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Inline synthio_sat16 and use ssat - #11621
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It runs once or more per sample in synthio, the biquad filter and the audio effects, so the call cost more than the saturation. Rounding without a branch and using ssat where the core has it keeps the inlined copies small.
dhalbert
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Oct 18, 2026
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Thanks! Will be merged assuming the job that failed succeeds on a second run.
dhalbert
enabled auto-merge
October 18, 2026 23:30
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synthio_sat16runs at least once per sample in synthio, the biquad filter, Freeverb, Phaser and Flanger. It was a normal function in another file, so every call cost more than the work it did. It is now inline, rounds without a branch, and uses the ssat instruction on cores that have it.Time per 1024-sample buffer on Fruit Jam (RP2350):
On the PicoPad (RP2040), the synth with biquad is 4% faster. The output is the same, bit for bit. Flash is 96 bytes smaller on RP2350 and 8 bytes smaller on RP2040.
Tested on Fruit Jam and PicoPad by reading the output with
audiocore.get_buffer(). The code was written with AI help.