DRF_MW_SIZE
#define DRF_LW_IDX(o,drf) (DRF_LO(DRF_MW(drf)) / DRF_MW_SIZE(o))
#define DRF_LW_LO(o,drf) (DRF_LO(DRF_MW(drf)) % DRF_MW_SIZE(o))
#define DRF_LW_HI(o,drf) (DRF_MW_SPANS((o),drf) ? (DRF_MW_SIZE(o) - 1) : DRF_HW_HI((o),drf))
#define DRF_HW_IDX(o,drf) (DRF_HI(DRF_MW(drf)) / DRF_MW_SIZE(o))
#define DRF_HW_HI(o,drf) (DRF_HI(DRF_MW(drf)) % DRF_MW_SIZE(o))