SYSERR; }

        head = queuehead(q);
        tail = queuetail(q);

        prev = head;
        next = queuetab[head].next;
        while ( (queuetab[next].key <= key) && (next != tail) )
        {
            key -= queuetab[next].key;
            prev = next;
            next = queuetab[next].next;
        }
        queuetab[pid].next  = next;
        queuetab[pid].prev  = prev;
        queuetab[pid].key   = key;
        queuetab[prev].next = pid;
        queuetab[next].prev = pid;
        if (next != tail)
        { queuetab[next].key -= key; }

        return OK;
}

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