ReaperOfVeriod
5f0396e3d7
The previous commit fixed on one signature. Measuring all of them shows the
pattern is the norm. Taking delta = offset[i+1] - offset[i] against the chunk's
own first delta, levels 0-2, 2,953 deltas:
0 1,723 -4 549 +4 426
-8 146 +8 32
-12 71 +12 21
-16 34 +16 4
-20 27 +20 1
-24 13
Every deviation is a multiple of 4 and most are exactly +/-4; worst observed is 24
bytes in a 7-record chunk. 1,252 of 1,509 chunks have at least one, across 66 of
74 signatures.
WHY THIS DOES NOT BECOME A FIX
Two models produce this offset table and they are observationally identical:
1. records are genuinely variable-length, padded to 4 bytes, stride = largest
2. records are fixed at stride and the offset table carries inter-record
padding, so the gap to the next record is record + padding
Nothing in the offsets distinguishes them. Both say where records start. Both
produce 92, 88, 84, 92, 92, 92, 84, 88 for the case already discussed.
I wrote the change that slices each record against its successor -- model 1 -- and
then reverted it. Two things came out of writing it:
First, it broke three tests, which is the informative part. Those tests assert
"1,509 of 1,509 chunks have uniform record length" and they passed BECAUSE the
parser forced uniformity by slicing every record at a single stride. They were
asserting the parser's behaviour back at itself, and would have kept passing
forever regardless of what the disc contains.
Second, shipping it would have replaced one unverified model with another and
silently changed the record boundaries of 1,252 chunks on the strength of a
guess. The repo's own rule applies: a heuristic count is not an identification,
and here it is not even a count -- it is two equally good explanations of one
table.
WHAT WOULD SETTLE IT: a field inside the record whose end is independently
observable -- a terminator, a count implying a length, or a known value pinning
its position. Under model 2 the disputed bytes are padding and will be uniform or
zero; under model 1 they are data and will not be. For [75 42 ef] those 8 bytes
read a0 00 27 20 at both the tail of one slice and the head of the next, which is
arithmetic rather than evidence, since it is the same eight bytes seen twice.
The uniform model stays, the ambiguity is recorded in resolve()'s documentation
and here, and the 1,509-of-1,509 assertion stands as a statement about what the
parser does rather than about what the disc contains. 243 tests, clippy clean.
Going Commando
A native PC reimplementation of Ratchet & Clank: Going Commando (PlayStation 2, 2003), written in Rust.
The game is reimplemented, not emulated. There is no MIPS interpreter here and no CPU emulator: the systems are ported to Rust so they run as ordinary native code.
Status: initial scaffold. The disc is identified and verified, the
workspace builds, and nothing else is implemented yet. See
docs/roadmap.md for where things stand and what comes next.
The target
| Game | Ratchet & Clank: Going Commando |
| Platform | PlayStation 2 |
| Disc | SCUS_972.68 v1.01, USA Black Label |
| Video | NTSC, 60 Hz |
| Boot ELF SHA-1 | bacda860cbd6723142e86db56f197e47e728970f |
Verified against a real disc — see docs/disc-identification.md.
This is the build the reference projects pin; Greatest Hits v2.00 is a
different binary and is not the target.
No game content
This repository contains no game assets, no disc images, no BIOS dumps and no proprietary toolchains. You supply your own legally obtained copy of the disc as an input, the way the upstream reference projects do.
A pre-commit hook enforces this, blocking disc images, asset directories, container signatures and files over 50 MiB. If you clone elsewhere, enable it:
git config core.hooksPath .githooks
Layout
crates/
gc-formats/ asset format parsers (pure, no I/O beyond the caller's buffer)
gc-extract/ disc pipeline: identify, unpack, verify
gc-game/ game logic: hero, weapons, moby classes, progression, saves
gc-video/ IPU / MPEG-2 decode
gc-engine/ Bevy app: Graphics Synthesizer, VU0/VU1, renderer, frame loop
docs/
disc-identification.md which disc we build against, verified
roadmap.md phases, gates, current status
plan/ one file per subsystem, written as work proceeds
formats/ format specs, written as formats are reversed
tools/
identify-disc.py identify any Going Commando disc image
vendor/
rerac/ pinned upstream reference checkout (not tracked)
Building
Requires a Rust toolchain via rustup.
cargo check --workspace
cargo test --workspace
The host audio backend is disabled in Cargo.toml (see the comment there) so
that the workspace builds without system ALSA development headers. Audio decode
is the last phase of the port and lives in gc-video; re-enable it and install
alsa-lib-devel when that work starts.
Identifying a disc
python3 tools/identify-disc.py <your-disc.iso>
Reports the serial, version and video mode from SYSTEM.CNF, hashes the boot
executable, and warns when the disc is not the supported build. Reads only a
few megabytes, so it is near-instant.
How it will be verified
Visual and behavioural comparison against PCSX2, replaying recorded input and
comparing frames, level by level. The PS2 float model is reproduced rather than
approximated — see AGENTS.md.
PCSX2 is installed and working on this machine; the comparison loop that reads
the game's own memory over its debug protocol is up, and level 0's and level
1's tfrag lighting are verified byte-exact against it. See
docs/plan/pcsx2-verification.md for the
setup and how to run it.
Credits and licensing
This project learns from and is built on the work of others. Licences are
recorded in PROVENANCE.md and notices must travel with any
code derived from them.
- ReRAC — a native Rust/Bevy port of Ratchet & Clank (2002), the first game. ISC. The architecture this project follows.
- OpenRAC / rac2-gc-decomp — matching decompilation research for this game. MIT. Source of verified struct layouts and engine documentation.
- Wrench — community documentation of Insomniac's container formats. GPL, used as a specification reference only; no code is copied.
Ratchet & Clank is a trademark of Sony Interactive Entertainment. This is an unofficial fan project, not affiliated with or endorsed by Sony Interactive Entertainment or Insomniac Games.