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//////////////////////////////////////////////////////////////////////

////                                                              ////

////  MP3 demo Flash interface                                    ////

////                                                              ////

////  This file is part of the MP3 demo application               ////

////  http://www.opencores.org/cores/or1k/mp3/                    ////

////                                                              ////

////  Description                                                 ////

////  Connects MP3 demo tp Flash found on XSV board.              ////

////                                                              ////

////  To Do:                                                      ////

////   - nothing really                                           ////

////                                                              ////

////  Author(s):                                                  ////

////      - Lior Shtram, lior.shtram@flextronicssemi.com          ////

////                                                              ////

//////////////////////////////////////////////////////////////////////

////                                                              ////

//// Copyright (C) 2001 Authors                                   ////

////                                                              ////

//// This source file may be used and distributed without         ////

//// restriction provided that this copyright statement is not    ////

//// removed from the file and that any derivative work contains  ////

//// the original copyright notice and the associated disclaimer. ////

////                                                              ////

//// This source file is free software; you can redistribute it   ////

//// and/or modify it under the terms of the GNU Lesser General   ////

//// Public License as published by the Free Software Foundation; ////

//// either version 2.1 of the License, or (at your option) any   ////

//// later version.                                               ////

////                                                              ////

//// This source is distributed in the hope that it will be       ////

//// useful, but WITHOUT ANY WARRANTY; without even the implied   ////

//// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR      ////

//// PURPOSE.  See the GNU Lesser General Public License for more ////

//// details.                                                     ////

////                                                              ////

//// You should have received a copy of the GNU Lesser General    ////

//// Public License along with this source; if not, download it   ////

//// from http://www.opencores.org/lgpl.shtml                     ////

////                                                              ////

//////////////////////////////////////////////////////////////////////

//

// CVS Revision History

//

// $Log: not supported by cvs2svn $

//

// synopsys translate_off

`include "timescale.v"

// synopsys translate_on

module flash_top (

  clk, rstn,

  wb_dat_i, wb_dat_o, wb_adr_i, wb_sel_i, wb_we_i, wb_cyc_i,

  wb_stb_i, wb_ack_o, wb_err_o,

  flash_rstn, cen, oen, wen, rdy, d, a, a_oe

);

input   clk;

input   rstn;

input [31:0]  wb_dat_i;

output [31:0] wb_dat_o;

input [31:0]  wb_adr_i;

input [3:0] wb_sel_i;

input   wb_we_i;

input   wb_cyc_i;

input   wb_stb_i;

output    wb_ack_o;

output    wb_err_o;

output    flash_rstn;

output    oen;

output    cen;

output    wen;

input   rdy;

inout [7:0] d;

output [20:0] a;

output  a_oe;

reg [4:0] counter;

reg [31:0]  data_sr;

reg   f_ack;

reg [3:0] middle_tphqv;

always @(posedge clk or negedge rstn)

begin

  if(!rstn)

    counter <= 5'h0;

  else

  if(!wb_cyc_i | (counter == 5'h10) | (|middle_tphqv))

    counter <= #1 5'h0;

  else

    counter <= #1 counter + 1;

end

always @(posedge clk or negedge rstn)

begin

  if(!rstn)

    f_ack <= 1'h0;

  else

  if(counter == 5'h0f && !(|middle_tphqv))

    f_ack <= #1 1'h1;

  else

    f_ack <= #1 1'h0;

end

assign wb_ack_o = f_ack;

assign flash_rstn = rstn;

assign a = { ~wb_adr_i[20], wb_adr_i[19:2], counter[3:2] };

assign a_oe = (wb_cyc_i &! (|middle_tphqv));

assign wb_dat_o = data_sr;

assign oen = |middle_tphqv;

assign wen = 1'b1;

/* SIMON */

//assign cen = |middle_tphqv | (counter[1:0] == 2'b01);

assign cen = |middle_tphqv | (counter[1:0] == 2'b01) | (counter[4:0] == 5'b0);

assign wb_err_o = 1'b0;

// synopsys translate_off

integer fflash;

initial fflash = $fopen("flash.log");

always @(posedge clk)

        if (wb_cyc_i & !(|middle_tphqv)) begin // wb_ack_o should be qualified with wb_stb_i as well however OR1200 doesn't do this currently

                if (wb_stb_i & wb_we_i) begin

//      $fdisplay(fflash, "%t Trying to write into flash at %h", $time, wb_adr_i);

//      #100 $finish;

                end else if (wb_ack_o)

                        $fdisplay(fflash, "%t [%h] -> read %h", $time, wb_adr_i, wb_dat_o);

        end

// synopsys translate_on

always @(posedge clk or negedge rstn)

        if (!rstn)

                middle_tphqv <= #1 4'hf;

        else if (middle_tphqv)

                middle_tphqv <= #1 middle_tphqv - 1;

always @(posedge clk or negedge rstn)

begin

  if (!rstn) data_sr <= 32'b0;

  else

  if (counter[1:0] == 2'h3)

    begin

      case (counter[3:2])

        2'h0 : data_sr[31:24] <= #1 d;

        2'h1 : data_sr[23:16] <= #1 d;

        2'h2 : data_sr[15:8]  <= #1 d;

        2'h3 : data_sr[7:0]   <= #1 d;

        default : data_sr <= 32'bx;

      endcase

    end

end

endmodule