The waterfall showed mirrored/upside-down garbage because the FFT
never produced a valid spectrum:
1. g3.c.f() (high-precision sin) had its quadrant-0 case mangled by
jadx into a nested-if that returned NaN for small angles - the
twiddle factor table ended up with 329/1024 NaN entries.
Restored the smali switch: case0->g(), case1->c(), case2->-g(),
case3->-c().
2. i3.d.k() routed the runtime FFT (a5==0, single-thread path) into
the else of if(a5!=1) instead of if(a5!=0), so the FFT never ran
and the output stayed in the time domain (peak at bin 357 for a
669Hz tone instead of bin 86).
Verified with a JVM harness (static-block tables + pure-tone inputs):
200Hz->bin26, 400Hz->bin51, 669Hz->bin86, 1000Hz->bin128, all exact.
Twiddle table NaN count: 329 -> 0.
mckero
f731775346