function maximum (
    l, r : integer)                    -- inputs
    return integer is
  begin  -- function max
    if l > r then return l;
    else return r;
    end if;
  end function maximum;

  function minimum (
    l, r : integer)                    -- inputs
    return integer is
  begin  -- function min
    if l > r then return r;
    else return l;
    end if;
  end function minimum;

  function to_string (value : UNRESOLVED_UNSIGNED) return STRING is
  begin
    return to_string(STD_ULOGIC_VECTOR (value));
  end function to_string;

  function to_string (value : UNRESOLVED_SIGNED) return STRING is
  begin
    return to_string(STD_ULOGIC_VECTOR (value));
  end function to_string;