CAS_MAC_RX_ALIGN_ERR
bus_space_write_4(t, h, CAS_MAC_RX_ALIGN_ERR, 0);
bus_space_read_4(t, mac, CAS_MAC_RX_ALIGN_ERR) +
bus_space_write_4(t, mac, CAS_MAC_RX_ALIGN_ERR, 0);