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comparison pytouhou/formats/pbg3.py @ 0:6b2c7af2384c

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Hello Gensokyo _o/
author Thibaut Girka <thib@sitedethib.com>
date Sun, 31 Jul 2011 21:32:12 +0200
parents
children ab826bc29aa2
comparison
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-1:000000000000 0:6b2c7af2384c
1 from pytouhou.utils.bitstream import BitStream
2 import pytouhou.utils.lzss as lzss
3
4
5 class PBG3BitStream(BitStream):
6 def read_int(self):
7 size = self.read(2)
8 return self.read((size + 1) * 8)
9
10
11 def read_string(self, maxsize):
12 string = []
13 for i in range(maxsize):
14 byte = self.read(8)
15 if byte == 0:
16 break
17 string.append(byte)
18 return ''.join(chr(byte) for byte in string)
19
20
21
22 class PBG3(object):
23 def __init__(self, entries, bitstream=None):
24 self.entries = entries
25 self.bitstream = bitstream #TODO
26
27
28 @classmethod
29 def read(cls, file):
30 magic = file.read(4)
31 if magic != b'PBG3':
32 raise Exception #TODO
33
34 bitstream = PBG3BitStream(file)
35 entries = {}
36
37 nb_entries = bitstream.read_int()
38 offset = bitstream.read_int()
39 bitstream.seek(offset)
40 for i in range(nb_entries):
41 unknown1 = bitstream.read_int()
42 unknown2 = bitstream.read_int()
43 checksum = bitstream.read_int() # Checksum of *compressed data*
44 offset = bitstream.read_int()
45 size = bitstream.read_int()
46 name = bitstream.read_string(255).decode('ascii')
47 entries[name] = (unknown1, unknown2, checksum, offset, size)
48
49 return PBG3(entries, bitstream)
50
51
52 def list_files(self):
53 return self.entries.keys()
54
55
56 def extract(self, filename, check=False):
57 unkwn1, unkwn2, checksum, offset, size = self.entries[filename]
58 self.bitstream.seek(offset)
59 data = lzss.decompress(self.bitstream, size)
60 if check:
61 # Checking the checksum
62 compressed_size = self.bitstream.io.tell() - offset
63 self.bitstream.seek(offset)
64 value = 0
65 for c in self.bitstream.io.read(compressed_size):
66 value += ord(c)
67 value &= 0xFFFFFFFF
68 if value != checksum:
69 print('Warning: corrupted data') #TODO
70 return data
71