Starting in Quartus® II software version 10.1, the variable streaming Floating Point FFT is updated to use a mixed radix-4/2 architecture. The “bit reverse order” is related to the radix-2 algorithm. Because of this algorithm change in implementing the variable streaming Floating Point FFT, the “bit reverse order” is no longer valid.
In the Quartus II software version 11.0, the “bit reverse order” is changed to “digit reverse order” whenever floating Point FFT is configured.
In the Quartus II software version 10.1, treat the “bit reverse order” as “digit reverse order” whenever floating Point FFT is configured.