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[/] [System09/] [trunk/] [rtl/] [VHDL/] [keyboard.vhd] - Blame information for rev 115

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1 99 davidgb
--===========================================================================--
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--                                                                           --
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--  keyboard.vhd - Synthesizable Interface to PS/2 Keyboard Module           --
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--                                                                           --
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--===========================================================================--
6 19 dilbert57
--
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--  File name      : keyboard.vhd
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--
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--  Entity name    : keyboard
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--
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--  Purpose        : Implements a CPU interface to John Clayton's PS/2 Keyboard
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--                  
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--  Dependencies   : ieee.std_logic_1164
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--                   ieee.std_logic_arith
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--                   ieee.std_logic_unsigned
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--                   ieee.numeric_std
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--                   unisim.vcomponents
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--
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--  Uses           : ps2_keyboard_interface
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--
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--  Author         : John E. Kent
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--
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--  Email          : dilbert57@opencores.org      
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--
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--  Web            : http://opencores.org/project,system09
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--
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--  Registers      :
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--
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--  IO address + 0 read - Status Register
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--
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--      Bit[0] - RX Data Ready
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--      Bit[1] - TX Data Empty
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--      Bit[2] - Extended
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--      Bit[3] - Released
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--      Bit[4] - Shift On
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--      Bit[5] - Error (no keyboard acknowledge received)
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--      Bit[6] - TX Interrupt Flag
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--      Bit[7] - RX Interrupt Flag
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--
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--  IO address + 0 write - Control Register
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--
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--      Bit[0] - Undefined
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--      Bit[1] - Undefined
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--      Bit[2] - Undefined
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--      Bit[3] - Undefined
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--      Bit[4] - Undefined
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--      Bit[5] - Undefined
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--      Bit[6] - TX Interrupt Enable
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--      Bit[7] - RX Interrupt Enable
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--
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--  IO address + 1 read - Receive Data Register
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--
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--  IO address + 1 write - Transmit Data Register
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--
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--  Copyright (C) 2004 - 2010 John Kent
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--
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--  This program is free software: you can redistribute it and/or modify
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--  it under the terms of the GNU General Public License as published by
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--  the Free Software Foundation, either version 3 of the License, or
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--  (at your option) any later version.
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--
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--  This program is distributed in the hope that it will be useful,
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--  but WITHOUT ANY WARRANTY; without even the implied warranty of
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--  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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--  GNU General Public License for more details.
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--
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--  You should have received a copy of the GNU General Public License
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--  along with this program.  If not, see <http://www.gnu.org/licenses/>.
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--
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--===========================================================================--
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--                                                                           --
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--                              Revision  History                            --
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--                                                                           --
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--===========================================================================--
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--
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-- Version  Author     Date               Description
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-- 0.1      John Kent  2nd April 2004     Interface to John Clayton's PS2 keyboard
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-- 0.2      John Kent  7th Februaury 2007 Added Generics for Keyboard Timing
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-- 0.3      John Kent  30th May 2010      Updated Header, added unisim library
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-- 0.4      John Kent  17th June 2010     Cleaned up signal names, 
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--                                        added TX interrupt enable
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--                                        Modified assignment of status register
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--                                        Revised hanshake control and input registers
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--                                        
85 19 dilbert57
 
86
library ieee;
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   use ieee.std_logic_1164.all;
88 99 davidgb
   use ieee.std_logic_arith.all;
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   use ieee.std_logic_unsigned.all;
90 19 dilbert57
   use ieee.numeric_std.all;
91 99 davidgb
library unisim;
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   use unisim.vcomponents.all;
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94
entity keyboard is
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  generic (
96 99 davidgb
  KBD_CLK_FREQ : integer
97 19 dilbert57
  );
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99 99 davidgb
  port(
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  --
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  -- CPU Interface Signals
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  --
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  clk             : in    std_logic;
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  rst             : in    std_logic;
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  cs              : in    std_logic;
106 99 davidgb
  addr            : in    std_logic;
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  rw              : in    std_logic;
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  data_in         : in    std_logic_vector(7 downto 0);
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  data_out        : out   std_logic_vector(7 downto 0);
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  irq             : out   std_logic;
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  --
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  -- Keyboard Interface Signals
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  --
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  kbd_clk         : inout std_logic;
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  kbd_data        : inout std_logic
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  );
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end keyboard;
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architecture rtl of keyboard is
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constant CLK_FREQ_MHZ : integer := KBD_CLK_FREQ / 1000000;
122 19 dilbert57
 
123 99 davidgb
signal kbd_status     : std_logic_vector(7 downto 0);
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signal kbd_control    : std_logic_vector(7 downto 0);
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signal kbd_rx_data    : std_logic_vector(7 downto 0);
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signal kbd_tx_data    : std_logic_vector(7 downto 0);
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signal kbd_read       : std_logic;
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signal kbd_write      : std_logic;
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signal kbd_data_ready : std_logic; --  => kbd_status(0)
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signal kbd_data_empty : std_logic; --  => kbd_status(1)
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signal kbd_extended   : std_logic; --  => kbd_status(2)
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signal kbd_released   : std_logic; --  => kbd_status(3)
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signal kbd_shift_on   : std_logic; --  => kbd_status(4)
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signal kbd_error      : std_logic; --  => kbd_status(5) (No receive acknowledge)
135 19 dilbert57
 
136 99 davidgb
component ps2_keyboard
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  generic (
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  CLK_FREQ_MHZ    : integer := CLK_FREQ_MHZ
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  );
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  port(
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  clk             : in    std_logic;
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  reset           : in    std_logic;
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  rx_data         : out   std_logic_vector(7 downto 0);
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  rx_read         : in    std_logic;
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  rx_data_ready   : out   std_logic;
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  rx_extended     : out   std_logic;
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  rx_released     : out   std_logic;
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  rx_shift_on     : out   std_logic;
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  tx_data         : in    std_logic_vector(7 downto 0);
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  tx_write        : in    std_logic;
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  tx_data_empty   : out   std_logic;
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  tx_error        : out   std_logic;
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  ps2_clk         : inout std_logic;
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  ps2_data        : inout std_logic
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  );
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end component;
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begin
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my_ps2_keyboard : ps2_keyboard
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  generic map (
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  CLK_FREQ_MHZ   => CLK_FREQ_MHz
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  )
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  port map(
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  clk             => clk,
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  reset           => rst,
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  rx_data         => kbd_rx_data,
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  rx_read         => kbd_read,
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  rx_data_ready   => kbd_data_ready,
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  rx_extended     => kbd_extended,
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  rx_released     => kbd_released,
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  rx_shift_on     => kbd_shift_on,
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  tx_data         => kbd_tx_data,
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  tx_write        => kbd_write,
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  tx_data_empty   => kbd_data_empty,
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  tx_error        => kbd_error,
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  ps2_clk         => kbd_clk,
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  ps2_data        => kbd_data
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  );
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  --
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  -- Keyboard Read strobe
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  --
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  keyboard_read : process( clk, rst, cs, rw, kbd_data_ready  )
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  begin
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    if rst = '1' then
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      kbd_read <= '0';
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    elsif( clk'event and clk='0' ) then
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      if( cs = '1' and addr = '1' and rw = '1' ) then
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        kbd_read <= '1';
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      elsif kbd_data_ready = '1' then
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        kbd_read <= '0';
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      end if;
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    end if;
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  end process;
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  --
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  -- Keyboard Write strobe
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  --
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  keyboard_write : process( clk, rst, cs, rw, addr,
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                                                                         kbd_write, kbd_data_empty )
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  begin
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    if rst = '1' then
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                kbd_write   <= '0';
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    elsif( clk'event and clk='0' ) then
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                if( cs = '1' and addr = '1' and rw = '0' ) then
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         kbd_write <= '1';
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      elsif kbd_data_empty = '1' then
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         kbd_write <= '0';
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      end if;
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    end if;
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  end process;
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  --
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  -- Keyboard register input
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  --
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  keyboard_in : process( clk, rst, cs, rw, addr, data_in, kbd_rx_data )
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  begin
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    if rst = '1' then
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                kbd_control <= (others => '0');
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      kbd_tx_data <= (others => '0');
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    elsif( clk'event and clk='0' ) then
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                if( cs = '1' and rw = '0' ) then
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         if addr = '0' then
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            kbd_control <= data_in;
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         else
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            kbd_tx_data <= data_in;
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         end if;
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      end if;
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    end if;
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  end process;
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  --
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  -- Keyboard register output
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  --
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  keyboard_out : process( addr, kbd_rx_data, kbd_status )
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  begin
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    if( addr = '0' ) then
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      data_out <= kbd_status;
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    else
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      data_out <= kbd_rx_data;
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    end if;
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  end process;
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  --
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  -- Assign Keyboard Status bits
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  --
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  keyboard_status : process( kbd_data_ready, kbd_data_empty,
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                             kbd_extended, kbd_released, kbd_shift_on, kbd_error,
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                             kbd_control)
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  begin
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    kbd_status(0) <= kbd_data_ready;
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    kbd_status(1) <= kbd_data_empty;
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    kbd_status(2) <= kbd_extended;
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    kbd_status(3) <= kbd_released;
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    kbd_status(4) <= kbd_shift_on;
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    kbd_status(5) <= kbd_error;
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    kbd_status(6) <= kbd_control(6) and kbd_data_empty; -- TX Interrupt Flag
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    kbd_status(7) <= kbd_control(7) and kbd_data_ready; -- RX Interrupt Flag
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    irq           <= kbd_status(7) or kbd_status(6);
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  end process;
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end rtl;
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