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annotate pytouhou/utils/bitstream.pyx @ 252:b5c7369abd7c

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Improve data reading perfs
author Thibaut Girka <thib@sitedethib.com>
date Sun, 22 Jan 2012 15:54:51 +0100
parents fab7ad2f0d8b
children 2674c789e0c3
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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 unsigned char byte
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20
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21 def __init__(BitStream self, io):
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22 self.io = io
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23 self.bits = 0
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24 self.byte = 0
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25
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26
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27 def __enter__(self):
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28 return self
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29
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30
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31 def __exit__(self, type, value, traceback):
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32 return self.io.__exit__(type, value, traceback)
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33
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34
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35 def seek(BitStream self, offset, whence=0):
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36 self.io.seek(offset, whence)
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37 self.byte = 0
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38 self.bits = 0
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39
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40
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41 def tell(BitStream self):
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42 return self.io.tell()
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43
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44
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45 def tell2(BitStream self):
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46 return self.io.tell(), self.bits
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47
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48
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49 cpdef unsigned char read_bit(BitStream self):
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50 if not self.bits:
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51 self.byte = ord(self.io.read(1))
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52 self.bits = 8
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53 self.bits -= 1
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54 return (self.byte >> self.bits) & 0x01
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55
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57 cpdef unsigned int read(BitStream self, int nb_bits):
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58 cdef unsigned int value = 0
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59 cdef int i
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60
0
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61 for i in range(nb_bits - 1, -1, -1):
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62 value |= self.read_bit() << i
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63 return value
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64
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66 cpdef write_bit(BitStream self, bit):
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67 if self.bits == 8:
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68 self.io.write(chr(self.byte))
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69 self.bits = 0
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70 self.byte = 0
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71 self.byte &= ~(1 << (7 - self.bits))
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72 self.byte |= bit << (7 - self.bits)
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73 self.bits += 1
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74
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75
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76 def write(BitStream self, bits, nb_bits):
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77 for i in range(nb_bits):
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78 self.write_bit(bits >> (nb_bits - 1 - i) & 0x01)
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79
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81 def flush(BitStream self):
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82 self.io.write(chr(self.byte))
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83 self.bits = 0
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84 self.byte = 0
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85 self.io.flush()
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86