Call a function in a shared library: Difference between revisions

type HANDLE is new Unsigned_32;

function LoadLibrary (lpFileName : char_array) return HANDLE;

 

function GetProcAddress (hModule : HANDLE; lpProcName : char_array)

return Address;

--

-- The interface of the function we want to call. It is a pointer (access type)

end if;

end Shared_Library_Call;</lang>

===Linux===

Here we are using the ''dl'' library statically (-ldl switch upon linking) and ''Xlib'' dynamically (''libX11.so''). The function ''dlopen'' loads a library. The function ''dlsym'' looks up for an entry point there. From ''libX11.so'', first ''XOpenDisplay'' is called to open an X11 display, which name is in the DISPLAY environment variable. Then XDisplayWidth of the display is obtained an printed into the standard output.