25 lines
1.2 KiB
Plaintext
25 lines
1.2 KiB
Plaintext
BACKGROUND:
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I started coding this because I couldn't find a fixed point FFT that didn't
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use assembly code. I started with floating point numbers so I could get the
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theory straight before working on fixed point issues. In the end, I had a
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little bit of code that could be recompiled easily to do ffts with short, float
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or double (other types should be easy too).
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Once I got my FFT working, I was curious about the speed compared to
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a well respected and highly optimized fft library. I don't want to criticize
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this great library, so let's call it FFT_BRANDX.
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During this process, I learned:
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1. FFT_BRANDX has more than 100K lines of code. The core of kiss_fft is about 500 lines (cpx 1-d).
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2. It took me an embarrassingly long time to get FFT_BRANDX working.
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3. A simple program using FFT_BRANDX is 522KB. A similar program using kiss_fft is 18KB (without optimizing for size).
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4. FFT_BRANDX is roughly twice as fast as KISS FFT in default mode.
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It is wonderful that free, highly optimized libraries like FFT_BRANDX exist.
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But such libraries carry a huge burden of complexity necessary to extract every
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last bit of performance.
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Sometimes simpler is better, even if it's not better.
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-- Mark Borgerding |