-- numconv.vhd: numeric conversion between two's complement 
--   and sign-magnitude
-- Dan R. K. Ports  <drkp@mit.edu>
-- 6.111 Lab 3, 2003/10/22

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;
use ieee.std_logic_unsigned.all;

entity numconv is
  
  generic (
    width : integer := 8);

  port (
    input  : in  std_logic_vector(width-1 downto 0);
    output : out std_logic_vector(width-1 downto 0));

end numconv;

architecture behavioral of numconv is

begin  -- behavioral

  -- purpose: convert input between sign/magnitude and two's complement
  -- type   : combinational
  -- inputs : input
  -- outputs: output
  convert: process (input)
  begin  -- process convert
    if input(width-1) = '0' then
      output <= input;
    else

      if input(width-2 downto 0) = 0 then
        output <= (others => '0');
      else
        output(width-1) <= '1';
        output(width-2 downto 0) <= (not input(width-2 downto 0)) + 1;
      end if;

    end if;
  end process convert;

end behavioral;