romdev-m2c

A plain JavaScript (ESM) port of m2c, the MIPS/PowerPC/ARM/SuperH to C decompiler used by matching-decompilation projects. It takes the same flags as upstream's command line and prints the same C. No Python is needed.

It is part of romdev and is kept in its own package so that m2c's GPL terms stay separate from romdev's MIT code, which only calls it.

Upstream and license

• Upstream: m2c, https://github.com/matt-kempster/m2c
• Ported from commit 1d1c4454a445326541305f83f2b0cb680a9ecb2d
• License: GPL-3.0-only (a derivative of m2c). See LICENSE and NOTICE.
• src/*.js translate m2c/*.py module by module; m2c_macros.h is copied unchanged. The CodeWarrior demangler is based on arookas' demangler.cs (BSD-3-Clause, notice kept in the source file).
• The C parser is the separate romdev-pycparser package. --visualize SVG output uses the @viz-js/viz dependency (Graphviz compiled to WebAssembly, EPL-1.0), which runs as a separate program on the dot text m2c produces.

The end-to-end tests run upstream's tests/end_to_end corpus through the port and compare each result byte for byte with upstream's expected output.

How romdev uses it

romdevtools' decomp tool calls it to produce a first C candidate for a function: decomp({op:'generate', ...}) runs m2c on the function's assembly with the translation unit's type context, and decomp({op:'compare'}) then compiles that candidate with the project's original compiler.

Command line

npx romdev-m2c --target mips-ido-c --context ctx.c func.s

The bin is romdev-m2c. It accepts upstream m2c's flags, writes the same stdout and stderr, and exits with the same code.

API

import { decompile, decompileInWorker, UPSTREAM } from "romdev-m2c";

const { code, stdout, stderr } = await decompile([
  "--target", "mips-ido-c", "--context", "ctx.c", "func.s",
]);

• decompile(flags): runs m2c in process with upstream's CLI flags and resolves to { code, stdout, stderr }. Assembly inputs may also be passed inline as { name, text } objects.
• decompileInWorker(flags, { timeoutMs }): the same in a worker thread; resolves to { code, stdout, stderr, timedOut } and terminates the worker on timeout.
• parse_flags, run, ArgumentError: lower-level entry points.
• UPSTREAM: { repo, commit } of the ported m2c.

Exports: . and ./m2c_macros.h (the header m2c's output expects).

Requirements

Node >= 24, ESM only. No Python, no native code.

Versions

romdev-m2c 0.1.0 ports m2c at commit 1d1c4454.