patch PCM sections in Wii VC ROMs with original data

pcmpatch.py

#!/usr/bin/env python3
import io
import re
import sys

import Wii  # https://pypi.org/project/Wii.py/
import lzss3  # https://github.com/magical/nlzss
import lzh83  # https://gist.github.com/mnml/1b61ddf0e8141a99018d327dc9e5f21b

if len(sys.argv) <= 2:
    sys.exit(f"usage: {sys.argv[0]} <WAD> <original ROM> <output>")

filename, rom = next(f for f in Wii.U8.load(Wii.WAD.loadFile(sys.argv[1])[5]).files if f[0].endswith(b".rom"))

if filename.startswith(b"LZ77"):
    rom = lzss3.decompress(rom)
elif filename.startswith(b"LZH8"):
    rom = lzh83.decompress(io.BytesIO(rom))

rom = bytearray(rom)

with open(sys.argv[2], "rb") as origf:
    orig = origf.read()

for m in re.finditer(rb"PCMF.{5}", rom, re.DOTALL):
    rom[slice(*m.span())] = orig[slice(*m.span())]

with open(sys.argv[3], "wb") as outf:
    outf.write(rom)