| /* -*- Mode: js; js-indent-level: 2; -*- */ |
| /* |
| * Copyright 2011 Mozilla Foundation and contributors |
| * Licensed under the New BSD license. See LICENSE or: |
| * http://opensource.org/licenses/BSD-3-Clause |
| */ |
| |
| var intToCharMap = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'.split(''); |
| |
| /** |
| * Encode an integer in the range of 0 to 63 to a single base 64 digit. |
| */ |
| exports.encode = function (number) { |
| if (0 <= number && number < intToCharMap.length) { |
| return intToCharMap[number]; |
| } |
| throw new TypeError("Must be between 0 and 63: " + number); |
| }; |
| |
| /** |
| * Decode a single base 64 character code digit to an integer. Returns -1 on |
| * failure. |
| */ |
| exports.decode = function (charCode) { |
| var bigA = 65; // 'A' |
| var bigZ = 90; // 'Z' |
| |
| var littleA = 97; // 'a' |
| var littleZ = 122; // 'z' |
| |
| var zero = 48; // '0' |
| var nine = 57; // '9' |
| |
| var plus = 43; // '+' |
| var slash = 47; // '/' |
| |
| var littleOffset = 26; |
| var numberOffset = 52; |
| |
| // 0 - 25: ABCDEFGHIJKLMNOPQRSTUVWXYZ |
| if (bigA <= charCode && charCode <= bigZ) { |
| return (charCode - bigA); |
| } |
| |
| // 26 - 51: abcdefghijklmnopqrstuvwxyz |
| if (littleA <= charCode && charCode <= littleZ) { |
| return (charCode - littleA + littleOffset); |
| } |
| |
| // 52 - 61: 0123456789 |
| if (zero <= charCode && charCode <= nine) { |
| return (charCode - zero + numberOffset); |
| } |
| |
| // 62: + |
| if (charCode == plus) { |
| return 62; |
| } |
| |
| // 63: / |
| if (charCode == slash) { |
| return 63; |
| } |
| |
| // Invalid base64 digit. |
| return -1; |
| }; |