Is it possible to change fft data type during run time?

mborgerding / kissfft

a Fast Fourier Transform (FFT) library that tries to Keep it Simple, Stupid

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Is it possible to change fft data type during run time? #34

Closed chensterliu closed 4 years ago

chensterliu commented 4 years ago

Hello,

my project requires multiple FFTs with different data types (int32, int16). It seems that the kiss_fft_scalar is fixed after compiling. I tried to define FIXED_POINT with different values in the code, but the result is incorrect. Could anyone tell me if my requirement is possible to be met?

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mborgerding commented 4 years ago

You'd have to make the changes yourself. I must ask one question -- are you sure you want fixed point FFTs? If so, is there a vendor supplied FFT library you should be using?

chensterliu commented 4 years ago

We are working on FFT hardware implementation, just use this software code for reference. So no such vendor.

mborgerding commented 4 years ago

Sorry, that is not really supported at the current time. But you might be able to do one of the following.

compile kissfft into different shared libs, having an interface that is unique to the data type.
perform the computation in separate executable utilities

use the preprocessor to effectively make K copies of the library for the K different data types.e.g.

#define kiss_fft_alloc kiss_fft_alloc_int32
#define kiss_fft kiss_fft_int32
... and so on, then
#include "kiss_fft.c"

chensterliu commented 4 years ago

That's an awesome solution, thanks for your hints.