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