source: Dev/trunk/src/client/dojox/encoding/base64.js

define(["dojo/_base/lang"], function(lang) {
        
        var base64 = lang.getObject("dojox.encoding.base64", true);

        var p="=";
        var tab="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

        base64.encode=function(/* byte[] */ba){
                // summary:
                //              Encode an array of bytes as a base64-encoded string
                var s=[], l=ba.length;
                var rm=l%3;
                var x=l-rm;
                for (var i=0; i<x;){
                        var t=ba[i++]<<16|ba[i++]<<8|ba[i++];
                        s.push(tab.charAt((t>>>18)&0x3f));
                        s.push(tab.charAt((t>>>12)&0x3f));
                        s.push(tab.charAt((t>>>6)&0x3f));
                        s.push(tab.charAt(t&0x3f));
                }
                //      deal with trailers, based on patch from Peter Wood.
                switch(rm){
                        case 2:{
                                var t=ba[i++]<<16|ba[i++]<<8;
                                s.push(tab.charAt((t>>>18)&0x3f));
                                s.push(tab.charAt((t>>>12)&0x3f));
                                s.push(tab.charAt((t>>>6)&0x3f));
                                s.push(p);
                                break;
                        }
                        case 1:{
                                var t=ba[i++]<<16;
                                s.push(tab.charAt((t>>>18)&0x3f));
                                s.push(tab.charAt((t>>>12)&0x3f));
                                s.push(p);
                                s.push(p);
                                break;
                        }
                }
                return s.join("");      //      string
        };

        base64.decode=function(/* string */str){
                // summary:
                //              Convert a base64-encoded string to an array of bytes
                var s=str.split(""), out=[];
                var l=s.length;
                while(s[--l]==p){ }     //      strip off trailing padding
                for (var i=0; i<l;){
                        var t=tab.indexOf(s[i++])<<18;
                        if(i<=l){ t|=tab.indexOf(s[i++])<<12 };
                        if(i<=l){ t|=tab.indexOf(s[i++])<<6 };
                        if(i<=l){ t|=tab.indexOf(s[i++]) };
                        out.push((t>>>16)&0xff);
                        out.push((t>>>8)&0xff);
                        out.push(t&0xff);
                }
                //      strip off any null bytes
                while(out[out.length-1]==0){ out.pop(); }
                return out;     //      byte[]
        };
        
        return base64;
});