Pseudocode for Fast Fourier Transform

can anyone provide a pseudocode/link/information of the Fast Fourier Transform for arrays of length n = 2^(l), where(l) is a positive integer.

Asking so that I can gain more insight on how to code using FFT without using a built in command (fft)

*update: im not asking for a code, so don't close this question. A pseudocode is not a code....

[John D'Errico]

Just google "fast fourier transform algorithm"