annotate pytouhou/formats/pbg3.py @ 377:70e2ed71b09c

Add meaningful exceptions in format parsing.
author Emmanuel Gil Peyrot <linkmauve@linkmauve.fr>
date Wed, 29 Aug 2012 18:34:28 +0200
parents b5c7369abd7c
children 1b532e7dd521
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
52
ab826bc29aa2 Add some documentation, GPLv3 headers, README and COPYING file.
Thibaut Girka <thib@sitedethib.com>
parents: 0
diff changeset
1 # -*- encoding: utf-8 -*-
ab826bc29aa2 Add some documentation, GPLv3 headers, README and COPYING file.
Thibaut Girka <thib@sitedethib.com>
parents: 0
diff changeset
2 ##
ab826bc29aa2 Add some documentation, GPLv3 headers, README and COPYING file.
Thibaut Girka <thib@sitedethib.com>
parents: 0
diff changeset
3 ## Copyright (C) 2011 Thibaut Girka <thib@sitedethib.com>
ab826bc29aa2 Add some documentation, GPLv3 headers, README and COPYING file.
Thibaut Girka <thib@sitedethib.com>
parents: 0
diff changeset
4 ##
ab826bc29aa2 Add some documentation, GPLv3 headers, README and COPYING file.
Thibaut Girka <thib@sitedethib.com>
parents: 0
diff changeset
5 ## This program is free software; you can redistribute it and/or modify
ab826bc29aa2 Add some documentation, GPLv3 headers, README and COPYING file.
Thibaut Girka <thib@sitedethib.com>
parents: 0
diff changeset
6 ## it under the terms of the GNU General Public License as published
ab826bc29aa2 Add some documentation, GPLv3 headers, README and COPYING file.
Thibaut Girka <thib@sitedethib.com>
parents: 0
diff changeset
7 ## by the Free Software Foundation; version 3 only.
ab826bc29aa2 Add some documentation, GPLv3 headers, README and COPYING file.
Thibaut Girka <thib@sitedethib.com>
parents: 0
diff changeset
8 ##
ab826bc29aa2 Add some documentation, GPLv3 headers, README and COPYING file.
Thibaut Girka <thib@sitedethib.com>
parents: 0
diff changeset
9 ## This program is distributed in the hope that it will be useful,
ab826bc29aa2 Add some documentation, GPLv3 headers, README and COPYING file.
Thibaut Girka <thib@sitedethib.com>
parents: 0
diff changeset
10 ## but WITHOUT ANY WARRANTY; without even the implied warranty of
ab826bc29aa2 Add some documentation, GPLv3 headers, README and COPYING file.
Thibaut Girka <thib@sitedethib.com>
parents: 0
diff changeset
11 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
ab826bc29aa2 Add some documentation, GPLv3 headers, README and COPYING file.
Thibaut Girka <thib@sitedethib.com>
parents: 0
diff changeset
12 ## GNU General Public License for more details.
ab826bc29aa2 Add some documentation, GPLv3 headers, README and COPYING file.
Thibaut Girka <thib@sitedethib.com>
parents: 0
diff changeset
13 ##
ab826bc29aa2 Add some documentation, GPLv3 headers, README and COPYING file.
Thibaut Girka <thib@sitedethib.com>
parents: 0
diff changeset
14
204
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
15 """PBG3 archive files handling.
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
16
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
17 This module provides classes for handling the PBG3 file format.
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
18 The PBG3 format is the archive format used by Touhou: EoSD.
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
19
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
20 PBG3 files are merely a bitstream composed of a header,
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
21 a file table, and LZSS-compressed files.
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
22 """
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
23
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
24 from collections import namedtuple
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
25
58
3da4de9decd0 Use logging module
Thibaut Girka <thib@sitedethib.com>
parents: 52
diff changeset
26 from pytouhou.utils.bitstream import BitStream
3da4de9decd0 Use logging module
Thibaut Girka <thib@sitedethib.com>
parents: 52
diff changeset
27 import pytouhou.utils.lzss as lzss
3da4de9decd0 Use logging module
Thibaut Girka <thib@sitedethib.com>
parents: 52
diff changeset
28
3da4de9decd0 Use logging module
Thibaut Girka <thib@sitedethib.com>
parents: 52
diff changeset
29 from pytouhou.utils.helpers import get_logger
3da4de9decd0 Use logging module
Thibaut Girka <thib@sitedethib.com>
parents: 52
diff changeset
30
377
70e2ed71b09c Add meaningful exceptions in format parsing.
Emmanuel Gil Peyrot <linkmauve@linkmauve.fr>
parents: 252
diff changeset
31 from pytouhou.formats import WrongFormatError
70e2ed71b09c Add meaningful exceptions in format parsing.
Emmanuel Gil Peyrot <linkmauve@linkmauve.fr>
parents: 252
diff changeset
32
58
3da4de9decd0 Use logging module
Thibaut Girka <thib@sitedethib.com>
parents: 52
diff changeset
33 logger = get_logger(__name__)
3da4de9decd0 Use logging module
Thibaut Girka <thib@sitedethib.com>
parents: 52
diff changeset
34
3da4de9decd0 Use logging module
Thibaut Girka <thib@sitedethib.com>
parents: 52
diff changeset
35
0
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
36 class PBG3BitStream(BitStream):
204
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
37 """Helper class to handle strings and integers in PBG3 bitstreams."""
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
38
0
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
39 def read_int(self):
204
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
40 """Read an integer from the bitstream.
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
41
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
42 Integers have variable sizes. They begin with a two-bit value indicating
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
43 the number of (non-aligned) bytes to read.
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
44 """
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
45
0
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
46 size = self.read(2)
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
47 return self.read((size + 1) * 8)
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
48
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
49
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
50 def read_string(self, maxsize):
204
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
51 """Read a string from the bitstream.
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
52
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
53 Strings are stored as standard NULL-termianted sequences of bytes.
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
54 The only catch is that they are not byte-aligned.
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
55 """
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
56
0
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
57 string = []
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
58 for i in range(maxsize):
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
59 byte = self.read(8)
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
60 if byte == 0:
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
61 break
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
62 string.append(byte)
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
63 return ''.join(chr(byte) for byte in string)
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
64
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
65
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
66
204
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
67 PBG3Entry = namedtuple('PBG3Entry', 'unknown1 unknown2 checksum offset size')
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
68
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
69
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
70
0
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
71 class PBG3(object):
204
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
72 """Handle PBG3 archive files.
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
73
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
74 PBG3 is a file archive format used in Touhou 6: EoSD.
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
75 This class provides a representation of such files, as well as functions to
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
76 read and extract files from a PBG3 archive.
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
77
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
78 Instance variables:
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
79 entries -- list of PBG3Entry objects describing files present in the archive
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
80 bitstream -- PBG3BitStream object
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
81 """
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
82
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
83 def __init__(self, entries=None, bitstream=None):
252
b5c7369abd7c Improve data reading perfs
Thibaut Girka <thib@sitedethib.com>
parents: 204
diff changeset
84 self.entries = entries or {}
0
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
85 self.bitstream = bitstream #TODO
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
86
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
87
97
ac2e5e1c2c3c Refactor \o/
Thibaut Girka <thib@sitedethib.com>
parents: 58
diff changeset
88 def __enter__(self):
ac2e5e1c2c3c Refactor \o/
Thibaut Girka <thib@sitedethib.com>
parents: 58
diff changeset
89 return self
ac2e5e1c2c3c Refactor \o/
Thibaut Girka <thib@sitedethib.com>
parents: 58
diff changeset
90
ac2e5e1c2c3c Refactor \o/
Thibaut Girka <thib@sitedethib.com>
parents: 58
diff changeset
91
ac2e5e1c2c3c Refactor \o/
Thibaut Girka <thib@sitedethib.com>
parents: 58
diff changeset
92 def __exit__(self, type, value, traceback):
ac2e5e1c2c3c Refactor \o/
Thibaut Girka <thib@sitedethib.com>
parents: 58
diff changeset
93 return self.bitstream.__exit__(type, value, traceback)
ac2e5e1c2c3c Refactor \o/
Thibaut Girka <thib@sitedethib.com>
parents: 58
diff changeset
94
ac2e5e1c2c3c Refactor \o/
Thibaut Girka <thib@sitedethib.com>
parents: 58
diff changeset
95
0
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
96 @classmethod
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
97 def read(cls, file):
204
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
98 """Read a PBG3 file.
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
99
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
100 Raise an exception if the file is invalid.
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
101 Return a PBG3 instance otherwise.
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
102 """
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
103
0
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
104 magic = file.read(4)
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
105 if magic != b'PBG3':
377
70e2ed71b09c Add meaningful exceptions in format parsing.
Emmanuel Gil Peyrot <linkmauve@linkmauve.fr>
parents: 252
diff changeset
106 raise WrongFormatError(magic)
0
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
107
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
108 bitstream = PBG3BitStream(file)
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
109 entries = {}
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
110
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
111 nb_entries = bitstream.read_int()
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
112 offset = bitstream.read_int()
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
113 bitstream.seek(offset)
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
114 for i in range(nb_entries):
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
115 unknown1 = bitstream.read_int()
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
116 unknown2 = bitstream.read_int()
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
117 checksum = bitstream.read_int() # Checksum of *compressed data*
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
118 offset = bitstream.read_int()
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
119 size = bitstream.read_int()
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
120 name = bitstream.read_string(255).decode('ascii')
204
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
121 entries[name] = PBG3Entry(unknown1, unknown2, checksum, offset, size)
0
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
122
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
123 return PBG3(entries, bitstream)
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
124
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
125
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
126 def list_files(self):
204
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
127 """List files present in the archive."""
0
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
128 return self.entries.keys()
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
129
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
130
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
131 def extract(self, filename, check=False):
204
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
132 """Extract a given file.
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
133
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
134 If “filename” is in the archive, extract it and return its contents.
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
135 Otherwise, raise an exception.
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
136
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
137 By default, the checksum of the file won't be verified,
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
138 you can however force the verification using the “check” argument.
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
139 """
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
140
0
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
141 unkwn1, unkwn2, checksum, offset, size = self.entries[filename]
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
142 self.bitstream.seek(offset)
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
143 data = lzss.decompress(self.bitstream, size)
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
144 if check:
204
88361534c77e Add some documentation (argh, so much left to document!)
Thibaut Girka <thib@sitedethib.com>
parents: 97
diff changeset
145 # Verify the checksum
0
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
146 compressed_size = self.bitstream.io.tell() - offset
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
147 self.bitstream.seek(offset)
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
148 value = 0
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
149 for c in self.bitstream.io.read(compressed_size):
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
150 value += ord(c)
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
151 value &= 0xFFFFFFFF
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
152 if value != checksum:
58
3da4de9decd0 Use logging module
Thibaut Girka <thib@sitedethib.com>
parents: 52
diff changeset
153 logger.warn('corrupted data!')
0
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
154 return data
6b2c7af2384c Hello Gensokyo _o/
Thibaut Girka <thib@sitedethib.com>
parents:
diff changeset
155