mirror of
https://github.com/notwa/mm
synced 2024-11-05 02:49:02 -08:00
102 lines
2.5 KiB
Python
Executable file
102 lines
2.5 KiB
Python
Executable file
#!/bin/python
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# fixes the checksums in a Majora's Mask US 1.0 savefile for Bizhawk
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# note: copies are ignored and overwritten, so don't bother editing them.
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import sys
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import struct
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lament = lambda *args, **kwargs: print(*args, file=sys.stderr, **kwargs)
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chunkize = lambda a, n: (a[i:i+n] for i in range(0, len(a), n))
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# seems redundant, but it's a lot less error-prone
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pack_u8 = lambda data: struct.pack('>B', data)
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pack_u16 = lambda data: struct.pack('>H', data)
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unpack_u8 = lambda data: struct.unpack('>B', data)[0]
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unpack_u16 = lambda data: struct.unpack('>H', data)[0]
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save_1 = 0x20800
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save_2 = 0x24800
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owl_1 = 0x28800
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owl_2 = 0x30800
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save_1_copy = 0x22800
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save_2_copy = 0x26800
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owl_1_copy = 0x2C800
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owl_2_copy = 0x34800
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def calc_sum(data):
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chksum = 0
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for b in chunkize(data, 1):
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chksum += unpack_u8(b)
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chksum &= 0xFFFF
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return chksum
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def fix_sum(f, addr, owl=False):
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sum_pos = 0x100A
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f.seek(addr)
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data = f.read(0x2000)
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chksum = calc_sum(data[:sum_pos])
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if owl and data != b'\x00'*0x2000:
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chksum += 0x24 # don't know why
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chksum &= 0xFFFF
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f.seek(addr + sum_pos)
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old_chksum = unpack_u16(f.read(2))
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f.seek(addr + sum_pos)
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f.write(pack_u16(chksum))
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lament('{:04X} -> {:04X}'.format(old_chksum, chksum))
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def copy_save(f, addr, addr2):
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sum_pos = 0x100A
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f.seek(addr)
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data = f.read(0x2000)
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f.seek(addr2)
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f.write(data)
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def delete_save(f, addr):
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f.seek(addr)
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f.write(b'\x00'*0x2000)
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def swap_endian(f):
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f.seek(0)
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data = f.read()
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f.seek(0)
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for s in chunkize(data, 4):
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f.write(s[::-1])
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def run(args):
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args = args[1:]
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if len(args) == 0:
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lament("TODO: convert stdin to stdout")
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return 0
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for fn in args:
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with open(fn, 'r+b') as f:
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# dumb way to determine byte order
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endian = 'big'
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f.seek(0x10000)
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if f.read(4) != b'\x03\x00\x03\x00':
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endian = 'little'
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if endian == 'little':
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swap_endian(f)
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copy_save(f, save_1, save_1_copy)
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copy_save(f, save_2, save_2_copy)
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copy_save(f, owl_1, owl_1_copy)
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copy_save(f, owl_2, owl_2_copy)
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fix_sum(f, save_1)
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fix_sum(f, save_2)
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fix_sum(f, owl_1, owl=True)
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fix_sum(f, owl_2, owl=True)
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if endian == 'little':
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swap_endian(f)
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return 0
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if __name__ == '__main__':
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ret = 0
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try:
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ret = run(sys.argv)
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except KeyboardInterrupt:
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sys.exit(1)
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sys.exit(ret)
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