Do a dual-MAC energy loop and a divide-free threshold make the Cortex-M4 voice gate cheaper?
research/ambient-gatesimd
Do a dual-MAC energy loop and a divide-free threshold make the Cortex-M4 voice gate cheaper: 17-37% fewer instructions with the block-minimum floor, slower without it, RAM doubled; decisions unchanged (emulator counts, synthetic audio)
What it found
A stylised follow-up to ambient-gatem4. With the block-minimum floor the SMLALD energy loop cuts executed instructions per frame by 17% at -Os and 37% at -O2, but without it the gate gets slower (64-bit ring entries), RAM doubles and code grows by about 60%. A divide-free sum-domain threshold matched the original decision on all 36,000 frames per configuration and removes the only library call; the divide itself is not counted, so its saving is unmeasured. Emulator instruction counts on synthetic audio, not cycles and not hardware.
A figure from its own output
Paper, code and results
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Produced with AI assistance (Claude). Results are from the code in this repository and are simulated or stylised unless the abstract says otherwise; nothing here implies affiliation with or endorsement by any lab, researcher or company cited. MIT licensed.