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--code_tran.vhd keyboard position to button code transformer 
library ieee ; 
use ieee.std_logic_1164.all; 
use ieee.std_logic_arith.all; 
use ieee.std_logic_unsigned.all; 
entity code_tran is 
port( 
  scan_cnt : in  std_logic_vector(3 downto 0) ;--keybord scan count 
  clk : in std_logic ;--clock 
  butt_code : out std_logic_vector(3 downto 0)) ;--button code 
end code_tran ; 
architecture behavior of code_tran is 
begin  
  code_tran:process(clk) 
  begin 
     if(clk'event and clk='1') then 
          case scan_cnt is					--encoding 
    	      	when "0000"=>  butt_code <= "0001";--1 
        	  	when "0001"=>  butt_code <= "0010";--2 
	       		when "0010"=>  butt_code <= "0011";--3 
    	      	when "0011"=>  butt_code <= "1100";--c 
        	  	when "0100"=>  butt_code <= "0100";--4 
	          	when "0101"=>  butt_code <= "0101";--5 
    	      	when "0110"=>  butt_code <= "0110";--6 
        	  	when "0111"=>  butt_code <= "1101";--d 
          		when "1000"=>  butt_code <= "0111";--7 
	          	when "1001"=>  butt_code <= "1000";--8 
    	      	when "1010"=>  butt_code <= "1001";--9 
        	  	when "1011"=>  butt_code <= "1110";--e 
	          	when "1100"=>  butt_code <= "1010";--a 
    	      	when "1101"=>  butt_code <= "0000";--0 
        	  	when "1110"=>  butt_code <= "1011";--b 
	          	when others => butt_code <= "1111";--f 
   	      end case; 
     end if; 
  end process;   
end behavior;