ID_REG_MASK
if ((c & ID_REG_MASK) != ID_REG_SIG)
if ((d & ID_REG_MASK) != ID_REG_SIG)
if ((d & ID_REG_MASK) != ID_REG_SIG)
if ((d & ID_REG_MASK) != ID_REG_SIG)
if ((d & ID_REG_MASK) != ID_REG_SIG)