If you need to use fft for not educational purposes please check the code composer directory ....\ti\c5500\dsplib\
this is digital processing library (with several fft routines included).
You can check the assembly code for several fft routines as well as several examples how to use them.
Actually I got c6711 and in DSPLIB i didn't find fft source.
In examples I found a fft256c But it seems to be not working well with pink noise only works well with sine wave.