-- procedure in a process
stim:process
  procedure wait_cycles(n : natural)
  begin
    for i in 0 to n-1 loop
      wait until rising_edge(clk);
    end loop;
  end procedure;
begin
  report "starting simulation";
  wait until reset_n='0';

  wait_cycles(100);
  report "100 clock cycles elapsed";
  wait; --forever
end process;

end bhv;