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// synthesis translate_off
`timescale 1ns / 1ps
// synthesis translate_on

// turn off superfluous verilog processor warnings 
// altera message_level Level1 
// altera message_off 10034 10035 10036 10037 10230 10240 10030 

module touch_panel_pen_irq_n (
                               // inputs:
                                address,
                                chipselect,
                                clk,
                                in_port,
                                reset_n,
                                write_n,
                                writedata,

                               // outputs:
                                irq,
                                readdata
                             )
;

  output           irq;
  output           readdata;
  input   [  1: 0] address;
  input            chipselect;
  input            clk;
  input            in_port;
  input            reset_n;
  input            write_n;
  input            writedata;

  wire             clk_en;
  reg              d1_data_in;
  reg              d2_data_in;
  wire             data_in;
  reg              edge_capture;
  wire             edge_capture_wr_strobe;
  wire             edge_detect;
  wire             irq;
  reg              irq_mask;
  wire             read_mux_out;
  reg              readdata;
  assign clk_en = 1;
  //s1, which is an e_avalon_slave
  assign read_mux_out = ({1 {(address == 0)}} & data_in) |
    ({1 {(address == 2)}} & irq_mask) |
    ({1 {(address == 3)}} & edge_capture);

  always @(posedge clk or negedge reset_n)
    begin
      if (reset_n == 0)
          readdata <= 0;
      else if (clk_en)
          readdata <= read_mux_out;
    end


  assign data_in = in_port;
  always @(posedge clk or negedge reset_n)
    begin
      if (reset_n == 0)
          irq_mask <= 0;
      else if (chipselect && ~write_n && (address == 2))
          irq_mask <= writedata;
    end


  assign irq = |(edge_capture & irq_mask);
  assign edge_capture_wr_strobe = chipselect && ~write_n && (address == 3);
  always @(posedge clk or negedge reset_n)
    begin
      if (reset_n == 0)
          edge_capture <= 0;
      else if (clk_en)
          if (edge_capture_wr_strobe)
              edge_capture <= 0;
          else if (edge_detect)
              edge_capture <= -1;
    end


  always @(posedge clk or negedge reset_n)
    begin
      if (reset_n == 0)
        begin
          d1_data_in <= 0;
          d2_data_in <= 0;
        end
      else if (clk_en)
        begin
          d1_data_in <= data_in;
          d2_data_in <= d1_data_in;
        end
    end


  assign edge_detect = ~d1_data_in & d2_data_in;

endmodule

