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//////////////////////////////////////////////////////////////////////
////                                                              ////
////  eth_wishbone.v                                              ////
////                                                              ////
////  This file is part of the Ethernet IP core project           ////
////  http://www.opencores.org/project,ethmac                   ////
////                                                              ////
////  Author(s):                                                  ////
////      - Igor Mohor (igorM@opencores.org)                      ////
////                                                              ////
////  All additional information is available in the Readme.txt   ////
////  file.                                                       ////
////                                                              ////
//////////////////////////////////////////////////////////////////////
////                                                              ////
//// Copyright (C) 2001, 2002 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                     ////
////                                                              ////
//////////////////////////////////////////////////////////////////////
 
`include "ethmac_defines.v"
`include "timescale.v"
 
 
module eth_wishbone
  (
 
   // WISHBONE common
   WB_CLK_I, WB_DAT_I, WB_DAT_O, 
 
   // WISHBONE slave
   WB_ADR_I, WB_WE_I, WB_ACK_O, 
   BDCs, 
 
   Reset, 
 
   // WISHBONE master
   m_wb_adr_o, m_wb_sel_o, m_wb_we_o, 
   m_wb_dat_o, m_wb_dat_i, m_wb_cyc_o, 
   m_wb_stb_o, m_wb_ack_i, m_wb_err_i, 
 
`ifdef ETH_WISHBONE_B3
   m_wb_cti_o, m_wb_bte_o, 
`endif
 
   //TX
   MTxClk, TxStartFrm, TxEndFrm, TxUsedData, TxData, 
   TxRetry, TxAbort, TxUnderRun, TxDone, PerPacketCrcEn, 
   PerPacketPad, 
 
   //RX
   MRxClk, RxData, RxValid, RxStartFrm, RxEndFrm, RxAbort, RxStatusWriteLatched_sync2, 
 
   // Register
   r_TxEn, r_RxEn, r_TxBDNum, r_RxFlow, r_PassAll, 
 
   // Interrupts
   TxB_IRQ, TxE_IRQ, RxB_IRQ, RxE_IRQ, Busy_IRQ, 
 
   // Rx Status
   InvalidSymbol, LatchedCrcError, RxLateCollision, ShortFrame, DribbleNibble,
   ReceivedPacketTooBig, RxLength, LoadRxStatus, ReceivedPacketGood, AddressMiss, 
   ReceivedPauseFrm, 
 
   // Tx Status
   RetryCntLatched, RetryLimit, LateCollLatched, DeferLatched, RstDeferLatched, CarrierSenseLost
 
   // Bist
`ifdef ETH_BIST
   ,
   // debug chain signals
   mbist_si_i,       // bist scan serial in
   mbist_so_o,       // bist scan serial out
   mbist_ctrl_i        // bist chain shift control
`endif
 
`ifdef WISHBONE_DEBUG
   ,
   dbg_dat0
`endif
 
 
   );
 
 
   //parameter Tp = 1;
   parameter Tp = 0;
 
 
   // WISHBONE common
   input           WB_CLK_I;       // WISHBONE clock
   input [31:0]    WB_DAT_I;       // WISHBONE data input
   output [31:0]   WB_DAT_O;       // WISHBONE data output
 
   // WISHBONE slave
   input [9:2] 	   WB_ADR_I;       // WISHBONE address input
   input           WB_WE_I;        // WISHBONE write enable input
   input [3:0] 	   BDCs;           // Buffer descriptors are selected
   output          WB_ACK_O;       // WISHBONE acknowledge output
 
   // WISHBONE master
   output [29:0]   m_wb_adr_o;     // 
   output [3:0]    m_wb_sel_o;     // 
   output          m_wb_we_o;      // 
   output [31:0]   m_wb_dat_o;     // 
   output          m_wb_cyc_o;     // 
   output          m_wb_stb_o;     // 
   input [31:0]    m_wb_dat_i;     // 
   input           m_wb_ack_i;     // 
   input           m_wb_err_i;     // 
 
`ifdef ETH_WISHBONE_B3
   output [2:0]    m_wb_cti_o;     // Cycle Type Identifier
 `ifdef BURST_4BEAT   
   output reg [1:0] m_wb_bte_o;     // Burst Type Extension
 `else
   output [1:0]     m_wb_bte_o;     // Burst Type Extension
 `endif
   reg [2:0] 	    m_wb_cti_o;     // Cycle Type Identifier
`endif
 
   input 	    Reset;       // Reset signal
 
   // Rx Status signals
   input 	    InvalidSymbol;    // Invalid symbol was received during 
                                      // reception in 100 Mbps mode
   input 	    LatchedCrcError;  // CRC error
   input 	    RxLateCollision;  // Late collision occured while receiving
                                      // frame
   input 	    ShortFrame;       // Frame shorter then the minimum size 
                                      // (r_MinFL) was received while small 
                                      // packets are enabled (r_RecSmall)
   input 	    DribbleNibble;    // Extra nibble received
   input 	    ReceivedPacketTooBig;// Received packet is bigger than 
                                         // r_MaxFL
   input [15:0]     RxLength;         // Length of the incoming frame
   input 	    LoadRxStatus;     // Rx status was loaded
   input 	    ReceivedPacketGood;// Received packet's length and CRC are 
                                       // good
   input 	    AddressMiss;      // When a packet is received AddressMiss 
                                      // status is written to the Rx BD
   input 	    r_RxFlow;
   input 	    r_PassAll;
   input 	    ReceivedPauseFrm;
 
   // Tx Status signals
   input [3:0] 	    RetryCntLatched;  // Latched Retry Counter
   input 	    RetryLimit;       // Retry limit reached (Retry Max value +
                                      //  1 attempts were made)
   input 	    LateCollLatched;  // Late collision occured
   input 	    DeferLatched;     // Defer indication (Frame was defered 
                                      // before sucessfully sent)
   output 	    RstDeferLatched;
   input 	    CarrierSenseLost; // Carrier Sense was lost during the 
                                      // frame transmission
 
   // Tx
   input 	    MTxClk;         // Transmit clock (from PHY)
   input 	    TxUsedData;     // Transmit packet used data
   input 	    TxRetry;        // Transmit packet retry
   input 	    TxAbort;        // Transmit packet abort
   input 	    TxDone;         // Transmission ended
   output 	    TxStartFrm;     // Transmit packet start frame
   output 	    TxEndFrm;       // Transmit packet end frame
   output [7:0]     TxData;         // Transmit packet data byte
   output 	    TxUnderRun;     // Transmit packet under-run
   output 	    PerPacketCrcEn; // Per packet crc enable
   output 	    PerPacketPad;   // Per packet pading
 
   // Rx
   input 	    MRxClk;         // Receive clock (from PHY)
   input [7:0] 	    RxData;         // Received data byte (from PHY)
   input 	    RxValid;        // 
   input 	    RxStartFrm;     // 
   input 	    RxEndFrm;       // 
   input 	    RxAbort;        // This signal is set when address doesn't
                                    // match.
   output 	    RxStatusWriteLatched_sync2;
 
   //Register
   input 	    r_TxEn;         // Transmit enable
   input 	    r_RxEn;         // Receive enable
   input [7:0] 	    r_TxBDNum;      // Receive buffer descriptor number
 
   // Interrupts
   output 	    TxB_IRQ;
   output 	    TxE_IRQ;
   output 	    RxB_IRQ;
   output 	    RxE_IRQ;
   output 	    Busy_IRQ;
 
 
   // Bist
`ifdef ETH_BIST
   input 	    mbist_si_i;       // bist scan serial in
   output 	    mbist_so_o;       // bist scan serial out
   input [`ETH_MBIST_CTRL_WIDTH - 1:0] mbist_ctrl_i; // bist chain shift control
`endif
 
`ifdef WISHBONE_DEBUG
   output [31:0] 		       dbg_dat0;
`endif
 
 
 
   reg 				       TxB_IRQ;
   reg 				       TxE_IRQ;
   reg 				       RxB_IRQ;
   reg 				       RxE_IRQ;
 
   reg 				       TxStartFrm;
   reg 				       TxEndFrm;
   reg [7:0] 			       TxData;
 
   reg 				       TxUnderRun;
   reg 				       TxUnderRun_wb;
 
   reg 				       TxBDRead;
   wire 			       TxStatusWrite;
 
   reg [1:0] 			       TxValidBytesLatched;
 
   reg [15:0] 			       TxLength;
   reg [15:0] 			       LatchedTxLength;
   reg [14:11] 			       TxStatus;
 
   reg [14:13] 			       RxStatus;
 
   reg 				       TxStartFrm_wb;
   reg 				       TxRetry_wb;
   reg 				       TxAbort_wb;
   reg 				       TxDone_wb;
 
   reg 				       TxDone_wb_q;
   reg 				       TxAbort_wb_q;
   reg 				       TxRetry_wb_q;
   reg 				       TxRetryPacket;
   reg 				       TxRetryPacket_NotCleared;
   reg 				       TxDonePacket;
   reg 				       TxDonePacket_NotCleared;
   reg 				       TxAbortPacket;
   reg 				       TxAbortPacket_NotCleared;
   reg 				       RxBDReady;
   reg 				       RxBDOK;
   reg 				       TxBDReady;
 
   reg 				       RxBDRead;
 
   reg [31:0] 			       TxDataLatched;
   reg [1:0] 			       TxByteCnt;
   reg 				       LastWord;
   reg 				       ReadTxDataFromFifo_tck;
 
   reg 				       BlockingTxStatusWrite;
   reg 				       BlockingTxBDRead;
 
   reg 				       Flop;
 
   reg [7:1] 			       TxBDAddress;
   reg [7:1] 			       RxBDAddress;
 
   reg 				       TxRetrySync1;
   reg 				       TxAbortSync1;
   reg 				       TxDoneSync1;
 
   reg 				       TxAbort_q;
   reg 				       TxRetry_q;
   reg 				       TxUsedData_q;
 
   reg [31:0] 			       RxDataLatched2;
 
   reg [31:8] 			       RxDataLatched1;     // Big Endian Byte Ordering
 
   reg [1:0] 			       RxValidBytes;
   reg [1:0] 			       RxByteCnt;
   reg 				       LastByteIn;
   reg 				       ShiftWillEnd;
 
   reg 				       WriteRxDataToFifo;
   reg [15:0] 			       LatchedRxLength;
   reg 				       RxAbortLatched;
 
   reg 				       ShiftEnded;
   reg 				       RxOverrun;
 
   reg [3:0] 			       BDWrite;                    // BD Write Enable for access from WISHBONE side
   reg 				       BDRead;                     // BD Read access from WISHBONE side
   wire [31:0] 			       RxBDDataIn;                 // Rx BD data in
   wire [31:0] 			       TxBDDataIn;                 // Tx BD data in
 
   reg 				       TxEndFrm_wb;
 
   wire 			       TxRetryPulse;
   wire 			       TxDonePulse;
   wire 			       TxAbortPulse;
 
   wire 			       StartRxBDRead;
 
   wire 			       StartTxBDRead;
 
   wire 			       TxIRQEn;
   wire 			       WrapTxStatusBit;
 
   wire 			       RxIRQEn;
   wire 			       WrapRxStatusBit;
 
   wire [1:0] 			       TxValidBytes;
 
   wire [7:1] 			       TempTxBDAddress;
   wire [7:1] 			       TempRxBDAddress;
 
   wire 			       RxStatusWrite;
   wire 			       RxBufferFull;
   wire 			       RxBufferAlmostEmpty;
   wire 			       RxBufferEmpty;
 
   reg 				       WB_ACK_O;
 
   wire [8:0] 			       RxStatusIn;
   reg [8:0] 			       RxStatusInLatched;
 
   reg 				       WbEn, WbEn_q;
   reg 				       RxEn, RxEn_q;
   reg 				       TxEn, TxEn_q;
   reg 				       r_TxEn_q;
   reg 				       r_RxEn_q;
 
   wire 			       ram_ce;
   wire [3:0] 			       ram_we;
   wire 			       ram_oe;
   reg [7:0] 			       ram_addr;
   reg [31:0] 			       ram_di;
   wire [31:0] 			       ram_do;
 
   wire 			       StartTxPointerRead;
   reg 				       TxPointerRead;
   reg 				       TxEn_needed;
   reg 				       RxEn_needed;
 
   wire 			       StartRxPointerRead;
   reg 				       RxPointerRead;
 
   // RX shift ending signals
   reg ShiftEnded_rck;
   reg ShiftEndedSync1;
   reg ShiftEndedSync2;
   reg ShiftEndedSync3;
   reg ShiftEndedSync_c1;
   reg ShiftEndedSync_c2;
 
   wire StartShiftWillEnd;
 
   // Pulse for wishbone side having finished writing back
   reg 	rx_wb_writeback_finished;
   // Indicator of last set of writes from the Wishbone master coming up
   reg 	rx_wb_last_writes;
 
 
`ifdef TXBD_POLL
   reg [31:0] 			       TxBDReadySamples; // -- jb
   wire 			       TxBDNotReady; // -- jb
`endif   
 
`ifdef ETH_WISHBONE_B3
 `ifndef BURST_4BEAT   
   assign m_wb_bte_o = 2'b00;    // Linear burst
 `endif
`endif
 
   assign m_wb_stb_o = m_wb_cyc_o;
 
   always @ (posedge WB_CLK_I)
     begin
	WB_ACK_O <= (|BDWrite) & WbEn & WbEn_q | BDRead & WbEn & ~WbEn_q;
     end
 
   assign WB_DAT_O = ram_do;
 
   // Generic synchronous single-port RAM interface
   eth_spram_256x32
     #(1) // Write enable width
     bd_ram
     (
      .clk     (WB_CLK_I), 
      .rst     (Reset), 
      .ce      (ram_ce), 
      .we      (ram_we[0]), 
      .oe      (ram_oe), 
      .addr    (ram_addr), 
      .di      (ram_di), 
      .do      (ram_do)
`ifdef ETH_BIST
      ,
      .mbist_si_i       (mbist_si_i),
      .mbist_so_o       (mbist_so_o),
      .mbist_ctrl_i       (mbist_ctrl_i)
`endif
      );
 
   assign ram_ce = 1'b1;
   assign ram_we = (BDWrite & {4{(WbEn & WbEn_q)}}) | 
		   {4{(TxStatusWrite | RxStatusWrite)}};
   assign ram_oe = BDRead & WbEn & WbEn_q | TxEn & TxEn_q & 
		   (TxBDRead | TxPointerRead) | RxEn & RxEn_q & 
		   (RxBDRead | RxPointerRead);
 
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  TxEn_needed <= 1'b0;
	else
	  if(~TxBDReady & r_TxEn & WbEn & ~WbEn_q)
	    TxEn_needed <= 1'b1;
	  else
	    if(TxPointerRead & TxEn & TxEn_q)
	      TxEn_needed <= 1'b0;
     end
 
   // Enabling access to the RAM for three devices.
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  begin
	     WbEn <= 1'b1;
	     RxEn <= 1'b0;
	     TxEn <= 1'b0;
	     ram_addr <= 8'h0;
	     ram_di <= 32'h0;
	     BDRead <= 1'b0;
	     BDWrite <= 1'b0;
	  end
	else
	  begin
	     // Switching between three stages depends on enable signals
	     case ({WbEn_q, RxEn_q, TxEn_q, RxEn_needed, TxEn_needed})  // synopsys parallel_case
               5'b100_10, 5'b100_11 :
		 begin
		    WbEn <= 1'b0;
		    RxEn <= 1'b1;  // wb access stage and r_RxEn is enabled
		    TxEn <= 1'b0;
		    ram_addr <= {RxBDAddress, RxPointerRead};
		    ram_di <= RxBDDataIn;
		 end
               5'b100_01 :
		 begin
		    WbEn <= 1'b0;
		    RxEn <= 1'b0;
		    TxEn <= 1'b1;  // wb access stage, r_RxEn is disabled but 
		                   // r_TxEn is enabled
		    ram_addr <= {TxBDAddress, TxPointerRead};
		    ram_di <= TxBDDataIn;
		 end
               5'b010_00, 5'b010_10 :
		 begin
		    WbEn <= 1'b1;  // RxEn access stage and r_TxEn is disabled
		    RxEn <= 1'b0;
		    TxEn <= 1'b0;
		    ram_addr <= WB_ADR_I[9:2];
		    ram_di <= WB_DAT_I;
		    BDWrite <= BDCs[3:0] & {4{WB_WE_I}};
		    BDRead <= (|BDCs) & ~WB_WE_I;
		 end
               5'b010_01, 5'b010_11 :
		 begin
		    WbEn <= 1'b0;
		    RxEn <= 1'b0;
		    TxEn <= 1'b1;  // RxEn access stage and r_TxEn is enabled
		    ram_addr <= {TxBDAddress, TxPointerRead};
		    ram_di <= TxBDDataIn;
		 end
               5'b001_00, 5'b001_01, 5'b001_10, 5'b001_11 :
		 begin
		    WbEn <= 1'b1;  // TxEn access stage (we always go to wb 
		                   // access stage)
		    RxEn <= 1'b0;
		    TxEn <= 1'b0;
		    ram_addr <= WB_ADR_I[9:2];
		    ram_di <= WB_DAT_I;
		    BDWrite <= BDCs[3:0] & {4{WB_WE_I}};
		    BDRead <= (|BDCs) & ~WB_WE_I;
		 end
               5'b100_00 :
		 begin
		    WbEn <= 1'b0;  // WbEn access stage and there is no need 
		                   // for other stages. WbEn needs to be 
		                   // switched off for a bit
		 end
               5'b000_00 :
		 begin
		    WbEn <= 1'b1;  // Idle state. We go to WbEn access stage.
		    RxEn <= 1'b0;
		    TxEn <= 1'b0;
		    ram_addr <= WB_ADR_I[9:2];
		    ram_di <= WB_DAT_I;
		    BDWrite <= BDCs[3:0] & {4{WB_WE_I}};
		    BDRead <= (|BDCs) & ~WB_WE_I;
		 end
	     endcase
	  end
     end
 
 
   // Delayed stage signals
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  begin
	     WbEn_q <= 1'b0;
	     RxEn_q <= 1'b0;
	     TxEn_q <= 1'b0;
	     r_TxEn_q <= 1'b0;
	     r_RxEn_q <= 1'b0;
	  end
	else
	  begin
	     WbEn_q <= WbEn;
	     RxEn_q <= RxEn;
	     TxEn_q <= TxEn;
	     r_TxEn_q <= r_TxEn;
	     r_RxEn_q <= r_RxEn;
	  end
     end
 
   // Changes for tx occur every second clock. Flop is used for this manner.
   always @ (posedge MTxClk or posedge Reset)
     begin
	if(Reset)
	  Flop <= 1'b0;
	else
	  if(TxDone | TxAbort | TxRetry_q)
	    Flop <= 1'b0;
	  else
	    if(TxUsedData)
	      Flop <= ~Flop;
     end
 
   wire ResetTxBDReady;
   assign ResetTxBDReady = TxDonePulse | TxAbortPulse | TxRetryPulse;
 
   // Latching READY status of the Tx buffer descriptor
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  TxBDReady <= 1'b0;
	else
	  if(TxEn & TxEn_q & TxBDRead)
	    // TxBDReady is sampled only once at the beginning.
	    TxBDReady <= ram_do[15] & (ram_do[31:16] > 4); 
	  else
	    // Only packets larger then 4 bytes are transmitted.
	    if(ResetTxBDReady)
	      TxBDReady <= 1'b0;
     end
 
`ifdef TXBD_POLL
   // Register TxBDReady 4 times, when all are low we know this one is not 
   // good to transmit
   always @(posedge WB_CLK_I or posedge Reset) // -- jb
     begin 
	if (Reset) TxBDReadySamples <= 32'hffffffff;
	else begin 
	   if (r_TxEn) 
	     begin
		if (TxBDNotReady)
		  TxBDReadySamples <= 32'hffffffff;
		else
		  TxBDReadySamples[31:0] <= {TxBDReadySamples[30:0],TxBDReady};
	     end
	   else
	     TxBDReadySamples <= 32'hffffffff;
	end // else: !if(Reset)
     end // always @ (posedge WB_CLK_I or posedge Reset)
   // When all low, this goes high -- jb
   assign TxBDNotReady = ~(|TxBDReadySamples); 
 
 
`endif
 
   // Reading the Tx buffer descriptor
   assign StartTxBDRead = (TxRetryPacket_NotCleared | TxStatusWrite) & 
			  ~BlockingTxBDRead & ~TxBDReady;
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  TxBDRead <= 1'b1;
	else
	  if(StartTxBDRead)
	    TxBDRead <= 1'b1;
	  else
	    if(TxBDReady)
	      TxBDRead <= 1'b0;
     end
 
 
   // Reading Tx BD pointer
   assign StartTxPointerRead = TxBDRead & TxBDReady;
 
   // Reading Tx BD Pointer
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  TxPointerRead <= 1'b0;
	else
	  if(StartTxPointerRead)
	    TxPointerRead <= 1'b1;
	  else
	    if(TxEn_q)
	      TxPointerRead <= 1'b0;
     end
 
 
   // Writing status back to the Tx buffer descriptor
   assign TxStatusWrite = (TxDonePacket_NotCleared | TxAbortPacket_NotCleared)&
			  TxEn & TxEn_q & ~BlockingTxStatusWrite;
 
 
 
   // Status writing must occur only once. Meanwhile it is blocked.
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  BlockingTxStatusWrite <= 1'b0;
	else
	  if(~TxDone_wb & ~TxAbort_wb)
	    BlockingTxStatusWrite <= 1'b0;
	  else
	    if(TxStatusWrite)
	      BlockingTxStatusWrite <= 1'b1;
     end
 
 
   reg BlockingTxStatusWrite_sync1;
   reg BlockingTxStatusWrite_sync2;
   reg BlockingTxStatusWrite_sync3;
 
   // Synchronizing BlockingTxStatusWrite to MTxClk
   always @ (posedge MTxClk or posedge Reset)
     begin
	if(Reset)
	  BlockingTxStatusWrite_sync1 <= 1'b0;
	else
	  BlockingTxStatusWrite_sync1 <= BlockingTxStatusWrite;
     end
 
   // Synchronizing BlockingTxStatusWrite to MTxClk
   always @ (posedge MTxClk or posedge Reset)
     begin
	if(Reset)
	  BlockingTxStatusWrite_sync2 <= 1'b0;
	else
	  BlockingTxStatusWrite_sync2 <= BlockingTxStatusWrite_sync1;
     end
 
   // Synchronizing BlockingTxStatusWrite to MTxClk
   always @ (posedge MTxClk or posedge Reset)
     begin
	if(Reset)
	  BlockingTxStatusWrite_sync3 <= 1'b0;
	else
	  BlockingTxStatusWrite_sync3 <= BlockingTxStatusWrite_sync2;
     end
 
   assign RstDeferLatched = BlockingTxStatusWrite_sync2 & 
			    ~BlockingTxStatusWrite_sync3;
 
   // TxBDRead state is activated only once. 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  BlockingTxBDRead <= 1'b0;
	else
	  if(StartTxBDRead)
	    BlockingTxBDRead <= 1'b1;
	  else
	    if(~StartTxBDRead & ~TxBDReady)
	      BlockingTxBDRead <= 1'b0;
     end
 
 
   // Latching status from the tx buffer descriptor
   // Data is avaliable one cycle after the access is started (at that time 
   // signal TxEn is not active)
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  TxStatus <= 4'h0;
	else
	  if(TxEn & TxEn_q & TxBDRead)
	    TxStatus <= ram_do[14:11];
     end
 
   reg ReadTxDataFromMemory;
   wire WriteRxDataToMemory;
   reg WriteRxDataToMemory_r;
 
   // Register WriteRxDataToMemory in Wishbone clock domain
   // so it doesn't get out of sync with burst capability indication signals
   always @(posedge WB_CLK_I or posedge Reset)
     if (Reset)
       WriteRxDataToMemory_r <= 0;
     else
       WriteRxDataToMemory_r <= WriteRxDataToMemory;
 
   reg 	MasterWbTX;
   reg 	MasterWbRX;
 
   reg [29:0] m_wb_adr_o;
   reg        m_wb_cyc_o;
   reg [3:0]  m_wb_sel_o;
   reg        m_wb_we_o;
 
   wire       TxLengthEq0;
   wire       TxLengthLt4;
 
   reg 	      BlockingIncrementTxPointer;
   reg [31:2] TxPointerMSB;
   reg [1:0]  TxPointerLSB;
   reg [1:0]  TxPointerLSB_rst;
   reg [31:2] RxPointerMSB;
   reg [1:0]  RxPointerLSB_rst;
 
   wire       RxBurstAcc;
   wire       RxWordAcc;
   wire       RxHalfAcc;
   wire       RxByteAcc;
 
   //Latching length from the buffer descriptor;
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  TxLength <= 16'h0;
	else
	  if(TxEn & TxEn_q & TxBDRead)
	    TxLength <= ram_do[31:16];
	  else
	    if(MasterWbTX & m_wb_ack_i)
	      begin
		 if(TxLengthLt4)
		   TxLength <= 16'h0;
		 else
		   if(TxPointerLSB_rst==2'h0)
		     TxLength <= TxLength - 3'h4;    // Length is subtracted at
		                                     // the data request
		   else
		     if(TxPointerLSB_rst==2'h1)
		       TxLength <= TxLength - 3'h3;    // Length is subtracted 
		                                       // at the data request
		     else
		       if(TxPointerLSB_rst==2'h2)
			 TxLength <= TxLength - 3'h2;    // Length is subtracted
		                                         // at the data request
		       else
			 if(TxPointerLSB_rst==2'h3)
			   TxLength <= TxLength - 3'h1;  // Length is subtracted
		                                         // at the data request
	      end
     end
 
 
 
   //Latching length from the buffer descriptor;
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  LatchedTxLength <= 16'h0;
	else
	  if(TxEn & TxEn_q & TxBDRead)
	    LatchedTxLength <= ram_do[31:16];
     end
 
   assign TxLengthEq0 = TxLength == 0;
   assign TxLengthLt4 = TxLength < 4;
 
   reg cyc_cleared;
   reg IncrTxPointer;
 
 
   // Latching Tx buffer pointer from buffer descriptor. Only 30 MSB bits are 
   // latched because TxPointerMSB is only used for word-aligned accesses.
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  TxPointerMSB <= 30'h0;
	else
	  if(TxEn & TxEn_q & TxPointerRead)
	    TxPointerMSB <= ram_do[31:2];
	  else
	    if(IncrTxPointer & ~BlockingIncrementTxPointer)
	      // TxPointer is word-aligned
	      TxPointerMSB <= TxPointerMSB + 1'b1;
     end
 
 
   // Latching 2 MSB bits of the buffer descriptor. Since word accesses are 
   // performed, valid data does not necesserly start at byte 0 (could be byte 
   // 0, 1, 2 or 3). This signals are used for proper selection of the start 
   // byte (TxData and TxByteCnt) are set by this two bits.
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  TxPointerLSB[1:0] <= 0;
	else
	  if(TxEn & TxEn_q & TxPointerRead)
	    TxPointerLSB[1:0] <= ram_do[1:0];
     end
 
 
   // Latching 2 MSB bits of the buffer descriptor. 
   // After the read access, TxLength needs to be decremented for the number of
   // the valid bytes (1 to 4 bytes are valid in the first word). After the 
   // first read all bytes are valid so this two bits are reset to zero. 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  TxPointerLSB_rst[1:0] <= 0;
	else
	  if(TxEn & TxEn_q & TxPointerRead)
	    TxPointerLSB_rst[1:0] <= ram_do[1:0];
	  else
	    // After first access pointer is word alligned
	    if(MasterWbTX & m_wb_ack_i)  
	      TxPointerLSB_rst[1:0] <= 0;
     end
 
 
   reg  [3:0] RxByteSel;
   wire       MasterAccessFinished;
 
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  BlockingIncrementTxPointer <= 0;
	else
	  if(MasterAccessFinished)
	    BlockingIncrementTxPointer <= 0;
	  else
	    if(IncrTxPointer)
	      BlockingIncrementTxPointer <= 1'b1;
     end
 
 
   wire TxBufferAlmostFull;
   wire TxBufferFull;
   wire TxBufferEmpty;
   wire TxBufferAlmostEmpty;
   wire SetReadTxDataFromMemory;
 
   reg 	BlockReadTxDataFromMemory;
 
   assign SetReadTxDataFromMemory = TxEn & TxEn_q & TxPointerRead;
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  ReadTxDataFromMemory <= 1'b0;
	else
	  if(TxLengthEq0 | TxAbortPulse | TxRetryPulse)
	    ReadTxDataFromMemory <= 1'b0;
	  else
	    if(SetReadTxDataFromMemory)
	      ReadTxDataFromMemory <= 1'b1;
     end
 
   reg tx_burst_en;
   reg rx_burst_en;
   reg [`ETH_BURST_CNT_WIDTH-1:0] tx_burst_cnt;
 
   wire 			  ReadTxDataFromMemory_2;
   wire 			  tx_burst;
 
 
   wire [31:0] 			  TxData_wb;
   wire 			  ReadTxDataFromFifo_wb;
 
   assign ReadTxDataFromMemory_2 = ReadTxDataFromMemory & 
				   ~BlockReadTxDataFromMemory | (|tx_burst_cnt);
 
   assign tx_burst = ReadTxDataFromMemory_2 & tx_burst_en;
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  BlockReadTxDataFromMemory <= 1'b0;
	else
	  if((TxBufferAlmostFull | TxLength <= 4)& MasterWbTX & 
	     (~cyc_cleared) & (!(TxAbortPacket_NotCleared | 
				 TxRetryPacket_NotCleared)))
	    BlockReadTxDataFromMemory <= 1'b1;
	  else
	    if(ReadTxDataFromFifo_wb | TxDonePacket | TxAbortPacket | 
	       TxRetryPacket)
	      BlockReadTxDataFromMemory <= 1'b0;
     end
 
`define TX_BURST_EN_CONDITION (txfifo_cnt<(`ETH_TX_FIFO_DEPTH-`ETH_BURST_LENGTH) & (TxLength>(`ETH_BURST_LENGTH*4+4)))
 
   assign MasterAccessFinished = m_wb_ack_i | m_wb_err_i;
   wire [`ETH_TX_FIFO_CNT_WIDTH-1:0] txfifo_cnt;
   wire [`ETH_RX_FIFO_CNT_WIDTH-1:0] rxfifo_cnt;
 
   reg [`ETH_BURST_CNT_WIDTH-1:0]    rx_burst_cnt;
 
   wire 			     rx_burst;
   wire 			     enough_data_in_rxfifo_for_burst;
   wire 			     enough_data_in_rxfifo_for_burst_plus1;
 
   // Enabling master wishbone access to the memory for two devices TX and RX.
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  begin
	     MasterWbTX <= 1'b0;
	     MasterWbRX <= 1'b0;
	     m_wb_adr_o <= 30'h0;
	     m_wb_cyc_o <= 1'b0;
	     m_wb_we_o  <= 1'b0;
	     m_wb_sel_o <= 4'h0;
	     cyc_cleared<= 1'b0;
	     tx_burst_cnt<= 0;
	     rx_burst_cnt<= 0;
	     IncrTxPointer<= 1'b0;
	     tx_burst_en<= 1'b1;
	     rx_burst_en<= 1'b0;
`ifdef ETH_WISHBONE_B3
             m_wb_cti_o <= 3'b0;
 `ifdef BURST_4BEAT
	     m_wb_bte_o <= 2'b00;
 `endif       
`endif
	  end
	else
	  begin
	     // Switching between two stages depends on enable signals
	     casex ({MasterWbTX,
		     MasterWbRX,
		     ReadTxDataFromMemory_2,
		     WriteRxDataToMemory_r,
		     MasterAccessFinished,
		     cyc_cleared,
		     tx_burst,
		     rx_burst})  // synopsys parallel_case
 
               8'b00_10_00_10, // Idle and MRB needed
	       8'b10_1x_10_1x, // MRB continues
	       8'b10_10_01_10, // Clear (previously MR) and MRB needed
	       8'b01_1x_01_1x: // Clear (previously MW) and MRB needed
		   begin
		      MasterWbTX <= 1'b1;  // tx burst
		      MasterWbRX <= 1'b0;
		      m_wb_cyc_o <= 1'b1;
		      m_wb_we_o  <= 1'b0;
		      m_wb_sel_o <= 4'hf;
		      cyc_cleared<= 1'b0;
		      IncrTxPointer<= 1'b1;
		      tx_burst_cnt <= tx_burst_cnt+3'h1;
		      if(tx_burst_cnt==0)
			m_wb_adr_o <= TxPointerMSB;
		      else
			m_wb_adr_o <= m_wb_adr_o+1'b1;
 
		      if(tx_burst_cnt==(`ETH_BURST_LENGTH-1))
			begin
			   tx_burst_en<= 1'b0;
`ifdef ETH_WISHBONE_B3
			   m_wb_cti_o <= 3'b111;
`endif
			end
		      else
			begin
`ifdef ETH_WISHBONE_B3
			   m_wb_cti_o <= 3'b010;
 `ifdef BURST_4BEAT   		 
			   m_wb_bte_o <= 2'b01;
 `endif
`endif
			end
		   end // case: 8'b00_10_00_10,...
`ifdef ETH_RX_BURST_EN	
         8'b00_x1_00_x1,             // Idle and MWB needed
         8'b01_x1_10_x1,             // MWB continues
         8'b01_01_01_01,             // Clear (previously MW) and MWB needed
         8'b10_x1_01_x1 :            // Clear (previously MR) and MWB needed
           begin
              MasterWbTX <= 1'b0;  // rx burst
              MasterWbRX <= 1'b1;
              m_wb_cyc_o <= 1'b1;
              m_wb_we_o  <= 1'b1;
              m_wb_sel_o <= RxByteSel;
              IncrTxPointer<= 1'b0;
              cyc_cleared<= 1'b0;
              rx_burst_cnt <= rx_burst_cnt+3'h1;
 
              if(rx_burst_cnt==0)
		m_wb_adr_o <= RxPointerMSB;
              else
		m_wb_adr_o <= m_wb_adr_o+1'b1;
 
              if(rx_burst_cnt==(`ETH_BURST_LENGTH-1))
		begin
                   rx_burst_en<= 1'b0;
 `ifdef ETH_WISHBONE_B3
                   m_wb_cti_o <= 3'b111;
 `endif
		end
              else
		begin
 `ifdef ETH_WISHBONE_B3               
  `ifdef BURST_4BEAT
		   m_wb_cti_o <= 3'b010;
		   m_wb_bte_o <= 2'b01;
  `endif    
 `endif
		end
           end // case: 8'b00_x1_00_x1,...
`endif //  `ifdef ETH_RX_BURST_EN
               8'b00_x1_00_x0 ,//idle and MW is needed (data write to rx buffer)
	       8'b01_x1_00_x0 :// Sometimes gets caught changing states - JB
		   begin
		      MasterWbTX <= 1'b0;
		      MasterWbRX <= !RxBufferEmpty;
		      m_wb_adr_o <= RxPointerMSB;
		      m_wb_cyc_o <= !RxBufferEmpty;
		      m_wb_we_o  <= !RxBufferEmpty;
		      m_wb_sel_o <= RxByteSel;
		      IncrTxPointer<= 1'b0;
`ifdef ETH_WISHBONE_B3 
 `ifdef ETH_RX_BURST_EN
  `ifdef BURST_4BEAT
		      if ((RxPointerMSB[3:2]==2'b00) & !RxBufferEmpty &
			  enough_data_in_rxfifo_for_burst & !m_wb_cyc_o)
			// Added "& !_m_wb_cyc_o" here to stop burst signals
			// going high during a transfer
			begin
			   rx_burst_en<= 1'b1;
			   m_wb_cti_o <= 3'b010;
			   m_wb_bte_o <= 2'b01;
			   rx_burst_cnt<= 1;
			end
  `endif
 `endif
`endif //  `ifdef ETH_WISHBONE_B3
 
		   end
               8'b00_10_00_00 : // idle and MR is needed (data read from tx 
		                // buffer)
		 begin
		    MasterWbTX <= 1'b1;
		    MasterWbRX <= 1'b0;
		    m_wb_adr_o <= TxPointerMSB;
		    m_wb_cyc_o <= 1'b1;
		    m_wb_we_o  <= 1'b0;
		    m_wb_sel_o <= 4'hf;
		    IncrTxPointer<= 1'b1;
`ifdef BURST_4BEAT	     
 
		    // Attempt ethernet bugfix, start bursts later
		    if ((TxPointerMSB[3:2]==2'b00) && `TX_BURST_EN_CONDITION)
		      begin
 `ifdef TX_BURST_EN_VERBOSE		  
			 $display("(%t)(%m): %b enabling tx_burst_en",$time, 
				  {MasterWbTX,MasterWbRX,ReadTxDataFromMemory_2,
				   WriteRxDataToMemory,MasterAccessFinished,
				   cyc_cleared,tx_burst,rx_burst});
 `endif		  
			 tx_burst_en<= 1'b1;
			 tx_burst_cnt <= 3'h1;
 
 `ifdef ETH_WISHBONE_B3
			 m_wb_cti_o <= 3'b010;
			 m_wb_bte_o <= 2'b01;
 `endif		  
		      end
`endif	     
		 end
               8'b10_10_01_00,// MR and MR is needed (data read from tx buffer)
	       8'b01_1x_01_0x  :// MW and MR is needed (data read from tx 
		                  // buffer)
		   begin
		      MasterWbTX <= 1'b1; // Only switch to TX here
		                          // when not end of RX
		      MasterWbRX <= 1'b0;
		      m_wb_adr_o <= TxPointerMSB;
		      m_wb_cyc_o <= 1'b1;
		      m_wb_we_o  <= 1'b0;
		      m_wb_sel_o <= 4'hf;
		      cyc_cleared<= 1'b0;
		      IncrTxPointer<= 1'b1;
`ifdef BURST_4BEAT	     
		      if ((TxPointerMSB[3:2]==2'b00) & `TX_BURST_EN_CONDITION)
			begin
 `ifdef TX_BURST_EN_VERBOSE
			   $display("(%t)(%m): %b enabling tx_burst_en",$time, 
				    {MasterWbTX,MasterWbRX,
				     ReadTxDataFromMemory_2,
				     WriteRxDataToMemory,
				     MasterAccessFinished,
				     cyc_cleared,
				     tx_burst,
				     rx_burst});
 `endif		  
			   tx_burst_en<= 1'b1;
			   tx_burst_cnt <= 3'h1;
 `ifdef ETH_WISHBONE_B3
			   m_wb_cti_o <= 3'b010;
			   m_wb_bte_o <= 2'b01;
 `endif		  
			end
`endif
 
		   end
               8'b01_01_01_00,// MW and MW needed (data write to rx buffer)
	       8'b10_x1_01_x0 ://MR and MW is needed (data write to rx buffer)
		   begin
		      MasterWbTX <= 1'b0;
		      MasterWbRX <= !RxBufferEmpty;
		      rx_burst_cnt<= 0;	     
		      m_wb_adr_o <= RxPointerMSB;
		      m_wb_cyc_o <= !RxBufferEmpty;
		      m_wb_we_o  <= !RxBufferEmpty;
		      m_wb_sel_o <= RxByteSel;
`ifdef ETH_WISHBONE_B3 
 `ifdef ETH_RX_BURST_EN
  `ifdef BURST_4BEAT
		      if ((RxPointerMSB[3:2]==2'b00) & 
			  enough_data_in_rxfifo_for_burst & !RxBufferEmpty)
			  //enough_data_in_rxfifo_for_burst_plus1)
 
 
			begin
			   rx_burst_en<= 1'b1;
			   m_wb_cti_o <= 3'b010;
			   m_wb_bte_o <= 2'b01;
			   rx_burst_cnt<= 1;
			end
  `endif	     
 `endif //  `ifdef ETH_RX_BURST_EN	     
`endif //  `ifdef ETH_WISHBONE_B3	     
		      cyc_cleared<= 1'b0;
		      IncrTxPointer<= 1'b0;   
		   end
               8'b01_01_10_00,// MW and MW needed (cycle is cleared between 
		              // previous and next access)
	       8'b01_1x_10_x0,// MW and MW or MR or MRB needed (cycle is 
		              // cleared between previous and next access)
	       8'b10_10_10_00,// MR and MR needed (cycle is cleared between 
		              // previous  and next access)
	       8'b10_x1_10_0x :// MR and MR or MW or MWB (cycle is cleared 
		               // between previous and next access)
		   begin
		      m_wb_cyc_o <= 1'b0;// whatever and master read or write is
	                                 // needed. We need to clear m_wb_cyc_o
		                         //  before next access is started
		      cyc_cleared<= 1'b1;
		      IncrTxPointer<= 1'b0;
		      tx_burst_cnt<= 0;
`ifdef BURST_4BEAT
		      // Caused a bug!
		      // if (TxPointerMSB[3:2]==2'b00)	     
		      //tx_burst_en<= `TX_BURST_EN_CONDITION;	     
		      // Set this to 0 here
		      tx_burst_en<= 0;
 
`endif	     
		      rx_burst_cnt<= 0;
`ifdef ETH_WISHBONE_B3
		      m_wb_bte_o <= 2'b00;
		      m_wb_cti_o <= 3'b0;
`endif
		   end
               8'bxx_00_10_00,// whatever and no master read or write is needed
		              // (ack or err comes finishing previous access)
		 8'bxx_00_01_00 : // Between cyc_cleared request was cleared
		   begin
		      MasterWbTX <= 1'b0;
		      MasterWbRX <= 1'b0;
		      m_wb_cyc_o <= 1'b0;
		      cyc_cleared<= 1'b0;
		      IncrTxPointer<= 1'b0;
		      rx_burst_cnt<= 0;
		      m_wb_bte_o <= 2'b00;	     
		      m_wb_cti_o <= 3'b0;	     
		   end
               8'b00_00_00_00:  // whatever and no master read or write is 
		                // needed (ack or err comes finishing previous 
		                // access)
		 begin
		    tx_burst_cnt<= 0;
`ifdef BURST_4BEAT
 
		    // This caused tx_burst to remain set between
		    // transmits, and sometimes we would burst immediately
		    // and maybe get the wrong data because the offset of
		    // the buffer pointer wasn't 16-byte aligned.
		    //if (TxPointerMSB[3:2]==2'b00)
		    //  tx_burst_en<= `TX_BURST_EN_CONDITION;
 
		    // Fix for transmit problems... maybe - jb
		    if(TxEn & TxEn_q & TxPointerRead & (ram_do[3:0]===4'h0))
		      begin
 `ifdef TX_BURST_EN_VERBOSE		  
			 $display("(%t)(%m): %b enabling tx_burst_en",$time, 
				  {MasterWbTX,MasterWbRX,ReadTxDataFromMemory_2,
				   WriteRxDataToMemory,MasterAccessFinished,
				   cyc_cleared,tx_burst,rx_burst});
 `endif		  
			 tx_burst_en<= `TX_BURST_EN_CONDITION;
		      end
		    else
		      tx_burst_en<= 0;
`endif	     
		 end
               default:                    // Don't touch
		 begin
		    MasterWbTX <= MasterWbTX;
		    MasterWbRX <= MasterWbRX;
		    m_wb_cyc_o <= m_wb_cyc_o;
		    m_wb_sel_o <= m_wb_sel_o;
		    IncrTxPointer<= IncrTxPointer;
		 end
	     endcase
	  end
     end
 
 
   wire TxFifoClear;
 
   assign TxFifoClear = (TxAbortPacket | TxRetryPacket | StartTxPointerRead);
 
   eth_fifo 
     #(
       `ETH_TX_FIFO_DATA_WIDTH, 
       `ETH_TX_FIFO_DEPTH, 
       `ETH_TX_FIFO_CNT_WIDTH
       )
   tx_fifo 
     ( 
       .data_in(m_wb_dat_i),
       .data_out(TxData_wb),
       .clk(WB_CLK_I),
       .reset(Reset),
       .write(MasterWbTX & m_wb_ack_i),
       .read(ReadTxDataFromFifo_wb & ~TxBufferEmpty),
       .clear(TxFifoClear),
       .full(TxBufferFull), 
       .almost_full(TxBufferAlmostFull),
       .almost_empty(TxBufferAlmostEmpty),
       .empty(TxBufferEmpty),
       .cnt(txfifo_cnt)
       );
 
 
   reg 	StartOccured;
   reg 	TxStartFrm_sync1;
   reg 	TxStartFrm_sync2;
   reg 	TxStartFrm_syncb1;
   reg 	TxStartFrm_syncb2;
 
 
 
   // Start: Generation of the TxStartFrm_wb which is then synchronized to the MTxClk
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  TxStartFrm_wb <= 1'b0;
	else
	  if(TxBDReady & ~StartOccured & (TxBufferFull | TxLengthEq0))
	    TxStartFrm_wb <= 1'b1;
	  else
	    if(TxStartFrm_syncb2)
	      TxStartFrm_wb <= 1'b0;
     end
 
   // StartOccured: TxStartFrm_wb occurs only ones at the beginning. Then it's 
   // blocked.
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  StartOccured <= 1'b0;
	else
	  if(TxStartFrm_wb)
	    StartOccured <= 1'b1;
	  else
	    if(ResetTxBDReady)
	      StartOccured <= 1'b0;
     end
 
   // Synchronizing TxStartFrm_wb to MTxClk
   always @ (posedge MTxClk or posedge Reset)
     begin
	if(Reset)
	  TxStartFrm_sync1 <= 1'b0;
	else
	  TxStartFrm_sync1 <= TxStartFrm_wb;
     end
 
   always @ (posedge MTxClk or posedge Reset)
     begin
	if(Reset)
	  TxStartFrm_sync2 <= 1'b0;
	else
	  TxStartFrm_sync2 <= TxStartFrm_sync1;
     end
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  TxStartFrm_syncb1 <= 1'b0;
	else
	  TxStartFrm_syncb1 <= TxStartFrm_sync2;
     end
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  TxStartFrm_syncb2 <= 1'b0;
	else
	  TxStartFrm_syncb2 <= TxStartFrm_syncb1;
     end
 
   always @ (posedge MTxClk or posedge Reset)
     begin
	if(Reset)
	  TxStartFrm <= 1'b0;
	else
	  if(TxStartFrm_sync2)
	    TxStartFrm <= 1'b1;
	  else
	    if(TxUsedData_q | ~TxStartFrm_sync2 & 
	       (TxRetry & (~TxRetry_q) | TxAbort & (~TxAbort_q)))
	      TxStartFrm <= 1'b0;
     end
   // End: Generation of the TxStartFrm_wb which is then synchronized to the 
   // MTxClk
 
 
   // TxEndFrm_wb: indicator of the end of frame
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  TxEndFrm_wb <= 1'b0;
	else
	  if(TxLengthEq0 & TxBufferAlmostEmpty & TxUsedData)
	    TxEndFrm_wb <= 1'b1;
	  else
	    if(TxRetryPulse | TxDonePulse | TxAbortPulse)
	      TxEndFrm_wb <= 1'b0;
     end
 
 
   // Marks which bytes are valid within the word.
   assign TxValidBytes = TxLengthLt4 ? TxLength[1:0] : 2'b0;
 
   reg LatchValidBytes;
   reg LatchValidBytes_q;
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  LatchValidBytes <= 1'b0;
	else
	  if(TxLengthLt4 & TxBDReady)
	    LatchValidBytes <= 1'b1;
	  else
	    LatchValidBytes <= 1'b0;
     end
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  LatchValidBytes_q <= 1'b0;
	else
	  LatchValidBytes_q <= LatchValidBytes;
     end
 
 
   // Latching valid bytes
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  TxValidBytesLatched <= 2'h0;
	else
	  if(LatchValidBytes & ~LatchValidBytes_q)
	    TxValidBytesLatched <= TxValidBytes;
	  else
	    if(TxRetryPulse | TxDonePulse | TxAbortPulse)
	      TxValidBytesLatched <= 2'h0;
     end
 
 
   assign TxIRQEn          = TxStatus[14];
   assign WrapTxStatusBit  = TxStatus[13];
   assign PerPacketPad     = TxStatus[12];
   assign PerPacketCrcEn   = TxStatus[11];
 
 
   assign RxIRQEn         = RxStatus[14];
   assign WrapRxStatusBit = RxStatus[13];
 
 
   // Temporary Tx and Rx buffer descriptor address
`ifdef TXBD_POLL
   assign TempTxBDAddress[7:1] = {7{ (TxStatusWrite|TxBDNotReady)     & ~WrapTxStatusBit}}   & (TxBDAddress + 1'b1) ; // Tx BD increment or wrap (last BD) -- jb
`else    
   assign TempTxBDAddress[7:1] = {7{ TxStatusWrite     & ~WrapTxStatusBit}}   & (TxBDAddress + 1'b1) ; // Tx BD increment or wrap (last BD)
`endif
   assign TempRxBDAddress[7:1] = {7{ WrapRxStatusBit}} & (r_TxBDNum[6:0])     | // Using first Rx BD
				 {7{~WrapRxStatusBit}} & (RxBDAddress + 1'b1) ; // Using next Rx BD (incremenrement address)
 
 
   // Latching Tx buffer descriptor address
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  TxBDAddress <= 7'h0;
	else if (r_TxEn & (~r_TxEn_q))
	  TxBDAddress <= 7'h0;
`ifdef TXBD_POLL
	else if (TxStatusWrite | TxBDNotReady)  // -- jb
`else    
	  else if (TxStatusWrite)
`endif      
	    TxBDAddress <= TempTxBDAddress;
     end
 
 
   // Latching Rx buffer descriptor address
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  RxBDAddress <= 7'h0;
	else if(r_RxEn & (~r_RxEn_q))
	  RxBDAddress <= r_TxBDNum[6:0];
	else if(RxStatusWrite)
	  RxBDAddress <= TempRxBDAddress;
     end
 
   wire [8:0] TxStatusInLatched = {TxUnderRun, RetryCntLatched[3:0], 
				   RetryLimit, LateCollLatched, DeferLatched, 
				   CarrierSenseLost};
 
   assign RxBDDataIn = {LatchedRxLength, 1'b0, RxStatus, 4'h0, 
			RxStatusInLatched};
   assign TxBDDataIn = {LatchedTxLength, 1'b0, TxStatus, 2'h0, 
			TxStatusInLatched};
 
 
   // Signals used for various purposes
   assign TxRetryPulse   = TxRetry_wb   & ~TxRetry_wb_q;
   assign TxDonePulse    = TxDone_wb    & ~TxDone_wb_q;
   assign TxAbortPulse   = TxAbort_wb   & ~TxAbort_wb_q;
 
 
 
   // Generating delayed signals
   always @ (posedge MTxClk or posedge Reset)
     begin
	if(Reset)
	  begin
	     TxAbort_q      <= 1'b0;
	     TxRetry_q      <= 1'b0;
	     TxUsedData_q   <= 1'b0;
	  end
	else
	  begin
	     TxAbort_q      <= TxAbort;
	     TxRetry_q      <= TxRetry;
	     TxUsedData_q   <= TxUsedData;
	  end
     end
 
   // Generating delayed signals
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  begin
	     TxDone_wb_q   <= 1'b0;
	     TxAbort_wb_q  <= 1'b0;
	     TxRetry_wb_q  <= 1'b0;
	  end
	else
	  begin
	     TxDone_wb_q   <= TxDone_wb;
	     TxAbort_wb_q  <= TxAbort_wb;
	     TxRetry_wb_q  <= TxRetry_wb;
	  end
     end
 
 
   reg TxAbortPacketBlocked;
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  TxAbortPacket <= 1'b0;
	else
	  if(TxAbort_wb & (~tx_burst_en) & MasterWbTX & MasterAccessFinished & 
	     (~TxAbortPacketBlocked) | TxAbort_wb & (~MasterWbTX) & 
	     (~TxAbortPacketBlocked))
	    TxAbortPacket <= 1'b1;
	  else
	    TxAbortPacket <= 1'b0;
     end
 
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  TxAbortPacket_NotCleared <= 1'b0;
	else
	  if(TxEn & TxEn_q & TxAbortPacket_NotCleared)
	    TxAbortPacket_NotCleared <= 1'b0;
	  else
	    if(TxAbort_wb & (~tx_burst_en) & MasterWbTX & 
	       MasterAccessFinished & (~TxAbortPacketBlocked) | TxAbort_wb & 
	       (~MasterWbTX) & (~TxAbortPacketBlocked))
	      TxAbortPacket_NotCleared <= 1'b1;
     end
 
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  TxAbortPacketBlocked <= 1'b0;
	else
	  if(!TxAbort_wb & TxAbort_wb_q)
	    TxAbortPacketBlocked <= 1'b0;
	  else
	    if(TxAbortPacket)
	      TxAbortPacketBlocked <= 1'b1;
     end
 
 
   reg TxRetryPacketBlocked;
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  TxRetryPacket <= 1'b0;
	else
	  if(TxRetry_wb & !tx_burst_en & MasterWbTX & MasterAccessFinished & 
	     !TxRetryPacketBlocked | TxRetry_wb & !MasterWbTX & 
	     !TxRetryPacketBlocked)
	    TxRetryPacket <= 1'b1;
	  else
	    TxRetryPacket <= 1'b0;
     end
 
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  TxRetryPacket_NotCleared <= 1'b0;
	else
	  if(StartTxBDRead)
	    TxRetryPacket_NotCleared <= 1'b0;
	  else
	    if(TxRetry_wb & !tx_burst_en & MasterWbTX & MasterAccessFinished & 
	       !TxRetryPacketBlocked | TxRetry_wb & !MasterWbTX & 
	       !TxRetryPacketBlocked)
	      TxRetryPacket_NotCleared <= 1'b1;
     end
 
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  TxRetryPacketBlocked <= 1'b0;
	else
	  if(!TxRetry_wb & TxRetry_wb_q)
	    TxRetryPacketBlocked <= 1'b0;
	  else
	    if(TxRetryPacket)
	      TxRetryPacketBlocked <= 1'b1;
     end
 
 
   reg TxDonePacketBlocked;
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  TxDonePacket <= 1'b0;
	else
	  if(TxDone_wb & !tx_burst_en & MasterWbTX & MasterAccessFinished & 
	     !TxDonePacketBlocked | TxDone_wb & !MasterWbTX & 
	     !TxDonePacketBlocked)
	    TxDonePacket <= 1'b1;
	  else
	    TxDonePacket <= 1'b0;
     end
 
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  TxDonePacket_NotCleared <= 1'b0;
	else
	  if(TxEn & TxEn_q & TxDonePacket_NotCleared)
	    TxDonePacket_NotCleared <= 1'b0;
	  else
	    if(TxDone_wb & !tx_burst_en & MasterWbTX & MasterAccessFinished 
	       & (~TxDonePacketBlocked) | TxDone_wb & !MasterWbTX 
	       & (~TxDonePacketBlocked))
	      TxDonePacket_NotCleared <= 1'b1;
     end
 
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  TxDonePacketBlocked <= 1'b0;
	else
	  if(!TxDone_wb & TxDone_wb_q)
	    TxDonePacketBlocked <= 1'b0;
	  else
	    if(TxDonePacket)
	      TxDonePacketBlocked <= 1'b1;
     end
 
 
   // Indication of the last word
   always @ (posedge MTxClk or posedge Reset)
     begin
	if(Reset)
	  LastWord <= 1'b0;
	else
	  if((TxEndFrm | TxAbort | TxRetry) & Flop)
	    LastWord <= 1'b0;
	  else
	    if(TxUsedData & Flop & TxByteCnt == 2'h3)
	      LastWord <= TxEndFrm_wb;
     end
 
 
   // Tx end frame generation
   always @ (posedge MTxClk or posedge Reset)
     begin
	if(Reset)
	  TxEndFrm <= 1'b0;
	else
	  if(Flop & TxEndFrm | TxAbort | TxRetry_q)
	    TxEndFrm <= 1'b0;        
	  else
	    if(Flop & LastWord)
	      begin
		 case (TxValidBytesLatched)  // synopsys parallel_case
		   1 : TxEndFrm <= TxByteCnt == 2'h0;
		   2 : TxEndFrm <= TxByteCnt == 2'h1;
		   3 : TxEndFrm <= TxByteCnt == 2'h2;
		   0 : TxEndFrm <= TxByteCnt == 2'h3;
		   default : TxEndFrm <= 1'b0;
		 endcase
	      end
     end
 
 
   // Tx data selection (latching)
   always @ (posedge MTxClk or posedge Reset)
     begin
	if(Reset)
	  TxData <= 0;
	else
	  if(TxStartFrm_sync2 & ~TxStartFrm)
	    case(TxPointerLSB)  // synopsys parallel_case
	      2'h0 : TxData <= TxData_wb[31:24];// Big Endian Byte Ordering
	      2'h1 : TxData <= TxData_wb[23:16];// Big Endian Byte Ordering
	      2'h2 : TxData <= TxData_wb[15:08];// Big Endian Byte Ordering
	      2'h3 : TxData <= TxData_wb[07:00];// Big Endian Byte Ordering
	    endcase
	  else
	    if(TxStartFrm & TxUsedData & TxPointerLSB==2'h3)
	      TxData <= TxData_wb[31:24];// Big Endian Byte Ordering
	    else
	      if(TxUsedData & Flop)
		begin
		   case(TxByteCnt)  // synopsys parallel_case
		     // Big Endian Byte Ordering
		     0 : TxData <= TxDataLatched[31:24];
		     1 : TxData <= TxDataLatched[23:16];
		     2 : TxData <= TxDataLatched[15:8];
		     3 : TxData <= TxDataLatched[7:0];
		   endcase
		end
     end
 
 
   // Latching tx data
   always @ (posedge MTxClk or posedge Reset)
     begin
	if(Reset)
	  TxDataLatched[31:0] <= 32'h0;
	else
	  if(TxStartFrm_sync2 & ~TxStartFrm | TxUsedData & Flop & 
	     TxByteCnt == 2'h3 | TxStartFrm & TxUsedData & Flop & 
	     TxByteCnt == 2'h0)
	    TxDataLatched[31:0] <= TxData_wb[31:0];
     end
 
 
   // Tx under run
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  TxUnderRun_wb <= 1'b0;
	else
	  if(TxAbortPulse)
	    TxUnderRun_wb <= 1'b0;
	  else
	    if(TxBufferEmpty & ReadTxDataFromFifo_wb)
	      TxUnderRun_wb <= 1'b1;
     end
 
 
   reg TxUnderRun_sync1;
 
   // Tx under run
   always @ (posedge MTxClk or posedge Reset)
     begin
	if(Reset)
	  TxUnderRun_sync1 <= 1'b0;
	else
	  if(TxUnderRun_wb)
	    TxUnderRun_sync1 <= 1'b1;
	  else
	    if(BlockingTxStatusWrite_sync2)
	      TxUnderRun_sync1 <= 1'b0;
     end
 
   // Tx under run
   always @ (posedge MTxClk or posedge Reset)
     begin
	if(Reset)
	  TxUnderRun <= 1'b0;
	else
	  if(BlockingTxStatusWrite_sync2)
	    TxUnderRun <= 1'b0;
	  else
	    if(TxUnderRun_sync1)
	      TxUnderRun <= 1'b1;
     end
 
 
   // Tx Byte counter
   always @ (posedge MTxClk or posedge Reset)
     begin
	if(Reset)
	  TxByteCnt <= 2'h0;
	else
	  if(TxAbort_q | TxRetry_q)
	    TxByteCnt <= 2'h0;
	  else
	    if(TxStartFrm & ~TxUsedData)
	      case(TxPointerLSB)  // synopsys parallel_case
		2'h0 : TxByteCnt <= 2'h1;
		2'h1 : TxByteCnt <= 2'h2;
		2'h2 : TxByteCnt <= 2'h3;
		2'h3 : TxByteCnt <= 2'h0;
	      endcase
	    else
	      if(TxUsedData & Flop)
		TxByteCnt <= TxByteCnt + 1'b1;
     end
 
 
   // Start: Generation of the ReadTxDataFromFifo_tck signal and synchronization to the WB_CLK_I
   reg ReadTxDataFromFifo_sync1;
   reg ReadTxDataFromFifo_sync2;
   reg ReadTxDataFromFifo_sync3;
   reg ReadTxDataFromFifo_syncb1;
   reg ReadTxDataFromFifo_syncb2;
   reg ReadTxDataFromFifo_syncb3;
 
 
   always @ (posedge MTxClk or posedge Reset)
     begin
	if(Reset)
	  ReadTxDataFromFifo_tck <= 1'b0;
	else
	  if(TxStartFrm_sync2 & ~TxStartFrm | TxUsedData & Flop & 
	     TxByteCnt == 2'h3 & ~LastWord | TxStartFrm & TxUsedData & Flop & 
	     TxByteCnt == 2'h0)
	    ReadTxDataFromFifo_tck <= 1'b1;
	  else
	    if(ReadTxDataFromFifo_syncb2 & ~ReadTxDataFromFifo_syncb3)
	      ReadTxDataFromFifo_tck <= 1'b0;
     end
 
   // Synchronizing TxStartFrm_wb to MTxClk
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  ReadTxDataFromFifo_sync1 <= 1'b0;
	else
	  ReadTxDataFromFifo_sync1 <= ReadTxDataFromFifo_tck;
     end
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  ReadTxDataFromFifo_sync2 <= 1'b0;
	else
	  ReadTxDataFromFifo_sync2 <= ReadTxDataFromFifo_sync1;
     end
 
   always @ (posedge MTxClk or posedge Reset)
     begin
	if(Reset)
	  ReadTxDataFromFifo_syncb1 <= 1'b0;
	else
	  ReadTxDataFromFifo_syncb1 <= ReadTxDataFromFifo_sync2;
     end
 
   always @ (posedge MTxClk or posedge Reset)
     begin
	if(Reset)
	  ReadTxDataFromFifo_syncb2 <= 1'b0;
	else
	  ReadTxDataFromFifo_syncb2 <= ReadTxDataFromFifo_syncb1;
     end
 
   always @ (posedge MTxClk or posedge Reset)
     begin
	if(Reset)
	  ReadTxDataFromFifo_syncb3 <= 1'b0;
	else
	  ReadTxDataFromFifo_syncb3 <= ReadTxDataFromFifo_syncb2;
     end
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  ReadTxDataFromFifo_sync3 <= 1'b0;
	else
	  ReadTxDataFromFifo_sync3 <= ReadTxDataFromFifo_sync2;
     end
 
   assign ReadTxDataFromFifo_wb = ReadTxDataFromFifo_sync2 & 
				  ~ReadTxDataFromFifo_sync3;
   // End: Generation of the ReadTxDataFromFifo_tck signal and synchronization 
   // to the WB_CLK_I
 
 
   // Synchronizing TxRetry signal (synchronized to WISHBONE clock)
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  TxRetrySync1 <= 1'b0;
	else
	  TxRetrySync1 <= TxRetry;
     end
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  TxRetry_wb <= 1'b0;
	else
	  TxRetry_wb <= TxRetrySync1;
     end
 
 
   // Synchronized TxDone_wb signal (synchronized to WISHBONE clock)
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  TxDoneSync1 <= 1'b0;
	else
	  TxDoneSync1 <= TxDone;
     end
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  TxDone_wb <= 1'b0;
	else
	  TxDone_wb <= TxDoneSync1;
     end
 
   // Synchronizing TxAbort signal (synchronized to WISHBONE clock)
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  TxAbortSync1 <= 1'b0;
	else
	  TxAbortSync1 <= TxAbort;
     end
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  TxAbort_wb <= 1'b0;
	else
	  TxAbort_wb <= TxAbortSync1;
     end
 
 
   reg RxAbortSync1;
   reg RxAbortSync2;
   reg RxAbortSync3;
   reg RxAbortSync4;
   reg RxAbortSyncb1;
   reg RxAbortSyncb2;
 
   assign StartRxBDRead = RxStatusWrite | RxAbortSync3 & ~RxAbortSync4 | 
			  r_RxEn & ~r_RxEn_q;
 
   // Reading the Rx buffer descriptor
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  RxBDRead <= 1'b0;
	else
	  if(StartRxBDRead)
	    RxBDRead <= 1'b1;
	  else
	    if(RxBDReady)
	      RxBDRead <= 1'b0;
     end
 
 
   // Reading of the next receive buffer descriptor starts after reception 
   // status is written to the previous one.
 
   // Latching READY status of the Rx buffer descriptor
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  RxBDReady <= 1'b0;
	else
	  if(RxPointerRead)
	    RxBDReady <= 1'b0;
	  else
	    if(RxEn & RxEn_q & RxBDRead)
	      // RxBDReady is sampled only once at the beginning
	      RxBDReady <= ram_do[15]; 
     end // always @ (posedge WB_CLK_I or posedge Reset)
 
   // Indicate we just read the RX buffer descriptor and that RxBDReady is 
   // valid.
   reg rx_just_read_bd;
   always @ (posedge WB_CLK_I or posedge Reset)
     if(Reset)
       rx_just_read_bd <= 0;
     else if (rx_just_read_bd)
       rx_just_read_bd <= 0;
     else 
       rx_just_read_bd <= (RxEn & RxEn_q & RxBDRead);
 
   // Signal to indicate we've checked and the RxBD we want to use is not free
   reg rx_waiting_for_bd_to_become_free;
   always @ (posedge WB_CLK_I or posedge Reset)
     if(Reset)
       rx_waiting_for_bd_to_become_free <= 0;
     else if (rx_just_read_bd & !RxBDReady)
       // Assert if we read the BD and it's not cool
       rx_waiting_for_bd_to_become_free <= 1;
     else if (RxBDOK)
       rx_waiting_for_bd_to_become_free <= 0;
 
 
 
   // Latching Rx buffer descriptor status
   // Data is avaliable one cycle after the access is started (at that time 
   // signal RxEn is not active)
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  RxStatus <= 2'h0;
	else
	  if(RxEn & RxEn_q & RxBDRead)
	    RxStatus <= ram_do[14:13];
     end
 
 
   // RxBDOK generation
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  RxBDOK <= 1'b0;
	else
	  if(rx_wb_writeback_finished | RxAbortSync2 & ~RxAbortSync3 | 
	     ~r_RxEn & r_RxEn_q)
	    RxBDOK <= 1'b0;
	  else
	    if(RxBDReady)
	      RxBDOK <= 1'b1;
     end    
 
   // Reading Rx BD pointer
   assign StartRxPointerRead = RxBDRead & RxBDReady;
 
   // Reading Tx BD Pointer
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  RxPointerRead <= 1'b0;
	else
	  if(StartRxPointerRead)
	    RxPointerRead <= 1'b1;
	  else
	    if(RxEn & RxEn_q)
	      RxPointerRead <= 1'b0;
     end
 
 
   //Latching Rx buffer pointer from buffer descriptor;
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  RxPointerMSB <= 30'h0;
	else
	  if(RxEn & RxEn_q & RxPointerRead)
	    RxPointerMSB <= ram_do[31:2];
	  else
	    if(MasterWbRX & m_wb_ack_i)
	      // Word access  (always word access. m_wb_sel_o are used for 
	      // selecting bytes)
	      RxPointerMSB <= RxPointerMSB + 1'b1; 
     end
 
 
   //Latching last addresses from buffer descriptor (used as byte-half-word 
   // indicator);
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  RxPointerLSB_rst[1:0] <= 0;
	else
	  if(MasterWbRX & m_wb_ack_i)
	    // After first write all RxByteSel are active
	    RxPointerLSB_rst[1:0] <= 0;
	  else
	    if(RxEn & RxEn_q & RxPointerRead)
	      RxPointerLSB_rst[1:0] <= ram_do[1:0];
     end
 
 
   always @ (RxPointerLSB_rst)
     begin
	case(RxPointerLSB_rst[1:0])  // synopsys parallel_case
	  2'h0 : RxByteSel[3:0] = 4'hf;
	  2'h1 : RxByteSel[3:0] = 4'h7;
	  2'h2 : RxByteSel[3:0] = 4'h3;
	  2'h3 : RxByteSel[3:0] = 4'h1;
	endcase
     end
 
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  RxEn_needed <= 1'b0;
	else
	  if(/*~RxReady &*/ r_RxEn & WbEn & ~WbEn_q)
	    RxEn_needed <= 1'b1;
	  else
	    if(RxPointerRead & RxEn & RxEn_q)
	      RxEn_needed <= 1'b0;
     end
 
 
   // Reception status is written back to the buffer descriptor after the end 
   // of frame is detected.
   assign RxStatusWrite = rx_wb_writeback_finished & RxEn & RxEn_q;
 
   reg RxEnableWindow;
 
   // Indicating that last byte is being reveived
   always @ (posedge MRxClk or posedge Reset)
     begin
	if(Reset)
	  LastByteIn <= 1'b0;
	else
	  if(ShiftWillEnd & (&RxByteCnt) | RxAbort)
	    LastByteIn <= 1'b0;
	  else
	    if(RxValid /*& RxReady*/& RxEndFrm & ~(&RxByteCnt) & RxEnableWindow)
	      LastByteIn <= 1'b1;
     end
 
   assign StartShiftWillEnd = LastByteIn  | RxValid & RxEndFrm & (&RxByteCnt) &
			      RxEnableWindow;
 
   // Indicating that data reception will end
   always @ (posedge MRxClk or posedge Reset)
     begin
	if(Reset)
	  ShiftWillEnd <= 1'b0;
	else
	  if(ShiftEnded_rck | RxAbort)
	    ShiftWillEnd <= 1'b0;
	  else
	    if(StartShiftWillEnd)
	      ShiftWillEnd <= 1'b1;
     end     
 
   // Receive byte counter
   always @ (posedge MRxClk or posedge Reset)
     begin
	if(Reset)
	  RxByteCnt <= 2'h0;
	else
	  if(ShiftEnded_rck | RxAbort)
	    RxByteCnt <= 2'h0;
	  else
	    if(RxValid & RxStartFrm /*& RxReady*/)
	      case(RxPointerLSB_rst)  // synopsys parallel_case
		2'h0 : RxByteCnt <= 2'h1;
		2'h1 : RxByteCnt <= 2'h2;
		2'h2 : RxByteCnt <= 2'h3;
		2'h3 : RxByteCnt <= 2'h0;
	      endcase
	    else
	      if(RxValid & RxEnableWindow /*& RxReady*/ | LastByteIn)
		RxByteCnt <= RxByteCnt + 1'b1;
     end
 
 
   // Indicates how many bytes are valid within the last word
   always @ (posedge MRxClk or posedge Reset)
     begin
	if(Reset)
	  RxValidBytes <= 2'h1;
	else
	  if(RxValid & RxStartFrm)
	    case(RxPointerLSB_rst)  // synopsys parallel_case
	      2'h0 : RxValidBytes <= 2'h1;
	      2'h1 : RxValidBytes <= 2'h2;
	      2'h2 : RxValidBytes <= 2'h3;
	      2'h3 : RxValidBytes <= 2'h0;
	    endcase
	  else
	    if(RxValid & ~LastByteIn & ~RxStartFrm & RxEnableWindow)
	      RxValidBytes <= RxValidBytes + 1'b1;
     end
 
 
   always @ (posedge MRxClk or posedge Reset)
     begin
	if(Reset)
	  RxDataLatched1       <= 24'h0;
	else
	  if(RxValid /*& RxReady*/ & ~LastByteIn)
	    if(RxStartFrm)
	      begin
		 case(RxPointerLSB_rst)     // synopsys parallel_case
		   // Big Endian Byte Ordering
		   2'h0:        RxDataLatched1[31:24] <= RxData;            
		   2'h1:        RxDataLatched1[23:16] <= RxData;
		   2'h2:        RxDataLatched1[15:8]  <= RxData;
		   2'h3:        RxDataLatched1        <= RxDataLatched1;
		 endcase
	      end
	    else if (RxEnableWindow)
	      begin
		 case(RxByteCnt)     // synopsys parallel_case
		   // Big Endian Byte Ordering
		   2'h0:        RxDataLatched1[31:24] <= RxData;
		   2'h1:        RxDataLatched1[23:16] <= RxData;
		   2'h2:        RxDataLatched1[15:8]  <= RxData;
		   2'h3:        RxDataLatched1        <= RxDataLatched1;
		 endcase
	      end
     end
 
   wire SetWriteRxDataToFifo;
 
   // Assembling data that will be written to the rx_fifo
   always @ (posedge MRxClk or posedge Reset)
     begin
	if(Reset)
	  RxDataLatched2 <= 32'h0;
	else
	  if(SetWriteRxDataToFifo & ~ShiftWillEnd)
	    // Big Endian Byte Ordering
	    RxDataLatched2 <= {RxDataLatched1[31:8], RxData};
	  else
	    if(SetWriteRxDataToFifo & ShiftWillEnd)
	      case(RxValidBytes)  // synopsys parallel_case
		// Big Endian Byte Ordering
		0 : RxDataLatched2 <= {RxDataLatched1[31:8],  RxData};
		1 : RxDataLatched2 <= {RxDataLatched1[31:24], 24'h0};
		2 : RxDataLatched2 <= {RxDataLatched1[31:16], 16'h0};
		3 : RxDataLatched2 <= {RxDataLatched1[31:8],   8'h0};
	      endcase
     end
 
 
   reg WriteRxDataToFifoSync1;
   reg WriteRxDataToFifoSync2;
   reg WriteRxDataToFifoSync3;
 
 
   // Indicating start of the reception process
   assign SetWriteRxDataToFifo = (RxValid &/* RxReady &*/ ~RxStartFrm & 
				  RxEnableWindow & (&RxByteCnt)) | 
				 (RxValid &/* RxReady &*/  RxStartFrm & 
				  (&RxPointerLSB_rst))           | 
				 (ShiftWillEnd & LastByteIn & (&RxByteCnt));
 
   always @ (posedge MRxClk or posedge Reset)
     begin
	if(Reset)
	  WriteRxDataToFifo <= 1'b0;
	else
	  if(SetWriteRxDataToFifo & ~RxAbort)
	    WriteRxDataToFifo <= 1'b1;
	  else
	    if(WriteRxDataToFifoSync2 | RxAbort)
	      WriteRxDataToFifo <= 1'b0;
     end
 
 
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  WriteRxDataToFifoSync1 <= 1'b0;
	else
	  if(WriteRxDataToFifo)
	    WriteRxDataToFifoSync1 <= 1'b1;
	  else
	    WriteRxDataToFifoSync1 <= 1'b0;
     end
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  WriteRxDataToFifoSync2 <= 1'b0;
	else
	  WriteRxDataToFifoSync2 <= WriteRxDataToFifoSync1;
     end
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  WriteRxDataToFifoSync3 <= 1'b0;
	else
	  WriteRxDataToFifoSync3 <= WriteRxDataToFifoSync2;
     end
 
   wire WriteRxDataToFifo_wb;
   assign WriteRxDataToFifo_wb = WriteRxDataToFifoSync2 & 
				 ~WriteRxDataToFifoSync3;
   // Receive fifo selection register - JB
   reg [3:0] rx_shift_ended_wb_shr;   
   reg 	     rx_ethside_fifo_sel;
   reg 	     rx_wbside_fifo_sel;
 
   // Shift in this - our detection of end of data RX
   always @(posedge WB_CLK_I)
     rx_shift_ended_wb_shr <= {rx_shift_ended_wb_shr[2:0],
			       ShiftEndedSync1 & ~ShiftEndedSync2};
 
 
   always @ (posedge WB_CLK_I or posedge Reset)
     if(Reset)
       rx_ethside_fifo_sel <= 0;
     else 
       if(rx_shift_ended_wb_shr[3:2] == 2'b01)
	 // Switch over whenever we've finished receiving last frame's data
	 rx_ethside_fifo_sel <= ~rx_ethside_fifo_sel;
 
   // Wishbone side looks at other FIFO when we write back the status of this 
   // received frame
   always @ (posedge WB_CLK_I or posedge Reset)
     if(Reset)
       rx_wbside_fifo_sel <= 0;
     else 
       if(rx_wb_writeback_finished & RxEn & RxEn_q)
	 // Switch over whenever we've finished receiving last frame's data
	 rx_wbside_fifo_sel <= ~rx_wbside_fifo_sel;
 
   reg 	LatchedRxStartFrm;
   reg 	SyncRxStartFrm;
   reg 	SyncRxStartFrm_q;
   reg 	SyncRxStartFrm_q2;
   wire RxFifoReset;
 
   always @ (posedge MRxClk or posedge Reset)
     begin
	if(Reset)
	  LatchedRxStartFrm <= 0;
	else
	  if(RxStartFrm & ~SyncRxStartFrm_q)
	    LatchedRxStartFrm <= 1;
	  else
	    if(SyncRxStartFrm_q)
	      LatchedRxStartFrm <= 0;
     end
 
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  SyncRxStartFrm <= 0;
	else
	  if(LatchedRxStartFrm)
	    SyncRxStartFrm <= 1;
	  else
	    SyncRxStartFrm <= 0;
     end
 
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  SyncRxStartFrm_q <= 0;
	else
	  SyncRxStartFrm_q <= SyncRxStartFrm;
     end
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  SyncRxStartFrm_q2 <= 0;
	else
	  SyncRxStartFrm_q2 <= SyncRxStartFrm_q;
     end
   wire rx_startfrm_wb;
   assign rx_startfrm_wb = SyncRxStartFrm_q & ~SyncRxStartFrm_q2;
 
 
   assign RxFifoReset = rx_startfrm_wb;
 
 
   wire [31:0] rx_fifo0_data_out;
   wire        rx_fifo0_write;
   wire        rx_fifo0_read;
   wire        rx_fifo0_clear;
   wire        rx_fifo0_full;
   wire        rx_fifo0_afull;
   wire        rx_fifo0_empty;
   wire        rx_fifo0_aempty;
 
 
   wire [31:0] rx_fifo1_data_out;
   wire        rx_fifo1_write;
   wire        rx_fifo1_read;
   wire        rx_fifo1_clear;
   wire        rx_fifo1_full;
   wire        rx_fifo1_afull;
   wire        rx_fifo1_empty;
   wire        rx_fifo1_aempty;
 
   wire [`ETH_RX_FIFO_CNT_WIDTH-1:0] rx_fifo0_cnt;
   wire [`ETH_RX_FIFO_CNT_WIDTH-1:0] rx_fifo1_cnt;
 
   // RX FIFO buffer 0 controls
   assign rx_fifo0_write = (!rx_ethside_fifo_sel) & WriteRxDataToFifo_wb & 
			   ~rx_fifo0_full;
 
   assign rx_fifo0_read = (!rx_wbside_fifo_sel) & MasterWbRX & m_wb_ack_i &
			  ~rx_fifo0_empty;
 
   assign rx_fifo0_clear = (!rx_ethside_fifo_sel) & RxFifoReset;
 
   // RX FIFO buffer 1 controls
   assign rx_fifo1_write = (rx_ethside_fifo_sel) & WriteRxDataToFifo_wb & 
			   ~rx_fifo1_full;
 
   assign rx_fifo1_read = (rx_wbside_fifo_sel) & MasterWbRX & m_wb_ack_i &
			   ~rx_fifo1_empty;
 
   assign rx_fifo1_clear = (rx_ethside_fifo_sel) & RxFifoReset;
 
   eth_fifo #(
	      `ETH_RX_FIFO_DATA_WIDTH, 
	      `ETH_RX_FIFO_DEPTH, 
	      `ETH_RX_FIFO_CNT_WIDTH
	      )
   rx_fifo0 (
	     .clk            (WB_CLK_I         ),
             .reset          (Reset            ), 
	     // Inputs
	     .data_in        (RxDataLatched2   ),            
             .write          (rx_fifo0_write   ),
	     .read           (rx_fifo0_read    ),
             .clear          (rx_fifo0_clear   ),
	     // Outputs
	     .data_out       (rx_fifo0_data_out),
             .full           (rx_fifo0_full    ),
             .almost_full    (),
             .almost_empty   (rx_fifo0_aempty  ),
             .empty          (rx_fifo0_empty   ),
             .cnt            (rx_fifo0_cnt     )
             );
 
   eth_fifo #(
	      `ETH_RX_FIFO_DATA_WIDTH, 
	      `ETH_RX_FIFO_DEPTH, 
	      `ETH_RX_FIFO_CNT_WIDTH
	      )
   rx_fifo1 (
	     .clk            (WB_CLK_I         ),
             .reset          (Reset            ), 
	     // Inputs
	     .data_in        (RxDataLatched2   ),            
             .write          (rx_fifo1_write   ),
	     .read           (rx_fifo1_read    ),
             .clear          (rx_fifo1_clear   ),
	     // Outputs
	     .data_out       (rx_fifo1_data_out),
             .full           (rx_fifo1_full    ),
             .almost_full    (),
             .almost_empty   (rx_fifo1_aempty  ),
             .empty          (rx_fifo1_empty   ),
             .cnt            (rx_fifo1_cnt     )
             );   
 
   assign m_wb_dat_o = rx_wbside_fifo_sel ? 
		       rx_fifo1_data_out : rx_fifo0_data_out;
   assign rxfifo_cnt = rx_wbside_fifo_sel ?
		       rx_fifo1_cnt : rx_fifo0_cnt;
 
   assign RxBufferAlmostEmpty = rx_wbside_fifo_sel ?
				rx_fifo1_aempty : rx_fifo0_aempty;
 
   assign RxBufferEmpty = rx_wbside_fifo_sel ?
			  rx_fifo1_empty : rx_fifo0_empty;
 
   assign RxBufferFull = rx_wbside_fifo_sel ?
			 rx_fifo1_full : rx_fifo0_full;
 
 
 
 
 
   wire 			     write_rx_data_to_memory_wait;
   assign write_rx_data_to_memory_wait = !RxBDOK | RxPointerRead;
   wire 			     write_rx_data_to_memory_go;
 
`ifdef ETH_RX_BURST_EN
   assign enough_data_in_rxfifo_for_burst = rxfifo_cnt>=(`ETH_BURST_LENGTH);
   assign enough_data_in_rxfifo_for_burst_plus1 = rxfifo_cnt>(`ETH_BURST_LENGTH - 1);
   // While receiving, don't flog the bus too hard, only write out when
   // we can burst. But when finishing keep going until we've emptied the fifo
   assign write_rx_data_to_memory_go = 
				       RxEnableWindow & (rx_wbside_fifo_sel == rx_ethside_fifo_sel) ? 
				       (rxfifo_cnt>(`ETH_BURST_LENGTH)+2) | 
				       (|rx_burst_cnt) : ~RxBufferEmpty;
 
`else
   assign enough_data_in_rxfifo_for_burst = rxfifo_cnt>=`ETH_BURST_LENGTH;
   assign enough_data_in_rxfifo_for_burst_plus1 = rxfifo_cnt>`ETH_BURST_LENGTH;
   assign write_rx_data_to_memory_go = ~RxBufferEmpty;
`endif // !`ifdef ETH_RX_BURST_EN
 
   assign WriteRxDataToMemory = write_rx_data_to_memory_go & !write_rx_data_to_memory_wait;
 
   assign rx_burst = rx_burst_en & WriteRxDataToMemory;
 
 
   // Generation of the end-of-frame signal
   always @ (posedge MRxClk or posedge Reset)
     begin
	if(Reset)
	  ShiftEnded_rck <= 1'b0;
	else
	  if(~RxAbort & SetWriteRxDataToFifo & StartShiftWillEnd)
	    ShiftEnded_rck <= 1'b1;
	  else
	    if(RxAbort | ShiftEndedSync_c1 & ShiftEndedSync_c2)
	      ShiftEnded_rck <= 1'b0;
     end
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  ShiftEndedSync1 <= 1'b0;
	else
	  ShiftEndedSync1 <= ShiftEnded_rck;
     end
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  ShiftEndedSync2 <= 1'b0;
	else
	  ShiftEndedSync2 <= ShiftEndedSync1;
     end
 
   // indicate end of wishbone RX is coming up
   always @ (posedge WB_CLK_I or posedge Reset)
     if(Reset)
       rx_wb_last_writes <= 1'b0;
     else if (!rx_wb_last_writes)
       rx_wb_last_writes <= ShiftEndedSync1 & ~ShiftEndedSync2;
     else if (rx_wb_writeback_finished & RxEn & RxEn_q)
       rx_wb_last_writes <= 0;
 
   // Pulse indicating last of RX data has been written out
   always @ (posedge WB_CLK_I or posedge Reset)
     if(Reset)
       rx_wb_writeback_finished <= 0;
     else if (rx_wb_writeback_finished & RxEn & RxEn_q)
       rx_wb_writeback_finished <= 0;
     else
       rx_wb_writeback_finished <= rx_wb_last_writes & RxBufferEmpty & 
				   !WriteRxDataToFifo_wb;
 
 
   always @ (posedge MRxClk or posedge Reset)
     begin
	if(Reset)
	  ShiftEndedSync_c1 <= 1'b0;
	else
	  ShiftEndedSync_c1 <= ShiftEndedSync2;
     end
 
   always @ (posedge MRxClk or posedge Reset)
     begin
	if(Reset)
	  ShiftEndedSync_c2 <= 1'b0;
	else
	  ShiftEndedSync_c2 <= ShiftEndedSync_c1;
     end
 
   // Generation of the end-of-frame signal
   always @ (posedge MRxClk or posedge Reset)
     begin
	if(Reset)
	  RxEnableWindow <= 1'b0;
	else
	  if(RxStartFrm)
	    RxEnableWindow <= 1'b1;
	  else
	    if(RxEndFrm | RxAbort)
	      RxEnableWindow <= 1'b0;
     end
 
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  RxAbortSync1 <= 1'b0;
	else
	  RxAbortSync1 <= RxAbortLatched;
     end
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  RxAbortSync2 <= 1'b0;
	else
	  RxAbortSync2 <= RxAbortSync1;
     end
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  RxAbortSync3 <= 1'b0;
	else
	  RxAbortSync3 <= RxAbortSync2;
     end
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  RxAbortSync4 <= 1'b0;
	else
	  RxAbortSync4 <= RxAbortSync3;
     end
 
   always @ (posedge MRxClk or posedge Reset)
     begin
	if(Reset)
	  RxAbortSyncb1 <= 1'b0;
	else
	  RxAbortSyncb1 <= RxAbortSync2;
     end
 
   always @ (posedge MRxClk or posedge Reset)
     begin
	if(Reset)
	  RxAbortSyncb2 <= 1'b0;
	else
	  RxAbortSyncb2 <= RxAbortSyncb1;
     end
 
 
   always @ (posedge MRxClk or posedge Reset)
     begin
	if(Reset)
	  RxAbortLatched <= 1'b0;
	else
	  if(RxAbortSyncb2)
	    RxAbortLatched <= 1'b0;
	  else
	    if(RxAbort)
	      RxAbortLatched <= 1'b1;
     end
 
 
   always @ (posedge MRxClk or posedge Reset)
     begin
	if(Reset)
	  LatchedRxLength[15:0] <= 16'h0;
	else
	  if(LoadRxStatus)
	    LatchedRxLength[15:0] <= RxLength[15:0];
     end
 
 
   assign RxStatusIn = {ReceivedPauseFrm, AddressMiss, RxOverrun, InvalidSymbol, DribbleNibble, ReceivedPacketTooBig, ShortFrame, LatchedCrcError, RxLateCollision};
 
   always @ (posedge MRxClk or posedge Reset)
     begin
	if(Reset)
	  RxStatusInLatched <= 'h0;
	else
	  if(LoadRxStatus)
	    RxStatusInLatched <= RxStatusIn;
     end
 
 
   // Rx overrun
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  RxOverrun <= 1'b0;
	else
	  if(RxStatusWrite)
	    RxOverrun <= 1'b0;
	  else
	    if(RxBufferFull & WriteRxDataToFifo_wb)
	      RxOverrun <= 1'b1;
     end
 
 
 
   wire TxError;
   assign TxError = TxUnderRun | RetryLimit | LateCollLatched | CarrierSenseLost;
 
   wire RxError;
 
   // ShortFrame (RxStatusInLatched[2]) can not set an error because short 
   // frames are aborted when signal r_RecSmall is set to 0 in MODER register. 
   // AddressMiss is identifying that a frame was received because of the 
   // promiscous mode and is not an error
   assign RxError = (|RxStatusInLatched[6:3]) | (|RxStatusInLatched[1:0]);
 
 
 
   reg 	RxStatusWriteLatched;
   reg 	RxStatusWriteLatched_sync1;
   reg 	RxStatusWriteLatched_sync2;
   reg 	RxStatusWriteLatched_syncb1;
   reg 	RxStatusWriteLatched_syncb2;
 
 
   // Latching and synchronizing RxStatusWrite signal. This signal is used for 
   // clearing the ReceivedPauseFrm signal
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  RxStatusWriteLatched <= 1'b0;
	else
	  if(RxStatusWriteLatched_syncb2)
	    RxStatusWriteLatched <= 1'b0;        
	  else
	    if(RxStatusWrite)
	      RxStatusWriteLatched <= 1'b1;
     end
 
 
   always @ (posedge MRxClk or posedge Reset)
     begin
	if(Reset)
	  begin
	     RxStatusWriteLatched_sync1 <= 1'b0;
	     RxStatusWriteLatched_sync2 <= 1'b0;
	  end
	else
	  begin
	     RxStatusWriteLatched_sync1 <= RxStatusWriteLatched;
	     RxStatusWriteLatched_sync2 <= RxStatusWriteLatched_sync1;
	  end
     end
 
 
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  begin
	     RxStatusWriteLatched_syncb1 <= 1'b0;
	     RxStatusWriteLatched_syncb2 <= 1'b0;
	  end
	else
	  begin
	     RxStatusWriteLatched_syncb1 <= RxStatusWriteLatched_sync2;
	     RxStatusWriteLatched_syncb2 <= RxStatusWriteLatched_syncb1;
	  end
     end
 
 
 
   // Tx Done Interrupt
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  TxB_IRQ <= 1'b0;
	else
	  if(TxStatusWrite & TxIRQEn)
	    TxB_IRQ <= ~TxError;
	  else
	    TxB_IRQ <= 1'b0;
     end
 
 
   // Tx Error Interrupt
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  TxE_IRQ <= 1'b0;
	else
	  if(TxStatusWrite & TxIRQEn)
	    TxE_IRQ <= TxError;
	  else
	    TxE_IRQ <= 1'b0;
     end
 
 
   // Rx Done Interrupt
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  RxB_IRQ <= 1'b0;
	else
	  if(RxStatusWrite & RxIRQEn & ReceivedPacketGood & 
	     (~ReceivedPauseFrm | ReceivedPauseFrm & r_PassAll & (~r_RxFlow)))
	    RxB_IRQ <= (~RxError);
	  else
	    RxB_IRQ <= 1'b0;
     end
 
 
   // Rx Error Interrupt
   always @ (posedge WB_CLK_I or posedge Reset)
     begin
	if(Reset)
	  RxE_IRQ <= 1'b0;
	else
	  if(RxStatusWrite & RxIRQEn & (~ReceivedPauseFrm | ReceivedPauseFrm 
					& r_PassAll & (~r_RxFlow)))
	    RxE_IRQ <= RxError;
	  else
	    RxE_IRQ <= 1'b0;
     end
 
   // Set this high when we started receiving another packet while the wishbone
   // side was still writing out the last one. This makes sure we check at the
   // right time if the next buffer descriptor is free.
   reg rxstartfrm_occurred;
   always @ (posedge WB_CLK_I)
     if (Reset)
       rxstartfrm_occurred <= 0;
     else if (rx_just_read_bd)
       rxstartfrm_occurred <= 0;
     else if (((rx_ethside_fifo_sel != rx_wbside_fifo_sel) | StartRxBDRead | 
	       RxBDRead) & rx_startfrm_wb)
       rxstartfrm_occurred <= 1;
 
 
 
   reg busy_wb;
   always @ (posedge WB_CLK_I or posedge Reset)
     if(Reset)
       busy_wb <= 0;
     else if (busy_wb)
       busy_wb <= 0;
     else if
       // Indicate busy if either:
       // a) RX is idle and we get a start frame and current BD indicates not
       //    ready.
       // b) RX is already receiving another packet and we got a startframe,
       //    indicated by rx_startfrm_occurred, and we then read the BD and
       //    it says it's not ready.
       // This actually may not work since it's in the MII RX clock domain.
       ((rx_ethside_fifo_sel == rx_wbside_fifo_sel) &
	((rxstartfrm_occurred & rx_just_read_bd & ~RxBDReady) | 
	 (!rxstartfrm_occurred & !StartRxBDRead & !RxBDRead & rx_startfrm_wb & 
	  rx_waiting_for_bd_to_become_free))
	)
       busy_wb <= 1;
 
 
   assign Busy_IRQ = busy_wb;
 
   always @(posedge Busy_IRQ)
     $display("(%t)(%m) Ethernet MAC BUSY signal asserted", $time);
 
 
   // Assign the debug output
`ifdef WISHBONE_DEBUG
   // Top byte, burst progress counters
   assign dbg_dat0[31] = 0;   
   assign dbg_dat0[30] = 0;        
   assign dbg_dat0[29:28] = rx_burst_cnt;
   assign dbg_dat0[27] = 0;   
   assign dbg_dat0[26] = 0;     
   assign dbg_dat0[25:24] = tx_burst_cnt;
 
   // Third byte
   assign dbg_dat0[23] = 0;   
   assign dbg_dat0[22] = 0;  
   assign dbg_dat0[21] = rx_burst;   
   assign dbg_dat0[20] = rx_burst_en;
   assign dbg_dat0[19] = 0;   
   assign dbg_dat0[18] = 0;   
   assign dbg_dat0[17] = tx_burst;   
   assign dbg_dat0[16] = tx_burst_en;
   // Second byte - TxBDAddress - or TX BD address pointer
   assign dbg_dat0[15:8] = { 1'b0, TxBDAddress};
   // Bottom byte - FSM controlling vector
   assign dbg_dat0[7:0] = {MasterWbTX,MasterWbRX,
			   ReadTxDataFromMemory_2,WriteRxDataToMemory,
			   MasterAccessFinished,cyc_cleared, 
			   tx_burst,rx_burst};
 
`endif
 
 
 
endmodule