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CLyna
Beginner
501 Views

Caesar Cipher

I am trying to create a simple Caesar cipher but the same issue keeps arising. I am sure that there is a few issues with my code. I am just starting out VHDL. The code is below any help would be great.

library IEEE;

use IEEE.STD_LOGIC_1164.ALL;

use IEEE.STD_LOGIC_UNSIGNED.ALL;

use IEEE.NUMERIC_STD.ALL;

 

entity caesar is

  Port ( clk : in STD_LOGIC;

      enableSwitch : in STD_LOGIC;

      SW : in STD_LOGIC_VECTOR (7 downto 0)      

     );

end caesar;

 

 

 

architecture Behavioral of caesar is

 

type counterType is array (7 downto 0) of STD_LOGIC_VECTOR(5 downto 0); 

signal counter : counterType;

signal clkSignal : STD_LOGIC_VECTOR( 2 downto 0 ) := "000" ;

signal clkDivider : STD_LOGIC_VECTOR( 15 downto 0 ) := "0000000000000000" ;

 

shared variable clkSignalHolder : unsigned(2 downto 0) := "000"; -- Seems prudent to ensure all else is based on this

begin process (clk) is

  begin

 

 

     if ( clk='1' and clk'event) then

      if enableSwitch='1' then

        clkDivider <= clkDivider + 1;

      end if;

      if clkDivider = "1111111111111111" then

        clkSignal <= clkSignal + 1;

      end if;

    end if;

 

clkSignalHolder := TO_INTEGER(unsigned(clkSignal));

 

     if RISING_EDGE(SW(clkSignalHolder)) then

      counter(clkSignalHolder) <= counter(clkSignalHolder) + 1;

      if (counter(clkSignalHolder) > "011001") then 

        counter(clkSignalHolder) <= "000000";

      end if;

    end if;

 

     

    if RISING_EDGE(enableSwitch) then

      for I in 0 to 7 loop

        counter(I) <= counter(I) + 13;

        if (counter(I) > "011001") then 

          counter(I) <= counter(I) - 26;

        end if;

        

end loop;

    end if;

     

    

     

end process;

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1 Reply
Vicky1
Employee
43 Views

Hi Ciara, Could you please check with declaration of shared variable using 'integer' instead of unsigned? Please let me know if you have any concern. Regards, Vikas
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