library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
use IEEE.std_logic_arith.all;

package usefuls is
  constant num_servo_observer : integer := 8;
  constant num_servo_driver : integer := 8;
  constant servo_resolution : integer := 12;

  --- find minimum number of bits required to
  --- represent N as an unsigned binary number
  ---
  function log2_ceil(N: natural) return positive;
end;

package body usefuls is
  --- find minimum number of bits required to
  --- represent N as an unsigned binary number
  ---
  function log2_ceil(N: natural) return positive is
  begin
    if N < 2 then
      return 1;
    else
      return 1 + log2_ceil(N/2);
    end if;
  end;
end;