webmcp
view framework/env/encode/mime/base64.lua @ 522:349991337008
Fixed typo
| author | jbe |
|---|---|
| date | Mon Aug 21 20:23:12 2017 +0200 (2017-08-21) |
| parents | 9fdfb27f8e67 |
| children |
line source
1 local alphabet = {
2 "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M",
3 "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z",
4 "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m",
5 "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z",
6 "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "+", "/"
7 }
9 function encode.mime.base64(str)
10 local parts = {}
11 local pos = 1
12 local block_count = 0
13 while pos <= #str do
14 local s = string.sub(str, pos, pos + 2)
15 local n = 0
16 for i = 1, 3 do
17 n = n * 256
18 if i <= #s then
19 n = n + string.byte(string.sub(s, i, i))
20 end
21 end
22 parts[#parts+1] = alphabet[math.floor(n / 262144) + 1]
23 parts[#parts+1] = alphabet[math.floor(n / 4096) % 64 + 1]
24 if #s > 1 then
25 parts[#parts+1] = alphabet[math.floor(n / 64) % 64 + 1]
26 else
27 parts[#parts+1] = "="
28 end
29 if #s > 2 then
30 parts[#parts+1] = alphabet[n % 64 + 1]
31 else
32 parts[#parts+1] = "="
33 end
34 block_count = block_count + 1
35 if block_count == 19 then
36 parts[#parts+1] = "\r\n"
37 block_count = 0
38 end
39 pos = pos + #s
40 end
41 if block_count > 0 then
42 parts[#parts+1] = "\r\n"
43 end
44 return table.concat(parts)
45 end