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Syplheed-Reborn/docs/re
Sylpheed RE agent 5670716566 re: both trigger kinds watch a ROUTE -- the unit-reaches-route mechanism
The kind-0 condition tester sub_8226DAF8 resolves a symbol as well, but from
payload+4 rather than +28:

    8226DB14  rlwinm r10, r5, 2, 0, 29   ; r5 = payload+4, x4
    8226DB24  lwz    r11, 244(r30)       ; [phase+244] = symbol table 1
    8226DB3C  lwzx   r10, r10, r11
    8226DB50  addi   r4, r11, 4          ; -> the name string

Both appenders write local[12] into whichever slot their own path reads -- built-in 19
into +4, built-in 25 into +4 and +28 -- so the same operand is the symbol either way,
and it resolves cleanly:

    built-in 19   local[12] -> symtab 1   79 / 79   all symbol type 1
    built-in 25   local[12] -> symtab 1   25 / 25   all symbol type 1

isl-builtins.md records symtab-1 type 1 as the Route_* names, and the samples agree:
Route_ADN106_p1F, Route_ADN1xxe1_p1F, Route_ADS101_p1F, Route_TCN004_p1S.

So both built-ins register a trigger on a UNIT reaching a ROUTE -- payload+0 is the
unit, local[12] the route.  They differ only in the payoff: built-in 19 additionally
carries a handler routine (local[32] -> payload+28, kind 0 -> spawn) while built-in 25
carries none (kind 1 -> no spawn).  That is a third independent agreement with
isl.py's SYM1_SLOTS, which lists slot 12 for both and was derived from operand ranges
alone.

It also joins up with the closed REMAINING OB work, where the counter was measured to
rise at a squadron's route arrival time -- route triggers are the mechanism that would
do that.  Recorded as a connection, not a demonstration: nothing here traces a trigger
to that counter.

All artefacts regenerate byte-identical; documentation only.

Still unread: what the conditions actually COMPARE -- only sub_8226DAF8's first ~34
instructions are read, up to the name lookup, and sub_8226DC80 not at all -- and
payload+8, a computed value passed to both testers.  A waypoint index would fit it,
which is exactly why it is not being called one.
2026-08-27 08:00:22 +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.

The status markers

The table above is the confidence scale. The markers that appear in BACKLOG.md and the structures/ pages are a separate, and until now undefined, vocabulary. They mean:

Marker Meaning
Confirmed — verified against ground truth.
🟡 Partial: true as far as it goes, or true under a stated assumption.
Open question. Nobody has answered it yet.
🔴 Refuted — shown false — or blocked by something the container cannot do.
A specific claim that was tried and failed. Prefer 🔴.
🚧 Work started and not finished.

🔴 never means "we have not run it yet." That is or 🚧. Reserve 🔴's "blocked" sense for a real limit of the box — no push credentials, no hardware Vulkan (lavapipe only), or a decision only the user can make. The box can run the emulator, script input, screenshot, read guest memory, and build and test Rust, so "needs a run" is never a blocker. This paragraph exists because the marker was undefined for 98 uses and three of them were mislabelled that way.

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.