func readstr(pos uint32) string {
	pos2 := int64(pos)
	var retval string
	lenbyte := make([]byte, 1)
	_, err := f.ReadAt(lenbyte, pos2)
	if err != nil {
		fmt.Println("File read failed:", err)
	}
	strlen := lenbyte[0]
	data := make([]byte, strlen)
	_, err = f.ReadAt(data, pos2 + 1)
	if err != nil {
		fmt.Println("File read failed:", err)
	}
	retval = string(data[:strlen])
	return retval
}
func readstr(pos uint32) string {
	pos2 := int64(pos)
	var retval string
	lenbyte := make([]byte, 1)
	_, err := f.ReadAt(lenbyte, pos2)
	if err != nil {
		fmt.Println("File read failed:", err)
	}
	strlen := lenbyte[0]
	data := make([]byte, strlen)
	_, err = f.ReadAt(data, pos2 + 1)
	if err != nil {
		fmt.Println("File read failed:", err)
	}
	retval = string(data[:strlen])
	return retval
}
// read string