{
    IOAPIC_REDIRECTION_REGISTER ReDirReg;
    IN UCHAR Vector;

    /* Start with lowest vector */
    Vector = IrqlToTpr(Irql) & 0xF0;

    /* Find an empty vector */
    while (HalpVectorToIndex[Vector] != 0xFF)
    {
        Vector++;

        /* Check if we went over the edge */
        if (TprToIrql(Vector) > Irql)
        {
            /* Nothing free, return failure */
            return 0;
        }
    }

    /* Save irq in the table */
    HalpVectorToIndex[Vector] = Irq;

    /* Setup a redirection entry */
    ReDirReg.Vector = Vector;
    ReDirReg.DeliveryMode = APIC_MT_LowestPriority;
    ReDirReg.DestinationMode = APIC_DM_Logical;
    ReDirReg.DeliveryStatus = 0;
    ReDirReg.Polarity = 0;
    ReDirReg.RemoteIRR = 0;
    ReDirReg.TriggerMode = APIC_TGM_Edge;
    ReDirReg.Mask = 1;
    ReDirReg.Reserved = 0;
    ReDirReg.Destination = 0;

    /* Initialize entry */
    IOApicWrite(IOAPIC_REDTBL + 2 * Irq, ReDirReg.Long0);
    IOApicWrite(IOAPIC_REDTBL + 2 * Irq + 1, ReDirReg.Long1);

    return Vector;
}

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