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

--

-- T48 Microcontroller Core

--

-- $Id: t48_core.vhd,v 1.2 2004-03-28 13:13:20 arniml Exp $

--

-- Copyright (c) 2004, 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/t48/

--

-- Limitations :

-- =============

--

-- Compared to the original MCS-48 architecture, the following limitations

-- apply:

--

--   * DA A instruction not implemented.

--     Implementation targeted for Beta milestone.

--

--   * Nibble-wide instructions addressing expander port not implemented.

--     Implementation targeted for Beta milestone.

--

--   * Single-step mode not implemented.

--     Not selected for future implementation.

--

--   * Reading of internal Program Memory not implemented.

--     Not selected for future implementation.

--

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

library ieee;

use ieee.std_logic_1164.all;

entity t48_core is

  generic (

    -- divide XTAL1 by 3 to derive Clock States

    xtal_div_3_g          : integer := 1;

    -- store mnemonic in flip-flops (registered-out)

    register_mnemonic_g   : integer := 1;

    -- include the port 1 module

    include_port1_g       : integer := 1;

    -- include the port 2 module

    include_port2_g       : integer := 1;

    -- include the BUS module

    include_bus_g         : integer := 1;

    -- include the timer module

    include_timer_g       : integer := 1;

    -- state in which T1 is sampled (3 or 4)

    sample_t1_state_g     : integer := 4

  );

  port (

    -- T48 Interface ----------------------------------------------------------

    xtal_i      : in  std_logic;

    reset_i     : in  std_logic;

    t0_i        : in  std_logic;

    t0_o        : out std_logic;

    t0_dir_o    : out std_logic;

    int_n_i     : in  std_logic;

    ea_i        : in  std_logic;

    rd_n_o      : out std_logic;

    psen_n_o    : out std_logic;

    wr_n_o      : out std_logic;

    ale_o       : out std_logic;

    db_i        : in  std_logic_vector( 7 downto 0);

    db_o        : out std_logic_vector( 7 downto 0);

    db_dir_o    : out std_logic;

    t1_i        : in  std_logic;

    p2_i        : in  std_logic_vector( 7 downto 0);

    p2_o        : out std_logic_vector( 7 downto 0);

    p2_limp_o   : out std_logic;

    p1_i        : in  std_logic_vector( 7 downto 0);

    p1_o        : out std_logic_vector( 7 downto 0);

    p1_limp_o   : out std_logic;

    prog_n_o    : out std_logic;

    -- Core Interface ---------------------------------------------------------

    clk_i       : in  std_logic;

    en_clk_i    : in  std_logic;

    xtal3_o     : out std_logic;

    dmem_addr_o : out std_logic_vector( 7 downto 0);

    dmem_we_o   : out std_logic;

    dmem_data_i : in  std_logic_vector( 7 downto 0);

    dmem_data_o : out std_logic_vector( 7 downto 0);

    pmem_addr_o : out std_logic_vector(11 downto 0);

    pmem_data_i : in  std_logic_vector( 7 downto 0)

  );

end t48_core;

use work.alu_pack.alu_op_t;

use work.cond_branch_pack.branch_conditions_t;

use work.cond_branch_pack.comp_value_t;

use work.dmem_ctrl_pack.dmem_addr_ident_t;

use work.pmem_ctrl_pack.pmem_addr_ident_t;

use work.t48_comp_pack.all;

use work.t48_pack.bus_idle_level_c;

use work.t48_pack.word_t;

use work.t48_pack.pmem_addr_t;

use work.t48_pack.mstate_t;

use work.t48_pack.to_stdLogic;

use work.t48_pack.to_boolean;

architecture struct of t48_core is

  signal t48_data_s : word_t;

  signal en_clk_s   : boolean;

  -- ALU signals

  signal alu_data_s           : word_t;

  signal alu_write_accu_s     : boolean;

  signal alu_write_shadow_s   : boolean;

  signal alu_write_temp_reg_s : boolean;

  signal alu_read_alu_s       : boolean;

  signal alu_carry_s          : std_logic;

  signal alu_aux_carry_s      : std_logic;

  signal alu_op_s             : alu_op_t;

  signal alu_use_carry_s      : boolean;

  -- BUS signals

  signal bus_write_bus_s  : boolean;

  signal bus_read_bus_s   : boolean;

  signal bus_output_pcl_s : boolean;

  signal bus_bidir_bus_s  : boolean;

  signal bus_data_s       : word_t;

  -- Clock Controller signals

  signal clk_multi_cycle_s  : boolean;

  signal clk_assert_psen_s  : boolean;

  signal clk_assert_prog_s  : boolean;

  signal clk_assert_rd_s    : boolean;

  signal clk_assert_wr_s    : boolean;

  signal clk_mstate_s       : mstate_t;

  signal clk_second_cycle_s : boolean;

  signal psen_s             : boolean;

  signal prog_s             : boolean;

  signal rd_s               : boolean;

  signal wr_s               : boolean;

  signal ale_s              : boolean;

  signal xtal3_s            : boolean;

  -- Conditional Branch Logic signals

  signal cnd_compute_take_s : boolean;

  signal cnd_branch_cond_s  : branch_conditions_t;

  signal cnd_take_branch_s  : boolean;

  signal cnd_comp_value_s   : comp_value_t;

  signal cnd_f1_s           : std_logic;

  signal cnd_tf_s           : std_logic;

  -- Data Memory Controller signals

  signal dm_write_dmem_addr_s : boolean;

  signal dm_write_dmem_s      : boolean;

  signal dm_read_dmem_s       : boolean;

  signal dm_addr_type_s       : dmem_addr_ident_t;

  signal dm_data_s            : word_t;

  -- Decoder signals

  signal dec_data_s           : word_t;

  -- Port 1 signals

  signal p1_write_p1_s : boolean;

  signal p1_read_p1_s  : boolean;

  signal p1_read_reg_s : boolean;

  signal p1_data_s     : word_t;

  -- Port 2 signals

  signal p2_write_p2_s   : boolean;

  signal p2_write_exp_s  : boolean;

  signal p2_read_p2_s    : boolean;

  signal p2_read_reg_s   : boolean;

  signal p2_read_exp_s   : boolean;

  signal p2_output_pch_s : boolean;

  signal p2_output_exp_s : boolean;

  signal p2_data_s       : word_t;

  -- Program Memory Controller signals

  signal pm_write_pcl_s       : boolean;

  signal pm_read_pcl_s        : boolean;

  signal pm_write_pch_s       : boolean;

  signal pm_read_pch_s        : boolean;

  signal pm_read_pmem_s       : boolean;

  signal pm_inc_pc_s          : boolean;

  signal pm_write_pmem_addr_s : boolean;

  signal pm_data_s            : word_t;

  signal pm_addr_type_s       : pmem_addr_ident_t;

  signal pmem_addr_s          : pmem_addr_t;

  -- PSW signals

  signal psw_read_psw_s        : boolean;

  signal psw_read_sp_s         : boolean;

  signal psw_write_psw_s       : boolean;

  signal psw_write_sp_s        : boolean;

  signal psw_carry_s           : std_logic;

  signal psw_aux_carry_s       : std_logic;

  signal psw_f0_s              : std_logic;

  signal psw_bs_s              : std_logic;

  signal psw_special_data_s    : std_logic;

  signal psw_inc_stackp_s      : boolean;

  signal psw_dec_stackp_s      : boolean;

  signal psw_write_carry_s     : boolean;

  signal psw_write_aux_carry_s : boolean;

  signal psw_write_f0_s        : boolean;

  signal psw_write_bs_s        : boolean;

  signal psw_data_s            : word_t;

  -- Timer signals

  signal tim_overflow_s    : boolean;

  signal tim_of_s          : std_logic;

  signal tim_read_timer_s  : boolean;

  signal tim_write_timer_s : boolean;

  signal tim_start_t_s     : boolean;

  signal tim_start_cnt_s   : boolean;

  signal tim_stop_tcnt_s   : boolean;

  signal tim_data_s        : word_t;

begin

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

  -- Check generics for valid values.

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

  -- pragma translate_off

  assert include_timer_g = 0 or include_timer_g = 1

    report "include_timer_g must be either 1 or 0!"

    severity failure;

  assert include_port1_g = 0 or include_port1_g = 1

    report "include_port1_g must be either 1 or 0!"

    severity failure;

  assert include_port2_g = 0 or include_port2_g = 1

    report "include_port2_g must be either 1 or 0!"

    severity failure;

  assert include_bus_g   = 0 or include_bus_g = 1

    report "include_bus_g must be either 1 or 0!"

    severity failure;

  -- pragma translate_on

  en_clk_s <= to_boolean(en_clk_i);

  alu_b : alu

    port map (

      clk_i              => clk_i,

      res_i              => reset_i,

      en_clk_i           => en_clk_s,

      data_i             => t48_data_s,

      data_o             => alu_data_s,

      write_accu_i       => alu_write_accu_s,

      write_shadow_i     => alu_write_shadow_s,

      write_temp_reg_i   => alu_write_temp_reg_s,

      read_alu_i         => alu_read_alu_s,

      carry_i            => psw_carry_s,

      carry_o            => alu_carry_s,

      aux_carry_i        => psw_aux_carry_s,

      aux_carry_o        => alu_aux_carry_s,

      alu_op_i           => alu_op_s,

      use_carry_i        => alu_use_carry_s

    );

  bus_mux_b : bus_mux

    port map (

      alu_data_i => alu_data_s,

      bus_data_i => bus_data_s,

      dec_data_i => dec_data_s,

      dm_data_i  => dm_data_s,

      pm_data_i  => pm_data_s,

      p1_data_i  => p1_data_s,

      p2_data_i  => p2_data_s,

      psw_data_i => psw_data_s,

      tim_data_i => tim_data_s,

      data_o     => t48_data_s

    );

  clock_ctrl_b : clock_ctrl

    generic map (

      xtal_div_3_g   => xtal_div_3_g

    )

    port map (

      clk_i          => clk_i,

      xtal_i         => xtal_i,

      res_i          => reset_i,

      en_clk_i       => en_clk_s,

      xtal3_o        => xtal3_s,

      multi_cycle_i  => clk_multi_cycle_s,

      assert_psen_i  => clk_assert_psen_s,

      assert_prog_i  => clk_assert_prog_s,

      assert_rd_i    => clk_assert_rd_s,

      assert_wr_i    => clk_assert_wr_s,

      mstate_o       => clk_mstate_s,

      second_cycle_o => clk_second_cycle_s,

      ale_o          => ale_s,

      psen_o         => psen_s,

      prog_o         => prog_s,

      rd_o           => rd_s,

      wr_o           => wr_s

    );

  cond_branch_b : cond_branch

    port map (

      clk_i          => clk_i,

      res_i          => reset_i,

      en_clk_i       => en_clk_s,

      compute_take_i => cnd_compute_take_s,

      branch_cond_i  => cnd_branch_cond_s,

      take_branch_o  => cnd_take_branch_s,

      accu_i         => alu_data_s,

      t0_i           => To_X01Z(t0_i),

      t1_i           => To_X01Z(t1_i),

      int_n_i        => int_n_i,

      f0_i           => psw_f0_s,

      f1_i           => cnd_f1_s,

      tf_i           => cnd_tf_s,

      carry_i        => psw_carry_s,

      comp_value_i   => cnd_comp_value_s

    );

  use_db_bus: if include_bus_g = 1 generate

    db_bus_b : db_bus

      port map (

        clk_i        => clk_i,

        res_i        => reset_i,

        en_clk_i     => en_clk_s,

        ea_i         => ea_i,

        data_i       => t48_data_s,

        data_o       => bus_data_s,

        write_bus_i  => bus_write_bus_s,

        read_bus_i   => bus_read_bus_s,

        output_pcl_i => bus_output_pcl_s,

        bidir_bus_i  => bus_bidir_bus_s,

        pcl_i        => pmem_addr_s(word_t'range),

        db_i         => db_i,

        db_o         => db_o,

        db_dir_o     => db_dir_o

      );

  end generate;

  skip_db_bus: if include_bus_g = 0 generate

    bus_data_s <= (others => bus_idle_level_c);

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

    db_dir_o   <= '0';

  end generate;

  decoder_b : decoder

    generic map (

      register_mnemonic_g => register_mnemonic_g

    )

    port map (

      clk_i                  => clk_i,

      res_i                  => reset_i,

      en_clk_i               => en_clk_s,

      ea_i                   => ea_i,

      ale_i                  => ale_s,

      int_n_i                => int_n_i,

      t0_dir_o               => t0_dir_o,

      data_i                 => t48_data_s,

      data_o                 => dec_data_s,

      alu_write_accu_o       => alu_write_accu_s,

      alu_write_shadow_o     => alu_write_shadow_s,

      alu_write_temp_reg_o   => alu_write_temp_reg_s,

      alu_read_alu_o         => alu_read_alu_s,

      bus_write_bus_o        => bus_write_bus_s,

      bus_read_bus_o         => bus_read_bus_s,

      dm_write_dmem_addr_o   => dm_write_dmem_addr_s,

      dm_write_dmem_o        => dm_write_dmem_s,

      dm_read_dmem_o         => dm_read_dmem_s,

      p1_write_p1_o          => p1_write_p1_s,

      p1_read_p1_o           => p1_read_p1_s,

      pm_write_pcl_o         => pm_write_pcl_s,

      p2_write_p2_o          => p2_write_p2_s,

      p2_write_exp_o         => p2_write_exp_s,

      p2_read_p2_o           => p2_read_p2_s,

      pm_read_pcl_o          => pm_read_pcl_s,

      pm_write_pch_o         => pm_write_pch_s,

      pm_read_pch_o          => pm_read_pch_s,

      pm_read_pmem_o         => pm_read_pmem_s,

      psw_read_psw_o         => psw_read_psw_s,

      psw_read_sp_o          => psw_read_sp_s,

      psw_write_psw_o        => psw_write_psw_s,

      psw_write_sp_o         => psw_write_sp_s,

      alu_carry_i            => alu_carry_s,

      alu_aux_carry_i        => alu_aux_carry_s,

      alu_op_o               => alu_op_s,

      alu_use_carry_o        => alu_use_carry_s,

      bus_output_pcl_o       => bus_output_pcl_s,

      bus_bidir_bus_o        => bus_bidir_bus_s,

      clk_multi_cycle_o      => clk_multi_cycle_s,

      clk_assert_psen_o      => clk_assert_psen_s,

      clk_assert_prog_o      => clk_assert_prog_s,

      clk_assert_rd_o        => clk_assert_rd_s,

      clk_assert_wr_o        => clk_assert_wr_s,

      clk_mstate_i           => clk_mstate_s,

      clk_second_cycle_i     => clk_second_cycle_s,

      cnd_compute_take_o     => cnd_compute_take_s,

      cnd_branch_cond_o      => cnd_branch_cond_s,

      cnd_take_branch_i      => cnd_take_branch_s,

      cnd_comp_value_o       => cnd_comp_value_s,

      cnd_f1_o               => cnd_f1_s,

      cnd_tf_o               => cnd_tf_s,

      dm_addr_type_o         => dm_addr_type_s,

      tim_read_timer_o       => tim_read_timer_s,

      tim_write_timer_o      => tim_write_timer_s,

      tim_start_t_o          => tim_start_t_s,

      tim_start_cnt_o        => tim_start_cnt_s,

      tim_stop_tcnt_o        => tim_stop_tcnt_s,

      p1_read_reg_o          => p1_read_reg_s,

      p2_read_reg_o          => p2_read_reg_s,

      p2_read_exp_o          => p2_read_exp_s,

      p2_output_pch_o        => p2_output_pch_s,

      p2_output_exp_o        => p2_output_exp_s,

      pm_inc_pc_o            => pm_inc_pc_s,

      pm_write_pmem_addr_o   => pm_write_pmem_addr_s,

      pm_addr_type_o         => pm_addr_type_s,

      psw_special_data_o     => psw_special_data_s,

      psw_carry_i            => psw_carry_s,

      psw_f0_i               => psw_f0_s,

      psw_inc_stackp_o       => psw_inc_stackp_s,

      psw_dec_stackp_o       => psw_dec_stackp_s,

      psw_write_carry_o      => psw_write_carry_s,

      psw_write_aux_carry_o  => psw_write_aux_carry_s,

      psw_write_f0_o         => psw_write_f0_s,

      psw_write_bs_o         => psw_write_bs_s,

      tim_overflow_i         => tim_overflow_s

    );

  dmem_ctrl_b : dmem_ctrl

    port map (

      clk_i             => clk_i,

      res_i             => reset_i,

      en_clk_i          => en_clk_s,

      data_i            => t48_data_s,

      write_dmem_addr_i => dm_write_dmem_addr_s,

      write_dmem_i      => dm_write_dmem_s,

      read_dmem_i       => dm_read_dmem_s,

      addr_type_i       => dm_addr_type_s,

      bank_select_i     => psw_bs_s,

      data_o            => dm_data_s,

      dmem_data_i       => dmem_data_i,

      dmem_addr_o       => dmem_addr_o,

      dmem_we_o         => dmem_we_o,

      dmem_data_o       => dmem_data_o

    );

  use_timer: if include_timer_g = 1 generate

    timer_b : timer

      generic map (

        sample_t1_state_g => sample_t1_state_g

      )

      port map (

        clk_i         => clk_i,

        res_i         => reset_i,

        en_clk_i      => en_clk_s,

        t1_i          => To_X01Z(t1_i),

        clk_mstate_i  => clk_mstate_s,

        data_i        => t48_data_s,

        data_o        => tim_data_s,

        read_timer_i  => tim_read_timer_s,

        write_timer_i => tim_write_timer_s,

        start_t_i     => tim_start_t_s,

        start_cnt_i   => tim_start_cnt_s,

        stop_tcnt_i   => tim_stop_tcnt_s,

        overflow_o    => tim_of_s

      );

  end generate;

  skip_timer: if include_timer_g = 0 generate

    tim_data_s <= (others => bus_idle_level_c);

    tim_of_s   <= '0';

  end generate;

  tim_overflow_s <= to_boolean(tim_of_s);

  use_p1: if include_port1_g = 1 generate

    p1_b : p1

      port map (

        clk_i      => clk_i,

        res_i      => reset_i,

        en_clk_i   =>  en_clk_s,

        data_i     => t48_data_s,

        data_o     => p1_data_s,

        write_p1_i => p1_write_p1_s,

        read_p1_i  => p1_read_p1_s,

        read_reg_i => p1_read_reg_s,

        p1_i       => p1_i,

        p1_o       => p1_o,

        p1_limp_o  => p1_limp_o

      );

  end generate;

  skip_p1: if include_port1_g = 0 generate

    p1_data_s <= (others => bus_idle_level_c);

    p1_o      <= (others => '0');

    p1_limp_o <= '0';

  end generate;

  use_p2: if include_port2_g = 1 generate

    p2_b : p2

      port map (

        clk_i        => clk_i,

        res_i        => reset_i,

        en_clk_i     => en_clk_s,

        data_i       => t48_data_s,

        data_o       => p2_data_s,

        write_p2_i   => p2_write_p2_s,

        write_exp_i  => p2_write_exp_s,

        read_p2_i    => p2_read_p2_s,

        read_reg_i   => p2_read_reg_s,

        read_exp_i   => p2_read_exp_s,

        output_pch_i => p2_output_pch_s,

        output_exp_i => p2_output_exp_s,

        pch_i        => pmem_addr_s(11 downto 8),

        p2_i         => p2_i,

        p2_o         => p2_o,

        p2_limp_o    => p2_limp_o

      );

  end generate;

  skip_p2: if include_port2_g = 0 generate

    p2_data_s <= (others => bus_idle_level_c);

    p2_o      <= (others => '0');

    p2_limp_o <= '0';

  end generate;

  pmem_ctrl_b : pmem_ctrl

    port map (

      clk_i             => clk_i,

      res_i             => reset_i,

      en_clk_i          => en_clk_s,

      data_i            => t48_data_s,

      data_o            => pm_data_s,

      write_pcl_i       => pm_write_pcl_s,

      read_pcl_i        => pm_read_pcl_s,

      write_pch_i       => pm_write_pch_s,

      read_pch_i        => pm_read_pch_s,

      inc_pc_i          => pm_inc_pc_s,

      write_pmem_addr_i => pm_write_pmem_addr_s,

      addr_type_i       => pm_addr_type_s,

      read_pmem_i       => pm_read_pmem_s,

      pmem_addr_o       => pmem_addr_s,

      pmem_data_i       => pmem_data_i

    );

  psw_b : psw

    port map (

      clk_i              => clk_i,

      res_i              => reset_i,

      en_clk_i           => en_clk_s,

      data_i             => t48_data_s,

      data_o             => psw_data_s,

      read_psw_i         => psw_read_psw_s,

      read_sp_i          => psw_read_sp_s,

      write_psw_i        => psw_write_psw_s,

      write_sp_i         => psw_write_sp_s,

      special_data_i     => psw_special_data_s,

      inc_stackp_i       => psw_inc_stackp_s,

      dec_stackp_i       => psw_dec_stackp_s,

      write_carry_i      => psw_write_carry_s,

      write_aux_carry_i  => psw_write_aux_carry_s,

      write_f0_i         => psw_write_f0_s,

      write_bs_i         => psw_write_bs_s,

      carry_o            => psw_carry_s,

      aux_carry_o        => psw_aux_carry_s,

      f0_o               => psw_f0_s,

      bs_o               => psw_bs_s

    );

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

  -- Output Mapping.

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

  ale_o       <= to_stdLogic(ale_s);

  t0_o        <= clk_i;

  psen_n_o    <= to_stdLogic(not psen_s);

  prog_n_o    <= to_stdLogic(not prog_s);

  rd_n_o      <= to_stdLogic(not rd_s);

  wr_n_o      <= to_stdLogic(not wr_s);

  xtal3_o     <= to_stdLogic(xtal3_s);

  pmem_addr_o <= pmem_addr_s;

end struct;

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

-- File History:

--

-- $Log: not supported by cvs2svn $

-- Revision 1.1  2004/03/23 21:31:53  arniml

-- initial check-in

--

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