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[/] [openrisc/] [trunk/] [orpsocv2/] [rtl/] [verilog/] [usbhostslave/] [updateCRC5.v] - Rev 584
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////////////////////////////////////////////////////////////////////// //// //// //// updateCRC5.v //// //// //// //// This file is part of the usbhostslave opencores effort. //// <http://www.opencores.org/cores//> //// //// //// //// Module Description: //// //// //// //// //// To Do: //// //// //// //// //// Author(s): //// //// - Steve Fielding, sfielding@base2designs.com //// //// //// ////////////////////////////////////////////////////////////////////// //// //// //// Copyright (C) 2004 Steve Fielding and OPENCORES.ORG //// //// //// //// 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> //// //// //// ////////////////////////////////////////////////////////////////////// // `include "timescale.v" module updateCRC5 (rstCRC, CRCResult, CRCEn, CRC5_8BitIn, dataIn, ready, clk, rst); input rstCRC; input CRCEn; input CRC5_8BitIn; input [7:0] dataIn; input clk; input rst; output [4:0] CRCResult; output ready; wire rstCRC; wire CRCEn; wire CRC5_8BitIn; wire [7:0] dataIn; wire clk; wire rst; reg [4:0] CRCResult; reg ready; reg doUpdateCRC; reg [7:0] data; reg [3:0] loopEnd; reg [3:0] i; always @(posedge clk) begin if (rst == 1'b1 || rstCRC == 1'b1) begin doUpdateCRC <= 1'b0; i <= 4'h0; CRCResult <= 5'h1f; ready <= 1'b1; end else begin if (doUpdateCRC == 1'b0) begin if (CRCEn == 1'b1) begin ready <= 1'b0; doUpdateCRC <= 1'b1; data <= dataIn; if (CRC5_8BitIn == 1'b1) begin loopEnd <= 4'h7; end else begin loopEnd <= 4'h2; end end end else begin i <= i + 1'b1; if ( (CRCResult[0] ^ data[0]) == 1'b1) begin CRCResult <= {1'b0, CRCResult[4:1]} ^ 5'h14; end else begin CRCResult <= {1'b0, CRCResult[4:1]}; end data <= {1'b0, data[7:1]}; if (i == loopEnd) begin doUpdateCRC <= 1'b0; i <= 4'h0; ready <= 1'b1; end end end end endmodule
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