71 lines
1.7 KiB
Python
71 lines
1.7 KiB
Python
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CHARSET = 'qpzry9x8gf2tvdw0s3jn54khce6mua7l'
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def polymod(values):
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chk = 1
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generator = [
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(0x01, 0x98f2bc8e61),
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(0x02, 0x79b76d99e2),
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(0x04, 0xf33e5fb3c4),
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(0x08, 0xae2eabe2a8),
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(0x10, 0x1e4f43e470)]
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for value in values:
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top = chk >> 35
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chk = ((chk & 0x07ffffffff) << 5) ^ value
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for i in generator:
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if top & i[0] != 0:
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chk ^= i[1]
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return chk ^ 1
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def prefix_expand(prefix):
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return [ord(x) & 0x1f for x in prefix] + [0]
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def calculate_checksum(prefix, payload):
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poly = polymod(prefix_expand(prefix) + payload + [0, 0, 0, 0, 0, 0, 0, 0])
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out = list()
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for i in range(8):
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out.append((poly >> 5 * (7 - i)) & 0x1f)
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return out
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def verify_checksum(prefix, payload):
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return polymod(prefix_expand(prefix) + payload) == 0
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def b32decode(inputs):
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out = list()
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for letter in inputs:
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out.append(CHARSET.find(letter))
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return out
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def b32encode(inputs):
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out = ''
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for char_code in inputs:
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out += CHARSET[char_code]
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return out
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def convertbits(data, frombits, tobits, pad=True):
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acc = 0
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bits = 0
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ret = []
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maxv = (1 << tobits) - 1
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max_acc = (1 << (frombits + tobits - 1)) - 1
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for value in data:
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if value < 0 or (value >> frombits):
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return None
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acc = ((acc << frombits) | value) & max_acc
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bits += frombits
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while bits >= tobits:
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bits -= tobits
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ret.append((acc >> bits) & maxv)
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if pad:
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if bits:
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ret.append((acc << (tobits - bits)) & maxv)
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elif bits >= frombits or ((acc << (tobits - bits)) & maxv):
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return None
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return ret
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