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-- Copyright (c)2021 Jeremy Seth Henry

-- All rights reserved.

--

-- Redistribution and use in source and binary forms, with or without

-- modification, are permitted provided that the following conditions are met:

--     * Redistributions of source code must retain the above copyright

--       notice, this list of conditions and the following disclaimer.

--     * Redistributions in binary form must reproduce the above copyright

--       notice, this list of conditions and the following disclaimer in the

--       documentation and/or other materials provided with the distribution,

--       where applicable (as part of a user interface, debugging port, etc.)

--

-- THIS SOFTWARE IS PROVIDED BY JEREMY SETH HENRY ``AS IS'' AND ANY

-- EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

-- WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE

-- DISCLAIMED. IN NO EVENT SHALL JEREMY SETH HENRY BE LIABLE FOR ANY

-- DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES

-- (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;

-- LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND

-- ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

-- (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS

-- SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

--

-- VHDL Entity: vector_tx

-- Description: Reads  the pushbuttons and switches on the DE1-SOC board and

--               sends a vector command and argument to a vector_rx receiver

--               which executes them in lieu of a parallel controller.

--

-- Revision History

-- Author          Date     Change

------------------ -------- ---------------------------------------------------

-- Seth Henry      05/06/20 Added version block

-- Seth Henry      04/07/21 Modified to replace hard-coded blocks with true

--                           argument inputs.

-- Seth Henry      09/15/21 Added flow control and made the Magic_Num a generic

library ieee;

  use ieee.std_logic_1164.all;

  use ieee.std_logic_unsigned.all;

  use ieee.std_logic_arith.all;

  use ieee.std_logic_misc.all;

library work;

  use work.open8_pkg.all;

entity vector_tx is

generic(

  Magic_Num                  : DATA_TYPE := x"4D";

  Bit_Rate                   : real;

  Enable_Parity              : boolean;

  Parity_Odd_Even_n          : std_logic;

  Clock_Frequency            : real;

  Reset_Level                : std_logic

);

port(

  Clock                      : in  std_logic;

  Reset                      : in  std_logic;

  --

  Tx_Enable                  : in  std_logic;

  Tx_Command                 : in  DATA_TYPE;

  Tx_Arg_Lower               : in  DATA_TYPE;

  Tx_Arg_Upper               : in  DATA_TYPE;

  --

  Tx_Busy                    : out std_logic;

  --

  Tx_Out                     : out std_logic;

  Tx_FC                      : in  std_logic := '1'

);

end entity;

architecture behave of vector_tx is

  signal Command_Buffer      : DATA_TYPE := x"00";

  signal Arg_Lower_Buffer    : DATA_TYPE := x"00";

  signal Arg_Upper_Buffer    : DATA_TYPE := x"00";

  type VECTOR_TX_STATES is (IDLE, WAIT_FC,

                            SEND_CMD, WAIT_CMD,

                            SEND_ARG_LB, WAIT_ARG_LB,

                            SEND_ARG_UB, WAIT_ARG_UB,

                            SEND_SUM_LB, WAIT_SUM_LB,

                            SEND_SUM_UB, WAIT_SUM_UB );

  signal Vector_State        : VECTOR_TX_STATES := IDLE;

  constant BAUD_RATE_DIV     : integer := integer(Clock_Frequency / Bit_Rate);

  signal Checksum            : ADDRESS_TYPE := x"0000";

  alias  Checksum_LB         is Checksum(7 downto 0);

  alias  Checksum_UB         is Checksum(15 downto 8);

  signal Tx_Data             : DATA_TYPE := x"00";

  signal Tx_Valid            : std_logic := '0';

  signal Tx_Done             : std_logic := '0';

begin

  TX_FSM_proc: process( Clock, Reset )

  begin

    if( Reset = Reset_Level )then

      Vector_State           <= IDLE;

      Command_Buffer         <= x"00";

      Arg_Lower_Buffer       <= x"00";

      Arg_Upper_Buffer       <= x"00";

      Tx_Busy                <= '0';

      Tx_Data                <= x"00";

      Tx_Valid               <= '0';

    elsif( rising_edge(Clock) )then

      Tx_Busy                <= '1';

      Tx_Data                <= x"00";

      Tx_Valid               <= '0';

      case( Vector_State )is

        when IDLE =>

          Tx_Busy            <= '0';

          Checksum           <= x"00" & MAGIC_NUM;

          if( Tx_Enable = '1' )then

            Command_Buffer   <= Tx_Command;

            Arg_Lower_Buffer <= Tx_Arg_Lower;

            Arg_Upper_Buffer <= Tx_Arg_Upper;

            Vector_State     <= WAIT_FC;

          end if;

        when WAIT_FC =>

          if( Tx_FC = '1' )then

            Vector_State     <= SEND_CMD;

          end if;

        when SEND_CMD =>

          Tx_Data            <= Command_Buffer;

          Tx_Valid           <= '1';

          Checksum           <= Checksum + Command_Buffer;

          Vector_State       <= WAIT_CMD;

        when WAIT_CMD =>

          if( Tx_Done = '1' )then

            Vector_State     <= SEND_ARG_LB;

          end if;

        when SEND_ARG_LB =>

          Tx_Data            <= Arg_Lower_Buffer;

          Tx_Valid           <= '1';

          Checksum           <= Checksum + Arg_Lower_Buffer;

          Vector_State       <= WAIT_ARG_LB;

        when WAIT_ARG_LB =>

          if( Tx_Done = '1' )then

            Vector_State     <= SEND_ARG_UB;

          end if;

        when SEND_ARG_UB =>

          Tx_Data            <= Arg_Upper_Buffer;

          Tx_Valid           <= '1';

          Checksum           <= Checksum + Arg_Upper_Buffer;

          Vector_State       <= WAIT_ARG_UB;

        when WAIT_ARG_UB =>

          if( Tx_Done = '1' )then

            Vector_State     <= SEND_SUM_LB;

          end if;

        when SEND_SUM_LB =>

          Tx_Data            <= Checksum_LB;

          Tx_Valid           <= '1';

          Vector_State       <= WAIT_SUM_LB;

        when WAIT_SUM_LB =>

          if( Tx_Done = '1' )then

            Vector_State     <= SEND_SUM_UB;

          end if;

        when SEND_SUM_UB =>

          Tx_Data            <= Checksum_UB;

          Tx_Valid           <= '1';

          Vector_State       <= WAIT_SUM_UB;

        when WAIT_SUM_UB =>

          if( Tx_Done = '1' )then

            Vector_State     <= IDLE;

          end if;

      end case;

    end if;

  end process;

  U_TX : entity work.async_ser_tx

  generic map(

    Reset_Level              => Reset_Level,

    Enable_Parity            => Enable_Parity,

    Parity_Odd_Even_n        => Parity_Odd_Even_n,

    Clock_Divider            => BAUD_RATE_DIV

  )

  port map(

    Clock                    => Clock,

    Reset                    => Reset,

    --

    Tx_Data                  => Tx_Data,

    Tx_Valid                 => Tx_Valid,

    --

    Tx_Out                   => Tx_Out,

    Tx_Done                  => Tx_Done

  );

end architecture;