list_ch03_11_gen_add.vhd

This VHDL convert a hex number to seven segments codes.

--Listing 3.11
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
entity gen_add_w_carry is
   generic(N: integer:=4);
   port(
      a, b: in std_logic_vector(N-1 downto 0);
      cout: out std_logic;
      sum: out std_logic_vector(N-1 downto 0)
   );
end gen_add_w_carry;

architecture arch of gen_add_w_carry is
   signal a_ext, b_ext, sum_ext: unsigned(N downto 0);
begin
   a_ext <= unsigned('0' & a);
   b_ext <= unsigned('0' & b);
   sum_ext <= a_ext + b_ext;
   sum <= std_logic_vector(sum_ext(N-1 downto 0));
   cout <= sum_ext(N);
end arch;