Build and simulate SR flip-flop and D flip-flop in VHDL

SR flip-flop and D flip-flop

D Flip – Flop with enable and reset

Code:

library ieee;
use ieee.std_logic_1164.all;
entity flip_flop is 
  port (clk,Din,rst,en : in std_logic;
        Q: out std_logic;
        Qnot : out std_logic);
 end flip_flop;
architecture my_flipflop of flip_flop is 
  signal t : std_logic;
  begin   
    process (clk,en,Din,rst)	
      begin 
        if(en='0') then 
		  Q <='Z';
		  Qnot <= 'Z';
		 elsif(rst='1') then
		  Q <='0';
		  Qnot <='1';
		 elsif(clk'event and clk='1') then
		  Q <= Din;
		  t <= Din;
		  Qnot <= not t;
		 end if;
	end process;
end my_flipflop;

Simulation waveforms:

RS Flip-Flop

Code:

library ieee;
use ieee.std_logic_1164.all;
entity flip_flop is 
  port (clk,r,s : in std_logic;
        Q: out std_logic;
        Qnot : out std_logic);
 end flip_flop;
architecture my_flipflop of flip_flop is   
  signal t1,t2 : std_logic;  
  begin     
    t1 <= r nor t2;
    t2 <= s nor t1;
	process (clk,r,s)	
      begin 
       if(clk'event and clk='1' ) then
		 if(r='0' and s='0') then 
		  Q <=t1;
		  Qnot <= t2;
		 elsif(r='0' and s='1') then
		  Q <='1';
		  Qnot <='0';
		 elsif(r='1' and s='0') then
		  Q <='0';
		  Qnot <='1';
		 elsif(r='1' and s='1') then
		  Q <='X';
		  Qnot <='X';
		 end if;
		end if;		
	end process;
end my_flipflop;

Simulation waveforms:

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