function tis620_to_utf8($tis) {
  for( $i=0 ; $i< strlen($tis) ; $i++ ){
    $s = substr($tis, $i, 1);
    $val = ord($s);
    if( $val < 0x80 ){
	 $utf8 .= $s;
    } elseif ((0xA1 <= $val and $val <= 0xDA) 
              or (0xDF <= $val and $val <= 0xFB))  {
	 $unicode = 0x0E00 + $val - 0xA0;
	 $utf8 .= chr( 0xE0 | ($unicode >> 12) );
	 $utf8 .= chr( 0x80 | (($unicode >> 6) & 0x3F) );
	 $utf8 .= chr( 0x80 | ($unicode & 0x3F) );
    }
  }
return $utf8;
}

function utf8_to_tis620($string) {
  $str = $string;
  $res = "";
  for ($i = 0; $i < strlen($str); $i++) {
	if (ord($str[$i]) == 224) {
	  $unicode = ord($str[$i+2]) & 0x3F;
	  $unicode |= (ord($str[$i+1]) & 0x3F) << 6;
	  $unicode |= (ord($str[$i]) & 0x0F) << 12;
	  $res .= chr($unicode-0x0E00+0xA0);
	  $i += 2;
	} else {
	  $res .= $str[$i];
	}
  }
  return $res;
}