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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