Base64 for ActionScript 3.0

/**********************************************************\  
|                                                          |  
| The implementation of PHPRPC Protocol 3.0                |  
|                                                          |  
| Base64.as                                                |  
|                                                          |  
| Release 3.0.0                                            |  
| Copyright (c) 2005-2007 by Team-PHPRPC                   |  
|                                                          |  
| WebSite:  http://www.phprpc.org/                         |  
|           http://www.phprpc.net/                         |  
|           http://www.phprpc.com/                         |  
|           http://sourceforge.net/projects/php-rpc/       |  
|                                                          |  
| Authors:  Ma Bingyao <[e-mail]>                  |  
|                                                          |  
| This file may be distributed and/or modified under the   |  
| terms of the GNU Lesser General Public License (LGPL)    |  
| version 3.0 as published by the Free Software Foundation |  
| and appearing in the included file LICENSE.              |  
|                                                          |  
\**********************************************************/   
/* Base64 library for ActionScript 3.0.  
 *  
 * Copyright (C) 2007 Ma Bingyao <[e-mail]>  
 * Version: 1.1  
 * LastModified: Oct 26, 2007  
 * This library is free.  You can redistribute it and/or modify it.  
 */   
/*  
 * interfaces:  
 * import org.phprpc.util.Base64;  
 * import flash.utils.ByteArray;  
 * var data:ByteArray = new ByteArray();  
 * data.writeUTFBytes("Hello PHPRPC");  
 * var b64:String = Base64.encode(data);  
 * trace(b64);  
 * trace(Base64.decode(b64));  
 */   
   
package org.phprpc.util{   
    import flash.utils.ByteArray;   
    public class Base64 {   
        private static  const encodeChars:Array =    
        ['A','B','C','D','E','F','G','H',   
        'I','J','K','L','M','N','O','P',   
        'Q','R','S','T','U','V','W','X',   
        'Y','Z','a','b','c','d','e','f',   
        'g','h','i','j','k','l','m','n',   
        'o','p','q','r','s','t','u','v',   
        'w','x','y','z','0','1','2','3',   
        '4','5','6','7','8','9','+','/'];   
        private static  const decodeChars:Array =    
        [-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];   
        public static function encode(data:ByteArray):String {   
            var out:Array = [];   
            var i:int = 0;   
            var j:int = 0;   
            var r:int = data.length % 3;   
            var len:int = data.length - r;   
            var c:int;   
            while (i < len) {   
                c = data[i++] << 16 | data[i++] << 8 | data[i++];   
                out[j++] = encodeChars[c >> 18] + encodeChars[c >> 12 & 0x3f] + encodeChars[c >> 6 & 0x3f] + encodeChars[c & 0x3f];   
            }   
            if (r == 1) {   
                c = data[i++];   
                out[j++] = encodeChars[c >> 2] + encodeChars[(c & 0x03) << 4] + "==";   
            }   
            else if (r == 2) {   
                c = data[i++] << 8 | data[i++];   
                out[j++] = encodeChars[c >> 10] + encodeChars[c >> 4 & 0x3f] + encodeChars[(c & 0x0f) << 2] + "=";   
            }   
            return out.join('');   
        }   
        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();   
            while (i < len) {   
                // c1   
                do {   
                    c1 = decodeChars[str.charCodeAt(i++) & 0xff];   
                } while (i < len && c1 == -1);   
                if (c1 == -1) {   
                    break;   
                }   
                // c2       
                do {   
                    c2 = decodeChars[str.charCodeAt(i++) & 0xff];   
                } while (i < len && c2 == -1);   
                if (c2 == -1) {   
                    break;   
                }   
                out.writeByte((c1 << 2) | ((c2 & 0x30) >> 4));   
                // c3   
                do {   
                    c3 = str.charCodeAt(i++) & 0xff;   
                    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 = str.charCodeAt(i++) & 0xff;   
                    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;   
        }   
    }   
}