xianshi.vhd

利用FPGA编写的键盘译码程序

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

entity xianshi is
  port( ch: in std_logic_vector(7 downto 0);
       sel: in std_logic_vector(3 downto 0);
         q: out std_logic_vector(15 downto 0));
end xianshi;

architecture rt1 of xianshi is
signal y: std_logic_vector(15 downto 0);
begin
  process(ch,sel)
	begin
      case ch is
           when "00000000"=>
           case sel is
             when "0000"=>q<="0000000000000000";
             when "0001"=>q<="0000000000000000";
             when "0010"=>q<="0000000000000000";
             when "0011"=>q<="0000000000000000";
             when "0100"=>q<="0000000000000000";

             when "0101"=>q<="0000000000000000";
             when "0110"=>q<="0000000000000000";
             when "0111"=>q<="0000000000000000";
             when "1000"=>q<="0000000000000000";
             when "1001"=>q<="0000000000000000";

             when "1010"=>q<="1111111100000000";
             when "1011"=>q<="1100001100000000";
             when "1100"=>q<="1100001100000000";
             when "1101"=>q<="1100001100000000";
             when "1110"=>q<="1111111100000000";

             when "1111"=>q<="0000000000000000";
             when others=>null;
          end case;
  when "00000001"=>
           case sel is
             when "0000"=>q<="0000000000000000";
             when "0001"=>q<="0000000000000000";
             when "0010"=>q<="0000000000000000";
             when "0011"=>q<="0000000000000000";
             when "0100"=>q<="0000000000000000";

             when "0101"=>q<="0000000000000000";
             when "0110"=>q<="0000000000000000";
             when "0111"=>q<="0000000000000000";
             when "1000"=>q<="0000000000000000";
             when "1001"=>q<="0000000000000000";

             when "1010"=>q<="0000000000000000";
             when "1011"=>q<="0000000000000000";
             when "1100"=>q<="0000000000000000";
             when "1101"=>q<="1111111100000000";
             when "1110"=>q<="1111111100000000";

             when "1111"=>q<="0000000000000000";
             when others=>null;
          end case;
 when "00000010"=>
           case sel is
             when "0000"=>q<="0000000000000000";
             when "0001"=>q<="0000000000000000";
             when "0010"=>q<="0000000000000000";
             when "0011"=>q<="0000000000000000";
             when "0100"=>q<="0000000000000000";

             when "0101"=>q<="0000000000000000";
             when "0110"=>q<="0000000000000000";
             when "0111"=>q<="0000000000000000";
             when "1000"=>q<="0000000000000000";
             when "1001"=>q<="0000000000000000";

             when "1010"=>q<="1101111100000000";
             when "1011"=>q<="1101111100000000";
             when "1100"=>q<="1101101100000000";
             when "1101"=>q<="1101101100000000";
             when "1110"=>q<="1111101100000000";

             when "1111"=>q<="0000000000000000";
             when others=>null;
          end case;
 when "00000011"=>
           case sel is
             when "0000"=>q<="0000000000000000";
             when "0001"=>q<="0000000000000000";
             when "0010"=>q<="0000000000000000";
             when "0011"=>q<="0000000000000000";
             when "0100"=>q<="0000000000000000";

             when "0101"=>q<="0000000000000000";
             when "0110"=>q<="0000000000000000";
             when "0111"=>q<="0000000000000000";
             when "1000"=>q<="0000000000000000";
             when "1001"=>q<="0000000000000000";

             when "1010"=>q<="1101101100000000";
             when "1011"=>q<="1101101100000000";
             when "1100"=>q<="1101101100000000";
             when "1101"=>q<="1111111100000000";
             when "1110"=>q<="1111111100000000";

             when "1111"=>q<="0000000000000000";
             when others=>null;
          end case;
 when "00000100"=>
           case sel is
             when "0000"=>q<="0000000000000000";
             when "0001"=>q<="0000000000000000";
             when "0010"=>q<="0000000000000000";
             when "0011"=>q<="0000000000000000";
             when "0100"=>q<="0000000000000000";

             when "0101"=>q<="0000000000000000";
             when "0110"=>q<="0000000000000000";
             when "0111"=>q<="0000000000000000";
             when "1000"=>q<="0000000000000000";
             when "1001"=>q<="0000000000000000";

             when "1010"=>q<="1111100000000000";
             when "1011"=>q<="1111100000000000";
             when "1100"=>q<="0001100000000000";
             when "1101"=>q<="1111111100000000";
             when "1110"=>q<="1111111100000000";

             when "1111"=>q<="0000000000000000";
             when others=>null;
          end case;
 when "00000101"=>
           case sel is
             when "0000"=>q<="0000000000000000";
             when "0001"=>q<="0000000000000000";
             when "0010"=>q<="0000000000000000";
             when "0011"=>q<="0000000000000000";
             when "0100"=>q<="0000000000000000";

             when "0101"=>q<="0000000000000000";
             when "0110"=>q<="0000000000000000";
             when "0111"=>q<="0000000000000000";
             when "1000"=>q<="0000000000000000";
             when "1001"=>q<="0000000000000000";

             when "1010"=>q<="1111101100000000";
             when "1011"=>q<="1111101100000000";
             when "1100"=>q<="1101101100000000";
             when "1101"=>q<="1101111100000000";
             when "1110"=>q<="1101111100000000";

             when "1111"=>q<="0000000000000000";
             when others=>null;
          end case;
 when "00000110"=>
           case sel is
             when "0000"=>q<="0000000000000000";
             when "0001"=>q<="0000000000000000";
             when "0010"=>q<="0000000000000000";
             when "0011"=>q<="0000000000000000";
             when "0100"=>q<="0000000000000000";

             when "0101"=>q<="0000000000000000";
             when "0110"=>q<="0000000000000000";
             when "0111"=>q<="0000000000000000";
             when "1000"=>q<="0000000000000000";
             when "1001"=>q<="0000000000000000";

             when "1010"=>q<="1111111100000000";
             when "1011"=>q<="1111111100000000";
             when "1100"=>q<="1101101100000000";
             when "1101"=>q<="1101101100000000";
             when "1110"=>q<="1101111100000000";

             when "1111"=>q<="0000000000000000";
             when others=>null;
          end case;
 when "00000111"=>
           case sel is
             when "0000"=>q<="0000000000000000";
             when "0001"=>q<="0000000000000000";
             when "0010"=>q<="0000000000000000";
             when "0011"=>q<="0000000000000000";
             when "0100"=>q<="0000000000000000";

             when "0101"=>q<="0000000000000000";
             when "0110"=>q<="0000000000000000";
             when "0111"=>q<="0000000000000000";
             when "1000"=>q<="0000000000000000";
             when "1001"=>q<="0000000000000000";

             when "1010"=>q<="1100000000000000";
             when "1011"=>q<="1100000000000000";
             when "1100"=>q<="1100000000000000";
             when "1101"=>q<="1111111100000000";
             when "1110"=>q<="1111111100000000";

             when "1111"=>q<="0000000000000000";
             when others=>null;
          end case;
 when "00001000"=>
           case sel is
             when "0000"=>q<="0000000000000000";
             when "0001"=>q<="0000000000000000";
             when "0010"=>q<="0000000000000000";
             when "0011"=>q<="0000000000000000";
             when "0100"=>q<="0000000000000000";

             when "0101"=>q<="0000000000000000";
             when "0110"=>q<="0000000000000000";
             when "0111"=>q<="0000000000000000";
             when "1000"=>q<="0000000000000000";
             when "1001"=>q<="0000000000000000";

             when "1010"=>q<="1111111100000000";
             when "1011"=>q<="1111111100000000";
             when "1100"=>q<="1101101100000000";
             when "1101"=>q<="1111111100000000";
             when "1110"=>q<="1111111100000000";

             when "1111"=>q<="0000000000000000";
             when others=>null;
          end case;
when "00001001"=>
           case sel is
             when "0000"=>q<="0000000000000000";
             when "0001"=>q<="0000000000000000";
             when "0010"=>q<="0000000000000000";
             when "0011"=>q<="0000000000000000";
             when "0100"=>q<="0000000000000000";

             when "0101"=>q<="0000000000000000";
             when "0110"=>q<="0000000000000000";
             when "0111"=>q<="0000000000000000";
             when "1000"=>q<="0000000000000000";
             when "1001"=>q<="0000000000000000";

             when "1010"=>q<="1111101100000000";
             when "1011"=>q<="1111101100000000";
             when "1100"=>q<="1101101100000000";
             when "1101"=>q<="1111111100000000";
             when "1110"=>q<="1111111100000000";

             when "1111"=>q<="0000000000000000";
             when others=>null;
          end case;
when "00010000"=>
           case sel is
             when "0000"=>q<="0000000000000000";
             when "0001"=>q<="0000000000000000";
             when "0010"=>q<="0000000000000000";
             when "0011"=>q<="0000000000000000";
             when "0100"=>q<="0000000000000000";

             when "0101"=>q<="0000000000000000";
             when "0110"=>q<="0000000000000000";
             when "0111"=>q<="0000000000000000";
             when "1000"=>q<="1111111100000000";
             when "1001"=>q<="1111111100000000";

             when "1010"=>q<="1111111100000000";
             when "1011"=>q<="1111111100000000";
             when "1100"=>q<="1100001100000000";
             when "1101"=>q<="1111111100000000";
             when "1110"=>q<="1111111100000000";

             when "1111"=>q<="0000000000000000";
             when others=>null;
          end case;
when "00010001"=>
           case sel is
             when "0000"=>q<="0000000000000000";
             when "0001"=>q<="0000000000000000";
             when "0010"=>q<="0000000000000000";
             when "0011"=>q<="0000000000000000";
             when "0100"=>q<="0000000000000000";

             when "0101"=>q<="0000000000000000";
             when "0110"=>q<="0000000000000000";
             when "0111"=>q<="0000000000000000";
             when "1000"=>q<="1111111100000000";
             when "1001"=>q<="1111111100000000";

             when "1010"=>q<="0000000000000000";
             when "1011"=>q<="0000000000000000";
             when "1100"=>q<="0000000000000000";
             when "1101"=>q<="1111111100000000";
             when "1110"=>q<="1111111100000000";

             when "1111"=>q<="0000000000000000";
             when others=>null;
          end case;
when "00010010"=>
           case sel is
             when "0000"=>q<="0000000000000000";
             when "0001"=>q<="0000000000000000";
             when "0010"=>q<="0000000000000000";
             when "0011"=>q<="0000000000000000";
             when "0100"=>q<="0000000000000000";

             when "0101"=>q<="0000000000000000";