This is covered in Chapter 2 of the book.
Encoding and decoding of a Hamming code:
hamming.c
The decoding algorithm used in hamming.c is unique in the sense that
the syndrome of the receive word gives directly the decimal representation
of the error position.
Encoding and decoding are implemented with lookup tables.
Encoding and decoding of the binary extended (24,12,8) Golay
code:
golay24.c
An arithmetic decoding algorithm. It is a very close relative of the
error-trapping decoding algorithms developed by Kasami in the 1960s.
Encoding and soft-decision decoding of the first-order RM code, RM(1,3):
rm13_awgn.c
Decoding with the Green machine. Binary transmission over an AWGN channel.