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Mark Borgerding 2004-01-31 16:26:42 +00:00
parent 2921d93dac
commit 75393dc4fa
2 changed files with 9 additions and 7 deletions
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12
README
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@ -51,12 +51,12 @@ theory straight before working on fixed point issues. In the end, I had a
little bit of code that could be recompiled easily to do ffts with short, float
or double (other types should be easy too).
Once I got my FFT working, I wanted to get some performance numbers against
Once I got my FFT working, I was curious about the speed compared to
a well respected and highly optimized fft library. I don't want to criticize
this great library, so let's call it FFT_BRANDX.
During this process, I learned:
1. FFT_BRANDX has more than 100K lines of code. KISS has less than 1k.
1. FFT_BRANDX has more than 100K lines of code. The core of kiss_fft is about 500 lines (cpx 1-d).
2. It took me an embarrassingly long time to get FFT_BRANDX working.
3. A simple program using FFT_BRANDX is 522KB. A similar program using kiss_fft is 18KB.
4. FFT_BRANDX is roughly twice as fast as KISS FFT.
@ -70,9 +70,11 @@ last bit of performance.
PERFORMANCE:
(on Athlon XP 2100+, with gcc 2.96, optimization O3, float data type)
Kiss performed 1000 1024-pt ffts in 100 ms of cpu time.
Kiss performed 1000 1024-pt cpx ffts in 100 ms of cpu time.
For comparison, it took md5sum 160ms cputime to process the same amount of data
Transforming 5 minutes of CD quality audio takes about 1 second (nfft=1024).
DO NOT:
... use Kiss if you need the Fastest Fourier Transform in the World
... ask me to add features that will bloat the code
@ -90,10 +92,10 @@ No scaling is done. Optimized butterflies are used for factors 2,3,4, and 5.
LICENSE:
BSD, see COPYING for details. Basically, "free to use, give credit where due, no guarantees"
BSD, see COPYING for details. Basically, "free to use&change, give credit where due, no guarantees"
TODO:
*) Add real optimization for odd length FFTs (DST)
*) Add real optimization for odd length FFTs (DST?)
*) Add real optimization to the n-dimensional FFT
*) Add simple windowing function, e.g. Hamming : w(i)=.54-.46*cos(2pi*i/(n-1))
*) Make the fixed point scaling and bit shifts more easily configurable.

4
tools/Makefile
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@ -15,9 +15,9 @@ endif
all: $(FFTUTIL) $(FASTFILT) $(FASTFILTREAL)
CFLAGS=-Wall -O3 -pedantic -march=pentiumpro -ffast-math -fomit-frame-pointer
#CFLAGS=-Wall -O3 -pedantic -march=pentiumpro -ffast-math -fomit-frame-pointer
# If the above flags do not work, try the following
#CFLAGS=-Wall -O3
CFLAGS=-Wall -O3
$(FASTFILTREAL): ../kiss_fft.c kiss_fastfir.c kiss_fftr.c
$(CC) -o $@ $(CFLAGS) -I.. $(TYPEFLAGS) -DREAL_FASTFIR -lm $+ -DFAST_FILT_UTIL