function encode_base64(psstr) {
   		return encode(psstr,psstr.length); 
}

function encode (psstrs, iLen) {
	 var map1="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
   var oDataLen = (iLen*4+2)/3;
   var oLen = ((iLen+2)/3)*4;
   var out='';
   var ip = 0;
   var op = 0;
   while (ip < iLen) {
      var xx = psstrs.charCodeAt(ip++);
      var yy = ip < iLen ? psstrs.charCodeAt(ip++) : 0;
      var zz = ip < iLen ? psstrs.charCodeAt(ip++) : 0;
      var aa = xx >>> 2;
      var bb = ((xx &   3) << 4) | (yy >>> 4);
      var cc = ((yy & 0xf) << 2) | (zz >>> 6);
      var dd = zz & 0x3F;
      out += map1.charAt(aa);
      op++;
      out += map1.charAt(bb);
      op++;
      out += op < oDataLen ? map1.charAt(cc) : '='; 
      op++;
      out += op < oDataLen ? map1.charAt(dd) : '='; 
      op++; 
   }
   return out; 
}