Custom Robo Arena Checksum Fixer

gistfile1.py

import sys, struct, zlib

print 'Checksum fixer for Custom Robot Arena (NDS)'
print 'The Lemon Man (c) 2011'
if len(sys.argv) < 2:
    print 'Usage :\n\t%s <save name.sav>' % sys.argv[0]
    sys.exit(1)
    
fil = open(sys.argv[1], 'r+b')

for slot in range(2):
    print 'Processing slot %i' % slot
    buf = fil.read(0x100)
    slot_crc = struct.unpack('<I', buf[0x30:0x34])[0]
    calc_crc = abs(zlib.crc32(buf[:0x30]))
    print 'Slot : %x' % slot_crc
    print 'Calc : %x' % calc_crc
    if slot_crc != calc_crc:
        print 'Fixing the checksum...'
        fil.seek(0x100 * slot + 0x30)
        fil.write(struct.pack('<I', calc_crc))
    else:
        print 'Checksum are matching...'