Non-systematic (7, 4) Hamming code encoder
AS I recall from the '70's it uses XOR gates but now in a small CPLD.
    P1=d0 ⊕ d2 ⊕ d4 ⊕ d6
    P2=d1 ⊕ d2 ⊕ d4 ⊕ d6
    P3=d3 ⊕ d4 ⊕ d5⊕ d6   

b3, b2, b1, P3, b0, P2, P1  7 bit string =  3 parity bits +  4 data bits  = Hamming 7,4
sent as   d6 d5 d4 d3 d2 d1 d0    repeat for both 4b nibble to get 14 bit string. 

Dave? @Jonk correct me if I missed something.