------------------------------------------------------------------------------
-- user_logic.vhd - entity/architecture pair
------------------------------------------------------------------------------
--
-- ***************************************************************************
-- ** Copyright (c) 1995-2010 Xilinx, Inc.  All rights reserved.            **
-- **                                                                       **
-- ** Xilinx, Inc.                                                          **
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-- ** SOLUTIONS FOR XILINX DEVICES.  BY PROVIDING THIS DESIGN, CODE,        **
-- ** OR INFORMATION AS ONE POSSIBLE IMPLEMENTATION OF THIS FEATURE,        **
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-- ** WARRANTY WHATSOEVER WITH RESPECT TO THE ADEQUACY OF THE               **
-- ** IMPLEMENTATION, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OR        **
-- ** REPRESENTATIONS THAT THIS IMPLEMENTATION IS FREE FROM CLAIMS OF       **
-- ** INFRINGEMENT, IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS       **
-- ** FOR A PARTICULAR PURPOSE.                                             **
-- **                                                                       **
-- ***************************************************************************
--
------------------------------------------------------------------------------
-- Filename:          user_logic.vhd
-- Version:           1.00.a
-- Description:       User logic.
-- Date:              Tue Sep 27 11:04:31 2011 (by Create and Import Peripheral Wizard)
-- VHDL Standard:     VHDL'93
------------------------------------------------------------------------------
-- Naming Conventions:
--   active low signals:                    "*_n"
--   clock signals:                         "clk", "clk_div#", "clk_#x"
--   reset signals:                         "rst", "rst_n"
--   generics:                              "C_*"
--   user defined types:                    "*_TYPE"
--   state machine next state:              "*_ns"
--   state machine current state:           "*_cs"
--   combinatorial signals:                 "*_com"
--   pipelined or register delay signals:   "*_d#"
--   counter signals:                       "*cnt*"
--   clock enable signals:                  "*_ce"
--   internal version of output port:       "*_i"
--   device pins:                           "*_pin"
--   ports:                                 "- Names begin with Uppercase"
--   processes:                             "*_PROCESS"
--   component instantiations:              "<ENTITY_>I_<#|FUNC>"
------------------------------------------------------------------------------

-- DO NOT EDIT BELOW THIS LINE --------------------
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;
use ieee.std_logic_unsigned.all;

library proc_common_v3_00_a;
use proc_common_v3_00_a.proc_common_pkg.all;

-- DO NOT EDIT ABOVE THIS LINE --------------------

--USER libraries added here

------------------------------------------------------------------------------
-- Entity section
------------------------------------------------------------------------------
-- Definition of Generics:
--   C_SLV_DWIDTH                 -- Slave interface data bus width
--   C_NUM_REG                    -- Number of software accessible registers
--   C_NUM_INTR                   -- Number of interrupt event
--
-- Definition of Ports:
--   Bus2IP_Clk                   -- Bus to IP clock
--   Bus2IP_Reset                 -- Bus to IP reset
--   Bus2IP_Data                  -- Bus to IP data bus
--   Bus2IP_BE                    -- Bus to IP byte enables
--   Bus2IP_RdCE                  -- Bus to IP read chip enable
--   Bus2IP_WrCE                  -- Bus to IP write chip enable
--   IP2Bus_Data                  -- IP to Bus data bus
--   IP2Bus_RdAck                 -- IP to Bus read transfer acknowledgement
--   IP2Bus_WrAck                 -- IP to Bus write transfer acknowledgement
--   IP2Bus_Error                 -- IP to Bus error response
--   IP2Bus_IntrEvent             -- IP to Bus interrupt event
------------------------------------------------------------------------------

entity user_logic is
  generic
  (
    -- ADD USER GENERICS BELOW THIS LINE ---------------
    --USER generics added here
    -- ADD USER GENERICS ABOVE THIS LINE ---------------

    -- DO NOT EDIT BELOW THIS LINE ---------------------
    -- Bus protocol parameters, do not add to or delete
    C_SLV_DWIDTH                   : integer              := 32;
    C_NUM_REG                      : integer              := 2;
    C_NUM_INTR                     : integer              := 1
    -- DO NOT EDIT ABOVE THIS LINE ---------------------
  );
  port
  (
    -- ADD USER PORTS BELOW THIS LINE ------------------
    --USER ports added here
    -- ADD USER PORTS ABOVE THIS LINE ------------------

    -- DO NOT EDIT BELOW THIS LINE ---------------------
    -- Bus protocol ports, do not add to or delete
    Bus2IP_Clk                     : in  std_logic;
    Bus2IP_Reset                   : in  std_logic;
    Bus2IP_Data                    : in  std_logic_vector(0 to C_SLV_DWIDTH-1);
    Bus2IP_BE                      : in  std_logic_vector(0 to C_SLV_DWIDTH/8-1);
    Bus2IP_RdCE                    : in  std_logic_vector(0 to C_NUM_REG-1);
    Bus2IP_WrCE                    : in  std_logic_vector(0 to C_NUM_REG-1);
    IP2Bus_Data                    : out std_logic_vector(0 to C_SLV_DWIDTH-1);
    IP2Bus_RdAck                   : out std_logic;
    IP2Bus_WrAck                   : out std_logic;
    IP2Bus_Error                   : out std_logic;
    IP2Bus_IntrEvent               : out std_logic_vector(0 to C_NUM_INTR-1)
    -- DO NOT EDIT ABOVE THIS LINE ---------------------
  );

  attribute SIGIS : string;
  attribute SIGIS of Bus2IP_Clk    : signal is "CLK";
  attribute SIGIS of Bus2IP_Reset  : signal is "RST";

end entity user_logic;

------------------------------------------------------------------------------
-- Architecture section
------------------------------------------------------------------------------

architecture IMP of user_logic is

  --USER signal declarations added here, as needed for user logic

signal timer_count : std_logic_vector(0 to C_SLV_DWIDTH-1);
signal timer_expired : std_logic;
signal timer_run : std_logic;

  ------------------------------------------
  -- Signals for user logic slave model s/w accessible register example
  ------------------------------------------
  signal slv_reg0                       : std_logic_vector(0 to C_SLV_DWIDTH-1);
  signal slv_reg1                       : std_logic_vector(0 to C_SLV_DWIDTH-1);
  signal slv_reg_write_sel              : std_logic_vector(0 to 1);
  signal slv_reg_read_sel               : std_logic_vector(0 to 1);
  signal slv_ip2bus_data                : std_logic_vector(0 to C_SLV_DWIDTH-1);
  signal slv_read_ack                   : std_logic;
  signal slv_write_ack                  : std_logic;

  ------------------------------------------
  -- Signals for user logic interrupt example
  ------------------------------------------
  signal intr_counter                   : std_logic_vector(0 to C_NUM_INTR-1);

begin

  --USER logic implementation added here


-- Timer connections
timer_run <= slv_reg1(1);

-- Timer process - times the delay between bursts
process (Bus2IP_Clk, Bus2IP_Reset)
begin
  -- if the peripheral is told to reset, then reset the timer
  if Bus2IP_Reset = '1' then
    timer_count <= (others => '0');
    timer_expired <= '1';
  -- otherwise, if there is a clock event, run the timer
  elsif Bus2IP_Clk'event and Bus2IP_Clk = '1' then
    -- if the timer is not running, then reset the timer
    if timer_run = '0' then
      timer_count <= slv_reg0;
      timer_expired <= '0';
    -- if the timer count is not zero then decrease the count
    elsif timer_count /= 0 then
      timer_count <= timer_count - 1;
      timer_expired <= '0';
    -- otherwise, the timer has expired
    else
      timer_expired <= '1';
    end if;
  end if;
end process;

-- Interrupt connections
IP2Bus_IntrEvent(0) <= timer_expired;

  ------------------------------------------
  -- Example code to read/write user logic slave model s/w accessible registers
  -- 
  -- Note:
  -- The example code presented here is to show you one way of reading/writing
  -- software accessible registers implemented in the user logic slave model.
  -- Each bit of the Bus2IP_WrCE/Bus2IP_RdCE signals is configured to correspond
  -- to one software accessible register by the top level template. For example,
  -- if you have four 32 bit software accessible registers in the user logic,
  -- you are basically operating on the following memory mapped registers:
  -- 
  --    Bus2IP_WrCE/Bus2IP_RdCE   Memory Mapped Register
  --                     "1000"   C_BASEADDR + 0x0
  --                     "0100"   C_BASEADDR + 0x4
  --                     "0010"   C_BASEADDR + 0x8
  --                     "0001"   C_BASEADDR + 0xC
  -- 
  ------------------------------------------
  slv_reg_write_sel <= Bus2IP_WrCE(0 to 1);
  slv_reg_read_sel  <= Bus2IP_RdCE(0 to 1);
  slv_write_ack     <= Bus2IP_WrCE(0) or Bus2IP_WrCE(1);
  slv_read_ack      <= Bus2IP_RdCE(0) or Bus2IP_RdCE(1);

  -- implement slave model software accessible register(s)
  SLAVE_REG_WRITE_PROC : process( Bus2IP_Clk ) is
  begin

    if Bus2IP_Clk'event and Bus2IP_Clk = '1' then
      if Bus2IP_Reset = '1' then
        slv_reg0 <= (others => '0');
        slv_reg1 <= (others => '0');
      else
        case slv_reg_write_sel is
          when "10" =>
            for byte_index in 0 to (C_SLV_DWIDTH/8)-1 loop
              if ( Bus2IP_BE(byte_index) = '1' ) then
                slv_reg0(byte_index*8 to byte_index*8+7) <= Bus2IP_Data(byte_index*8 to byte_index*8+7);
              end if;
            end loop;
          when "01" =>
            for byte_index in 0 to (C_SLV_DWIDTH/8)-1 loop
              if ( Bus2IP_BE(byte_index) = '1' ) then
                slv_reg1(byte_index*8 to byte_index*8+7) <= Bus2IP_Data(byte_index*8 to byte_index*8+7);
              end if;
            end loop;
          when others => null;
        end case;
      end if;
    end if;

  end process SLAVE_REG_WRITE_PROC;

  -- implement slave model software accessible register(s) read mux
  SLAVE_REG_READ_PROC : process( slv_reg_read_sel, slv_reg0, slv_reg1 ) is
  begin

    case slv_reg_read_sel is
      when "10" => slv_ip2bus_data <= slv_reg0;
		when "01" =>
			slv_ip2bus_data(1 to C_SLV_DWIDTH-1) <= slv_reg1(1 to C_SLV_DWIDTH-1);
			slv_ip2bus_data(0) <= timer_expired;
      when others => slv_ip2bus_data <= (others => '0');
    end case;

  end process SLAVE_REG_READ_PROC;

  ------------------------------------------
  -- Example code to drive IP to Bus signals
  ------------------------------------------
  IP2Bus_Data  <= slv_ip2bus_data when slv_read_ack = '1' else
                  (others => '0');

  IP2Bus_WrAck <= slv_write_ack;
  IP2Bus_RdAck <= slv_read_ack;
  IP2Bus_Error <= '0';

end IMP;
