In ./retro folder you can to find old sources of our old cwave production tool (cw). This is Windows only CLI program; and have lots of limitations (input -- 16 bit stereo WAV w/o any metadata and chunks different from 'fmt ' and 'data'; ASCII charset for file names and so). Its need FFTW3 (fftw.org) library to compile and work.
./retro/fftw-win contain some fftw-3.3.4 Visual Studio solution as well as our cw -only patch for original fftw-3.3.4 sources (./retro/fftw-win/fftw-3.3.4/kernel/assert.c). Please note, that the solution and patch are far from ideal, but somewhat works. Note also, that our assert.c is cw -only and inacceptable for generic fftw usage. To make a build (VS 2013) you should download original fftw-3.3.4.tar.gz from ftp.fftw.org, unpack it, copy content of our fftw-win/fftw-3.3.4 over original folder (replace kernel/assert.c) and rebuild fftw-3.3.4-libs/fftw-3.3.4-libs.sln.
./retro/linux folder contain the same code with the only "direct FFT" (L. Marple Jr., Computing the discrete-time analytic signal via FFT, IEEE Transactions on Signal Processing, 47(2001), 2600-2603) algorithm for U*x systems. You, probably, should review and fix our makefile.
Both implementations are scratch, but (with some fantasy skill) can be classified as "research quality software".