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

////                                                              ////

////  eth_txcounters.v                                            ////

////                                                              ////

////  This file is part of the Ethernet IP core project           ////

////  http://www.opencores.org/project,ethmac                   ////

////                                                              ////

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

////      - Igor Mohor (igorM@opencores.org)                      ////

////      - Novan Hartadi (novan@vlsi.itb.ac.id)                  ////

////      - Mahmud Galela (mgalela@vlsi.itb.ac.id)                ////

////                                                              ////

////  All additional information is avaliable in the Readme.txt   ////

////  file.                                                       ////

////                                                              ////

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

////                                                              ////

//// 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 $

// Revision 1.5  2002/04/22 14:54:14  mohor

// FCS should not be included in NibbleMinFl.

//

// Revision 1.4  2002/01/23 10:28:16  mohor

// Link in the header changed.

//

// Revision 1.3  2001/10/19 08:43:51  mohor

// eth_timescale.v changed to timescale.v This is done because of the

// simulation of the few cores in a one joined project.

//

// Revision 1.2  2001/09/11 14:17:00  mohor

// Few little NCSIM warnings fixed.

//

// Revision 1.1  2001/08/06 14:44:29  mohor

// A define FPGA added to select between Artisan RAM (for ASIC) and Block Ram (For Virtex).

// Include files fixed to contain no path.

// File names and module names changed ta have a eth_ prologue in the name.

// File eth_timescale.v is used to define timescale

// All pin names on the top module are changed to contain _I, _O or _OE at the end.

// Bidirectional signal MDIO is changed to three signals (Mdc_O, Mdi_I, Mdo_O

// and Mdo_OE. The bidirectional signal must be created on the top level. This

// is done due to the ASIC tools.

//

// Revision 1.1  2001/07/30 21:23:42  mohor

// Directory structure changed. Files checked and joind together.

//

// Revision 1.4  2001/06/27 21:27:45  mohor

// Few typos fixed.

//

// Revision 1.2  2001/06/19 10:38:07  mohor

// Minor changes in header.

//

// Revision 1.1  2001/06/19 10:27:57  mohor

// TxEthMAC initial release.

//

//

//

`include "timescale.v"

module eth_txcounters (StatePreamble, StateIPG, StateData, StatePAD, StateFCS, StateJam,

                       StateBackOff, StateDefer, StateIdle, StartDefer, StartIPG, StartFCS,

                       StartJam, StartBackoff, TxStartFrm, MTxClk, Reset, MinFL, MaxFL, HugEn,

                       ExDfrEn, PacketFinished_q, DlyCrcEn, StateSFD, ByteCnt, NibCnt,

                       ExcessiveDefer, NibCntEq7, NibCntEq15, MaxFrame, NibbleMinFl, DlyCrcCnt

                      );

parameter Tp = 1;

input MTxClk;             // Tx clock

input Reset;              // Reset

input StatePreamble;      // Preamble state

input StateIPG;           // IPG state

input [1:0] StateData;    // Data state

input StatePAD;           // PAD state

input StateFCS;           // FCS state

input StateJam;           // Jam state

input StateBackOff;       // Backoff state

input StateDefer;         // Defer state

input StateIdle;          // Idle state

input StateSFD;           // SFD state

input StartDefer;         // Defer state will be activated in next clock

input StartIPG;           // IPG state will be activated in next clock

input StartFCS;           // FCS state will be activated in next clock

input StartJam;           // Jam state will be activated in next clock

input StartBackoff;       // Backoff state will be activated in next clock

input TxStartFrm;         // Tx start frame

input [15:0] MinFL;       // Minimum frame length (in bytes)

input [15:0] MaxFL;       // Miximum frame length (in bytes)

input HugEn;              // Pakets bigger then MaxFL enabled

input ExDfrEn;            // Excessive deferral enabled

input PacketFinished_q;

input DlyCrcEn;           // Delayed CRC enabled

output [15:0] ByteCnt;    // Byte counter

output [15:0] NibCnt;     // Nibble counter

output ExcessiveDefer;    // Excessive Deferral occuring

output NibCntEq7;         // Nibble counter is equal to 7

output NibCntEq15;        // Nibble counter is equal to 15

output MaxFrame;          // Maximum frame occured

output NibbleMinFl;       // Nibble counter is greater than the minimum frame length

output [2:0] DlyCrcCnt;   // Delayed CRC Count

wire ExcessiveDeferCnt;

wire ResetNibCnt;

wire IncrementNibCnt;

wire ResetByteCnt;

wire IncrementByteCnt;

wire ByteCntMax;

reg [15:0] NibCnt;

reg [15:0] ByteCnt;

reg  [2:0] DlyCrcCnt;

assign IncrementNibCnt = StateIPG | StatePreamble | (|StateData) | StatePAD

                       | StateFCS | StateJam | StateBackOff | StateDefer & ~ExcessiveDefer & TxStartFrm;

assign ResetNibCnt = StateDefer & ExcessiveDefer & ~TxStartFrm | StatePreamble & NibCntEq15

                   | StateJam & NibCntEq7 | StateIdle | StartDefer | StartIPG | StartFCS | StartJam;

// Nibble Counter

always @ (posedge MTxClk or posedge Reset)

begin

  if(Reset)

    NibCnt <=  16'h0;

  else

    begin

      if(ResetNibCnt)

        NibCnt <=  16'h0;

      else

      if(IncrementNibCnt)

        NibCnt <=  NibCnt + 16'd1;

     end

end

assign NibCntEq7   = &NibCnt[2:0];

assign NibCntEq15  = &NibCnt[3:0];

assign NibbleMinFl = NibCnt >= (((MinFL-16'd4)<<1) -1);  // FCS should not be included in NibbleMinFl

assign ExcessiveDeferCnt = NibCnt[13:0] == 14'h17b7;

assign ExcessiveDefer  = NibCnt[13:0] == 14'h17b7 & ~ExDfrEn;   // 6071 nibbles

assign IncrementByteCnt = StateData[1] & ~ByteCntMax

                        | StateBackOff & (&NibCnt[6:0])

                        | (StatePAD | StateFCS) & NibCnt[0] & ~ByteCntMax;

assign ResetByteCnt = StartBackoff | StateIdle & TxStartFrm | PacketFinished_q;

// Transmit Byte Counter

always @ (posedge MTxClk or posedge Reset)

begin

  if(Reset)

    ByteCnt[15:0] <=  16'h0;

  else

    begin

      if(ResetByteCnt)

        ByteCnt[15:0] <=  16'h0;

      else

      if(IncrementByteCnt)

        ByteCnt[15:0] <=  ByteCnt[15:0] + 16'd1;

    end

end

assign MaxFrame = ByteCnt[15:0] == MaxFL[15:0] & ~HugEn;

assign ByteCntMax = &ByteCnt[15:0];

// Delayed CRC counter

always @ (posedge MTxClk or posedge Reset)

begin

  if(Reset)

    DlyCrcCnt <=  3'h0;

  else

    begin

      if(StateData[1] & DlyCrcCnt == 3'h4 | StartJam | PacketFinished_q)

        DlyCrcCnt <=  3'h0;

      else

      if(DlyCrcEn & (StateSFD | StateData[1] & (|DlyCrcCnt[2:0])))

        DlyCrcCnt <=  DlyCrcCnt + 3'd1;

    end

end

endmodule