Subversion Repositories t400

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

--

-- The Data memory controller.

--

-- $Id: t400_dmem_ctrl.vhd 179 2009-04-01 19:48:38Z arniml $

--

-- Copyright (c) 2006 Arnim Laeuger (arniml@opencores.org)

--

-- All rights reserved

--

-- Redistribution and use in source and synthezised 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 synthesized 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.

--

-- Neither the name of the author nor the names of other contributors may

-- be used to endorse or promote products derived from this software without

-- specific prior written permission.

--

-- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 THE AUTHOR OR CONTRIBUTORS 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.

--

-- Please report bugs to the author, but before you do so, please

-- make sure that this is not a derivative work and that

-- you have the latest version of this file.

--

-- The latest version of this file can be found at:

--      http://www.opencores.org/cvsweb.shtml/t400/

--

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

library ieee;

use ieee.std_logic_1164.all;

use work.t400_opt_pack.all;

use work.t400_pack.all;

entity t400_dmem_ctrl is

  generic (

    opt_type_g : integer := t400_opt_type_420_c

  );

  port (

    -- System Interface -------------------------------------------------------

    ck_i       : in  std_logic;

    ck_en_i    : in  boolean;

    por_i      : in  boolean;

    res_i      : in  boolean;

    -- Control Interface ------------------------------------------------------

    dmem_op_i  : in  dmem_op_t;

    b_op_i     : in  b_op_t;

    dec_data_i : in  dec_data_t;

    a_i        : in  dw_t;

    q_high_i   : in  dw_t;

    b_o        : out b_t;

    -- Data Memory Interface --------------------------------------------------

    dm_addr_o  : out dm_addr_t;

    dm_data_i  : in  dw_t;

    dm_data_o  : out dw_t;

    dm_we_o    : out std_logic

  );

end t400_dmem_ctrl;

library ieee;

use ieee.numeric_std.all;

architecture rtl of t400_dmem_ctrl is

  signal br_q : unsigned(br_range_t);

  signal bd_q : unsigned(bd_range_t);

begin

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

  -- Process b_reg

  --

  -- Purpose:

  --   Implements the B register.

  --

  b_reg: process (ck_i, por_i)

  begin

    if por_i then

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

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

    elsif ck_i'event and ck_i = '1' then

      if    res_i then

        -- synchronous reset upon external reset event

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

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

      elsif ck_en_i then

        case b_op_i is

          -- Set Bd from accumulator ------------------------------------------

          when B_SET_BD =>

            bd_q <= unsigned(a_i);

          -- Set Br from accumulator ------------------------------------------

          when B_SET_BR =>

            br_q <= unsigned(a_i(1 downto 0));

          -- Set Br and Bd from decoder data ----------------------------------

          when B_SET_B =>

            br_q <= unsigned(dec_data_i(br_range_t));

            bd_q <= unsigned(dec_data_i(bd_range_t));

          -- Set Br and Bd from decoder data, increment value for Bd ----------

          when B_SET_B_INC =>

            br_q <= unsigned(dec_data_i(br_range_t));

            bd_q <= unsigned(dec_data_i(bd_range_t)) + 1;

          -- XOR Br with decoder data -----------------------------------------

          when B_XOR_BR =>

            br_q <= br_q xor unsigned(dec_data_i(br_range_t));

          -- Increment Bd -----------------------------------------------------

          when B_INC_BD =>

            bd_q <= bd_q + 1;

          -- Increment Bd -----------------------------------------------------

          when B_DEC_BD =>

            bd_q <= bd_q - 1;

          when others =>

            null;

        end case;

      end if;

    end if;

  end process b_reg;

  --

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

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

  -- Process data_mux

  --

  -- Purpose:

  --   Multiplexes the data for writing to the memory.

  --

  data_mux: process (dmem_op_i,

                     br_q, bd_q,

                     a_i,

                     q_high_i,

                     dec_data_i,

                     dm_data_i,

                     ck_en_i)

    variable dm_addr_v : dm_addr_t;

    variable dm_data_v : dw_t;

    variable dm_we_v   : std_logic;

    variable bd_v      : std_logic_vector(2 downto 0);

  begin

    -- default assignment

    dm_addr_v(br_range_t) := std_logic_vector(br_q);

    dm_addr_v(bd_range_t) := std_logic_vector(bd_q);

    dm_data_v := (others => '0');

    dm_we_v   := '0';

    case dmem_op_i is

      -- Read data memory, indexed by B ---------------------------------------

      when DMEM_RB =>

        null;

      -- Write data memory, indexed by B, source is Q -------------------------

      when DMEM_WB_SRC_Q =>

        dm_we_v   := '1';

        dm_data_v := q_high_i;

      -- Write data memory, indexed by B, source is decoder data --------------

      when DMEM_WB_SRC_DEC =>

        dm_we_v   := '1';

        dm_data_v := dec_data_i(bd_range_t);

      -- Write data memory, indexed by B, source is accumulator ---------------

      when DMEM_WB_SRC_A =>

        dm_we_v   := '1';

        dm_data_v := a_i;

      -- Read data memory, indexed by decoder data ----------------------------

      when DMEM_RDEC =>

        dm_addr_v := dec_data_i(br_range_t'high downto 0);

      -- Write data memory, indexed by decoder data, source is accumulator ----

      when DMEM_WDEC_SRC_A =>

        dm_we_v   := '1';

        dm_addr_v := dec_data_i(br_range_t'high downto 0);

        dm_data_v := a_i;

      -- Write data memory, indexed by B, set bit -----------------------------

      when DMEM_WB_SET_BIT =>

        dm_we_v   := '1';

        dm_data_v := dm_data_i or dec_data_i(dw_range_t);

      -- Write data memory, indexed by B, reset bit ---------------------------

      when DMEM_WB_RES_BIT =>

        dm_we_v   := '1';

        dm_data_v := dm_data_i and not dec_data_i(dw_range_t);

      when others =>

        null;

    end case;

    -- adjust address vector for 41xL family members

    if opt_type_g = t400_opt_type_410_c then

      dm_addr_v := '0' & dm_addr_v(br_range_t) &

                         dm_addr_v(bd_range_t'high-1 downto 0);

    end if;

    dm_addr_o <= dm_addr_v;

    if ck_en_i then

      dm_we_o   <= dm_we_v;

    else

      dm_we_o   <= '0';

    end if;

    dm_data_o   <= dm_data_v;

  end process data_mux;

  --

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

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

  -- Output mapping

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

  b_o(br_range_t) <= std_logic_vector(br_q);

  b_o(bd_range_t) <= std_logic_vector(bd_q);

end rtl;