case (my_state_val & val_q) is when ("000" & "00") => do something; when ("001" & "00") => do something else; when ("010" & "10") => do a 3rd thing; when ("100" & "DONT CARE") => do a non-default thing because my_state_val is valid; when others => default state or null;
end case;If it was an if check, I could do: val_q /= "11" because I know my counter will never reach the top value. How can I do this in a case statement?
The reason why I want a case statement is because I don't want a 30+ depth branches.
if 1 then
elsif 2 then
...
elsif 25 then
elsif 26 then
elsif 27 then
else
end if;2 Answers
I would suggest either this:
case (my_state_val & val_q) is when ("000" & "00") => do something; when ("001" & "00") => do something else; when ("010" & "10") => do a 3rd thing; when others => if my_state_val == "100" then do a non-default thing because my_state_val is valid else default state or null; end if; end case;
Or this:
case (my_state_val) is when ("000") => Evaluate val_q; when ("001") => Evaluate val_q; when ("010") => Evaluate val_q; when ("100") => Evaluate val_q; when others => default state or null; end case;
I initially attempted this:
case (my_state_val & val_q) is when ... => ....; ... when ("100" & "--") => do something; when others => null;
end case;Simulation worked. However, my mentors are used to non-2008 VHDL and even if it was synthesize-able, it could raise questions by other engineers. So I want something that passes our coding guidelines.
I used an if-else wrapped around this case statement.
if my_state_val = "100" then my do something here; else case (my_state_val & val_q) is when ... => ....; ... -- removed "--" when others => null; end case;
end if;
