DRF_HW_HI
#define DRF_LW_HI(o,drf) (DRF_MW_SPANS((o),drf) ? (DRF_MW_SIZE(o) - 1) : DRF_HW_HI((o),drf))
#define DRF_HW_BITS(o,drf) (DRF_HW_HI((o),drf) - DRF_HW_LO((o),drf) + 1)