Twiddles Header File - 2024.2 English - XD100

Vitis Tutorials: AI Engine Development (XD100)

Document ID
XD100
Release Date
2024-12-06
Version
2024.2 English

The first header file, that contains all the twiddle factor entries, is a rather long file. Because of the regular structure of the code, and because the mathematical formula to compute the twiddles is well known, the better choice is to generate the header file using a script. The twiddle generation script, written in Python following the AIE API guidelines, along with an explanation of its functionalities can be found in the support twiddles folder of this repository.

In particular, the defined twiddles vectors are organized with two subscripts, the first indicating the FFT stage, and the second indicating the stage entry. Thus for instance, the third entry of the fifth stage of a radix-4 FFT stage will be named TWID4_2. Because this project is about a radix-4 staged implementation, the generated header file contains 15 twiddle tables, three per each of the five stages.