LEMAC_MCTBL_BITS
#if LEMAC_MCTBL_BITS < 0
crc >>= (32 + LEMAC_MCTBL_BITS);
crc &= (1 << -LEMAC_MCTBL_BITS) - 1;
crc &= (1 << LEMAC_MCTBL_BITS) - 1;
bzero(sc->sc_mctbl, LEMAC_MCTBL_BITS / 8);
#define LEMAC_MCTBL_SIZE (1 << (LEMAC_MCTBL_BITS - 3))