1/*
 2 * base64-arraybuffer
 3 * https://github.com/niklasvh/base64-arraybuffer
 4 *
 5 * Copyright (c) 2012 Niklas von Hertzen
 6 * Licensed under the MIT license.
 7 */
 8(function(chars){
 9  "use strict";
10
11  exports.encode = function(arraybuffer) {
12    var bytes = new Uint8Array(arraybuffer),
13    i, len = bytes.length, base64 = "";
14
15    for (i = 0; i < len; i+=3) {
16      base64 += chars[bytes[i] >> 2];
17      base64 += chars[((bytes[i] & 3) << 4) | (bytes[i + 1] >> 4)];
18      base64 += chars[((bytes[i + 1] & 15) << 2) | (bytes[i + 2] >> 6)];
19      base64 += chars[bytes[i + 2] & 63];
20    }
21
22    if ((len % 3) === 2) {
23      base64 = base64.substring(0, base64.length - 1) + "=";
24    } else if (len % 3 === 1) {
25      base64 = base64.substring(0, base64.length - 2) + "==";
26    }
27
28    return base64;
29  };
30
31  exports.decode =  function(base64) {
32    var bufferLength = base64.length * 0.75,
33    len = base64.length, i, p = 0,
34    encoded1, encoded2, encoded3, encoded4;
35
36    if (base64[base64.length - 1] === "=") {
37      bufferLength--;
38      if (base64[base64.length - 2] === "=") {
39        bufferLength--;
40      }
41    }
42
43    var arraybuffer = new ArrayBuffer(bufferLength),
44    bytes = new Uint8Array(arraybuffer);
45
46    for (i = 0; i < len; i+=4) {
47      encoded1 = chars.indexOf(base64[i]);
48      encoded2 = chars.indexOf(base64[i+1]);
49      encoded3 = chars.indexOf(base64[i+2]);
50      encoded4 = chars.indexOf(base64[i+3]);
51
52      bytes[p++] = (encoded1 << 2) | (encoded2 >> 4);
53      bytes[p++] = ((encoded2 & 15) << 4) | (encoded3 >> 2);
54      bytes[p++] = ((encoded3 & 3) << 6) | (encoded4 & 63);
55    }
56
57    return arraybuffer;
58  };
59})("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/");