76 lines
2.7 KiB
Python
76 lines
2.7 KiB
Python
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import binascii
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b2h = binascii.hexlify
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h2b = binascii.unhexlify
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class ROM:
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def __init__(self, filename):
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data = open(filename, "rb").read()
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#assert len(data) == 1024 * 1024
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self.banks = []
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for n in range(0x40):
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self.banks.append(bytearray(data[n*0x4000:(n+1)*0x4000]))
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def patch(self, bank_nr, addr, old, new, *, fill_nop=False):
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new = h2b(new)
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bank = self.banks[bank_nr]
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if old is not None:
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if isinstance(old, int):
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old = bank[addr:old]
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else:
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old = h2b(old)
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if fill_nop:
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assert len(old) >= len(new), "Length mismatch: %d != %d (%s != %s)" % (len(old), len(new), b2h(old), b2h(new))
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new += b'\x00' * (len(old) - len(new))
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else:
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assert len(old) == len(new), "Length mismatch: %d != %d (%s != %s)" % (len(old), len(new), b2h(old), b2h(new))
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assert addr >= 0 and addr + len(old) <= 16*1024
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if bank[addr:addr+len(old)] != old:
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if bank[addr:addr + len(old)] == new:
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# Patch is already applied.
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return
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loc = bank.find(old)
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while loc > -1:
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print("Possible at:", hex(loc))
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loc = bank.find(old, loc+1)
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assert False, "Patch mismatch:\n%s !=\n%s at 0x%04x" % (b2h(bank[addr:addr+len(old)]), b2h(old), addr)
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bank[addr:addr+len(new)] = new
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assert len(bank) == 0x4000
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def fixHeader(self, *, name=None):
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if name is not None:
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name = name.encode("utf-8")
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name = (name + (b"\x00" * 15))[:15]
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self.banks[0][0x134:0x143] = name
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checksum = 0
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for c in self.banks[0][0x134:0x14D]:
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checksum -= c + 1
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self.banks[0][0x14D] = checksum & 0xFF
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# zero out the checksum before calculating it.
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self.banks[0][0x14E] = 0
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self.banks[0][0x14F] = 0
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checksum = 0
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for bank in self.banks:
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checksum = (checksum + sum(bank)) & 0xFFFF
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self.banks[0][0x14E] = checksum >> 8
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self.banks[0][0x14F] = checksum & 0xFF
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def save(self, file, *, name=None):
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# don't pass the name to fixHeader
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self.fixHeader()
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if isinstance(file, str):
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f = open(file, "wb")
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for bank in self.banks:
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f.write(bank)
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f.close()
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print("Saved:", file)
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else:
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for bank in self.banks:
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file.write(bank)
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def readHexSeed(self):
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return self.banks[0x3E][0x2F00:0x2F10].hex().upper()
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