dianji.txt

QuartusII环境下

--错误
--1、Signal信号应该在begin之前；
--2、并行赋值语句不应在process中出现
--3、case语句应包含所有可能情况 （用when others）

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-- Company: 
-- Engineer: 
-- 
-- Create Date:    11:49:28 11/08/2008 
-- Design Name: 
-- Module Name:    cl_dianji - Behavioral 
-- Project Name: 
-- Target Devices: 
-- Tool versions: 
-- Description: 
--
-- Dependencies: 
--
-- Revision: 
-- Revision 0.01 - File Created
-- Additional Comments: 
--
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library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;

---- Uncomment the following library declaration if instantiating
---- any Xilinx primitives in this code.
--library UNISIM;
--use UNISIM.VComponents.all;

entity ep111 is
    Port ( clk : in  STD_LOGIC;
           reset : in  STD_LOGIC;
           dir : in  STD_LOGIC;
           A : out  STD_LOGIC;
           B : out  STD_LOGIC;
           C : out  STD_LOGIC);
end ep111;

architecture Behavioral of ep111 is
	Signal abc : STD_LOGIC_VECTOR(2 DOWNTO 0);
begin
	
	process(clk,reset)
		begin
		if rising_edge(clk) then
			if reset='1' then
				abc <= "100";
			elsif dir='0' then
				case abc is
					when "100" => abc <= "110";
					when "110" => abc <= "010";
					when "010" => abc <= "011";
					when "011" => abc <= "001";
					when "001" => abc <= "101";
					when "101" => abc <= "100";
					when others => abc <= "000";
				end case;
					
	--
		--		abc <= "110" when abc="100" else  
			--			 "010" when abc="110" else
				--		 "011" when abc="010" else
				--		 "001" when abc="011" else
				--	     "101" when abc="001" else
				--		 "100" when abc="101" else
				--		 "000";
			elsif dir='1' then
				case abc is
					when "110" => abc <= "100";
					when "010" => abc <= "110";
					when "011" => abc <= "010";
					when "001" => abc <= "011";
					when "101" => abc <= "001";
					when "100" => abc <= "101";
					when others => abc <= "000";
				end case;
		--		abc <= "101" when abc="100" else
		--				 "001" when abc="101" else
		--				 "011" when abc="001" else
		--				 "010" when abc="011" else
		--				 "110" when abc="010" else
		--				 "100" when abc="110" else
		--				 "000";
			end if;
		end if;
	end process;
	
	A <= abc(2);
	B <= abc(1);
	C <= abc(0);
	
end Behavioral;