XMOS simple FFT example

[Lefty4000]

Hello,

First time posting on XMOS forums so bear with me

I have two questions:

1) I am working with the simple FFT library and I noticed that the included functions do not return anything. I entirely understand that you send the functions the real and imaginary parts as well as the number of points to the functions.

I'm assuming that the functions change the already defined variable arrays and can be used as such:

int re[1024], im[1024]; //pretend these are both filled with 1024 points
N = 1024;
fftTwiddle(re, im, N);
//now the values in re and im are the output of said fftTwiddle function

is this right?

2) in the same FFT example, what is the :> operator? It doesn't seem to be a C operator and I cannot find it in the XC documentation.

Thanks for any help!

[Ross]

I've not looked at the code you have attached, but arrays are passed by reference so they could be modified by the fftTwiddle() function.

The :> operator is an input operation from a port, channel etc. It's use is fundamental to XC.

Take a look here for more info: https://www.xmos.com/download/public/XMOS-Multicore-Extensions-to-C(C).pdf