The code hasn't been updated in about a year: https://github.com/wbhart/bsdnt
The author appears to be planning a restart of the project, but that won't happen until next year: http://wbhart.blogspot.com/2011_10_01_archive.html
The author appears to be planning a restart of the project, but that won't happen until next year: http://wbhart.blogspot.com/2011_10_01_archive.html
https://github.com/wbhart/mpir-fft
For the time being it is implemented against the MPIR bignum library. But once BSDNT is up to it I will install it in BSDNT.