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/*
* Copyright (c) 2010 Nick Galbreath
* http://code.google.com/p/stringencoders/source/browse/#svn/trunk/javascript
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following
* conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
/* base64 encode/decode compatible with window.btoa/atob
*
* window.atob/btoa is a Firefox extension to convert binary data (the "b")
* to base64 (ascii, the "a").
*
* It is also found in Safari and Chrome. It is not available in IE.
*
* if (!window.btoa) window.btoa = base64.encode
* if (!window.atob) window.atob = base64.decode
*
* The original spec's for atob/btoa are a bit lacking
* https://developer.mozilla.org/en/DOM/window.atob
* https://developer.mozilla.org/en/DOM/window.btoa
*
* window.btoa and base64.encode takes a string where charCodeAt is [0,255]
* If any character is not [0,255], then an DOMException(5) is thrown.
*
* window.atob and base64.decode take a base64-encoded string
* If the input length is not a multiple of 4, or contains invalid characters
* then an DOMException(5) is thrown.
*/
var base64 = {};
base64.PADCHAR = '=';
base64.ALPHA = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
base64.makeDOMException = function() {
// sadly in FF,Safari,Chrome you can't make a DOMException
var e, tmp;
try {
return new DOMException(DOMException.INVALID_CHARACTER_ERR);
} catch (tmp) {
// not available, just passback a duck-typed equiv
// https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Global_Objects/Error
// https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Global_Objects/Error/prototype
var ex = new Error("DOM Exception 5");
// ex.number and ex.description is IE-specific.
ex.code = ex.number = 5;
ex.name = ex.description = "INVALID_CHARACTER_ERR";
// Safari/Chrome output format
ex.toString = function() { return 'Error: ' + ex.name + ': ' + ex.message; };
return ex;
}
}
base64.getbyte64 = function(s,i) {
// This is oddly fast, except on Chrome/V8.
// Minimal or no improvement in performance by using a
// object with properties mapping chars to value (eg. 'A': 0)
var idx = base64.ALPHA.indexOf(s.charAt(i));
if (idx === -1) {
throw base64.makeDOMException();
}
return idx;
}
base64.decode = function(s) {
// convert to string
s = '' + s;
var getbyte64 = base64.getbyte64;
var pads, i, b10;
var imax = s.length
if (imax === 0) {
return s;
}
if (imax % 4 !== 0) {
throw base64.makeDOMException();
}
pads = 0
if (s.charAt(imax - 1) === base64.PADCHAR) {
pads = 1;
if (s.charAt(imax - 2) === base64.PADCHAR) {
pads = 2;
}
// either way, we want to ignore this last block
imax -= 4;
}
var x = [];
for (i = 0; i < imax; i += 4) {
b10 = (getbyte64(s,i) << 18) | (getbyte64(s,i+1) << 12) |
(getbyte64(s,i+2) << 6) | getbyte64(s,i+3);
x.push(String.fromCharCode(b10 >> 16, (b10 >> 8) & 0xff, b10 & 0xff));
}
switch (pads) {
case 1:
b10 = (getbyte64(s,i) << 18) | (getbyte64(s,i+1) << 12) | (getbyte64(s,i+2) << 6);
x.push(String.fromCharCode(b10 >> 16, (b10 >> 8) & 0xff));
break;
case 2:
b10 = (getbyte64(s,i) << 18) | (getbyte64(s,i+1) << 12);
x.push(String.fromCharCode(b10 >> 16));
break;
}
return x.join('');
}
base64.getbyte = function(s,i) {
var x = s.charCodeAt(i);
if (x > 255) {
throw base64.makeDOMException();
}
return x;
}
base64.encode = function(s) {
if (arguments.length !== 1) {
throw new SyntaxError("Not enough arguments");
}
var padchar = base64.PADCHAR;
var alpha = base64.ALPHA;
var getbyte = base64.getbyte;
var i, b10;
var x = [];
// convert to string
s = '' + s;
var imax = s.length - s.length % 3;
if (s.length === 0) {
return s;
}
for (i = 0; i < imax; i += 3) {
b10 = (getbyte(s,i) << 16) | (getbyte(s,i+1) << 8) | getbyte(s,i+2);
x.push(alpha.charAt(b10 >> 18));
x.push(alpha.charAt((b10 >> 12) & 0x3F));
x.push(alpha.charAt((b10 >> 6) & 0x3f));
x.push(alpha.charAt(b10 & 0x3f));
}
switch (s.length - imax) {
case 1:
b10 = getbyte(s,i) << 16;
x.push(alpha.charAt(b10 >> 18) + alpha.charAt((b10 >> 12) & 0x3F) +
padchar + padchar);
break;
case 2:
b10 = (getbyte(s,i) << 16) | (getbyte(s,i+1) << 8);
x.push(alpha.charAt(b10 >> 18) + alpha.charAt((b10 >> 12) & 0x3F) +
alpha.charAt((b10 >> 6) & 0x3f) + padchar);
break;
}
return x.join('');
}
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