lofi-12xt-firmware/docs/firmware/v1.5.205.md

Firmware v1.5.205 — analyzed image

Deep dive on the newest analyzed release (the version running on the dumped unit: every strings≥6 in this image also occurs in IC300). Older releases and deltas: rev-diff.md. Container/code basics: FINDINGS.md §4.

Vitals

• File Lofi-12 XT.bin: 1,707,049 B, sha256 a8bffa65919c0a2d4ff2ce77d16301551af4d2964497b8804deed49ce4198026, checksum B17C0857, triple (1, 5, 205), container (1, 3).
• Entry C2CD1AA0 (DSP reset prelude), 7 sects, chain tiles EOF exactly.

Composition

#	Load addr	Len	Role
0	C2DA7600	86,168	asset/blob (7e xx bitmap/font/waveform pattern)
1	C2DA6DD4	688	float table (filter/window coeffs)
2	C2DA7400	512	fixed-record table (presets/patterns)
3	C2B80C00	1,490,112	code (C674x LE, entropy ~6.89, ~12.6% zeros)
4	C2B809E8	8	zero slot (alignment churn, not usable space)
5	C2D84DE0	125,081	rodata (all strings, vtables; 6,362 code-ptrs, 3,141 self-ptrs)
6	C2DA5680	4,312	float ramp tail

What it does (from strings/symbols)

• Groovebox app: patterns/songs/tracks/scenes, 16-slice engine, pad handling (AppPad), step sequencer + transport with precount, per-track swing/mute.
• Audio export (AppAudioExport*, DialogAudioExporting, MixDown~): pattern/song mixdown + individual tracks, MIXDOWN FILE NAME:.
• MIDI Note Map (AppMIDINoteMap), MIDI I/O + CC step-lock handling.
• Master FX: MIsolator, MRackComp, SlipRoll, HoldDelay; sample REVERSE; tag search, file normalize/convert, FILE DATABASE (1,024 files/folder).
• Storage: SD via N3HAL drivers; project chunk tags (PJST/SMPS/PTD2/PTDT/PJCF/SONG/TRAU/…); audio RIFF/WAVE/smpl/cue, MThd/MTrk; FileUtil recursive copy/search + removeResourceFork.
• UI: OLED via custom RenderBuffer pipeline + StepEditPageController (updateAppLED); SYSTEM INFO (VERSION/BOOT/SYSTEM/MCU); SYSTEM UPDATE; full C674x crash dumper (Legacy NMI Exception, A0–A31/B0–B31).
• Toolchain traces: libc++ RTTI (NSt3__…) ⇒ TI clang-based CGT.

Learned / verified

• Unpacked + repacked with tools/ → byte-identical (cmp clean).
• Threshold→ThresholX Level-0 mod forges to self-consistent 462F735B.
• Top string-sect zero gaps (388/256/223/≈196 B) bound same-build string growth without pointer surgery.
• v1.2→v1.5 added ~91 KiB code (export + note-map + 4 FX + transport rework); callback ABI migrated Fv→Fvi/Fvii/Fviii; display symbols turned over (RenderBufferIhLi128ELi128ELi1327E gone) — see rev-diff.md.