TIPS
上传用户:ozl2332
上传日期:2009-12-28
资源大小:38k
文件大小:1k
- 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.