eth_ocm/eth_crc.v

   1 //////////////////////////////////////////////////////////////////////
   2 ////                                                              ////
   3 ////  eth_crc.v                                                   ////
   4 ////                                                              ////
   5 ////  This file is part of the Ethernet IP core project           ////
   6 ////  http://www.opencores.org/projects/ethmac/                   ////
   7 ////                                                              ////
   8 ////  Author(s):                                                  ////
   9 ////      - Igor Mohor (igorM@opencores.org)                      ////
  10 ////      - Novan Hartadi (novan@vlsi.itb.ac.id)                  ////
  11 ////      - Mahmud Galela (mgalela@vlsi.itb.ac.id)                ////
  12 ////                                                              ////
  13 ////  All additional information is avaliable in the Readme.txt   ////
  14 ////  file.                                                       ////
  15 ////                                                              ////
  16 //////////////////////////////////////////////////////////////////////
  17 ////                                                              ////
  18 //// Copyright (C) 2001 Authors                                   ////
  19 ////                                                              ////
  20 //// This source file may be used and distributed without         ////
  21 //// restriction provided that this copyright statement is not    ////
  22 //// removed from the file and that any derivative work contains  ////
  23 //// the original copyright notice and the associated disclaimer. ////
  24 ////                                                              ////
  25 //// This source file is free software; you can redistribute it   ////
  26 //// and/or modify it under the terms of the GNU Lesser General   ////
  27 //// Public License as published by the Free Software Foundation; ////
  28 //// either version 2.1 of the License, or (at your option) any   ////
  29 //// later version.                                               ////
  30 ////                                                              ////
  31 //// This source is distributed in the hope that it will be       ////
  32 //// useful, but WITHOUT ANY WARRANTY; without even the implied   ////
  33 //// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR      ////
  34 //// PURPOSE.  See the GNU Lesser General Public License for more ////
  35 //// details.                                                     ////
  36 ////                                                              ////
  37 //// You should have received a copy of the GNU Lesser General    ////
  38 //// Public License along with this source; if not, download it   ////
  39 //// from http://www.opencores.org/lgpl.shtml                     ////
  40 ////                                                              ////
  41 //////////////////////////////////////////////////////////////////////
  42 //
  43 // CVS Revision History
  44 //
  45 // $Log: eth_crc.v,v $
  46 // Revision 1.3  2002/01/23 10:28:16  mohor
  47 // Link in the header changed.
  48 //
  49 // Revision 1.2  2001/10/19 08:43:51  mohor
  50 // eth_timescale.v changed to timescale.v This is done because of the
  51 // simulation of the few cores in a one joined project.
  52 //
  53 // Revision 1.1  2001/08/06 14:44:29  mohor
  54 // A define FPGA added to select between Artisan RAM (for ASIC) and Block Ram (For Virtex).
  55 // Include files fixed to contain no path.
  56 // File names and module names changed ta have a eth_ prologue in the name.
  57 // File eth_timescale.v is used to define timescale
  58 // All pin names on the top module are changed to contain _I, _O or _OE at the end.
  59 // Bidirectional signal MDIO is changed to three signals (Mdc_O, Mdi_I, Mdo_O
  60 // and Mdo_OE. The bidirectional signal must be created on the top level. This
  61 // is done due to the ASIC tools.
  62 //
  63 // Revision 1.1  2001/07/30 21:23:42  mohor
  64 // Directory structure changed. Files checked and joind together.
  65 //
  66 // Revision 1.3  2001/06/19 18:16:40  mohor
  67 // TxClk changed to MTxClk (as discribed in the documentation).
  68 // Crc changed so only one file can be used instead of two.
  69 //
  70 // Revision 1.2  2001/06/19 10:38:07  mohor
  71 // Minor changes in header.
  72 //
  73 // Revision 1.1  2001/06/19 10:27:57  mohor
  74 // TxEthMAC initial release.
  75 //
  76 //
  77 //
  78
  79
  80 `include "timescale.v"
  81
  82 module eth_crc (Clk, Reset, Data, Enable, Initialize, Crc, CrcError);
  83
  84
  85 parameter Tp = 1;
  86
  87 input Clk;
  88 input Reset;
  89 input [3:0] Data;
  90 input Enable;
  91 input Initialize;
  92
  93 output [31:0] Crc;
  94 output CrcError;
  95
  96 reg  [31:0] Crc;
  97
  98 wire [31:0] CrcNext;
  99
 100
 101 assign CrcNext[0] = Enable & (Data[0] ^ Crc[28]);
 102 assign CrcNext[1] = Enable & (Data[1] ^ Data[0] ^ Crc[28] ^ Crc[29]);
 103 assign CrcNext[2] = Enable & (Data[2] ^ Data[1] ^ Data[0] ^ Crc[28] ^ Crc[29] ^ Crc[30]);
 104 assign CrcNext[3] = Enable & (Data[3] ^ Data[2] ^ Data[1] ^ Crc[29] ^ Crc[30] ^ Crc[31]);
 105 assign CrcNext[4] = (Enable & (Data[3] ^ Data[2] ^ Data[0] ^ Crc[28] ^ Crc[30] ^ Crc[31])) ^ Crc[0];
 106 assign CrcNext[5] = (Enable & (Data[3] ^ Data[1] ^ Data[0] ^ Crc[28] ^ Crc[29] ^ Crc[31])) ^ Crc[1];
 107 assign CrcNext[6] = (Enable & (Data[2] ^ Data[1] ^ Crc[29] ^ Crc[30])) ^ Crc[ 2];
 108 assign CrcNext[7] = (Enable & (Data[3] ^ Data[2] ^ Data[0] ^ Crc[28] ^ Crc[30] ^ Crc[31])) ^ Crc[3];
 109 assign CrcNext[8] = (Enable & (Data[3] ^ Data[1] ^ Data[0] ^ Crc[28] ^ Crc[29] ^ Crc[31])) ^ Crc[4];
 110 assign CrcNext[9] = (Enable & (Data[2] ^ Data[1] ^ Crc[29] ^ Crc[30])) ^ Crc[5];
 111 assign CrcNext[10] = (Enable & (Data[3] ^ Data[2] ^ Data[0] ^ Crc[28] ^ Crc[30] ^ Crc[31])) ^ Crc[6];
 112 assign CrcNext[11] = (Enable & (Data[3] ^ Data[1] ^ Data[0] ^ Crc[28] ^ Crc[29] ^ Crc[31])) ^ Crc[7];
 113 assign CrcNext[12] = (Enable & (Data[2] ^ Data[1] ^ Data[0] ^ Crc[28] ^ Crc[29] ^ Crc[30])) ^ Crc[8];
 114 assign CrcNext[13] = (Enable & (Data[3] ^ Data[2] ^ Data[1] ^ Crc[29] ^ Crc[30] ^ Crc[31])) ^ Crc[9];
 115 assign CrcNext[14] = (Enable & (Data[3] ^ Data[2] ^ Crc[30] ^ Crc[31])) ^ Crc[10];
 116 assign CrcNext[15] = (Enable & (Data[3] ^ Crc[31])) ^ Crc[11];
 117 assign CrcNext[16] = (Enable & (Data[0] ^ Crc[28])) ^ Crc[12];
 118 assign CrcNext[17] = (Enable & (Data[1] ^ Crc[29])) ^ Crc[13];
 119 assign CrcNext[18] = (Enable & (Data[2] ^ Crc[30])) ^ Crc[14];
 120 assign CrcNext[19] = (Enable & (Data[3] ^ Crc[31])) ^ Crc[15];
 121 assign CrcNext[20] = Crc[16];
 122 assign CrcNext[21] = Crc[17];
 123 assign CrcNext[22] = (Enable & (Data[0] ^ Crc[28])) ^ Crc[18];
 124 assign CrcNext[23] = (Enable & (Data[1] ^ Data[0] ^ Crc[29] ^ Crc[28])) ^ Crc[19];
 125 assign CrcNext[24] = (Enable & (Data[2] ^ Data[1] ^ Crc[30] ^ Crc[29])) ^ Crc[20];
 126 assign CrcNext[25] = (Enable & (Data[3] ^ Data[2] ^ Crc[31] ^ Crc[30])) ^ Crc[21];
 127 assign CrcNext[26] = (Enable & (Data[3] ^ Data[0] ^ Crc[31] ^ Crc[28])) ^ Crc[22];
 128 assign CrcNext[27] = (Enable & (Data[1] ^ Crc[29])) ^ Crc[23];
 129 assign CrcNext[28] = (Enable & (Data[2] ^ Crc[30])) ^ Crc[24];
 130 assign CrcNext[29] = (Enable & (Data[3] ^ Crc[31])) ^ Crc[25];
 131 assign CrcNext[30] = Crc[26];
 132 assign CrcNext[31] = Crc[27];
 133
 134
 135 always @ (posedge Clk or posedge Reset)
 136 begin
 137   if (Reset)
 138     Crc <= #1 32'hffffffff;
 139   else
 140   if(Initialize)
 141     Crc <= #Tp 32'hffffffff;
 142   else
 143     Crc <= #Tp CrcNext;
 144 end
 145
 146 assign CrcError = Crc[31:0] != 32'hc704dd7b;  // CRC not equal to magic number
 147
 148 endmodule