webmcp
diff framework/env/encode/mime/base64.lua @ 0:9fdfb27f8e67
Version 1.0.0
author | jbe/bsw |
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date | Sun Oct 25 12:00:00 2009 +0100 (2009-10-25) |
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children |
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1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000 1.2 +++ b/framework/env/encode/mime/base64.lua Sun Oct 25 12:00:00 2009 +0100 1.3 @@ -0,0 +1,45 @@ 1.4 +local alphabet = { 1.5 + "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", 1.6 + "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z", 1.7 + "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", 1.8 + "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z", 1.9 + "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "+", "/" 1.10 +} 1.11 + 1.12 +function encode.mime.base64(str) 1.13 + local parts = {} 1.14 + local pos = 1 1.15 + local block_count = 0 1.16 + while pos <= #str do 1.17 + local s = string.sub(str, pos, pos + 2) 1.18 + local n = 0 1.19 + for i = 1, 3 do 1.20 + n = n * 256 1.21 + if i <= #s then 1.22 + n = n + string.byte(string.sub(s, i, i)) 1.23 + end 1.24 + end 1.25 + parts[#parts+1] = alphabet[math.floor(n / 262144) + 1] 1.26 + parts[#parts+1] = alphabet[math.floor(n / 4096) % 64 + 1] 1.27 + if #s > 1 then 1.28 + parts[#parts+1] = alphabet[math.floor(n / 64) % 64 + 1] 1.29 + else 1.30 + parts[#parts+1] = "=" 1.31 + end 1.32 + if #s > 2 then 1.33 + parts[#parts+1] = alphabet[n % 64 + 1] 1.34 + else 1.35 + parts[#parts+1] = "=" 1.36 + end 1.37 + block_count = block_count + 1 1.38 + if block_count == 19 then 1.39 + parts[#parts+1] = "\r\n" 1.40 + block_count = 0 1.41 + end 1.42 + pos = pos + #s 1.43 + end 1.44 + if block_count > 0 then 1.45 + parts[#parts+1] = "\r\n" 1.46 + end 1.47 + return table.concat(parts) 1.48 +end