VHDL错误:各位大佬,这是哪里错了啊,真的给孩子整崩溃了

library ieee;use ieee.std_logic_1164.all;use ieee.std_logic_unsigned.all;entity lucheng isport(clkl,start,rst,pause:in std_logic; cost_1,mileage:out integer range 0 to 8000; p:out std_logic);end lucheng;architecture analog of lucheng isbeginprocess(clkl,start,rst,pause)variable a,c:std_logic;variable b:integer range 0 to 50;variable cos,mile:integer range 0 to 8000;beginif(clkl'event and clkl='1')thenif(rst='1')then --车停止,未开动时cos:=0;b:=0;mile:=0;elsif(start='0')thena:='0';cos:=100;mile:=0; --计价器未开始计价工作时elsif(start='1'and pause='0')thenmile:=mile+1;b:=b+1;end if;if(b>=50)thena:='1';b:=0;elsea:='0';end if;if(mile<300)thenc:='0';elsif(cos<200 and a='1')then --超过起步路程后,价格小于20元,2元/公里cos:=cos+10; --每次计费是1元c:='1'; --超出起步价标志elsif(cos>=200 and a='1')or(mile>=900 and a='1')then --超过20元或9公里后每公里加收50%车费cos:=cos+15; --每次计费是500米加1.5元c:='1';end if;end if;cost_1<=cos;mileage<=mile;p<2c;end process;end analog;