Drew T 7f75442b67 docs(cookbook): S66 round 6 — §320 breaks the §43/§183 'return-type flip' wall, §321 typedef identity
From the two cast-at-use reconcile lanes (27 agents on drafts the gate DROPPED for in-TU decl
conflicts, not codegen). 24 reconciled to MATCH, 19 banked.

§320 — §43 and §183 item 4 both record the return-type flip pair (TU says void, body materializes
$v0 on every exit) as TU-EDIT-REQUIRED IMMOVABLE. It is not: three agents broke it three ways in a
single lane, each byte-proven.
  1. §202 asm-label alias — s32 aF800CCBC0(void) __asm__("func_800CCBC0") — TU untouched
     (func_800CCBC0 138/138 first try; func_800D30D0 76/76).
  2. register $2 + input-only asm barrier before a bare return, with the early exit routed through
     a goto to a SHARED label — measured bound: inline in the if body is NEAR closeness 10, shared
     exit is MATCH (func_800D2A24).
  3. Adopt the TU's own old-style K&R decl rather than writing a prototype (func_800CB1CC 47/47).
Plus: when every caller discards the result a TU void->s32 widening IS byte-neutral, but MEASURE it
(null-draft rebuild must still give 143dbb89…) — done twice here. And the process trap that cost a
pass: gate_main snapshots and RESTORES the TU between passes, so an uncommitted TU edit is reverted
before the gate sees it.

§321 — two anonymous struct typedefs are distinct types to gcc-2.7.2 even when spelled identically,
so a file-scope duplicate is fatal while the SAME TEXT at block scope is only a warning and is
codegen-neutral. Three dials, all byte-proven: demote to block scope; or hoist and delete the local
copy; or name a local typedef for its OWN address (SVEC_8017E07C, not a neighbour's SVEC_8017E158).
Not a cast-at-use case — the conflict is type IDENTITY, not width.
2026-08-31 00:00:08 -06:00
2026-06-10 22:02:07 -06:00
2026-06-10 22:02:07 -06:00

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 in ov_SC01_077 and propagated ×134 via tools/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.

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