Analog Devices VISUALDSP++ 3.5 Manual page 521

The samples generated are:
=
twid re k _ ( ) cos
= −
twid _ im ( k ) sin
where k = {0, 1, 2, ..., ¾n - 1}
Domain
The FFT length
VisualDSP++ 3.5 C/C++ Compiler and Library Manual
for ADSP-219x DSPs
π
2
 
k
 
 
n
π 2
 
 k 
n
 
must be a power of four and at least 16.
n
DSP Run-Time Library
4-105