mailiverse/web/WebContent/js/Base64.js

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JavaScript
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2013-07-21 13:40:17 -04:00
/**
* Uses the new array typed in javascript to binary base64 encode/decode
* at the moment just decodes a binary base64 encoded
* into either an ArrayBuffer (decodeArrayBuffer)
* or into an Uint8Array (decode)
*
* References:
* https://developer.mozilla.org/en/JavaScript_typed_arrays/ArrayBuffer
* https://developer.mozilla.org/en/JavaScript_typed_arrays/Uint8Array
*/
var Base64 = {
_key : "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",
_encode : null,
_decode : null,
initialize: function()
{
if (this._decode != null)
return;
this._decode = new Uint8Array(0xFF);
for (var i=0; i<this._key.length; ++i)
this._decode[this._key.charCodeAt(i)] = i;
this._encode = new Uint8Array(this._key.length);
for (var i=0; i<this._key.length; ++i)
this._encode[i] = this._key.charCodeAt(i) & 0xFF;
},
decode: function(input)
{
var bytes = new Uint8Array(input.length);
var i;
for (i=0; i<input.length; ++i)
bytes[i] = input.charCodeAt(i) & 0xFF;
return Base64.decodeBytes(bytes);
},
decodeBytes: function(input)
{
this.initialize();
//get last chars to see if are valid
var lkey1 = this._decode[input[input.length-1]];
var lkey2 = this._decode[input[input.length-2]];
var bytes = (input.length/4) * 3;
if (lkey1 == 64) bytes--; //padding chars, so skip
if (lkey2 == 64) bytes--; //padding chars, so skip
var out = [];
var chr1, chr2, chr3;
var enc1, enc2, enc3, enc4;
var i = 0;
var j = 0;
while (j < input.length)
{
enc1 = this._decode[input[j++]];
enc2 = this._decode[input[j++]];
enc3 = this._decode[input[j++]];
enc4 = this._decode[input[j++]];
chr1 = (enc1 << 2) | (enc2 >> 4);
chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
chr3 = ((enc3 & 3) << 6) | enc4;
out[i++] = chr1 & 0xFF;
if (enc3 != 64) out[i++] = chr2 & 0xFF;
if (enc4 != 64) out[i++] = chr3 & 0xFF;
}
return out;
},
encodeBytes : function(input)
{
this.initialize();
var length = input.length;
var bytes = ((length+2)/3)*4;
var output = [];
var i = 0;
var chr1, chr2, chr3, enc1, enc2, enc3, enc4;
var j=0;
while (i < length)
{
var count = length - i;
chr1 = input[i++] & 0xFF;
chr2 = (i<length) ? (input[i++]&0xFF) : 0;
chr3 = (i<length) ? (input[i++]&0xFF) : 0;
enc1 = chr1 >> 2;
enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
enc4 = chr3 & 63;
if (count == 1)
enc3 = enc4 = 64;
else
if (count == 2)
enc4 = 64;
output[j++] = this._encode[enc1];
output[j++] = this._encode[enc2];
output[j++] = this._encode[enc3];
output[j++] = this._encode[enc4];
}
return output;
},
encode: function(input)
{
var bytes = this.encodeBytes(input);
var s = "";
for (var i=0; i<bytes.length; ++i)
s += String.fromCharCode(bytes[i]);
return s;
}
} ;
/** end **/