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annotate pytouhou/utils/bitstream.pyx @ 133:2cad2e84a49e

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Add reading support for the MSG format.
author Emmanuel Gil Peyrot <linkmauve@linkmauve.fr>
date Sun, 11 Sep 2011 07:34:34 -0700
parents fab7ad2f0d8b
children b5c7369abd7c
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52
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1 # -*- encoding: utf-8 -*-
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2 ##
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3 ## Copyright (C) 2011 Thibaut Girka <thib@sitedethib.com>
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4 ##
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5 ## This program is free software; you can redistribute it and/or modify
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6 ## it under the terms of the GNU General Public License as published
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7 ## by the Free Software Foundation; version 3 only.
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8 ##
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9 ## This program is distributed in the hope that it will be useful,
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10 ## but WITHOUT ANY WARRANTY; without even the implied warranty of
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11 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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12 ## GNU General Public License for more details.
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13 ##
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15 cdef class BitStream:
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16 cdef public io
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17 cdef public int bits
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18 cdef public int byte
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19
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20 def __init__(BitStream self, io):
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21 self.io = io
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22 self.bits = 0
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23 self.byte = 0
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24
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25
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26 def __enter__(self):
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27 return self
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28
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29
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30 def __exit__(self, type, value, traceback):
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31 return self.io.__exit__(type, value, traceback)
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32
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33
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34 def seek(BitStream self, offset, whence=0):
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35 self.io.seek(offset, whence)
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36 self.byte = 0
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37 self.bits = 0
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40 def tell(BitStream self):
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41 return self.io.tell()
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42
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44 def tell2(BitStream self):
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45 return self.io.tell(), self.bits
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46
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48 cpdef unsigned char read_bit(BitStream self):
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49 if not self.bits:
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50 self.byte = ord(self.io.read(1))
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51 self.bits = 8
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52 self.bits -= 1
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53 return (self.byte >> self.bits) & 0x01
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54
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56 def read(BitStream self, nb_bits):
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57 cdef unsigned int value
0
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58 value = 0
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59 for i in range(nb_bits - 1, -1, -1):
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60 value |= self.read_bit() << i
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61 return value
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62
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64 cpdef write_bit(BitStream self, bit):
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65 if self.bits == 8:
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66 self.io.write(chr(self.byte))
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67 self.bits = 0
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68 self.byte = 0
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69 self.byte &= ~(1 << (7 - self.bits))
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70 self.byte |= bit << (7 - self.bits)
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71 self.bits += 1
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72
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74 def write(BitStream self, bits, nb_bits):
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75 for i in range(nb_bits):
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76 self.write_bit(bits >> (nb_bits - 1 - i) & 0x01)
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79 def flush(BitStream self):
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80 self.io.write(chr(self.byte))
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81 self.bits = 0
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82 self.byte = 0
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83 self.io.flush()
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84