VHDL四人抢答器代码有异常 麻烦给改下吧 急

VHDL四人抢答器代码有错误 麻烦给改下吧 急急急！
library ieee;

use ieee.std_logic_1164.all;


entity qiangdaqi is

port
(

        clk ,rest,allow             : in std_logic;

     answer                     : in std_logic_vector(3 downto 0);

stop_lamp,allow_lamp,co,q : out std_logic;
    answer_success,answer_foul  : out std_logic_vector(3 downto 0)

);


end entity;


architecture rtl of qiangdaqi is
signal alamp : std_logic; 
signal foul : std_logic_vector(3 downto 0);

begin


nclk:process (clk,allow) is

      begin
    if(rest='1')then   
      q<="0000";   
      co<='0';   
    else 

      if(allow_lamp='1')then   
    if(clk'event and clk='1') and (answer_success="0000")then  
        if(q="1111")then     
           q<="0000";      
           co<='1';     
        else     
           q<=q+'1';   
           co<='0';    
        end if;    
    end if;  
     end if;  
    end if;
     end process;
    
    lemp_rest_allow:process(rest,allow,co)is   
      begin     
        if(rest='1')then    
            stop_lamp<='1';      
            allow_lamp<='0'