case(state)
        `fetch_0: begin
            cp_oe       = 1;
            am_we       = 1;
            state_next  = `fetch_1;
        end

        `fetch_1: begin
            am_oe       = 1;
            state_next  = `fetch_2;
        end

        `fetch_2: begin
            ram_oe      = 1;
            ri_we       = 1;
            state_next  = `decode;
        end
...