I suggest you switch to a HIGH level language e.g. Pascal. There are freeware Pascal cross-compilers on the web.
The GPS units I have used output their data once per second and end it with a carriage return and line feed. Once you have captured the string from the GPS you can extract the bits you require from it.
The Pascal code would look something like this:


Var
GpsData : String[24]; (* defines string for gps data storage *)

Procedure GetGpsData ; (* capture 1 line of gps data *)
begin
ReadLn(GpsData) ;
end; { Procedure GetGpsData }

Good luck
Tony