[fm77]

In Turbo Pascal :-) you have to filter for NaN or else you will end up with a Runtime Error.

  const NaN = $FF shl 23;

  var x, t: longint;
      f: single absolute x;

  begin 
    t := 0;
    x := 0;
    repeat
      inc(t, ord((x and NaN <> NaN) and (0<=f) and (f<=1)));
      inc(x);
    until x = 0;
    WriteLn('total: ', t);
  end.

total: 1065353218 (in ca. 40 seconds)