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[/] [openrisc/] [trunk/] [orpsocv2/] [rtl/] [verilog/] [usbhostslave/] [updateCRC16.v] - Blame information for rev 745

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1 408 julius
//////////////////////////////////////////////////////////////////////
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////                                                              ////
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//// updateCRC16.v                                                ////
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////                                                              ////
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//// This file is part of the usbhostslave opencores effort.
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//// <http://www.opencores.org/cores//>                           ////
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////                                                              ////
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//// Module Description:                                          ////
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//// 
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////                                                              ////
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//// To Do:                                                       ////
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//// 
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////                                                              ////
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//// Author(s):                                                   ////
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//// - Steve Fielding, sfielding@base2designs.com                 ////
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////                                                              ////
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//////////////////////////////////////////////////////////////////////
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////                                                              ////
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//// Copyright (C) 2004 Steve Fielding and OPENCORES.ORG          ////
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////                                                              ////
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//// This source file may be used and distributed without         ////
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//// restriction provided that this copyright statement is not    ////
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//// removed from the file and that any derivative work contains  ////
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//// the original copyright notice and the associated disclaimer. ////
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////                                                              ////
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//// This source file is free software; you can redistribute it   ////
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//// and/or modify it under the terms of the GNU Lesser General   ////
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//// Public License as published by the Free Software Foundation; ////
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//// either version 2.1 of the License, or (at your option) any   ////
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//// later version.                                               ////
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////                                                              ////
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//// This source is distributed in the hope that it will be       ////
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//// useful, but WITHOUT ANY WARRANTY; without even the implied   ////
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//// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR      ////
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//// PURPOSE. See the GNU Lesser General Public License for more  ////
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//// details.                                                     ////
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////                                                              ////
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//// You should have received a copy of the GNU Lesser General    ////
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//// Public License along with this source; if not, download it   ////
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//// from <http://www.opencores.org/lgpl.shtml>                   ////
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////                                                              ////
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//////////////////////////////////////////////////////////////////////
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//
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`include "timescale.v"
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module updateCRC16 (rstCRC, CRCResult, CRCEn, dataIn, ready, clk, rst);
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input   rstCRC;
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input   CRCEn;
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input   [7:0] dataIn;
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input   clk;
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input   rst;
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output  [15:0] CRCResult;
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output ready;
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wire   rstCRC;
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wire   CRCEn;
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wire   [7:0] dataIn;
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wire   clk;
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wire   rst;
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reg    [15:0] CRCResult;
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reg    ready;
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reg doUpdateCRC;
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reg [7:0] data;
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reg [3:0] i;
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always @(posedge clk)
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begin
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  if (rst == 1'b1 || rstCRC == 1'b1) begin
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    doUpdateCRC <= 1'b0;
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    i <= 4'h0;
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    CRCResult <= 16'hffff;
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    ready <= 1'b1;
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  end
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  else
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  begin
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    if (doUpdateCRC == 1'b0)
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    begin
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      if (CRCEn == 1'b1) begin
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        doUpdateCRC <= 1'b1;
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        data <= dataIn;
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        ready <= 1'b0;
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    end
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    end
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    else begin
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      i <= i + 1'b1;
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      if ( (CRCResult[0] ^ data[0]) == 1'b1) begin
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        CRCResult <= {1'b0, CRCResult[15:1]} ^ 16'ha001;
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      end
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      else begin
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        CRCResult <= {1'b0, CRCResult[15:1]};
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      end
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      data <= {1'b0, data[7:1]};
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      if (i == 4'h7)
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      begin
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        doUpdateCRC <= 1'b0;
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        i <= 4'h0;
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        ready <= 1'b1;
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      end
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    end
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  end
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end
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endmodule

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