-- code from book

entity reg is
  generic ( width : positive );
  port ( d : in bit_vector(0 to width - 1);
         q : out bit_vector(0 to width - 1);
         -- . . . );
  -- not in book
         other_port : in bit := '0' );
  -- end not in book
end entity reg;

-- end code from book


architecture test of reg is
begin
  q <= d;
end architecture test;



entity ch_12_03 is

end entity ch_12_03;


----------------------------------------------------------------


architecture test of ch_12_03 is

  constant bus_size : positive := 16;

  -- code from book

  signal in_data, out_data : bit_vector(0 to bus_size - 1);
  -- . . .

  -- end code from book


begin

  -- code from book

  ok_reg : entity work.reg
    generic map ( width => bus_size )
    port map ( d => in_data,  q => out_data, -- . . . );
    -- not in book
               other_port => open );
    -- end not in book

  -- end code from book

end architecture test;