54 lines
1.8 KiB
Python
54 lines
1.8 KiB
Python
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import struct
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from typing import Dict, List, Tuple
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from bemani.protocol.lz77 import Lz77
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class ARC:
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"""
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Class representing an `.arc` file. These are found in DDR Ace, and possibly
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other games that use ESS. Given a serires of bytes, this will allow you to
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query included filenames as well as read the contents of any file inside the
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archive.
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"""
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def __init__(self, data: bytes) -> None:
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self.__files: Dict[str, Tuple[int, int, int]] = {}
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self.__data = data
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self.__parse_file(data)
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def __parse_file(self, data: bytes) -> None:
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# Check file header
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if data[0:4] != bytes([0x20, 0x11, 0x75, 0x19]):
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raise Exception('Unknown file format!')
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# Grab header offsets
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(_, numfiles, _) = struct.unpack('<III', data[4:16])
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for fno in range(numfiles):
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start = 16 + (16 * fno)
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end = start + 16
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(nameoffset, fileoffset, uncompressedsize, compressedsize) = struct.unpack('<IIII', data[start:end])
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name = ""
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while data[nameoffset] != 0:
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name = name + data[nameoffset:(nameoffset + 1)].decode('ascii')
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nameoffset = nameoffset + 1
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self.__files[name] = (fileoffset, uncompressedsize, compressedsize)
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@property
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def filenames(self) -> List[str]:
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return [f for f in self.__files]
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def read_file(self, filename: str) -> bytes:
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(fileoffset, uncompressedsize, compressedsize) = self.__files[filename]
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if compressedsize == uncompressedsize:
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# Just stored
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return self.__data[fileoffset:(fileoffset + compressedsize)]
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else:
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# Compressed
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lz77 = Lz77()
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return lz77.decompress(self.__data[fileoffset:(fileoffset + compressedsize)])
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