cc5631a2f3
The prime suspect from the previous iteration was that the phase scheduler
simply is not running, which would have made every arrival result meaningless.
It is refuted.
timer_probe.py takes three equally-spaced snapshots of the 32 MB game heap with
no pilot -- exactly the condition where nothing had been observed to change --
and keeps words whose two successive deltas are both positive and agree within
12 %, so linear rather than merely noisy. 286 words qualify, with a large
cluster advancing in lockstep at 16.5 per second.
That rate is not a coincidence: the existing performance notes put Canary
playback on this box at roughly 14-19 fps, and the dominant counter sits inside
that band, so these read as per-frame counters.
Which gives a mundane explanation for six arrival-free runs. If the scheduler is
frame-driven and the title targets 30 Hz, game time advances at about 55 % of
wall-clock here, so the 168, 190 and 240 second runs covered roughly 92, 105 and
132 seconds of game time. Route_S02 schedules phase-1 arrivals at 90, 120, 170,
210 and 240, so the longest run passed the first two and came nowhere near the
last three. No model has to be wrong for the observations to be empty.
Kept at 🟡, not promoted: two links are assumed rather than measured -- that
these counters are frame counters, and that the game's tick is 30 Hz. The values
also do not fit a naive frame count, since the cluster read 14193 about 255 s
after emulator start, which matches neither 16.5 nor 30 per second, so their
origin is genuinely unknown and no counter is claimed to be the mission clock.
Next is one long run, ~350 s of probe, watching for a 0 -> n transition near
t = 163 s and 218 s wall, where the t = 90 and t = 120 route entries land at 55 %
speed. If 350 s still yields nothing, the frame-rate explanation is itself
refuted and the event-gated model returns as the front-runner. The ~210 s title
movie at boot is the binding constraint on how much game time one turn can
observe.
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 toxenia-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
HYPOTHESISto at leastPROBABLE— 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 paths →
docs/re/functions/<name>.md(one file per function or tight cluster). - Data structures / formats →
docs/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 withxenia-rs/zq.py—zq.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-rswith 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; ourxenia-rsnever got past the intro video. Use canary to observe output (capture its framebuffer for texture colours), not usually to instrument code — though itsbuild-crosstoolchain 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.