mirror of
https://gitlab.com/ryandwyer/perfect-dark
synced 2026-05-25 07:22:44 -04:00
Ryan Dwyer
14f8d62e3e
* ROM is mismatching but functionally equivalent. * ROM does not shift, so any edits must use the same amount of bytecode. * Asset files such as stage setup and lang are not included yet (they are copied from the base ROM).
77 lines
1.6 KiB
Python
Executable File
77 lines
1.6 KiB
Python
Executable File
#!/usr/bin/python
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import sys;
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class Tool:
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def ROL(self, i, b):
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return ((i << b) | (i >> (32 - b))) & 0xffffffff
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def R4(self, b):
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return b[0]*0x1000000 + b[1]*0x10000 + b[2]*0x100 + b[3]
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def crc(self, f):
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seed = 0xdf26f436
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t1 = t2 = t3 = t4 = t5 = t6 = seed
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f.seek(0x0710 + 0x40)
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lookup = f.read(0x100)
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f.seek(0x1000)
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for i in range(0x1000, 0x101000, 4):
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d = self.R4(f.read(4))
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if ((t6 + d) & 0xffffffff) < t6:
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t4 += 1
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t4 &= 0xffffffff
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t6 += d
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t6 &= 0xffffffff
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t3 ^= d
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r = self.ROL(d, d & 0x1F)
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t5 += r
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t5 &= 0xffffffff
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if t2 > d:
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t2 ^= r
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else:
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t2 ^= t6 ^ d
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o = i & 0xFF
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temp = self.R4(lookup[o:o + 4])
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t1 += temp ^ d
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t1 &= 0xffffffff
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crc1 = t6 ^ t4 ^ t3
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crc2 = t5 ^ t2 ^ t1
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return crc1 & 0xffffffff, crc2 & 0xffffffff
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fd = open(sys.argv[1], 'rb')
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# Read existing CRC
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fd.seek(0x10)
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old = [
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int.from_bytes(fd.read(4), 'big'),
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int.from_bytes(fd.read(4), 'big'),
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]
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# Calculate new CRC
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tool = Tool()
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new = tool.crc(fd)
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fd.close()
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if '--verbose' in sys.argv:
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print('Old CRCs: %08x %08x' % (old[0], old[1]))
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print('New CRCs: %08x %08x' % (new[0], new[1]))
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if new != old and '--write' in sys.argv:
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fd = open(sys.argv[1], 'r+b')
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fd.seek(0x10)
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fd.write(new[0].to_bytes(4, 'big'))
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fd.write(new[1].to_bytes(4, 'big'))
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fd.close()
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