rr-decomp

Matching decompilation of Ridge Racer (PlayStation 1, Namco, 1994 — Japan release, RIDGERACER volume, SLPS-00001), and a static recompilation that runs it natively.

No game is distributed here, and none can be. There is no download that plays Ridge Racer: everything is built from PSX.EXE and the game reads its data from the disc. You need your own legally-owned copy (SLPS-00001), dumped from your own disc, to build or verify anything. Without it, what is offered is the code and the notes.

No copyrighted game data is committed here — no disc image, no executable, no textures, no audio, and no disassembly. asm/, assets/ and build/m0/asm/ are regenerated on your machine from your own copy by python3 tools/setup.py — the same practice as every project on decomp.dev.

Status

$ python3 tools/progress.py
game code: 408/408 functions in C, 186536/186536 bytes (100.00 %)
$ python3 build.py
build/PSX.EXE 31ec5d3616a0fdb456da27a984fc5b92259ff1f6 OK - matches the original

What that figure covers, exactly:

• All 408 game functions (0x800121F4–0x8003FA9C, the code Namco wrote) are plain C in src/fn/, one file per function. There is no INCLUDE_ASM, no __asm__ and no inline MIPS anywhere in src/. Each file is compiled by GCC 2.5.7 (-O2 -G0 -mips1 -msoft-float) through maspsx (ASPSX 2.21 mode). The result is linked, and the whole executable is compared with the original: byte-identical.
• The PsyQ libraries (Sony's runtime, from 0x8003FA9C) stay assembly (asm/psyq.s, regenerated locally). They are not part of the game.
• Data and rodata stay splat output (asm/data/, regenerated locally).

tools/progress.py counts a function as done only if it has a C file in src/fn/. The size column comes from the original's function table, not from the build.

History note. Until August 2026 this repo reported "949/949 byte-matching". That count came from transcribing the original MIPS into __asm__ blocks, so it matched by construction and proved nothing. It was replaced by the standard splat layout and an honest count: 23 % of functions and 5.6 % of instructions in real C. The figure above is that same honest count, now complete — every game function is real, compiled C.

Building the matching decomp

sh tools/toolchain.sh          # once: GCC 2.5.7 PSX, binutils-mips, m2c (Linux/WSL)
cp /path/to/PSX.EXE .          # SLPS-00001, sha1 31ec5d36...
python3 tools/setup.py         # splat: asm/ (libs + data), assets/, build/m0/asm/
python3 build.py               # compiles src/fn/*.c, links, checks the sha1

build.py reads RR_GCC (the compiler directory, /opt/decomp/gcc/2.5.7 by default). maspsx is vendored in tools/maspsx (MIT). splat is pinned to 0.50.0 / spimdisasm 1.42.4 by tools/setup.py.

path	what
rr.yaml, symbol_addrs.txt, undefined_syms.txt	splat config of the matching build
src/fn/*.c	the game, one file per function. func_80034050.c also holds func_8003446C: the two only match when compiled together (/* covers: */ marker)
include/	common.h, game.h, assembler macros
tools/segments.py	regenerates the src/fn subsegments of rr.yaml
tools/try.py	compiles one C file and diffs it against the original function
tools/jtbl.py, tools/fixjtbl.py	jump tables (/* jtbl: … */ markers in the C files)
tools/autodec.py, tools/perm_*	m2c drafts and decomp-permuter batches used while matching
m0.yaml, m0_symbol_addrs.txt, m0_reloc_addrs.txt	listing for the native runtime (below). m0_symbol_addrs.txt also holds the descriptive names found so far (st_race_main, car_simulate, …)

Notes from the matching

• The rodata boundary fix (0x29E8 → 0x29F4) and the game/PsyQ seam at 0x8003FA94, both found by the earlier pipeline, held.
• The earlier belief that the game was built with four flag sets (-O1 and -O2, GCC 2.5.7 and 2.7.2) did not hold: every game function matches GCC 2.5.7 -O2. The apparent -O1 units were -O2 register-allocation and scheduling effects that the C had not yet reproduced.
• What it took for the last hundred functions, for anyone matching GCC 2.5.7: nested assignments to fix operand order (m = i + (m = m + 1)), do { } while (0) to raise a pseudo's allocation priority, dead stores to break CSE, statements repeated in each branch to reproduce cross-jumping, globals accessed as struct fields to pin the scheduler, implicit-int callees for the delay-slot nop before a jal, and cc1 -dlg dumps to read the allocation order.

The native runtime

A second track runs alongside the decompilation: a static recompilation. tools/recomp.py translates every MIPS instruction of PSX.EXE into C mechanically, and tools/m0/ supplies a model of the hardware. The point is not emulation — it is to have a native milestone that boots today, so that each byte-matched function can replace its translated twin one at a time without ever breaking the whole.

It is playable today — v0.1.0. It boots from your own disc image to the loading screen, the title, the menu and a race; it draws, it plays the disc's twelve Red Book audio tracks and synthesises the SPU's twenty-four voices, and it takes a keyboard or a gamepad. Analogue steering and pedals go through the neGcon protocol the 1994 game already speaks. It builds natively on Linux and, with --windows, on Windows. CHANGELOG.md says what that covers, what it does not, and which defects had to be found on the way.

See tools/m0/README.md to build and run it, and RECOMP_NOTES.md for the defects found along the way — the translator's own bugs were found by differential testing against qemu-mipsel (114/116 functions bit-identical over 1856 cases), and the GTE's against an independent second implementation (11 600 comparisons, 29 encodings).

Its listing comes from m0.yaml, written to build/m0/asm/ by tools/setup.py. Nothing generated by this track is committed: game.c is the game's own code in another notation, exactly as asm/ is.

Asset formats

• MAP_RRM_FORMAT.md — track geometry file.
• TRACK_SPINE_FORMAT.md — the track centreline node tables in PSX.EXE. This closes the "Not found" item in the MAP.RRM writeup: there is no per-section transform because there is nothing to place. The track is a 20-byte-per-node polyline (D_8005A44C / D_8005B84C / D_8005CC4C) and MAP.RRM's quads are skinned along it. All three tables decode to closed loops.
• DISC_NOTES.md — disc layout.

Next steps

1. Names: carry the descriptive names in m0_symbol_addrs.txt (345 functions) into src/fn and symbol_addrs.txt, and type the globals.
2. Group src/fn back into the original translation units.
3. In the native runtime, replace the recompiled functions with the matched C, one at a time.

Transparency

Heavily AI-assisted: tooling, splitting and C conversions are driven by Anthropic's Claude under human direction and review. Nothing here requires trust — with your own copy of the game, python3 tools/setup.py && python3 build.py reproduces the result locally.