Files
Syplheed-Reborn/docs/re
Claude (auto-RE) 72365b217a re: memory-driven autopilot -- infrastructure, and an honest account of what is not solved
Reads the live world out of guest RAM and drives the pad from it. Working:
loop-rate memory reads, whole-RAM float scanning with numpy (1270 orthonormal
3x3 blocks in 6.2 s), entity enumeration by unit type (116 live instances in
Stage 02), pad control written straight into the vgamepad FIFO (the CLI spawns
a process per command and its tap/hold sleep inside the server, so neither is
usable in a control loop), unattended mission entry, and the Hangar loadout --
the "Recommended" control is AUTO SELECT, which at 5 % progress is a no-op
because only two weapons are developed and both are already mounted.

Not working, and the reason the craft is not yet flown: the class 0x820af030
is NOT the live entity. It has one object per spawned thing and carries the
unit-ID string, which is why it looked like the entity list, but every one of
its 384 words is constant across a 29 s in-flight capture. No transform lives
in it or one pointer hop from it. Input correlation (hard left yaw vs hard
right, looking for a turn axis that reverses) does find self-like objects at
cos = -0.99, but they cluster in what looks like a camera volume rather than
the craft, and with no definition pointer near them the trick of learning one
entity's layout and applying it to the rest has nothing to anchor on -- so the
33418 moving triples in a firefight cannot be split into enemies, friendlies
and bullets, and there is nothing to aim at.

Two dead ends are recorded so they are not repeated: RT is not the throttle
(the two-state speed scan therefore found nothing), and comparing orientation
matrices 2 s apart is outside the small-angle regime, which is what produced
"angular velocities" of 30000.

Also corrects the claim in unit-struct-runtime.md that 0x820af030 holds live
state. The definition class 0x820af844 and every value derived from it are
unaffected.

autopilot2.py (a PD controller using body angular velocity from consecutive
rotation matrices) is committed but has never had a valid config to run
against, and is marked as untested.
2026-07-29 19:04:33 +00:00
..

Reverse-engineering knowledge base

This directory is the spec-side of the clean-room: it records what the original Project Sylpheed binary does (behaviour) and how its data is laid out, so that the Rust port can be implemented from these specs without re-deriving anything and without ever copying original code.

It exists to answer one question fast: "do we already know how X works, and how sure are we?"


The one rule that matters

Never document a claim more confidently than the evidence supports, and never paste original code here.

A wrong-but-confident note is worse than no note: someone builds on it and the bug hides for weeks. Every entry therefore carries an explicit confidence and its evidence. This mirrors the project method — measure the oracle, never infer; refute before believing.

Clean-room firewall

  • Allowed: behaviour descriptions, field offsets/types, formulas, state machines, observed input→output pairs, and references to the original by address (sub_821B68C0) or to xenia-rs/sylpheed.db.
  • Forbidden here and in crates/: pasted decompiled C/C++ or verbatim disassembled function bodies presented as the thing to reimplement. Cite the address; describe the behaviour in your own words. Disassembly is a tool for understanding, not a source to copy.

Confidence levels

Level Meaning Bar to reach it
CONFIRMED Behaviour verified against ground truth. ≥2 independent observations or one observation cross-checked against an oracle (canary framebuffer, a known-correct value, a second code path).
PROBABLE Strong single-source inference. One clean observation, or an unambiguous static read of the disassembly.
HYPOTHESIS Educated guess, not yet tested. Anything else. Must say what would confirm/refute it.

Promotion requires new evidence, not re-reading the old evidence. A HYPOTHESIS that "looks right again" is still a HYPOTHESIS. Only an independent check promotes it. If evidence later contradicts an entry, demote it and record the contradiction — do not silently edit the conclusion.


When to document

  • Right after a function/structure crosses from HYPOTHESIS to at least PROBABLE — before moving to the next code path, so the knowledge isn't lost or re-derived.
  • Whenever confidence changes (up or down) — append to the Evidence log, don't overwrite.
  • Not while it's still a pure guess with no evidence — a one-liner in the relevant backlog/plan is enough until there's something to stand on.

What to document

  • Functions/code pathsdocs/re/functions/<name>.md (one file per function or tight cluster).
  • Data structures / formatsdocs/re/structures/<name>.md.
  • Keep the index in INDEX.md (one line each: name · confidence · one-line summary).

Use the templates: _TEMPLATE.function.md, _TEMPLATE.structure.md.


How we find and confirm code paths (the toolchain)

Everything joins on the guest virtual address (PC) — code addresses are fixed by the XEX load, identical across our emulator and canary.

  • Static (cheap, try first): xenia-rs/sylpheed.db (DuckDB: 25 481 functions, xrefs, strings, vtables, imports). Query with xenia-rs/zq.pyzq.py grep <str>, zq.py xref <addr>, zq.py dis <lo> <hi>, zq.py fn <pc>. Entry points are usually a string (zq.py grep MSG_DEMO) or an import (movie/XMA API) xref'd back to the loader.
  • Dynamic (when static is ambiguous): run xenia-rs with its probe suite — --pc-probe / --audit-pc-probe-hex (fires at block entry), --mem-watch (mid-block reads/writes of a VA), --lr-trace (call/return chains), --trace-instructions, --dump-addr (read guest memory). These already exist; prefer them over hacking canary.
  • Oracle (correctness ground truth): canary — the Wine cross-build xenia-canary/build-cross/bin/Windows/Debug/xenia_canary.exe (the native Linux ELF crashes / does not run — do not use it). This is the only emulator that reaches the in-game menu; our xenia-rs never got past the intro video. Use canary to observe output (capture its framebuffer for texture colours), not usually to instrument code — though its build-cross toolchain does compile, so small C++ probes + rebuild are possible when needed. Run muted, one emulator process at a time, point it at the real ISO (not the symlink).

⚠️ VA-equality caveat: join code by PC (fixed), but never assume a data VA holds the same bytes across emulators — allocators differ. Compare data by content/layout.