xor_mul.vhd

使用列表法

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

entity xor_mul is
port( 
      a,b : in std_logic_vector (7 downto 0);
      clk : in std_logic;
      product: out std_logic_vector (7 downto 0)
     );
end xor_mul;

architecture answer of xor_mul is

signal c : std_logic_vector (14 downto 0);
signal m : std_logic_vector (7 downto 0);

begin

 process ( clk, a, b )
  begin
   if clk'event and clk='1' then
   c(14)<=a(7) and b(7);
   c(13)<=(a(7) and b(6)) xor (a(6) and b(7));
   c(12)<=(a(7) and b(5)) xor (a(6) and b(6)) xor (a(5) and b(7));
   c(11)<=(a(7) and b(4)) xor (a(6) and b(5)) xor (a(5) and b(6)) xor (a(4) and b(7));
   c(10)<=(a(7) and b(3)) xor (a(6) and b(4)) xor (a(5) and b(5)) xor (a(4) and b(6)) xor (a(3) and b(7));
   c(9)<=(a(7) and b(2)) xor (a(6) and b(3)) xor (a(5) and b(4)) xor (a(4) and b(5)) xor (a(3) and b(6)) xor (a(2) and b(7));
   c(8)<=(a(7) and b(1)) xor (a(6) and b(2)) xor (a(5) and b(3)) xor (a(4) and b(4)) xor (a(3) and b(5)) xor (a(2) and b(6)) xor (a(1) and b(7));
   c(7)<=(a(7) and b(0)) xor (a(6) and b(1)) xor (a(5) and b(2)) xor (a(4) and b(3)) xor (a(3) and b(4)) xor (a(2) and b(5)) xor (a(1) and b(6)) xor (a(0) and b(7));
   c(6)<=(a(6) and b(0)) xor (a(5) and b(1)) xor (a(4) and b(2)) xor (a(3) and b(3)) xor (a(2) and b(4)) xor (a(1) and b(5)) xor (a(0) and b(6));
   c(5)<=(a(5) and b(0)) xor (a(4) and b(1)) xor (a(3) and b(2)) xor (a(2) and b(3)) xor (a(1) and b(4)) xor (a(0) and b(5));
   c(4)<=(a(4) and b(0)) xor (a(3) and b(1)) xor (a(2) and b(2)) xor (a(1) and b(3)) xor (a(0) and b(4));
   c(3)<=(a(3) and b(0)) xor (a(2) and b(1)) xor (a(1) and b(2)) xor (a(0) and b(3));
   c(2)<=(a(2) and b(0)) xor (a(1) and b(1)) xor (a(0) and b(2));
   c(1)<=(a(1) and b(0)) xor (a(0) and b(1));
   c(0)<=a(0) and b(0);

   m(7)<=c(7) xor c(11) xor c(12) xor c(14);
   m(6)<=c(6) xor c(10) xor c(11) xor c(13);
   m(5)<=c(5) xor c(9) xor c(10) xor c(12);
   m(4)<=c(4) xor c(8) xor c(9) xor c(11) xor c(14);
   m(3)<=c(3) xor c(8) xor c(10) xor c(11) xor c(12) xor c(13) xor c(14);
   m(2)<=c(2) xor c(9) xor c(10) xor c(13);
   m(1)<=c(1) xor c(8) xor c(9) xor c(12) xor c(14);
   m(0)<=c(0) xor c(8) xor c(12) xor c(13);

  end if;
end process;

process(clk)
 begin
  if clk'event and clk='1' then
    product<=m;
  end if;

end process;
 
end answer;