kopia lustrzana https://github.com/DL7AD/pecanpico9
94 wiersze
3.5 KiB
Python
94 wiersze
3.5 KiB
Python
# Base91 encode/decode for Python 2 and Python 3
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#
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# Copyright (c) 2012 Adrien Beraud
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# Copyright (c) 2015 Guillaume Jacquenot
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# All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions are met:
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#
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# * Redistributions of source code must retain the above copyright notice,
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# this list of conditions and the following disclaimer.
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# * Redistributions in binary form must reproduce the above copyright notice,
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# this list of conditions and the following disclaimer in the documentation
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# and/or other materials provided with the distribution.
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# * Neither the name of Adrien Beraud, Wisdom Vibes Pte. Ltd., nor the names
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# of its contributors may be used to endorse or promote products derived
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# from this software without specific prior written permission.
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#
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
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# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#
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import struct
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base91_alphabet = ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
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'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
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'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
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'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
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'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '!', '#', '$',
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'%', '&', '(', ')', '*', '+', ',', '.', '/', ':', ';', '<', '=',
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'>', '?', '@', '[', ']', '^', '_', '`', '{', '-', '}', '~', '"']
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decode_table = dict((v,k) for k,v in enumerate(base91_alphabet))
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def decode(encoded_str):
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''' Decode Base91 string to a bytearray '''
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v = -1
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b = 0
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n = 0
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out = bytearray()
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for strletter in encoded_str:
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if not strletter in decode_table:
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continue
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c = decode_table[strletter]
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if(v < 0):
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v = c
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else:
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v += c*91
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b |= v << n
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n += 13 if (v & 8191)>88 else 14
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while True:
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out += struct.pack('B', b&255)
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b >>= 8
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n -= 8
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if not n>7:
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break
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v = -1
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if v+1:
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out += struct.pack('B', (b | v << n) & 255 )
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return out
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def encode(bindata):
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''' Encode a bytearray to a Base91 string '''
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b = 0
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n = 0
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out = ''
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for count in range(len(bindata)):
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byte = bindata[count:count+1]
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b |= struct.unpack('B', byte)[0] << n
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n += 8
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if n>13:
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v = b & 8191
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if v > 88:
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b >>= 13
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n -= 13
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else:
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v = b & 16383
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b >>= 14
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n -= 14
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out += base91_alphabet[v % 91] + base91_alphabet[v // 91]
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if n:
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out += base91_alphabet[b % 91]
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if n>7 or b>90:
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out += base91_alphabet[b // 91]
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return out
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