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342
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1
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2 import struct
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3
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398
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4
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342
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5 def u16(h):
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6 return struct.pack('<H', h)
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7
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8
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9 def u32(x):
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10 return struct.pack('<I', x)
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11
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12
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398
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13 def u8(x):
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14 return struct.pack('<B', x)
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15
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16
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342
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17 def val2bit(v, bits):
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18 b = []
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19 for i in range(bits):
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398
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20 b.append(bool((1 << i) & v))
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342
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21 return b
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22
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23
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24 def bit_range(b, e):
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25 """ Property generator function """
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26 getter = lambda s: s[b:e]
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398
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27
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342
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28 def setter(s, v):
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29 s[b:e] = v
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30 return property(getter, setter)
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31
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32
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33 class Token:
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34 def __init__(self, bitsize):
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35 self.bitsize = bitsize
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36 self.bit_value = 0
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37
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38 def set_bit(self, i, value):
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39 value = bool(value)
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40 assert i in range(0, self.bitsize)
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41 mask = 1 << i
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42 if value:
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43 self.bit_value |= mask
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44 else:
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45 self.bit_value &= (~mask)
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46
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47 def __getitem__(self, key):
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48 return False
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49
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50 def __setitem__(self, key, value):
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51 if type(key) is int:
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52 self.set_bit(key, value)
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53 elif type(key) is slice:
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54 assert key.step is None
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55 bits = key.stop - key.start
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394
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56 assert value < (2**bits)
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342
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57 value_bits = val2bit(value, bits)
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58 for i in range(key.start, key.stop):
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59 self.set_bit(i, value_bits[i - key.start])
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60 else:
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61 raise KeyError()
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