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| 这个学期刚刚学完EDA,想毕设用EDA技术做 试着做了一个计数器
 功能是一个按键+1,一个按键可以-1,还有一个清零复位键
 麻烦大神看一下有没有问题
  LIBRARY IEEE;
 USE IEEE.STD_LOGIC_1164.ALL;
 USE IEEE.STD_LOGIC_UNSIGNED.ALL;
 ENTITY C1 IS
 PORT(rst,clk,A,B: IN STD_LOGIC;
 count: OUT STD_LOGIC_VECTOR(7 DOWNTO 0)
 END ENTITY CI;
 ARCHITECTURE behaviour OF C1 IS
 SIGNAL:Q STD_LOGIC_VECTOR(7 DOWNTO 0);
 BEGIN
 PROCESS(clk,rst,A,B)
 VARIABLE S:STD_LOGIC_VECTOR(1 DOWNTO 0);
 BEGIN
 S:=A&B;
 IF rst=‘1’ THEN Q:=(OTHERS=>‘0’);
 ELSIF CLK'EVENT AND CLK=‘1’ THEN
 CASE(S) IS
 WHEN“01”=> Q<=Q+1;
 WHEN“10”=> Q<=Q-1;
 WHEN OTHERS =>NULL;
 END CASE;
 END IF;
 END PROCESS;
 count<=Q;
 END ARCHITECTURE behaviour;
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