crc_ccitt_byte
hdlc->crc = crc_ccitt_byte(hdlc->crc,
hdlc->crc = crc_ccitt_byte(hdlc->crc,
dev->txfcs = crc_ccitt_byte(dev->txfcs, c);
dev->rxfcs = crc_ccitt_byte(FCS_INIT, c);
dev->rxfcs = crc_ccitt_byte(dev->rxfcs, c);
dev->rxfcs = crc_ccitt_byte(dev->rxfcs, c);
#define PPP_FCS(fcs, c) crc_ccitt_byte(fcs, c)
crc = crc_ccitt_byte(crc, *buffer++);