MMUCR_URB
urb = (mmucr & MMUCR_URB) >> MMUCR_URB_SHIFT;
status = ((status & MMUCR_URB) >> MMUCR_URB_SHIFT);
status = ((status & MMUCR_URB) >> MMUCR_URB_SHIFT);
urb = (status & MMUCR_URB) >> MMUCR_URB_SHIFT;
status &= ~MMUCR_URB;
urb = (status & MMUCR_URB) >> MMUCR_URB_SHIFT;
status &= ~MMUCR_URB;