1// Copyright 2014 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5// WebSafeBase64Escape and Unescape.
6function B64_encode(bytes, opt_length) {
7  if (!opt_length) opt_length = bytes.length;
8  var b64out =
9      'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_';
10  var result = '';
11  var shift = 0;
12  var accu = 0;
13  var inputIndex = 0;
14  while (opt_length--) {
15    accu <<= 8;
16    accu |= bytes[inputIndex++];
17    shift += 8;
18    while (shift >= 6) {
19      var i = (accu >> (shift - 6)) & 63;
20      result += b64out.charAt(i);
21      shift -= 6;
22    }
23  }
24  if (shift) {
25    accu <<= 8;
26    shift += 8;
27    var i = (accu >> (shift - 6)) & 63;
28    result += b64out.charAt(i);
29  }
30  return result;
31}
32
33// Normal base64 encode; not websafe, including padding.
34function base64_encode(bytes, opt_length) {
35  if (!opt_length) opt_length = bytes.length;
36  var b64out =
37      'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
38  var result = '';
39  var shift = 0;
40  var accu = 0;
41  var inputIndex = 0;
42  while (opt_length--) {
43    accu <<= 8;
44    accu |= bytes[inputIndex++];
45    shift += 8;
46    while (shift >= 6) {
47      var i = (accu >> (shift - 6)) & 63;
48      result += b64out.charAt(i);
49      shift -= 6;
50    }
51  }
52  if (shift) {
53    accu <<= 8;
54    shift += 8;
55    var i = (accu >> (shift - 6)) & 63;
56    result += b64out.charAt(i);
57  }
58  while (result.length % 4) result += '=';
59  return result;
60}
61
62var B64_inmap =
63[
64  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 63, 0, 0,
65 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 0, 0, 0, 0, 0, 0,
66  0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
67 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 0, 0, 0, 0, 64,
68  0, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41,
69 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 0, 0, 0, 0, 0
70];
71
72function B64_decode(string) {
73  var bytes = [];
74  var accu = 0;
75  var shift = 0;
76  for (var i = 0; i < string.length; ++i) {
77    var c = string.charCodeAt(i);
78    if (c < 32 || c > 127 || !B64_inmap[c - 32]) return [];
79    accu <<= 6;
80    accu |= (B64_inmap[c - 32] - 1);
81    shift += 6;
82    if (shift >= 8) {
83      bytes.push((accu >> (shift - 8)) & 255);
84      shift -= 8;
85    }
86  }
87  return bytes;
88}
89