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38 lines
999 B
Python
38 lines
999 B
Python
import fec
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# div_ceil() was copied from the pyutil library.
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def div_ceil(n, d):
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"""
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The smallest integer k such that k*d >= n.
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"""
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return (n/d) + (n%d != 0)
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class Encoder(object):
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def __init__(self, k, m):
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self.fec = fec.Encoder(k, m)
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def encode(self, data):
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"""
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@param data: string
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"""
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chunksize = div_ceil(len(data), self.fec.k)
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numchunks = div_ceil(len(data), chunksize)
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l = [ data[i:i+chunksize] for i in range(0, len(data), chunksize) ]
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# padding
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if len(l[-1]) != len(l[0]):
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l[-1] = l[-1] + ('\x00'*(len(l[0])-len(l[-1])))
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res = self.fec.encode(l)
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return res
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class Decoder(object):
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def __init__(self, k, m):
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self.fec = fec.Decoder(k, m)
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def decode(self, blocks, sharenums, padlen=0):
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blocks = self.fec.decode(blocks, sharenums)
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data = ''.join(blocks)
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if padlen:
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data = data[:-padlen]
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return data
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