$ivlh_file_open         vpiSysFuncVoid

$ivlh_readline          vpiSysFuncVoid
$ivlh_writeline         vpiSysFuncVoid

$ivlh_read              vpiSysFuncVoid
$ivlh_write             vpiSysFuncVoid
$ivlh_hread             vpiSysFuncVoid
$ivlh_hwrite            vpiSysFuncVoid