Compute SUM8, XOR8, LRC and the common CRC-8 / CRC-16 variants for one frame
Sum-8 adds the bytes and keeps the low 8 bits; XOR-8 is what NMEA-0183 uses; LRC is the two's complement of that sum for Modbus ASCII; CRC-16/MODBUS goes on the wire low byte first. Everything runs locally.