报错信息：Multiple non-tristate drivers for net count_int(7) in aa4
Multiple non-tristate drivers for net count_int(6) in aa4
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八个输出端都不对
--8位UP/DOWN计数器
LIBRARY ieee;
USE ieee.Std_logic_1164.ALL;
USE ieee.Std_logic_unsigned.ALL;
ENTITY aa4 IS
GENERIC(n : Positive := 8);
PORT(s1,s2,en,reset: IN Std_logic;
count : OUT Std_logic_vector((n-1) DOWNTO 0));
END aa4;
ARCHITECTURE v1 OF aa4 IS
SIGNAL count_int : Std_logic_vector((n-1) DOWNTO 0);
-- count_int <= (OTHERS => '0');
BEGIN
count_int <= (OTHERS => '0');
PROCESS
BEGIN
wait until (en='1'); --使能
if (reset='1') then
count_int <= (OTHERS => '0'); --清零
elsif(s1'EVENT AND s1 = '1' and s2='1') then
count_int<=count_int+1; --s1上升沿且s2为高时加记数
elsif(s1'EVENT AND s1 = '0' and s2='1') then
count_int<=count_int-1; --s1下降沿且s2为高时减记数
ELSE
NULL;
END IF;
END PROCESS;
count <= count_int;
END v1; | 
