Calculate RetroAchievements hash for PC Engine CD / TurboGrafx-CD games.

pcecdhash.py

#!/usr/bin/env python3
"""
pcecdhash.py - Calculate RetroAchievements hash for PC Engine CD / TurboGrafx-CD games.

Make it executable if needed:
    chmod +x pcecdhash.py

Usage:
    ./pcecdhash.py game.cue

Requirements:
    - Python 3.x
    - A Redump-style cue/bin set (not trimmed/conversions)

Authors:
    Chandu
    ChatGPT, 2025
    Countless others
"""

import sys, os, hashlib

SECTOR_SIZE = 2352
USERDATA_OFFSET = 16
USERDATA_SIZE = 2048
SECTORS_PER_SECOND = 75


def msf_to_sectors(msf: str) -> int:
    """Convert mm:ss:ff string to sector count."""
    mm, ss, ff = [int(x) for x in msf.split(":")]
    return mm * 60 * SECTORS_PER_SECOND + ss * SECTORS_PER_SECOND + ff


def read_sector(f, sector_index: int) -> bytes:
    """Read one sector of user data from a bin file."""
    f.seek(sector_index * SECTOR_SIZE + USERDATA_OFFSET)
    return f.read(USERDATA_SIZE)


def parse_cue_first_data_track(cue_path: str):
    """
    Return (bin filename, INDEX 01 sector offset) for the first MODE1/MODE2 track.
    """
    with open(cue_path, "r", encoding="utf-8", errors="ignore") as f:
        lines = f.readlines()

    current_file = None
    for i, line in enumerate(lines):
        parts = line.strip().split()
        if len(parts) >= 3 and parts[0].upper() == "FILE":
            filename = line.split('"')[1] if '"' in line else parts[1]
            current_file = os.path.join(os.path.dirname(cue_path), filename)
        if len(parts) >= 2 and parts[0].upper() == "TRACK":
            mode = parts[2].upper()
            if mode.startswith("MODE1") or mode.startswith("MODE2"):
                # find INDEX 01 for this track
                for subline in lines[i+1:]:
                    subparts = subline.strip().split()
                    if len(subparts) >= 3 and subparts[0].upper() == "INDEX" and subparts[1] == "01":
                        return current_file, msf_to_sectors(subparts[2])
    return None, 0


def compute_hash(cue_path: str) -> str:
    bin_path, start_sector = parse_cue_first_data_track(cue_path)
    if not bin_path or not os.path.exists(bin_path):
        raise FileNotFoundError("Could not locate data track from cue sheet.")

    with open(bin_path, "rb") as f:
        # Read 128 bytes from sector 1 relative to INDEX 01
        header_sector_index = start_sector + 1
        f.seek(header_sector_index * SECTOR_SIZE + USERDATA_OFFSET)
        header128 = f.read(128)

        # Verify magic string
        if b"PC Engine CD-ROM SYSTEM" not in header128[32:96]:
            raise ValueError("Invalid disc: Missing 'PC Engine CD-ROM SYSTEM' signature.")

        # Start building buffer
        buffer = bytearray(header128[-22:])  # last 22 bytes = disc title

        # Parse boot code info (big endian 3-byte index + 1-byte length)
        boot_index = (header128[0] << 16) | (header128[1] << 8) | header128[2]
        boot_sectors = header128[3]

        # Append boot code sectors
        for i in range(boot_sectors):
            buffer.extend(read_sector(f, start_sector + boot_index + i))

    # MD5 hash
    return hashlib.md5(buffer).hexdigest()


def main():
    if len(sys.argv) != 2:
        print("Usage: pcecdhash.py game.cue")
        sys.exit(1)

    cue_path = sys.argv[1]
    if not os.path.exists(cue_path):
        print(f"Error: File not found: {cue_path}")
        sys.exit(1)

    try:
        digest = compute_hash(cue_path)
        print(f"RetroAchievements hash: {digest}")
    except Exception as e:
        print(f"Error: {e}")
        sys.exit(1)


if __name__ == "__main__":
    main()