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#!/usr/bin/env python
#
# This is the MIT License
# http://www.opensource.org/licenses/mit-license.php
#
# Copyright (c) 2008 Nick Galbreath
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
#
gsCharToInt = [
256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256,
256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256,
256, 256, 256, 256, 256, 256, 256, 256, 256, 0, 256, 1,
2, 3, 256, 4, 5, 6, 7, 8, 256, 9, 10, 11,
12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 256,
23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34,
35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46,
47, 48, 49, 50, 51, 52, 53, 54, 256, 55, 56, 57,
58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69,
70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81,
82, 83, 84, 256, 256, 256, 256, 256, 256, 256, 256, 256,
256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256,
256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256,
256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256,
256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256,
256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256,
256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256,
256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256,
256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256,
256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256,
256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256,
256, 256, 256, 256]
gsIntToChar = [
'!', '#', '$', '%', '\'', '(', ')', '*', '+', '-',
'.', '/', '0', '1', '2', '3', '4', '5', '6', '7',
'8', '9', ':', '<', '=', '>', '?', '@', 'A', 'B',
'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L',
'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V',
'W', 'X', 'Y', 'Z', '[', ']', '^', '_', '`', 'a',
'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k',
'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u',
'v', 'w', 'x', 'y', 'z'
]
from struct import unpack, pack
# covert 4 characters into 5
def b85_encode(s):
parts = []
numchunks = len(s) // 4
format = '!' + str(numchunks) + 'I'
for x in unpack(format, s):
# network order (big endian), 32-bit unsigned integer
# note: x86 is little endian
parts.append(gsIntToChar[x // 52200625])
parts.append(gsIntToChar[(x // 614125) % 85])
parts.append(gsIntToChar[(x // 7225) % 85])
parts.append(gsIntToChar[(x // 85) % 85])
parts.append(gsIntToChar[x % 85])
return ''.join(parts)
#
# also does not use the 'struct' module which may be desirable
# to some
#
def b85_encode2(s):
parts = []
for i in xrange(0,len(s), 4):
chunk = s[i:i+4]
x = ord(chunk[3]) + 256*(ord(chunk[2]) + 256*(ord(chunk[1]) + 256*ord(chunk[0])))
# network order (big endian), 32-bit unsigned integer
# note: x86 is little endian
parts.append(gsIntToChar[x // 52200625])
parts.append(gsIntToChar[(x // 614125) % 85])
parts.append(gsIntToChar[(x // 7225) % 85])
parts.append(gsIntToChar[(x // 85) % 85])
parts.append(gsIntToChar[x % 85])
return ''.join(parts)
# convert 5 characters to 4
def b85_decode(s):
parts = []
for i in xrange(0, len(s), 5):
bsum = 0;
for j in xrange(0,5):
val = gsCharToInt[ord(s[i+j])]
bsum = 85*bsum + val
tmp = pack('!I', bsum)
parts.append(tmp)
#parts += tmp
#parts += unpack('cccc', tmp)
return ''.join(parts)
# convert 5 characters to 4
def b85_decode2(s):
parts = []
for i in xrange(0, len(s), 5):
bsum = 0;
for j in xrange(0,5):
val = gsCharToInt[ord(s[i+j])]
bsum = 85*bsum + val
parts.append(chr((bsum >> 24) & 0xff))
parts.append(chr((bsum >> 16) & 0xff))
parts.append(chr((bsum >> 8) & 0xff))
parts.append(chr(bsum & 0xff))
return ''.join(parts)
import unittest
class B85Test(unittest.TestCase):
def testDecode1(self):
s = b85_decode('!!!!#')
self.assertEquals(4, len(s))
self.assertEquals(0, ord(s[0]))
self.assertEquals(0, ord(s[1]))
self.assertEquals(0, ord(s[2]))
self.assertEquals(1, ord(s[3]))
e = b85_encode(s)
self.assertEquals('!!!!#', e)
if __name__ == '__main__':
from time import clock
#unittest.main()
s = '!!!!#' * 10
t0 = clock()
for i in xrange(1000000):
b85_decode(s)
t1 = clock()
print "decode v1", t1-t0
t0 = clock()
for i in xrange(1000000):
b85_decode2(s)
t1 = clock()
print "decode v2", t1-t0
s = b85_decode('!!!!#' * 10)
t0 = clock()
for i in xrange(1000000):
b85_encode(s)
t1 = clock()
print "encode v1", t1-t0
t0 = clock()
for i in xrange(1000000):
b85_encode2(s)
t1 = clock()
print "encode v2", t1-t0
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