if s_rxd_val = '0' then                  if s_m13_rxshift_en = '1' then                    s_recv_sh(7) <= s_rxd_val;		    s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);                v_rxstep := "01";                  end if;                else                    -- reject false start bits                  if s_m13_rxshift_en = '1' then                v_rxstep := "10";                                      end if;                end if;                                end if;            when ("0010") =>            -- D1              if s_m13_rxshift_en = '1' then                s_recv_sh(7) <= s_rxd_val;		s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);                v_rxstep := "01";              end if;            when ("0011") =>            -- D2              if s_m13_rxshift_en = '1' then                s_recv_sh(7) <= s_rxd_val;		s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);                v_rxstep := "01";              end if;            when ("0100") =>            -- D3              if s_m13_rxshift_en = '1' then                s_recv_sh(7) <= s_rxd_val;		s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);                v_rxstep := "01";              end if;            when ("0101") =>            -- D4              if s_m13_rxshift_en = '1' then                s_recv_sh(7) <= s_rxd_val;		s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);                v_rxstep := "01";              end if;            when ("0110") =>            -- D5              if s_m13_rxshift_en = '1' then                s_recv_sh(7) <= s_rxd_val;		s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);                v_rxstep := "01";              end if;            when ("0111") =>            -- D6              if s_m13_rxshift_en = '1' then                s_recv_sh(7) <= s_rxd_val;		s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);                v_rxstep := "01";              end if;            when ("1000") =>            -- D7              if s_m13_rxshift_en = '1' then                s_recv_sh(7) <= s_rxd_val;		s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);                v_rxstep := "01";              end if;            when ("1001") =>            -- D8              if s_m13_rxshift_en = '1' then                s_recv_sh(7) <= s_rxd_val;		s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);                v_rxstep := "01";              end if;            when ("1010") =>            -- D9 = STOP BIT              -- store data and set interrupt bit if conditions are met.              if (s_ri = '0' and s_sm2 = '0') or                 (s_ri = '0' and s_rxd_val = '1') then                if s_m13_rxshift_en = '1' then                  s_recv_sh(7) <= s_rxd_val;		  s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);                  v_rxstep := "10";                  s_recv_done <= '1';                  s_rb8 <= s_rxd_val;                  s_recv_buf <= s_recv_sh(7 downto 0);                end if;              -- forget data and recommence listening for a start bit              else                if s_m13_rxshift_en = '1' then                v_rxstep := "10";                                  end if;                              end if;            when others =>                v_rxstep := "10";            end case;--------------------------------------------------------------------------------- MODE 2-------------------------------------------------------------------------------          when ("10") =>            case s_recv_state is            when ("0000") =>            -- synchronise reception              if s_ren = '1' and s_detect = '1' then                v_rxstep := "01";                s_recv_sh <= conv_unsigned(0,8);                s_recv_done <= '0';              end if;            when ("0001") =>            -- D0 = START BIT              if s_rxd_val = '0' then                if s_m2_rxshift_en = '1' then                  s_recv_sh(7) <= s_rxd_val;		  s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);                v_rxstep := "01";                end if;              else                    -- reject false start bits                if s_m2_rxshift_en = '1' then                v_rxstep := "10";                                    end if;              end if;            when ("0010") =>            -- D1              if s_m2_rxshift_en = '1' then                s_recv_sh(7) <= s_rxd_val;		s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);                v_rxstep := "01";              end if;            when ("0011") =>            -- D2              if s_m2_rxshift_en = '1' then                s_recv_sh(7) <= s_rxd_val;		s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);                v_rxstep := "01";              end if;            when ("0100") =>            -- D3              if s_m2_rxshift_en = '1' then                s_recv_sh(7) <= s_rxd_val;		s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);                v_rxstep := "01";              end if;            when ("0101") =>            -- D4              if s_m2_rxshift_en = '1' then                s_recv_sh(7) <= s_rxd_val;		s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);                v_rxstep := "01";              end if;            when ("0110") =>            -- D5              if s_m2_rxshift_en = '1' then                s_recv_sh(7) <= s_rxd_val;		s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);                v_rxstep := "01";              end if;            when ("0111") =>            -- D6              if s_m2_rxshift_en = '1' then                s_recv_sh(7) <= s_rxd_val;		s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);                v_rxstep := "01";              end if;            when ("1000") =>            -- D7              if s_m2_rxshift_en = '1' then                s_recv_sh(7) <= s_rxd_val;		s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);                v_rxstep := "01";              end if;            when ("1001") =>            -- D8              if s_m2_rxshift_en = '1' then                s_recv_sh(7) <= s_rxd_val;		s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);                v_rxstep := "01";              end if;            when ("1010") =>            -- D9              -- store data and set interrupt bit if conditions are met.              if (s_ri = '0' and s_sm2 = '0') or                 (s_ri = '0' and s_rxd_val = '1') then                if s_m2_rxshift_en = '1' then                  s_recv_sh(7) <= s_rxd_val;		  s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);                  s_recv_done <= '1';                  s_rb8 <= s_rxd_val;                  s_recv_buf <= s_recv_sh(7 downto 0);                end if;              end if;              -- forget data               if s_m2_rxshift_en = '1' then                v_rxstep := "01";              end if;                            when ("1011") =>            -- D10 STOP BIT              -- recommence listening for a start bit              if s_m2_rxshift_en = '1' then                -- s_recv_state <= conv_unsigned(0,4);                v_rxstep := "10";              end if;            when others =>              -- s_recv_state <= conv_unsigned(0,4);                v_rxstep := "10";            end case;--------------------------------------------------------------------------------- MODE 3-------------------------------------------------------------------------------          when ("11") =>            case s_recv_state is            when ("0000") =>            -- synchronise reception              if s_ren = '1' and s_detect = '1' then                v_rxstep := "01";                s_recv_sh <= conv_unsigned(0,8);                s_recv_done <= '0';              end if;            when ("0001") =>            -- D0 = START BIT              if s_detect = '0' then                if s_rxd_val = '0' then                  if s_m13_rxshift_en = '1' then                    s_recv_sh(7) <= s_rxd_val;	            s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);                  v_rxstep := "01";                  end if;                else                    -- reject false start bits                  if s_m13_rxshift_en = '1' then                  v_rxstep := "10";                                      end if;                end if;              end if;            when ("0010") =>            -- D1              if s_m13_rxshift_en = '1' then                s_recv_sh(7) <= s_rxd_val;		s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);                v_rxstep := "01";              end if;            when ("0011") =>            -- D2              if s_m13_rxshift_en = '1' then                s_recv_sh(7) <= s_rxd_val;		s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);                v_rxstep := "01";              end if;            when ("0100") =>            -- D3              if s_m13_rxshift_en = '1' then                s_recv_sh(7) <= s_rxd_val;		s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);                v_rxstep := "01";              end if;            when ("0101") =>            -- D4              if s_m13_rxshift_en = '1' then                s_recv_sh(7) <= s_rxd_val;		s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);                v_rxstep := "01";              end if;            when ("0110") =>            -- D5              if s_m13_rxshift_en = '1' then                s_recv_sh(7) <= s_rxd_val;		s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);                v_rxstep := "01";              end if;            when ("0111") =>            -- D6              if s_m13_rxshift_en = '1' then                s_recv_sh(7) <= s_rxd_val;		s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);                v_rxstep := "01";              end if;            when ("1000") =>            -- D7              if s_m13_rxshift_en = '1' then                s_recv_sh(7) <= s_rxd_val;		s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);                v_rxstep := "01";              end if;            when ("1001") =>            -- D8              if s_m13_rxshift_en = '1' then                s_recv_sh(7) <= s_rxd_val;		s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);                v_rxstep := "01";              end if;            when ("1010") =>            -- D9              -- store data and set interrupt bit if conditions are met.              if (s_ri = '0' and s_sm2 = '0') or                 (s_ri = '0' and s_rxd_val = '1') then                if s_m13_rxshift_en = '1' then                  s_recv_sh(7) <= s_rxd_val;		  s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);                  s_recv_done <= '1';                  s_rb8 <= s_rxd_val;                  s_recv_buf <= s_recv_sh(7 downto 0);                end if;              end if;              -- forget data               if s_m13_rxshift_en = '1' then                v_rxstep := "01";              end if;                            when ("1011") =>            -- D10 STOP BIT              -- recommence listening for a start bit              if s_m13_rxshift_en = '1' then                v_rxstep := "10";              end if;            when others =>                v_rxstep := "10";            end case;          when others =>            null;          end case;	  case v_rxstep is	    when "01" =>	      s_recv_state <= s_recv_state + conv_unsigned(1,1);	    when "10" =>	      s_recv_state <= conv_unsigned(0,4);	    when others =>	      null;	  end case;	          end if;      end if;  end process p_receive;  end rtl;