# HG changeset patch
# User Myhailo Danylenko <isbear@ukrpost.net>
# Date 1350234832 -10800
# Node ID 89841bd3db8c00ff2c092bbe5aef06c1e0439b1e
# Parent  067712fb29f668ec724c7c33c5578bbf77b58bc9
[examples] Add pure-lua base64 implementation

diff -r 067712fb29f6 -r 89841bd3db8c examples/base64.lua
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/examples/base64.lua	Sun Oct 14 20:13:52 2012 +0300
@@ -0,0 +1,44 @@
+#!/usr/bin/env lua
+-- Lua 5.1+ base64 v3.0 (c) 2009 by Alex Kloss <alexthkloss@web.de>
+-- licensed under the terms of the LGPL2
+-- http://lua-users.org/wiki/BaseSixtyFour
+
+-- character table string
+local b='ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
+
+-- encoding
+local function enc(data)
+	return ((data:gsub('.', function(x) 
+		local r,b='',x:byte()
+		for i=8,1,-1 do r=r..(b%2^i-b%2^(i-1)>0 and '1' or '0') end
+		return r;
+	end)..'0000'):gsub('%d%d%d?%d?%d?%d?', function(x)
+		if (#x < 6) then return '' end
+		local c=0
+		for i=1,6 do c=c+(x:sub(i,i)=='1' and 2^(6-i) or 0) end
+		return b:sub(c+1,c+1)
+	end)..({ '', '==', '=' })[#data%3+1])
+end
+
+-- decoding
+local function dec(data)
+	data = string.gsub(data, '[^'..b..'=]', '')
+	return (data:gsub('.', function(x)
+		if (x == '=') then return '' end
+		local r,f='',(b:find(x)-1)
+		for i=6,1,-1 do r=r..(f%2^i-f%2^(i-1)>0 and '1' or '0') end
+		return r;
+	end):gsub('%d%d%d?%d?%d?%d?%d?%d?', function(x)
+		if (#x ~= 8) then return '' end
+		local c=0
+		for i=1,8 do c=c+(x:sub(i,i)=='1' and 2^(8-i) or 0) end
+		return string.char(c)
+	end))
+end
+
+return {
+		encode = enc,
+		decode = dec,
+	}
+
+-- the end vim: se ts=4 sw=4: