Mercurial > touhou
annotate pytouhou/utils/bitstream.py @ 110:3ac41b966fed
Add writing support to pytouhou.formats.std!
| author | Thibaut Girka <thib@sitedethib.com> |
|---|---|
| date | Tue, 06 Sep 2011 16:40:32 +0200 |
| parents | ac2e5e1c2c3c |
| children |
| rev | line source |
|---|---|
|
52
ab826bc29aa2
Add some documentation, GPLv3 headers, README and COPYING file.
Thibaut Girka <thib@sitedethib.com>
parents:
0
diff
changeset
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1 # -*- encoding: utf-8 -*- |
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ab826bc29aa2
Add some documentation, GPLv3 headers, README and COPYING file.
Thibaut Girka <thib@sitedethib.com>
parents:
0
diff
changeset
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2 ## |
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ab826bc29aa2
Add some documentation, GPLv3 headers, README and COPYING file.
Thibaut Girka <thib@sitedethib.com>
parents:
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diff
changeset
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3 ## Copyright (C) 2011 Thibaut Girka <thib@sitedethib.com> |
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ab826bc29aa2
Add some documentation, GPLv3 headers, README and COPYING file.
Thibaut Girka <thib@sitedethib.com>
parents:
0
diff
changeset
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4 ## |
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ab826bc29aa2
Add some documentation, GPLv3 headers, README and COPYING file.
Thibaut Girka <thib@sitedethib.com>
parents:
0
diff
changeset
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5 ## This program is free software; you can redistribute it and/or modify |
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ab826bc29aa2
Add some documentation, GPLv3 headers, README and COPYING file.
Thibaut Girka <thib@sitedethib.com>
parents:
0
diff
changeset
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6 ## it under the terms of the GNU General Public License as published |
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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. |
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ab826bc29aa2
Add some documentation, GPLv3 headers, README and COPYING file.
Thibaut Girka <thib@sitedethib.com>
parents:
0
diff
changeset
|
8 ## |
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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, |
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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 |
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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 |
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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 |
| 0 | 15 class BitStream(object): |
| 16 def __init__(self, io): | |
| 17 self.io = io | |
| 18 self.bits = 0 | |
| 19 self.byte = 0 | |
| 20 | |
| 21 | |
| 97 | 22 def __enter__(self): |
| 23 return self | |
| 24 | |
| 25 | |
| 26 def __exit__(self, type, value, traceback): | |
| 27 return self.io.__exit__(type, value, traceback) | |
| 28 | |
| 29 | |
| 0 | 30 def seek(self, offset, whence=0): |
| 31 self.io.seek(offset, whence) | |
| 32 self.byte = 0 | |
| 33 self.bits = 0 | |
| 34 | |
| 35 | |
| 36 def tell(self): | |
| 37 return self.io.tell() | |
| 38 | |
| 39 | |
| 40 def tell2(self): | |
| 41 return self.io.tell(), self.bits | |
| 42 | |
| 43 | |
| 44 def read_bit(self): | |
| 45 if not self.bits: | |
| 46 self.byte = ord(self.io.read(1)) | |
| 47 self.bits = 8 | |
| 48 self.bits -= 1 | |
| 49 return (self.byte >> self.bits) & 0x01 | |
| 50 | |
| 51 | |
| 52 def read(self, nb_bits): | |
| 53 value = 0 | |
| 54 for i in range(nb_bits - 1, -1, -1): | |
| 55 value |= self.read_bit() << i | |
| 56 return value | |
| 57 | |
| 58 | |
| 59 def write_bit(self, bit): | |
| 60 if self.bits == 8: | |
| 61 self.io.write(chr(self.byte)) | |
| 62 self.bits = 0 | |
| 63 self.byte = 0 | |
| 64 self.byte &= ~(1 << (7 - self.bits)) | |
| 65 self.byte |= bit << (7 - self.bits) | |
| 66 self.bits += 1 | |
| 67 | |
| 68 | |
| 69 def write(self, bits, nb_bits): | |
| 70 for i in range(nb_bits): | |
| 71 self.write_bit(bits >> (nb_bits - 1 - i) & 0x01) | |
| 72 | |
| 73 | |
| 74 def flush(self): | |
| 75 self.io.write(chr(self.byte)) | |
| 76 self.bits = 0 | |
| 77 self.byte = 0 | |
| 78 self.io.flush() | |
| 79 |