cuetools.net/CUETools.CLParity/fastdecode/new

You can find the actual encoding/decoding code in
reed_solomon.c and reed_solomon.h

The file main.c is just there as an example to show how to use the
encoding/decoding functions and to display the speed in MB/s.

Compile it with one of the following commands
gcc -O3 reed_solomon.c main.c -o test
gcc -O3 -DSSE -mssse3 reed_solomon.c main.c -o test_sse

Then the program work with
./test K N [S in Byte] [message size in MB]

Like 
./test 1024 2048 1024 50

We give three speed:
1. message size / encoding time
2. full coded size / encoding time
3. message size / decoding time

The current version is optimised for GF(2^16).
But all the code is present to work on other field of the form GF(2^m).