(vcom-1339) Case statement choices cover only 6 out of 10 cases

Question

Case statement choices cover only 6 out of 10 cases for my vending machine code I am getting this error after execution of my very long program in VHDL. However its said that When others => can be used only at the last statement of the code to avoid this particular error however there are many when statements used in the program. How to solve this issue?

library ieee;
use IEEE.std_logic_1164.all;
use ieee.numeric_std.all;

entity FSMM is
port (CLK : in std_logic; --Clock, active high
 RSTn : in std_logic; --Async. Reset, active low
 CoinIn : in std_logic_vector (1 downto 0); --Which coin was inserted
 gum : out std_logic; --Is Soda dispensed ?
 CoinOut : out std_logic_vector (1 downto 0) --Which coin is dispensed?
 );

end entity;

architecture behavior of FSMM is
-- add your code here
type state_type is (idle, --start state/reset
 put_money, --waiting to enter money
 in_5c,in_10c,in_15c,in_20c,in_25c,in_30c,in_35c, --represent the current sum of money after returning change
 gum_out --dispence soda can.
 ); --type of state machine.
signal current_s,next_s: state_type; --current and next state declaration.

begin

process(CLK,RSTn)
begin
 if(RSTn = '0') then
 current_s <= idle; --defualt state is on RESET
 elsif(clk'event and clk = '1') then
 current_s <= next_s;
 end if;
end process;
--------------------
--FSM process:
process(current_s,CoinIn)
begin
case current_s is
 when idle => --state reset or idle
 gum <= '0';
 CoinOut <= "00";
 next_s <= put_money;
 ------------------------------------------------------
 when put_money => --wait for money to be entered
 if(CoinIn = "00")then
 gum <= '0';
 CoinOut <= "00";
 next_s <= put_money;
 elsif(CoinIn = "01")then --insert 5$
 gum <= '0';
 CoinOut <= "00";
 next_s <= in_5c;
elsif(CoinIn = "10")then --insert 10$
 gum <= '0';
 CoinOut <= "00";
 next_s <= in_10c;
elsif(CoinIn = "11")then --insert 25$
 gum <= '0';
 CoinOut <= "00";
 next_s <= in_25c;
 end if;
 ------------------------------------------------------
 when in_5c => 
 if(CoinIn = "00") then--stay on the same state
 gum <= '0';
 CoinOut <= "00";
 next_s <= in_5c;
 elsif(CoinIn = "01") then--inserted another 1$
 gum <= '0';
 CoinOut <= "00";
 next_s <= in_10c;
 elsif(CoinIn = "01") then--inserted another 2$
 gum <= '0';
 CoinOut <= "00";
 next_s <= in_15c;
 elsif(CoinIn = "01") then--inserted another 2$
 gum <= '0';
 CoinOut <= "00";
 next_s <= in_20c;
 elsif(CoinIn = "01") then--inserted another 2$
 gum <= '0';
 CoinOut <= "00";
 next_s <= in_25c;
 elsif(CoinIn = "01") then--inserted another 2$
 gum <= '0';
 CoinOut <= "00";
 next_s <= in_30c;
 elsif(CoinIn = "01") then--inserted another 2$
 gum <= '0';
 CoinOut <= "00";
 next_s <= in_35c;
 elsif(CoinIn = "01") then--inserted another 2$
 gum <= '0';
 CoinOut <= "00";
 next_s <= gum_out;
 end if;
------------------------------------------------------
 when in_10c => 
 if(CoinIn = "00") then--stay on the same state
 gum <= '0';
 CoinOut <= "00";
 next_s <= in_10c;
 elsif(CoinIn = "10") then--inserted another 1$
 gum <= '0';
 CoinOut <= "00";
 next_s <= in_20c;
 elsif(CoinIn = "10") then--inserted another 1$
 gum <= '0';
 CoinOut <= "00";
 next_s <= in_30c;
 elsif(CoinIn = "10") then--inserted another 1$
 gum <= '0';
 CoinOut <= "00";
 next_s <= gum_out;
 end if;
------------------------------------------------------
 when in_25c => 
 if(CoinIn = "00") then--stay on the same state
 gum <= '0';
 CoinOut <= "00";
 next_s <= in_25c;
 elsif(CoinIn = "01") then--inserted another 1$
 gum <= '0';
 CoinOut <= "00";
 next_s <= in_30c;
 elsif(CoinIn = "01") then--inserted another 1$
 gum <= '0';
 CoinOut <= "00";
 next_s <= in_35c;
 elsif(CoinIn = "01") then--inserted another 1$
 gum <= '0';
 CoinOut <= "00";
 next_s <= gum_out;
 end if;
 ------------------------------------------------------
 when gum_out =>
 gum <= '1';
 CoinOut <= "00";
 next_s <= put_money; 

end case;
end process;
end behavior;

Answer 1

Your state_type is defined as an enumeration of 10 different values.

But your case statement covers only 6 of them. According to chapter 10.9 of the standard IEEE Std 1076-2008 you need to cover all cases.

This is what the error message tells you.

The solution is to cover all other cases, too, or to insert when others to catch these all together.