Worms 4 Mayhem (PS2) Checksum Calculator

calc-checksum.py

#!/usr/bin/python3
# Worms 4: Mayhem (PS2) Checksum Calculator.
# Created by Li 2/18/2023.

import struct

# Read save file
save = open("BESLES-53096W4MA", "rb").read()

# Set count to 0
cnt = 0

# Get total length
ttl = len(save) - 4
for i in range(0, ttl, 4):
    cnt += struct.unpack("i", save[i:i+4])[0]

# Keep only last 32 bits.
chk = cnt & 0xFFFFFFFF

print("Chk "+ hex(chk))

# Recalcuate save but with new checksum
bchk = struct.pack("I", chk)
save = save[:-4]+bchk

# Write new save to disk
open("BESLES-53096W4MA", "wb").write(save)