42 lines
1.2 KiB
Lua
42 lines
1.2 KiB
Lua
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-- Lua 5.1+ base64 v3.0 (c) 2009 by Alex Kloss <alexthkloss@web.de>
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-- licensed under the terms of the LGPL2
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local moduleName = ...
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local M = {}
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_G[moduleName] = M
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-- character table string
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local b='ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
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-- encoding
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function M.enc(data)
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return ((data:gsub('.', function(x)
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local r,b='',x:byte()
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for i=8,1,-1 do r=r..(b%2^i-b%2^(i-1)>0 and '1' or '0') end
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return r;
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end)..'0000'):gsub('%d%d%d?%d?%d?%d?', function(x)
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if (#x < 6) then return '' end
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local c=0
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for i=1,6 do c=c+(x:sub(i,i)=='1' and 2^(6-i) or 0) end
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return b:sub(c+1,c+1)
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end)..({ '', '==', '=' })[#data%3+1])
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end
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-- decoding
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function M.dec(data)
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data = string.gsub(data, '[^'..b..'=]', '')
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return (data:gsub('.', function(x)
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if (x == '=') then return '' end
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local r,f='',(b:find(x)-1)
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for i=6,1,-1 do r=r..(f%2^i-f%2^(i-1)>0 and '1' or '0') end
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return r;
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end):gsub('%d%d%d?%d?%d?%d?%d?%d?', function(x)
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if (#x ~= 8) then return '' end
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local c=0
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for i=1,8 do c=c+(x:sub(i,i)=='1' and 2^(7-i) or 0) end
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return string.char(c)
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end))
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end
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return M
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