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VHDL for FPGA Design/4-Bit Shift Register
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4-Bit Shift Register
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
entity Shift_register_VHDL is
port( clk: in std_logic;
L: in std_logic;
w: in std_logic; -- new data to shift in
Output: out std_logic_vector(3 downto 0);
Input: in std_logic_vector( 3 downto 0));
end Shift_register_VHDL;
architecture Behavioral of Shift_register_VHDL is
begin
process
variable temp: std_logic_vector(3 downto 0);
begin
wait until rising_edge (clk);
temp := Input;
if L='1' then
for i in 0 to 2 loop
temp(i) := temp(i+1);
end loop;
temp(3) := w;
end if;
Output <= temp;
end process;
end Behavioral;
Simulation results
Image:Shift reg f.png
fi:VHDL-kieli FPGA-suunnittelussa/4-bittinen siirtorekisteri