Question

How can I generate a single multiplexer with FOR loop.
Here is a snippet what I mean:

CASE test IS
    FOR i IN ... LOOP
        WHEN i => ... ;
    END LOOP;
END CASE;

I am aware that one can put FOR before CASE but in that case it will generate many multiplexers?

Answer 1

You can’t have a loop like that to generate the expressions for a case statement. You can probably do something close to what you want without the case, however, by just using the for loop:

FOR i IN ... LOOP
  IF test = i then
    output <= myarray(i);
  END IF;
END LOOP;

…but if all you’re doing is a simple multiplexer like the above, you don’t need the case or the loop, you can just index directly with your selection signal:

output <= myarray(to_integer(test));