SH4_MMUCR_URB_MASK
#define SH4_MMUCR_MASK (SH4_MMUCR_LRUT_MASK | SH4_MMUCR_URB_MASK | \
(r & SH4_MMUCR_URB_MASK) >> SH4_MMUCR_URB_SHIFT);
urb = (r & SH4_MMUCR_URB_MASK) >> SH4_MMUCR_URB_SHIFT;
a = _reg_read_4(SH4_MMUCR) & SH4_MMUCR_URB_MASK;