lineby.vhd

此为用VHDL编写的可实现动感图像的点阵

library ieee;
use  ieee.std_logic_1164.all;
use  ieee.std_logic_signed.all;
entity lineby  is
      port(
            clk:in  std_logic;
            cp:in  std_logic;--复位信号
             y:out std_logic_vector(0 to 7));
end lineby;
architecture   behavior  of  lineby  is
    signal b:std_logic_vector(5 downto 0):="000000";
    signal a:std_logic_vector(2 downto 0);
    signal e:std_logic_vector(2 downto 0);
    signal c:std_logic_vector(0 to 7);
    signal d:std_logic_vector(0 to 7);
  begin
  process(clk,cp)
  begin
  if(clk'event and clk='1') then
  if (cp ='1')then
     b<="000000";
  else
  b<=b+1;
  end if;
  end if;
  end process;
process(clk)
  begin
  a(0)<=b(0);
  a(1)<=b(1);
  a(2)<=b(3);
           if(clk'event and clk='1') then
           if    a="000"  then  c<="10000000";
           elsif a="001"  then  c<="01000000";
           elsif a="010"  then  c<="00100000";
           elsif a="011"  then  c<="00010000";
           elsif a="100"  then  c<="00001000";
           elsif a="101"  then  c<="00000100";
           elsif a="110"  then  c<="00000010";
           elsif a="111"  then  c<="00000001";
           end   if;
           end   if;
           y<=c;
    end process;
end behavior;