Drew T
45d26cc413
T2's central unknown is resolved, and it is NOT what the phase plan predicted. The plan
named the Arm-A splat `%lo +0x20` defect as T2's real substance. Four probes, each
isolating ONE variable, SHA vs config/check from a clean tree (SS125 rules):
1. sub-split the jr object at ARBITRARY addresses, pure -O2 -> BYTE-IDENTICAL
** the re-carve is NEUTRAL; Arm-A does not bite here **
2. same split, middle region routed to -O0 -> DIVERGED (2 vars at once)
3. same NAME as probe 1, only the -O0 flag added -> DIVERGED
** therefore the FLAG, not the subseg name **
4. -O0 regions cut to EXCLUDE the matched bodies -> BYTE-IDENTICAL
** route PROVEN end-to-end **
THE REAL OBSTACLE: an address range is not an optimization region. Interleaved among the
15 -O0 stubs at 0x80183CF0..0x80184920 are TWO already-MATCHED functions (func_80184440,
func_801848E4) that expand from engine_core.h and compile at -O2. Flipping the FILE to -O0
recompiles them too. Cut around them and it is byte-clean.
MY EARLIER "15 contiguous -O0 fns, clean cut" WAS AN UNDER-COUNT (R14 on myself): I derived
it by scanning asm/**/*.s for the frame-pointer prologue, and a MATCHED function emits no
.s -- so the scan was structurally blind to exactly the bodies that break the flip. Same
shape as SS124. Any T2 driver must derive -O0 bounds as (address range MINUS already-matched
bodies), never from an asm scan.
BANKED (3, whole-binary gate the sole arbiter): func_801846E4 + siblings func_8018473C /
func_80184794. Each global DERIVED FROM THE ASM (%hi/%lo operands), not taken from the
draft's comment; 3/3 match_one --o0 MATCH (22 ins) with a -O2 control showing the mismatch;
3/3 verified through harvest_verify; bank truth read from the SOURCE (SS55b trap 4).
MAKEFILE: the -O0 glob widened `ov_*_o0b.c` -> `ov_*_o0?.c` so ANY lettered -O0 sub-split is
covered by one rule. A MISSED rule is silent -- the region would compile -O2 and every
residual it produced would be a pure artifact (SS116). corpus.o0_sources() re-verified: 137
sources, resolves `?` via glob, both pre-existing rules intact.
CONFIG: ov_SC03_014_jr_8017EB7C sub-split into 5 regions (pre / _o0c / matched-O2 /
_o0d / post), reusing jr_isolate_all's plan+build_new_config+validation verbatim so the
carve-repoint and source-repartition semantics are the proven ones.
R22 CLEAN-FLEET: extract-all 139/139 (+main) ; check-all 140 passed, 0 failed of 140.
BFM-decomp
A matching decompilation of Brave Fencer Musashi (PlayStation, SLUS-00726, USA 1998) — the first public decompilation effort for this game.
What "matching" means
The goal is C source code that, compiled with the original-era toolchain (PsyQ 4.x / GCC 2.7.2-family + ASPSX via maspsx), produces a byte-for-byte identical SLUS_007.26 and, eventually, byte-identical overlay binaries. SHA1 checksums are the ground truth; "functionally equivalent" does not count.
No ROM content
This repository contains no game assets, no disassembly output, and no ROM-derived data — only source code, build configuration, symbol names/addresses, hashes, and documentation. To build or contribute you must provide your own dump of the game disc (4-track BIN/CUE, redump layout). See .gitignore for the firewall.
Project status
Latest (Phase 19, 2026-06-20): the project builds 136 binaries byte-identical from a clean tree (the EXE + the resident engine + all 134 location overlays);
make check-all→ 136/136. Fleet byte-identical-from-source is 58.0% (function-instance-weighted; see the PhaseEnds for the byte-weighted ~30% figure and what it includes). Shared engine functions are matched once inov_SC01_077and propagated ×134 viatools/dedup_propagate.py. (The narrative below is Phase-11/12-era; a full refresh is part of the public-flip prep.)
Gen1 (foundation) complete — the matching pipeline is proven end-to-end. make extract && make build && make check rebuilds SLUS_007.26 byte-for-byte identical (SHA1 143dbb89…) from C + assembly, reproducibly across many sessions.
- Compiler pinned by evidence:
gcc-2.7.2-psx -O2 -G0 -mips1 -mcpu=3000+maspsx --aspsx-version=2.56 --expand-div. - 52 functions hand-matched to byte-identical machine code — including the LZSS streaming decompressor — with a decomp-permuter + matching-cookbook "flywheel" to accelerate the next.
- 959 PsyQ SDK functions linked byte-identical (libcd, libgs, libgte, libspu/libsnd, libgpu, libc2, libmcrd, libapi/libcard, libetc) straight from the real PsyQ 4.0 libraries instead of re-decompiling them — bringing byte-identical-from-source coverage of the EXE to ~50%.
- File-loader / overlay system reverse-engineered, with the resident engine blob + location overlays' load addresses proven byte-identical against a live PCSX-Redux RAM dump.
About half the EXE is still INCLUDE_ASM stubs (correct bytes, not yet C), and the bulk of the game lives in compressed overlays inside the .CD archives — Gen2 (overlays & engine at scale) is underway:
- The build toolchain is binary-agnostic (one parameterized pipeline builds any binary), and the always-resident engine blob rebuilds byte-for-byte from source (SHA1
8e17e02f…) — the second binary reconstructed exactly, after the EXE — and is now 86% hand-matched C (123 / 146 functions, up from 0): its scripting turned out to be compiled-MIPS state/mode dispatch, not a bytecode VM, and the save-file + sound (SQV) formats are documented. The harvest used a reusable swarm-of-agents + bit-for-bit byte-gate method (a wrong match can't be accepted) —tools/harvest_verify.py+tools/match_one.py, which carry straight into the overlay phase. - A cross-binary deduplication pipeline is live: a Ghidra-free signer fingerprints all 134 location overlays, and the report finds ~9,000 byte-identical function groups shared across binaries (~28 MB of collapsible code) — a single engine function is byte-identical in all 134 overlays. This is "one match unlocks many": each engine match will be auto-credited across the overlay fleet.
Current phase and detailed progress live in phase-ends/ (newest PhaseEnd_*.md = current state); methodology, rules, and the full roadmap are in PROJECT_CONTEXT.md; environment setup in docs/SETUP.md.
This project is developed primarily by Claude Code driving Ghidra through an MCP server; see CLAUDE.md.
License
Private repository for now. AGPL-3.0 is planned at public release, modeled on sotn-decomp. tools/brave-CUE/ is CUE's BRAVE extractor (GPL, source included) and retains its own license.