src/es/xperiments/utils/Base64.as
/* Base64 library for ActionScript 3.0.
* Based on: Ma Bingyao code.
* Optimized by: Jean-Philippe Auclair / jpauclair.wordpress.com
* Copyright (C) 2007 Ma Bingyao <andot@ujn.edu.cn>
* LastModified: Oct 26, 2009
* This library is free. You can redistribute it and/or modify it.
*/
package es.xperiments.utils
{
import flash.utils.ByteArray;
public class Base64
{
private static const _encodeChars:Vector.<int> = InitEncoreChar();
private static const _decodeChars:Vector.<int> = InitDecodeChar();
public static function encodeString( string:String ):String
{
var ba:ByteArray = new ByteArray();
ba.writeUTFBytes( string );
return Base64.encode( ba );
}
public static function encode(data:ByteArray):String
{
var out:ByteArray = new ByteArray();
//Presetting the length keep the memory smaller and optimize speed since there is no "grow" needed
out.length = (2 + data.length - ((data.length + 2) % 3)) * 4 / 3; //Preset length //1.6 to 1.5 ms
var i:int = 0;
var r:int = data.length % 3;
var len:int = data.length - r;
var c:int; //read (3) character AND write (4) characters
while (i < len)
{
//Read 3 Characters (8bit * 3 = 24 bits)
c = data[i++] << 16 | data[i++] << 8 | data[i++];
//Cannot optimize this to read int because of the positioning overhead. (as3 bytearray seek is slow)
//Convert to 4 Characters (6 bit * 4 = 24 bits)
c = (_encodeChars[c >>> 18] << 24) | (_encodeChars[c >>> 12 & 0x3f] << 16) | (_encodeChars[c >>> 6 & 0x3f] << 8) | _encodeChars[c & 0x3f];
//Optimization: On older and slower computer, do one write Int instead of 4 write byte: 1.5 to 0.71 ms
out.writeInt(c);
/*
out.writeByte(_encodeChars[c >> 18] );
out.writeByte(_encodeChars[c >> 12 & 0x3f]);
out.writeByte(_encodeChars[c >> 6 & 0x3f]);
out.writeByte(_encodeChars[c & 0x3f]);
*/
}
if (r == 1) //Need two "=" padding
{
//Read one char, write two chars, write padding
c = data[i];
c = (_encodeChars[c >>> 2] << 24) | (_encodeChars[(c & 0x03) << 4] << 16) | 61 << 8 | 61;
out.writeInt(c);
}
else if (r == 2) //Need one "=" padding
{
c = data[i++] << 8 | data[i];
c = (_encodeChars[c >>> 10] << 24) | (_encodeChars[c >>> 4 & 0x3f] << 16) | (_encodeChars[(c & 0x0f) << 2] << 8) | 61;
out.writeInt(c);
}
out.position = 0;
return out.readUTFBytes(out.length);
}
public static function decode(str:String):ByteArray
{
var c1:int;
var c2:int;
var c3:int;
var c4:int;
var i:int;
var len:int;
var out:ByteArray;
len = str.length;
i = 0;
out = new ByteArray();
var byteString:ByteArray = new ByteArray();
byteString.writeUTFBytes(str);
while (i < len)
{
//c1
do
{
c1 = _decodeChars[byteString[i++]];
} while (i < len && c1 == -1);
if (c1 == -1) break;
//c2
do
{
c2 = _decodeChars[byteString[i++]];
} while (i < len && c2 == -1);
if (c2 == -1) break;
out.writeByte((c1 << 2) | ((c2 & 0x30) >> 4));
//c3
do
{
c3 = byteString[i++];
if (c3 == 61) return out;
c3 = _decodeChars[c3];
} while (i < len && c3 == -1);
if (c3 == -1) break;
out.writeByte(((c2 & 0x0f) << 4) | ((c3 & 0x3c) >> 2));
//c4
do {
c4 = byteString[i++];
if (c4 == 61) return out;
c4 = _decodeChars[c4];
} while (i < len && c4 == -1);
if (c4 == -1) break;
out.writeByte(((c3 & 0x03) << 6) | c4);
}
return out;
}
public static function InitEncoreChar() : Vector.<int>
{
var encodeChars:Vector.<int> = new Vector.<int>();
// We could push the number directly, but i think it's nice to see the characters (with no overhead on encode/decode)
var chars:String = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
for (var i:int = 0; i < 64; i++)
{
encodeChars.push(chars.charCodeAt(i));
}
/*
encodeChars.push(
65, 66, 67, 68, 69, 70, 71, 72,
73, 74, 75, 76, 77, 78, 79, 80,
81, 82, 83, 84, 85, 86, 87, 88,
89, 90, 97, 98, 99, 100, 101, 102,
103, 104, 105, 106, 107, 108, 109, 110,
111, 112, 113, 114, 115, 116, 117, 118,
119, 120, 121, 122, 48, 49, 50, 51,
52, 53, 54, 55, 56, 57, 43, 47);
*/
return encodeChars;
}
public static function InitDecodeChar() : Vector.<int>
{
var decodeChars:Vector.<int> = new Vector.<int>();
decodeChars.push(-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1,
-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,
-1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1);
return decodeChars;
}
}
}