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/* -*- 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;
};
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