ex_4_2_barrel.vhd

来自「This is the course for VHDL programming」· VHDL 代码 · 共 15 行

library IEEE;
use IEEE.std_logic_1164.all;
use IEEE.std_logic_unsigned.all;
entity barrel_shifter is
	port(A:in  std_logic_vector(7 downto 0);--Input
		  B:out std_logic_vector(7 downto 0);--Output
		  C:in std_logic_vector(3 downto 0));--Shift count C(3) = Direction 
end barrel_shifter;
architecture DF2 of barrel_shifter is
	signal s:integer;
begin
	s <= conv_integer(C(2 downto 0));
	B<= To_stdlogicvector(To_bitvector(A) sll s)   when C(3) = '0' else
	        To_stdlogicvector(To_bitvector(A) srl s);
end DF2;