mirror of
https://github.com/mborgerding/kissfft.git
synced 2025-05-27 21:20:27 -04:00
24 lines
1.1 KiB
Plaintext
24 lines
1.1 KiB
Plaintext
Speed:
|
|
* experiment with compiler flags
|
|
Special thanks to Oscar Lesta. He suggested some compiler flags
|
|
for gcc that make a big difference. They shave 10-15% off
|
|
execution time on some systems. Try some combination of:
|
|
-march=pentiumpro
|
|
-ffast-math
|
|
-fomit-frame-pointer
|
|
|
|
* If the input data has no imaginary component, use the kiss_fftr code under tools/.
|
|
Real ffts are roughly twice as fast as complex.
|
|
|
|
Reducing code size:
|
|
* remove some of the butterflies. There are currently butterflies optimized for radices
|
|
2,3,4,5. It is worth mentioning that you can still use FFT sizes that contain
|
|
these factors, they just won't be quite as fast. You can decide for yourself
|
|
whether to keep radix 2 or 4. If you do some work in this area, let me
|
|
know what you find.
|
|
|
|
* For platforms where ROM/code space is more plentiful than RAM,
|
|
consider creating a hardcoded kiss_fft_state. In other words, decide which
|
|
FFT size(s) you want and make a structure with the correct factors and twiddles.
|
|
|