#pas
library mlmaster;
uses SysUtils, Classes;
{{$R *.res}

function libLogin(Login, Pass, Admin, AdminsPass:PChar):PChar;
begin
  // ....
end;

exports
   libLogin;

begin
end.

#pas
...
function libLogin(Login, Pass, Admin, AdminsPass:PChar):PChar; external 'mlmaster.dll';

procedure THiAsmClass.ActionResult(var Data:TData; index:word);
begin
  data.data_type := data_str;
  data.sdata := libLogin(...);
end;
...