Subversion Repositories neorv32

library ieee;

use ieee.std_logic_1164.all;

use ieee.numeric_std.all;

use ieee.math_real.all;

use std.textio.all;

library vunit_lib;

context vunit_lib.vunit_context;

context vunit_lib.com_context;

context vunit_lib.vc_context;

use work.uart_rx_pkg.all;

entity uart_rx is

  generic (handle : uart_rx_t);

  port (

    clk : in std_ulogic;

    uart_txd : in std_ulogic

    );

end entity;

architecture a of uart_rx is

  signal uart_rx_sync : std_ulogic_vector(04 downto 0) := (others => '1');

  signal uart_rx_busy : std_ulogic := '0';

  signal uart_rx_sreg : std_ulogic_vector(08 downto 0) := (others => '0');

  signal uart_rx_baud_cnt : real;

  signal uart_rx_bitcnt : natural;

  file file_uart_tx_out : text open write_mode is "neorv32.testbench_" & get_name(handle.p_logger) & ".out";

  constant checker : checker_t := new_checker(handle.p_logger);

  constant character_queue : queue_t := new_queue;

begin

  control : process

    variable request_msg, reply_msg : msg_t;

    variable msg_type : msg_type_t;

    procedure put_characters_in_queue(s : string) is

    begin

      for idx in s'range loop

        push(character_queue, s(idx));

      end loop;

    end procedure put_characters_in_queue;

  begin

    receive(net, handle.p_actor, request_msg);

    msg_type := message_type(request_msg);

    -- Standard handling of standard wait_for_time messages = wait for the given time

    -- before proceeeding

    handle_wait_for_time(net, msg_type, request_msg);

    if msg_type = check_uart_msg then

      put_characters_in_queue(pop(request_msg));

    -- Custom handling of standard wait_until_idle message

    elsif msg_type = wait_until_idle_msg then

      while not is_empty(character_queue) loop

        wait until rising_edge(clk);

      end loop;

      reply_msg := new_msg(wait_until_idle_reply_msg);

      reply(net, request_msg, reply_msg);

    else

      unexpected_msg_type(msg_type);

    end if;

  end process;

  uart_rx_console : process(clk)

    variable i : integer;

    variable l : line;

    variable expected_character : character;

  begin

    -- "UART" --

    if rising_edge(clk) then

      -- synchronizer --

      uart_rx_sync <= uart_rx_sync(3 downto 0) & uart_txd;

      -- arbiter --

      if (uart_rx_busy = '0') then  -- idle

        uart_rx_busy <= '0';

        uart_rx_baud_cnt <= round(0.5 * handle.p_baud_val);

        uart_rx_bitcnt <= 9;

        if (uart_rx_sync(4 downto 1) = "1100") then  -- start bit? (falling edge)

          uart_rx_busy <= '1';

        end if;

      else

        if (uart_rx_baud_cnt <= 0.0) then

          if (uart_rx_bitcnt = 1) then

            uart_rx_baud_cnt <= round(0.5 * handle.p_baud_val);

          else

            uart_rx_baud_cnt <= round(handle.p_baud_val);

          end if;

          if (uart_rx_bitcnt = 0) then

            uart_rx_busy <= '0';  -- done

            i := to_integer(unsigned(uart_rx_sreg(8 downto 1)));

            if is_empty(character_queue) then

              check_failed(checker, "Extra characters received");

            else

              expected_character := pop(character_queue);

              check_equal(checker, character'val(i), expected_character);

            end if;

            if (i = 10) then  -- Linux line break

              writeline(file_uart_tx_out, l);

            elsif (i /= 13) then  -- Remove additional carriage return

              write(l, character'val(i));

            end if;

          else

            uart_rx_sreg <= uart_rx_sync(4) & uart_rx_sreg(8 downto 1);

            uart_rx_bitcnt <= uart_rx_bitcnt - 1;

          end if;

        else

          uart_rx_baud_cnt <= uart_rx_baud_cnt - 1.0;

        end if;

      end if;

    end if;

  end process uart_rx_console;

end architecture;