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--////////////////////////////////////////////////////////////////////

--//                                                              ////

--// search_item.vhd                                              ////

--//                                                              ////

--// This file is part of the open_hitter opencores effort.       ////

--// <http://www.opencores.org/cores/open_hitter/>                ////

--//                                                              ////

--// Module Description:                                          ////

--// This is the multipelexed search's repeated item. The project ////

--// buses perform the multiplex and are experienced by each item ////

--// as b1_* - input to search_item                               ////

--//    b2_* - output from search_item                            ////

--// there is also a small state-machine in each search_item.     ////

--// For now, the count of number of states is fixed, per px_type ////

--//                                                              ////

--// To Do:                                                       ////

--//                                                              ////

--// Author(s):                                                   ////

--// - Stephen Hawes                                              ////

--//                                                              ////

--////////////////////////////////////////////////////////////////////

--//                                                              ////

--// Copyright (C) 2015 Stephen Hawes and OPENCORES.ORG           ////

--//                                                              ////

--// This source file may be used and distributed without         ////

--// restriction provided that this copyright statement is not    ////

--// removed from the file and that any derivative work contains  ////

--// the original copyright notice and the associated disclaimer. ////

--//                                                              ////

--// This source file is free software; you can redistribute it   ////

--// and/or modify it under the terms of the GNU Lesser General   ////

--// Public License as published by the Free Software Foundation; ////

--// either version 2.1 of the License, or (at your option) any   ////

--// later version.                                               ////

--//                                                              ////

--// This source is distributed in the hope that it will be       ////

--// useful, but WITHOUT ANY WARRANTY; without even the implied   ////

--// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR      ////

--// PURPOSE. See the GNU Lesser General Public License for more  ////

--// details.                                                     ////

--//                                                              ////

--// You should have received a copy of the GNU Lesser General    ////

--// Public License along with this source; if not, download it   ////

--// from <http://www.opencores.org/lgpl.shtml>                   ////

--//                                                              ////

--////////////////////////////////////////////////////////////////////

--//

--// \$Id\$  TAKE OUT THE \'s and this comment in order to get this to work

--//

--// CVS Revision History

--//

--// \$Log\$  TAKE OUT THE \'s and this comment in order to get this to work

--//

library ieee;

use ieee.std_logic_1164.all;

entity search_item is

   port (

        RX_CLK: in std_logic;

        -- control flag(s) on the incoming bus

           b1_px_valid: in std_logic;

        -- pxdata: in price_packet

           b1_px_type: out std_logic_vector(4 downto 0);

           b1_buy_sell: out std_logic_vector(2 downto 0);   -- 111 buy, 000 sell

           b1_px: out std_logic_vector(15 downto 0);     -- price

           b1_qty: out std_logic_vector(15 downto 0);    -- quantity

           b1_sec: out std_logic_vector(55 downto 0);    -- 7x 8bits securities identifier

           b1_id: out std_logic_vector(15 downto 0);    -- unique/identifier/counter

        -- pxdata: out price_packet

           b2_px_type: out std_logic_vector(4 downto 0);

           b2_buy_sell: out std_logic_vector(2 downto 0);   -- 111 buy, 000 sell

           b2_px: out std_logic_vector(15 downto 0);     -- price

           b2_qty: out std_logic_vector(15 downto 0);    -- quantity

           b2_sec: out std_logic_vector(55 downto 0);    -- 7x 8bits securities identifier

           b2_id: out std_logic_vector(15 downto 0);     -- unique/identifier/counter

   );

end search_item;

architecture search_item_implementation of search_item is

      signal state : integer range 0 to 16 := 16;

   -- pxdata: out price_packet

      signal store_px_type: std_logic_vector(4 downto 0) := (others => '0');

      signal store_buy_sell: std_logic_vector(2 downto 0) := (others => '0');   -- 111 buy, 000 sell

      signal store_px: std_logic_vector(15 downto 0) := (others => '0');     -- price

      signal store_qty: std_logic_vector(15 downto 0) := (others => '0');    -- quantity

      signal store_sec: std_logic_vector(55 downto 0) := (others => '0');    -- 7x 8bits securities identifier

      signal store_id: std_logic_vector(15 downto 0) := (others => '0');     -- unique/identifier/counter

begin

   match: process (RX_CLK) is

   begin

      if rising_edge(RX_CLK) then

         if b1_px_valid then

            case b1_px_type is

               when '0000' =>

                   -- do reset store and outputs

                   store_px_type  <= (others => '0');

                   store_buy_sell <= (others => '0');   -- 111 buy, 000 sell

                   store_px       <= (others => '0');   -- price

                   store_qty      <= (others => '0');   -- quantity

                   store_sec      <= (others => '0');   -- 7x 8bits securities identifier

                   store_id       <= (others => '0');   -- unique/identifier/counter

                   --

                   b2_px_type  <= (others => 'Z');

                   b2_buy_sell <= (others => 'Z');   -- 111 buy, 000 sell

                   b2_px       <= (others => 'Z');   -- price

                   b2_qty      <= (others => 'Z');   -- quantity

                   b2_sec      <= (others => 'Z');   -- 7x 8bits securities identifier

                   b2_id       <= (others => 'Z');   -- unique/identifier/counter

                   --

                   b2_px_type <== '0000';

                   state <= 8;

               when '0110' =>

                   -- do set store from incoming price 

                   store_px_type  <= b1_px_type;

                   store_buy_sell <= b1_buy_sell;

                   store_px       <= b1_px;

                   store_qty      <= b1_qty;

                   store_sec      <= b1_sec;

                   store_id       <= b1_id;

                   --

                   b2_px_type <== '0000';

                   state <= 8;

               when '0101' =>

                   -- incoming price, register it and start the state machine

                   if (store_sec != b1_sec or store_buy_sell == b1_buy_sell or store_px_type != '0110')

                      -- not this store_item instance no action, also stop anything that might be going on

                      state <= 14;

                   elsif (store_qty == 0 or b1_qty == 0 or

                             (store_buy_sell == '111' and store_px < b1_px) or

                             (store_buy_sell == '000' and store_px > b1_px) )

                      -- no deal: this is the correct store_item but there's no match

                      b2_px_type <== '0000';

                      state <= 8;

                   else

                      -- send a return order

                      b2_px_type <= '1010';

                      b2_buy_sell <= store_buy_sell;   -- 111 buy, 000 sell

                      b2_px <= b1_px;                   -- price

                      b2_qty <= b1_qty when (b1_qty < store_qty) else store_qty;    -- quantity

                      b2_sec <= store_sec:                                          -- 7x 8bits securities identifier

                      b2_id <= store_id;                                            -- unique/identifier/counter

                      -- update the store

                      store_qty <= (store_qty-b1_qty) when (b1_qty < store_qty) else 0;

                      state <= 1;

                   end if;

               when others => null;

            end case;   -- b1_px_type

         else     -- b1_px_valid

            -- no incoming b1_px so check for state machine actions

            case state is

               when 1 =>

                   -- sent return order, so clean up

                   b2_px_type  <= (others => 'Z');

                   b2_buy_sell <= (others => 'Z');    -- 111 buy, 000 sell

                   b2_px       <= (others => 'Z');    -- price

                   b2_qty      <= (others => 'Z');    -- quantity

                   b2_sec      <= (others => 'Z');    -- 7x 8bits securities identifier

                   b2_id       <= (others => 'Z'):    -- unique/identifier/counter

                   state <= 16;

               when 8 =>

                    -- correct store_item but there was no match

                    b2_px_type <== 'ZZZZ';

                   state <= 16;

               when others => null;

            end case;   -- state

            if (state < 16) then

               state <= state + 1;

            end if;

         end if;     -- b1_px_valid

      end if;

   end process match;

end search_item_implementation;