program testsubs;

Type
  TSubStrFunc = function (const CString: PChar; FromPos, ToPos: longint): PChar;  cdecl;

Function dlopen(name : pchar; mode : longint) : pointer; cdecl; external 'dl';
Function dlsym(lib : pointer; name : pchar) : pointer; cdecl;external 'dl';
Function dlclose(lib : pointer) : longint; cdecl; external 'dl';

var
  s: PChar;
  FromPos, ToPos: Integer;
  lib : pointer;
  SubStr : TSubStrFunc;
  
begin
  s := 'Test';
  FromPos := 2;
  ToPos := 3;
  lib:=dlopen('libsubs.so',1);
  Pointer(Substr):=dlsym(lib,'SubStr');
  WriteLn(SubStr(s, FromPos, ToPos));
  dlclose(lib);
end.