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→audio-fft
Nnethercote (talk | contribs) |
Nnethercote (talk | contribs) |
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== audio-fft == | == audio-fft == | ||
'''Description.''' | |||
A ''kernel''. Computes a Fast Fourier Transform. | |||
'''Key features.''' | |||
A big chunk of run-time is in this loop: | |||
while ( i < bufferSize ) { | |||
off = i + halfSize; | |||
tr = (currentPhaseShiftReal * real[off]) - (currentPhaseShiftImag * imag | |||
[off]); | |||
ti = (currentPhaseShiftReal * imag[off]) + (currentPhaseShiftImag * real | |||
[off]); | |||
real[off] = real[i] - tr; | |||
imag[off] = imag[i] - ti; | |||
real[i] += tr; | |||
imag[i] += ti; | |||
i += halfSize << 1; | |||
} | |||
Array gets and sets dominate. | |||
'''Mozilla-specific things.''' | |||
In the above loop, 'i' and 'off' are loaded as doubles and have to be converted to integers using a combination of inline code and calls to js_DoubleToInt32(). This should be avoided ([https://bugzilla.mozilla.org/show_bug.cgi?id=606879 bug 606879]). | |||
== audio-oscillator == | == audio-oscillator == | ||