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| 这个是流水灯程序,很简单,我看不懂,红色部分我看不明白,懂得的朋友帮我解释下。谢谢! 
 
 LIBRARY IEEE;
 USE IEEE.STD_LOGIC_1164.ALL;
 USE IEEE.STD_LOGIC_UNSIGNED.ALL;
 ENTITY shift8 IS
 PORT(clk: IN STD_LOGIC;
 q: BUFFER STD_LOGIC_VECTOR (5 DOWNTO 0));
 END shift8;
 
 ARCHITECTURE fun OF shift8 IS
 SIGNAL b:STD_LOGIC_VECTOR (5 DOWNTO 0):="100000";
 BEGIN
 PROCESS(clk)
 BEGIN
 IF(clk'EVENT AND clk='1')
 THEN
 b<=b(0)&b(5 DOWNTO 1);
 q<=b;
 END IF;
 END PROCESS;
 END fun;
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