Base64.api

local Data = {
    Name = "Base64.api",
    Version = "1.1.1",
    Date = "16/2/2022",
    Time = "10:59",
    Author = "Unknown / http://www.computercraft.info/forums2/index.php?/topic/22560-base64-api/",
    Pastebin = "zAKYhveJ",
}

if fs.exists("OS/APIs/VersionUpdater.api") then
    os.loadAPI("OS/APIs/VersionUpdater.api")
else
    error("VersionUpdater API not found")
end
_G["VersionUpdater"] = _G["VersionUpdater.api"]
VersionUpdater.Update("Base64",Data)

-- Characters
local b = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"

-- Encoding
function encode(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
function decode(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