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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                     ////
////                                                              ////
//////////////////////////////////////////////////////////////////////
//
// CVS Revision History
//
// $Log: not supported by cvs2svn $
// Revision 1.57  2005/02/21 11:35:33  igorm
// Defer indication fixed.
//
// Revision 1.56  2004/04/30 10:30:00  igorm
// Accidently deleted line put back.
//
// Revision 1.55  2004/04/26 15:26:23  igorm
// - Bug connected to the TX_BD_NUM_Wr signal fixed (bug came in with the
//   previous update of the core.
// - TxBDAddress is set to 0 after the TX is enabled in the MODER register.
// - RxBDAddress is set to r_TxBDNum<<1 after the RX is enabled in the MODER
//   register. (thanks to Mathias and Torbjorn)
// - Multicast reception was fixed. Thanks to Ulrich Gries
//
// Revision 1.54  2003/11/12 18:24:59  tadejm
// WISHBONE slave changed and tested from only 32-bit accesss to byte access.
//
// Revision 1.53  2003/10/17 07:46:17  markom
// mbist signals updated according to newest convention
//
// Revision 1.52  2003/01/30 14:51:31  mohor
// Reset has priority in some flipflops.
//
// Revision 1.51  2003/01/30 13:36:22  mohor
// A new bug (entered with previous update) fixed. When abort occured sometimes
// data transmission was blocked.
//
// Revision 1.50  2003/01/22 13:49:26  tadejm
// When control packets were received, they were ignored in some cases.
//
// Revision 1.49  2003/01/21 12:09:40  mohor
// When receiving normal data frame and RxFlow control was switched on, RXB
// interrupt was not set.
//
// Revision 1.48  2003/01/20 12:05:26  mohor
// When in full duplex, transmit was sometimes blocked. Fixed.
//
// Revision 1.47  2002/11/22 13:26:21  mohor
// Registers RxStatusWrite_rck and RxStatusWriteLatched were not used
// anywhere. Removed.
//
// Revision 1.46  2002/11/22 01:57:06  mohor
// Rx Flow control fixed. CF flag added to the RX buffer descriptor. RxAbort
// synchronized.
//
// Revision 1.45  2002/11/19 17:33:34  mohor
// AddressMiss status is connecting to the Rx BD. AddressMiss is identifying
// that a frame was received because of the promiscous mode.
//
// Revision 1.44  2002/11/13 22:21:40  tadejm
// RxError is not generated when small frame reception is enabled and small
// frames are received.
//
// Revision 1.43  2002/10/18 20:53:34  mohor
// case changed to casex.
//
// Revision 1.42  2002/10/18 17:04:20  tadejm
// Changed BIST scan signals.
//
// Revision 1.41  2002/10/18 15:42:09  tadejm
// Igor added WB burst support and repaired BUG when handling TX under-run and retry.
//
// Revision 1.40  2002/10/14 16:07:02  mohor
// TxStatus is written after last access to the TX fifo is finished (in case of abort
// or retry). TxDone is fixed.
//
// Revision 1.39  2002/10/11 15:35:20  mohor
// txfifo_cnt and rxfifo_cnt counters width is defined in the eth_define.v file,
// TxDone and TxRetry are generated after the current WISHBONE access is
// finished.
//
// Revision 1.38  2002/10/10 16:29:30  mohor
// BIST added.
//
// Revision 1.37  2002/09/11 14:18:46  mohor
// Sometimes both RxB_IRQ and RxE_IRQ were activated. Bug fixed.
//
// Revision 1.36  2002/09/10 13:48:46  mohor
// Reception is possible after RxPointer is read and not after BD is read. For
// that reason RxBDReady is changed to RxReady.
// Busy_IRQ interrupt connected. When there is no RxBD ready and frame
// comes, interrupt is generated.
//
// Revision 1.35  2002/09/10 10:35:23  mohor
// Ethernet debug registers removed.
//
// Revision 1.34  2002/09/08 16:31:49  mohor
// Async reset for WB_ACK_O removed (when core was in reset, it was
// impossible to access BDs).
// RxPointers and TxPointers names changed to be more descriptive.
// TxUnderRun synchronized.
//
// Revision 1.33  2002/09/04 18:47:57  mohor
// Debug registers reg1, 2, 3, 4 connected. Synchronization of many signals
// changed (bugs fixed). Access to un-alligned buffers fixed. RxAbort signal
// was not used OK.
//
// Revision 1.32  2002/08/14 19:31:48  mohor
// Register TX_BD_NUM is changed so it contains value of the Tx buffer descriptors. No
// need to multiply or devide any more.
//
// Revision 1.31  2002/07/25 18:29:01  mohor
// WriteRxDataToMemory signal changed so end of frame (when last word is
// written to fifo) is changed.
//
// Revision 1.30  2002/07/23 15:28:31  mohor
// Ram , used for BDs changed from generic_spram to eth_spram_256x32.
//
// Revision 1.29  2002/07/20 00:41:32  mohor
// ShiftEnded synchronization changed.
//
// Revision 1.28  2002/07/18 16:11:46  mohor
// RxBDAddress takes `ETH_TX_BD_NUM_DEF value after reset.
//
// Revision 1.27  2002/07/11 02:53:20  mohor
// RxPointer bug fixed.
//
// Revision 1.26  2002/07/10 13:12:38  mohor
// Previous bug wasn't succesfully removed. Now fixed.
//
// Revision 1.25  2002/07/09 23:53:24  mohor
// Master state machine had a bug when switching from master write to
// master read.
//
// Revision 1.24  2002/07/09 20:44:41  mohor
// m_wb_cyc_o signal released after every single transfer.
//
// Revision 1.23  2002/05/03 10:15:50  mohor
// Outputs registered. Reset changed for eth_wishbone module.
//
// Revision 1.22  2002/04/24 08:52:19  mohor
// Compiler directives added. Tx and Rx fifo size incremented. A "late collision"
// bug fixed.
//
// Revision 1.21  2002/03/29 16:18:11  lampret
// Small typo fixed.
//
// Revision 1.20  2002/03/25 16:19:12  mohor
// Any address can be used for Tx and Rx BD pointers. Address does not need
// to be aligned.
//
// Revision 1.19  2002/03/19 12:51:50  mohor
// Comments in Slovene language removed.
//
// Revision 1.18  2002/03/19 12:46:52  mohor
// casex changed with case, fifo reset changed.
//
// Revision 1.17  2002/03/09 16:08:45  mohor
// rx_fifo was not always cleared ok. Fixed.
//
// Revision 1.16  2002/03/09 13:51:20  mohor
// Status was not latched correctly sometimes. Fixed.
//
// Revision 1.15  2002/03/08 06:56:46  mohor
// Big Endian problem when sending frames fixed.
//
// Revision 1.14  2002/03/02 19:12:40  mohor
// Byte ordering changed (Big Endian used). casex changed with case because
// Xilinx Foundation had problems. Tested in HW. It WORKS.
//
// Revision 1.13  2002/02/26 16:59:55  mohor
// Small fixes for external/internal DMA missmatches.
//
// Revision 1.12  2002/02/26 16:22:07  mohor
// Interrupts changed
//
// Revision 1.11  2002/02/15 17:07:39  mohor
// Status was not written correctly when frames were discarted because of
// address mismatch.
//
// Revision 1.10  2002/02/15 12:17:39  mohor
// RxStartFrm cleared when abort or retry comes.
//
// Revision 1.9  2002/02/15 11:59:10  mohor
// Changes that were lost when updating from 1.5 to 1.8 fixed.
//
// Revision 1.8  2002/02/14 20:54:33  billditt
// Addition  of new module eth_addrcheck.v
//
// Revision 1.7  2002/02/12 17:03:47  mohor
// RxOverRun added to statuses.
//
// Revision 1.6  2002/02/11 09:18:22  mohor
// Tx status is written back to the BD.
//
// Revision 1.5  2002/02/08 16:21:54  mohor
// Rx status is written back to the BD.
//
// Revision 1.4  2002/02/06 14:10:21  mohor
// non-DMA host interface added. Select the right configutation in eth_defines.
//
// Revision 1.3  2002/02/05 16:44:39  mohor
// Both rx and tx part are finished. Tested with wb_clk_i between 10 and 200
// MHz. Statuses, overrun, control frame transmission and reception still  need
// to be fixed.
//
// Revision 1.2  2002/02/01 12:46:51  mohor
// Tx part finished. TxStatus needs to be fixed. Pause request needs to be
// added.
//
// Revision 1.1  2002/01/23 10:47:59  mohor
// Initial version. Equals to eth_wishbonedma.v at this moment.
//
//
//
 
`include "eth_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
 
 
 
                );
 
 
parameter TX_FIFO_DATA_WIDTH = `ETH_TX_FIFO_DATA_WIDTH;
parameter TX_FIFO_DEPTH      = `ETH_TX_FIFO_DEPTH;
parameter TX_FIFO_CNT_WIDTH  = `ETH_TX_FIFO_CNT_WIDTH;
parameter RX_FIFO_DATA_WIDTH = `ETH_RX_FIFO_DATA_WIDTH;
parameter RX_FIFO_DEPTH      = `ETH_RX_FIFO_DEPTH;
parameter RX_FIFO_CNT_WIDTH  = `ETH_RX_FIFO_CNT_WIDTH;
 
 
// 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
output   [1:0]  m_wb_bte_o;     // Burst Type Extension
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
 
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             RxReady;
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;
 
`ifdef ETH_WISHBONE_B3
assign m_wb_bte_o = 2'b00;    // Linear burst
`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 bd_ram (
        .clk(WB_CLK_I), .rst(Reset), .ce(ram_ce), .we(ram_we), .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 <= ram_do[15] & (ram_do[31:16] > 4); // TxBDReady is sampled only once at the beginning.
  else                                                // Only packets larger then 4 bytes are transmitted.
  if(ResetTxBDReady)
    TxBDReady <= 1'b0;
end
 
 
// 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 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)
    TxPointerMSB <= TxPointerMSB + 1'b1;     // TxPointer is word-aligned
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
  if(MasterWbTX & m_wb_ack_i)                 // After first access pointer is word alligned
    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;
 
wire ReadTxDataFromMemory_2 = ReadTxDataFromMemory & ~BlockReadTxDataFromMemory;
wire tx_burst = ReadTxDataFromMemory_2 & tx_burst_en;
 
wire [31:0] TxData_wb;
wire ReadTxDataFromFifo_wb;
 
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
 
 
assign MasterAccessFinished = m_wb_ack_i | m_wb_err_i;
wire [TX_FIFO_CNT_WIDTH-1:0] txfifo_cnt;
wire [RX_FIFO_CNT_WIDTH-1:0] rxfifo_cnt;
reg  [`ETH_BURST_CNT_WIDTH-1:0] tx_burst_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;
      `endif
    end
  else
    begin
      // Switching between two stages depends on enable signals
      casex ({MasterWbTX, MasterWbRX, ReadTxDataFromMemory_2, WriteRxDataToMemory, 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;
              `endif
              end
          end
        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
                m_wb_cti_o <= 3'b010;
              `endif
              end
          end
        8'b00_x1_00_x0 :            // idle and MW is needed (data write to rx buffer)
          begin
            MasterWbTX <= 1'b0;
            MasterWbRX <= 1'b1;
            m_wb_adr_o <= RxPointerMSB;
            m_wb_cyc_o <= 1'b1;
            m_wb_we_o  <= 1'b1;
            m_wb_sel_o <= RxByteSel;
            IncrTxPointer<= 1'b0;
          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;
          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;
            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;
          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 <= 1'b1;
            m_wb_adr_o <= RxPointerMSB;
            m_wb_cyc_o <= 1'b1;
            m_wb_we_o  <= 1'b1;
            m_wb_sel_o <= RxByteSel;
            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;
            tx_burst_en<= txfifo_cnt<(TX_FIFO_DEPTH-`ETH_BURST_LENGTH) & (TxLength>(`ETH_BURST_LENGTH*4+4));
            rx_burst_cnt<= 0;
            rx_burst_en<= MasterWbRX ? enough_data_in_rxfifo_for_burst_plus1 : enough_data_in_rxfifo_for_burst;  // Counter is not decremented, yet, so plus1 is used.
            `ifdef ETH_WISHBONE_B3
              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;
            rx_burst_en<= MasterWbRX ? enough_data_in_rxfifo_for_burst_plus1 : enough_data_in_rxfifo_for_burst;  // Counter is not decremented, yet, so plus1 is used.
            `ifdef ETH_WISHBONE_B3
              m_wb_cti_o <= 3'b0;
            `endif
          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;
            tx_burst_en<= txfifo_cnt<(TX_FIFO_DEPTH-`ETH_BURST_LENGTH) & (TxLength>(`ETH_BURST_LENGTH*4+4));
          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);
 
eth_fifo #(.DATA_WIDTH(TX_FIFO_DATA_WIDTH),
           .DEPTH(TX_FIFO_DEPTH),
           .CNT_WIDTH(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 
assign TempTxBDAddress[7:1] = {7{ TxStatusWrite     & ~WrapTxStatusBit}}   & (TxBDAddress + 1'b1) ; // Tx BD increment or wrap (last BD)
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;
  else if (TxStatusWrite)
    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;
 
        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
 
        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 & ~RxReady)
    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 <= ram_do[15]; // RxBDReady is sampled only once at the beginning
end
 
// 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
 
 
// RxReady generation
always @ (posedge WB_CLK_I or posedge Reset)
begin
  if(Reset)
    RxReady <= 1'b0;
  else
  if(ShiftEnded | RxAbortSync2 & ~RxAbortSync3 | ~r_RxEn & r_RxEn_q)
    RxReady <= 1'b0;
  else
  if(RxEn & RxEn_q & RxPointerRead)
    RxReady <= 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)
      RxPointerMSB <= RxPointerMSB + 1'b1; // Word access  (always word access. m_wb_sel_o are used for selecting bytes)
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 = ShiftEnded & 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
 
reg ShiftEnded_rck;
reg ShiftEndedSync1;
reg ShiftEndedSync2;
reg ShiftEndedSync3;
reg ShiftEndedSync_c1;
reg ShiftEndedSync_c2;
 
wire StartShiftWillEnd;
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
        2'h0:        RxDataLatched1[31:24] <= RxData;            // Big Endian Byte Ordering
        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
        2'h0:        RxDataLatched1[31:24] <= RxData;            // Big Endian Byte Ordering
        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)
    RxDataLatched2 <= {RxDataLatched1[31:8], RxData};              // Big Endian Byte Ordering
  else
  if(SetWriteRxDataToFifo & ShiftWillEnd)
    case(RxValidBytes)  // synopsys parallel_case
 
      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;
 
 
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
 
 
assign RxFifoReset = SyncRxStartFrm_q & ~SyncRxStartFrm_q2;
 
eth_fifo #(.DATA_WIDTH(RX_FIFO_DATA_WIDTH),
           .DEPTH(RX_FIFO_DEPTH),
           .CNT_WIDTH(RX_FIFO_CNT_WIDTH))
rx_fifo (.data_in(RxDataLatched2),                      .data_out(m_wb_dat_o),
         .clk(WB_CLK_I),                                .reset(Reset),
         .write(WriteRxDataToFifo_wb & ~RxBufferFull),  .read(MasterWbRX & m_wb_ack_i),
         .clear(RxFifoReset),                           .full(RxBufferFull),
         .almost_full(),                                .almost_empty(RxBufferAlmostEmpty),
         .empty(RxBufferEmpty),                         .cnt(rxfifo_cnt)
        );
 
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 WriteRxDataToMemory = ~RxBufferEmpty;
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
 
always @ (posedge WB_CLK_I or posedge Reset)
begin
  if(Reset)
    ShiftEndedSync3 <= 1'b0;
  else
  if(ShiftEndedSync1 & ~ShiftEndedSync2)
    ShiftEndedSync3 <= 1'b1;
  else
  if(ShiftEnded)
    ShiftEndedSync3 <= 1'b0;
end
 
// Generation of the end-of-frame signal
always @ (posedge WB_CLK_I or posedge Reset)
begin
  if(Reset)
    ShiftEnded <= 1'b0;
  else
  if(ShiftEndedSync3 & MasterWbRX & m_wb_ack_i & RxBufferAlmostEmpty & ~ShiftEnded)
    ShiftEnded <= 1'b1;
  else
  if(RxStatusWrite)
    ShiftEnded <= 1'b0;
end
 
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
 
 
// Busy Interrupt
 
reg Busy_IRQ_rck;
reg Busy_IRQ_sync1;
reg Busy_IRQ_sync2;
reg Busy_IRQ_sync3;
reg Busy_IRQ_syncb1;
reg Busy_IRQ_syncb2;
 
 
always @ (posedge MRxClk or posedge Reset)
begin
  if(Reset)
    Busy_IRQ_rck <= 1'b0;
  else
  if(RxValid & RxStartFrm & ~RxReady)
    Busy_IRQ_rck <= 1'b1;
  else
  if(Busy_IRQ_syncb2)
    Busy_IRQ_rck <= 1'b0;
end
 
always @ (posedge WB_CLK_I)
begin
    Busy_IRQ_sync1 <= Busy_IRQ_rck;
    Busy_IRQ_sync2 <= Busy_IRQ_sync1;
    Busy_IRQ_sync3 <= Busy_IRQ_sync2;
end
 
always @ (posedge MRxClk)
begin
    Busy_IRQ_syncb1 <= Busy_IRQ_sync2;
    Busy_IRQ_syncb2 <= Busy_IRQ_syncb1;
end
 
assign Busy_IRQ = Busy_IRQ_sync2 & ~Busy_IRQ_sync3;
 
 
 
 
 
endmodule

Line No.	Rev	Author	Line
1	38	mohor	`//////////////////////////////////////////////////////////////////////`
2			`//// ////`
3			`//// eth_wishbone.v ////`
4			`//// ////`
5			`//// This file is part of the Ethernet IP core project ////`
6	346	olof	`//// http://www.opencores.org/project,ethmac ////`
7	38	mohor	`//// ////`
8			`//// Author(s): ////`
9			`//// - Igor Mohor (igorM@opencores.org) ////`
10			`//// ////`
11	166	mohor	`//// All additional information is available in the Readme.txt ////`
12	38	mohor	`//// file. ////`
13			`//// ////`
14			`//////////////////////////////////////////////////////////////////////`
15			`//// ////`
16	118	mohor	`//// Copyright (C) 2001, 2002 Authors ////`
17	38	mohor	`//// ////`
18			`//// This source file may be used and distributed without ////`
19			`//// restriction provided that this copyright statement is not ////`
20			`//// removed from the file and that any derivative work contains ////`
21			`//// the original copyright notice and the associated disclaimer. ////`
22			`//// ////`
23			`//// This source file is free software; you can redistribute it ////`
24			`//// and/or modify it under the terms of the GNU Lesser General ////`
25			`//// Public License as published by the Free Software Foundation; ////`
26			`//// either version 2.1 of the License, or (at your option) any ////`
27			`//// later version. ////`
28			`//// ////`
29			`//// This source is distributed in the hope that it will be ////`
30			`//// useful, but WITHOUT ANY WARRANTY; without even the implied ////`
31			`//// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR ////`
32			`//// PURPOSE. See the GNU Lesser General Public License for more ////`
33			`//// details. ////`
34			`//// ////`
35			`//// You should have received a copy of the GNU Lesser General ////`
36			`//// Public License along with this source; if not, download it ////`
37			`//// from http://www.opencores.org/lgpl.shtml ////`
38			`//// ////`
39			`//////////////////////////////////////////////////////////////////////`
40			`//`
41			`// CVS Revision History`
42			`//`
43			`// $Log: not supported by cvs2svn $`
44	333	igorm	`// Revision 1.57 2005/02/21 11:35:33 igorm`
45			`// Defer indication fixed.`
46			`//`
47	329	igorm	`// Revision 1.56 2004/04/30 10:30:00 igorm`
48			`// Accidently deleted line put back.`
49			`//`
50	323	igorm	`// Revision 1.55 2004/04/26 15:26:23 igorm`
51			`// - Bug connected to the TX_BD_NUM_Wr signal fixed (bug came in with the`
52			`// previous update of the core.`
53			`// - TxBDAddress is set to 0 after the TX is enabled in the MODER register.`
54			`// - RxBDAddress is set to r_TxBDNum<<1 after the RX is enabled in the MODER`
55			`// register. (thanks to Mathias and Torbjorn)`
56			`// - Multicast reception was fixed. Thanks to Ulrich Gries`
57			`//`
58	321	igorm	`// Revision 1.54 2003/11/12 18:24:59 tadejm`
59			`// WISHBONE slave changed and tested from only 32-bit accesss to byte access.`
60			`//`
61	304	tadejm	`// Revision 1.53 2003/10/17 07:46:17 markom`
62			`// mbist signals updated according to newest convention`
63			`//`
64	302	markom	`// Revision 1.52 2003/01/30 14:51:31 mohor`
65			`// Reset has priority in some flipflops.`
66			`//`
67	280	mohor	`// Revision 1.51 2003/01/30 13:36:22 mohor`
68			`// A new bug (entered with previous update) fixed. When abort occured sometimes`
69			`// data transmission was blocked.`
70			`//`
71	278	mohor	`// Revision 1.50 2003/01/22 13:49:26 tadejm`
72			`// When control packets were received, they were ignored in some cases.`
73			`//`
74	272	tadejm	`// Revision 1.49 2003/01/21 12:09:40 mohor`
75			`// When receiving normal data frame and RxFlow control was switched on, RXB`
76			`// interrupt was not set.`
77			`//`
78	270	mohor	`// Revision 1.48 2003/01/20 12:05:26 mohor`
79			`// When in full duplex, transmit was sometimes blocked. Fixed.`
80			`//`
81	269	mohor	`// Revision 1.47 2002/11/22 13:26:21 mohor`
82			`// Registers RxStatusWrite_rck and RxStatusWriteLatched were not used`
83			`// anywhere. Removed.`
84			`//`
85	264	mohor	`// Revision 1.46 2002/11/22 01:57:06 mohor`
86			`// Rx Flow control fixed. CF flag added to the RX buffer descriptor. RxAbort`
87			`// synchronized.`
88			`//`
89	261	mohor	`// Revision 1.45 2002/11/19 17:33:34 mohor`
90			`// AddressMiss status is connecting to the Rx BD. AddressMiss is identifying`
91			`// that a frame was received because of the promiscous mode.`
92			`//`
93	250	mohor	`// Revision 1.44 2002/11/13 22:21:40 tadejm`
94			`// RxError is not generated when small frame reception is enabled and small`
95			`// frames are received.`
96			`//`
97	239	tadejm	`// Revision 1.43 2002/10/18 20:53:34 mohor`
98			`// case changed to casex.`
99			`//`
100	229	mohor	`// Revision 1.42 2002/10/18 17:04:20 tadejm`
101			`// Changed BIST scan signals.`
102			`//`
103	227	tadejm	`// Revision 1.41 2002/10/18 15:42:09 tadejm`
104			`// Igor added WB burst support and repaired BUG when handling TX under-run and retry.`
105			`//`
106	226	tadejm	`// Revision 1.40 2002/10/14 16:07:02 mohor`
107			`// TxStatus is written after last access to the TX fifo is finished (in case of abort`
108			`// or retry). TxDone is fixed.`
109			`//`
110	221	mohor	`// Revision 1.39 2002/10/11 15:35:20 mohor`
111			`// txfifo_cnt and rxfifo_cnt counters width is defined in the eth_define.v file,`
112			`// TxDone and TxRetry are generated after the current WISHBONE access is`
113			`// finished.`
114			`//`
115	219	mohor	`// Revision 1.38 2002/10/10 16:29:30 mohor`
116			`// BIST added.`
117			`//`
118	210	mohor	`// Revision 1.37 2002/09/11 14:18:46 mohor`
119			`// Sometimes both RxB_IRQ and RxE_IRQ were activated. Bug fixed.`
120			`//`
121	167	mohor	`// Revision 1.36 2002/09/10 13:48:46 mohor`
122			`// Reception is possible after RxPointer is read and not after BD is read. For`
123			`// that reason RxBDReady is changed to RxReady.`
124			`// Busy_IRQ interrupt connected. When there is no RxBD ready and frame`
125			`// comes, interrupt is generated.`
126			`//`
127	166	mohor	`// Revision 1.35 2002/09/10 10:35:23 mohor`
128			`// Ethernet debug registers removed.`
129			`//`
130	164	mohor	`// Revision 1.34 2002/09/08 16:31:49 mohor`
131			`// Async reset for WB_ACK_O removed (when core was in reset, it was`
132			`// impossible to access BDs).`
133			`// RxPointers and TxPointers names changed to be more descriptive.`
134			`// TxUnderRun synchronized.`
135			`//`
136	159	mohor	`// Revision 1.33 2002/09/04 18:47:57 mohor`
137			`// Debug registers reg1, 2, 3, 4 connected. Synchronization of many signals`
138			`// changed (bugs fixed). Access to un-alligned buffers fixed. RxAbort signal`
139			`// was not used OK.`
140			`//`
141	150	mohor	`// Revision 1.32 2002/08/14 19:31:48 mohor`
142			`// Register TX_BD_NUM is changed so it contains value of the Tx buffer descriptors. No`
143			`// need to multiply or devide any more.`
144			`//`
145	134	mohor	`// Revision 1.31 2002/07/25 18:29:01 mohor`
146			`// WriteRxDataToMemory signal changed so end of frame (when last word is`
147			`// written to fifo) is changed.`
148			`//`
149	127	mohor	`// Revision 1.30 2002/07/23 15:28:31 mohor`
150			`// Ram , used for BDs changed from generic_spram to eth_spram_256x32.`
151			`//`
152	119	mohor	`// Revision 1.29 2002/07/20 00:41:32 mohor`
153			`// ShiftEnded synchronization changed.`
154			`//`
155	118	mohor	`// Revision 1.28 2002/07/18 16:11:46 mohor`
156			// RxBDAddress takes `ETH_TX_BD_NUM_DEF value after reset.
157			`//`
158	115	mohor	`// Revision 1.27 2002/07/11 02:53:20 mohor`
159			`// RxPointer bug fixed.`
160			`//`
161	113	mohor	`// Revision 1.26 2002/07/10 13:12:38 mohor`
162			`// Previous bug wasn't succesfully removed. Now fixed.`
163			`//`
164	112	mohor	`// Revision 1.25 2002/07/09 23:53:24 mohor`
165			`// Master state machine had a bug when switching from master write to`
166			`// master read.`
167			`//`
168	111	mohor	`// Revision 1.24 2002/07/09 20:44:41 mohor`
169			`// m_wb_cyc_o signal released after every single transfer.`
170			`//`
171	110	mohor	`// Revision 1.23 2002/05/03 10:15:50 mohor`
172			`// Outputs registered. Reset changed for eth_wishbone module.`
173			`//`
174	106	mohor	`// Revision 1.22 2002/04/24 08:52:19 mohor`
175			`// Compiler directives added. Tx and Rx fifo size incremented. A "late collision"`
176			`// bug fixed.`
177			`//`
178	105	mohor	`// Revision 1.21 2002/03/29 16:18:11 lampret`
179			`// Small typo fixed.`
180			`//`
181	97	lampret	`// Revision 1.20 2002/03/25 16:19:12 mohor`
182			`// Any address can be used for Tx and Rx BD pointers. Address does not need`
183			`// to be aligned.`
184			`//`
185	96	mohor	`// Revision 1.19 2002/03/19 12:51:50 mohor`
186			`// Comments in Slovene language removed.`
187			`//`
188	91	mohor	`// Revision 1.18 2002/03/19 12:46:52 mohor`
189			`// casex changed with case, fifo reset changed.`
190			`//`
191	90	mohor	`// Revision 1.17 2002/03/09 16:08:45 mohor`
192			`// rx_fifo was not always cleared ok. Fixed.`
193			`//`
194	88	mohor	`// Revision 1.16 2002/03/09 13:51:20 mohor`
195			`// Status was not latched correctly sometimes. Fixed.`
196			`//`
197	87	mohor	`// Revision 1.15 2002/03/08 06:56:46 mohor`
198			`// Big Endian problem when sending frames fixed.`
199			`//`
200	86	mohor	`// Revision 1.14 2002/03/02 19:12:40 mohor`
201			`// Byte ordering changed (Big Endian used). casex changed with case because`
202			`// Xilinx Foundation had problems. Tested in HW. It WORKS.`
203			`//`
204	82	mohor	`// Revision 1.13 2002/02/26 16:59:55 mohor`
205			`// Small fixes for external/internal DMA missmatches.`
206			`//`
207	80	mohor	`// Revision 1.12 2002/02/26 16:22:07 mohor`
208			`// Interrupts changed`
209			`//`
210	77	mohor	`// Revision 1.11 2002/02/15 17:07:39 mohor`
211			`// Status was not written correctly when frames were discarted because of`
212			`// address mismatch.`
213			`//`
214	64	mohor	`// Revision 1.10 2002/02/15 12:17:39 mohor`
215			`// RxStartFrm cleared when abort or retry comes.`
216			`//`
217	61	mohor	`// Revision 1.9 2002/02/15 11:59:10 mohor`
218			`// Changes that were lost when updating from 1.5 to 1.8 fixed.`
219			`//`
220	60	mohor	`// Revision 1.8 2002/02/14 20:54:33 billditt`
221			`// Addition of new module eth_addrcheck.v`
222			`//`
223			`// Revision 1.7 2002/02/12 17:03:47 mohor`
224			`// RxOverRun added to statuses.`
225			`//`
226			`// Revision 1.6 2002/02/11 09:18:22 mohor`
227			`// Tx status is written back to the BD.`
228			`//`
229	43	mohor	`// Revision 1.5 2002/02/08 16:21:54 mohor`
230			`// Rx status is written back to the BD.`
231			`//`
232	42	mohor	`// Revision 1.4 2002/02/06 14:10:21 mohor`
233			`// non-DMA host interface added. Select the right configutation in eth_defines.`
234			`//`
235	41	mohor	`// Revision 1.3 2002/02/05 16:44:39 mohor`
236			`// Both rx and tx part are finished. Tested with wb_clk_i between 10 and 200`
237			`// MHz. Statuses, overrun, control frame transmission and reception still need`
238			`// to be fixed.`
239			`//`
240	40	mohor	`// Revision 1.2 2002/02/01 12:46:51 mohor`
241			`// Tx part finished. TxStatus needs to be fixed. Pause request needs to be`
242			`// added.`
243			`//`
244	39	mohor	`// Revision 1.1 2002/01/23 10:47:59 mohor`
245			`// Initial version. Equals to eth_wishbonedma.v at this moment.`
246	38	mohor	`//`
247			`//`
248			`//`
249
250			`include "eth_defines.v"
251			`include "timescale.v"
252
253
254			`module eth_wishbone`
255			`(`
256
257			`// WISHBONE common`
258	40	mohor	`WB_CLK_I, WB_DAT_I, WB_DAT_O,`
259	38	mohor
260			`// WISHBONE slave`
261	77	mohor	`WB_ADR_I, WB_WE_I, WB_ACK_O,`
262	40	mohor	`BDCs,`
263	38	mohor
264	40	mohor	`Reset,`
265
266	39	mohor	`// WISHBONE master`
267			`m_wb_adr_o, m_wb_sel_o, m_wb_we_o,`
268			`m_wb_dat_o, m_wb_dat_i, m_wb_cyc_o,`
269			`m_wb_stb_o, m_wb_ack_i, m_wb_err_i,`
270
271	219	mohor	`ifdef ETH_WISHBONE_B3
272			`m_wb_cti_o, m_wb_bte_o,`
273			`endif
274
275	38	mohor	`//TX`
276	60	mohor	`MTxClk, TxStartFrm, TxEndFrm, TxUsedData, TxData,`
277	150	mohor	`TxRetry, TxAbort, TxUnderRun, TxDone, PerPacketCrcEn,`
278	38	mohor	`PerPacketPad,`
279
280			`//RX`
281	272	tadejm	`MRxClk, RxData, RxValid, RxStartFrm, RxEndFrm, RxAbort, RxStatusWriteLatched_sync2,`
282	38	mohor
283			`// Register`
284	321	igorm	`r_TxEn, r_RxEn, r_TxBDNum, r_RxFlow, r_PassAll,`
285	38	mohor
286			`// Interrupts`
287	150	mohor	`TxB_IRQ, TxE_IRQ, RxB_IRQ, RxE_IRQ, Busy_IRQ,`
288	42	mohor
289	60	mohor	`// Rx Status`
290	42	mohor	`InvalidSymbol, LatchedCrcError, RxLateCollision, ShortFrame, DribbleNibble,`
291	250	mohor	`ReceivedPacketTooBig, RxLength, LoadRxStatus, ReceivedPacketGood, AddressMiss,`
292	261	mohor	`ReceivedPauseFrm,`
293	60	mohor
294			`// Tx Status`
295	329	igorm	`RetryCntLatched, RetryLimit, LateCollLatched, DeferLatched, RstDeferLatched, CarrierSenseLost`
296	164	mohor
297	210	mohor	`// Bist`
298			`ifdef ETH_BIST
299	227	tadejm	`,`
300			`// debug chain signals`
301	302	markom	`mbist_si_i, // bist scan serial in`
302			`mbist_so_o, // bist scan serial out`
303			`mbist_ctrl_i // bist chain shift control`
304	210	mohor	`endif
305
306
307
308	38	mohor	`);`
309
310
311	349	olof	parameter TX_FIFO_DATA_WIDTH = `ETH_TX_FIFO_DATA_WIDTH;
312			parameter TX_FIFO_DEPTH = `ETH_TX_FIFO_DEPTH;
313			parameter TX_FIFO_CNT_WIDTH = `ETH_TX_FIFO_CNT_WIDTH;
314			parameter RX_FIFO_DATA_WIDTH = `ETH_RX_FIFO_DATA_WIDTH;
315			parameter RX_FIFO_DEPTH = `ETH_RX_FIFO_DEPTH;
316			parameter RX_FIFO_CNT_WIDTH = `ETH_RX_FIFO_CNT_WIDTH;
317	38	mohor
318	150	mohor
319	38	mohor	`// WISHBONE common`
320			`input WB_CLK_I; // WISHBONE clock`
321			`input [31:0] WB_DAT_I; // WISHBONE data input`
322			`output [31:0] WB_DAT_O; // WISHBONE data output`
323
324			`// WISHBONE slave`
325			`input [9:2] WB_ADR_I; // WISHBONE address input`
326			`input WB_WE_I; // WISHBONE write enable input`
327	304	tadejm	`input [3:0] BDCs; // Buffer descriptors are selected`
328	38	mohor	`output WB_ACK_O; // WISHBONE acknowledge output`
329
330	39	mohor	`// WISHBONE master`
331	329	igorm	`output [29:0] m_wb_adr_o; //`
332	39	mohor	`output [3:0] m_wb_sel_o; //`
333			`output m_wb_we_o; //`
334			`output [31:0] m_wb_dat_o; //`
335			`output m_wb_cyc_o; //`
336			`output m_wb_stb_o; //`
337			`input [31:0] m_wb_dat_i; //`
338			`input m_wb_ack_i; //`
339			`input m_wb_err_i; //`
340
341	219	mohor	`ifdef ETH_WISHBONE_B3
342			`output [2:0] m_wb_cti_o; // Cycle Type Identifier`
343			`output [1:0] m_wb_bte_o; // Burst Type Extension`
344			`reg [2:0] m_wb_cti_o; // Cycle Type Identifier`
345			`endif
346
347	40	mohor	`input Reset; // Reset signal`
348	39	mohor
349	60	mohor	`// Rx Status signals`
350	42	mohor	`input InvalidSymbol; // Invalid symbol was received during reception in 100 Mbps mode`
351			`input LatchedCrcError; // CRC error`
352			`input RxLateCollision; // Late collision occured while receiving frame`
353			`input ShortFrame; // Frame shorter then the minimum size (r_MinFL) was received while small packets are enabled (r_RecSmall)`
354			`input DribbleNibble; // Extra nibble received`
355			`input ReceivedPacketTooBig;// Received packet is bigger than r_MaxFL`
356			`input [15:0] RxLength; // Length of the incoming frame`
357			`input LoadRxStatus; // Rx status was loaded`
358	77	mohor	`input ReceivedPacketGood;// Received packet's length and CRC are good`
359	250	mohor	`input AddressMiss; // When a packet is received AddressMiss status is written to the Rx BD`
360	261	mohor	`input r_RxFlow;`
361	270	mohor	`input r_PassAll;`
362	261	mohor	`input ReceivedPauseFrm;`
363	39	mohor
364	60	mohor	`// Tx Status signals`
365			`input [3:0] RetryCntLatched; // Latched Retry Counter`
366			`input RetryLimit; // Retry limit reached (Retry Max value + 1 attempts were made)`
367			`input LateCollLatched; // Late collision occured`
368			`input DeferLatched; // Defer indication (Frame was defered before sucessfully sent)`
369	329	igorm	`output RstDeferLatched;`
370	60	mohor	`input CarrierSenseLost; // Carrier Sense was lost during the frame transmission`
371
372	38	mohor	`// Tx`
373			`input MTxClk; // Transmit clock (from PHY)`
374			`input TxUsedData; // Transmit packet used data`
375			`input TxRetry; // Transmit packet retry`
376			`input TxAbort; // Transmit packet abort`
377			`input TxDone; // Transmission ended`
378			`output TxStartFrm; // Transmit packet start frame`
379			`output TxEndFrm; // Transmit packet end frame`
380			`output [7:0] TxData; // Transmit packet data byte`
381			`output TxUnderRun; // Transmit packet under-run`
382			`output PerPacketCrcEn; // Per packet crc enable`
383			`output PerPacketPad; // Per packet pading`
384
385			`// Rx`
386			`input MRxClk; // Receive clock (from PHY)`
387			`input [7:0] RxData; // Received data byte (from PHY)`
388			`input RxValid; //`
389			`input RxStartFrm; //`
390			`input RxEndFrm; //`
391	40	mohor	`input RxAbort; // This signal is set when address doesn't match.`
392	272	tadejm	`output RxStatusWriteLatched_sync2;`
393	38	mohor
394			`//Register`
395			`input r_TxEn; // Transmit enable`
396			`input r_RxEn; // Receive enable`
397			`input [7:0] r_TxBDNum; // Receive buffer descriptor number`
398
399			`// Interrupts`
400			`output TxB_IRQ;`
401			`output TxE_IRQ;`
402			`output RxB_IRQ;`
403	77	mohor	`output RxE_IRQ;`
404	38	mohor	`output Busy_IRQ;`
405
406	77	mohor
407	210	mohor	`// Bist`
408			`ifdef ETH_BIST
409	302	markom	`input mbist_si_i; // bist scan serial in`
410			`output mbist_so_o; // bist scan serial out`
411			input [`ETH_MBIST_CTRL_WIDTH - 1:0] mbist_ctrl_i; // bist chain shift control
412	210	mohor	`endif
413
414	77	mohor	`reg TxB_IRQ;`
415			`reg TxE_IRQ;`
416			`reg RxB_IRQ;`
417			`reg RxE_IRQ;`
418
419	38	mohor	`reg TxStartFrm;`
420			`reg TxEndFrm;`
421			`reg [7:0] TxData;`
422
423			`reg TxUnderRun;`
424	60	mohor	`reg TxUnderRun_wb;`
425	38	mohor
426			`reg TxBDRead;`
427	39	mohor	`wire TxStatusWrite;`
428	38	mohor
429			`reg [1:0] TxValidBytesLatched;`
430
431			`reg [15:0] TxLength;`
432	60	mohor	`reg [15:0] LatchedTxLength;`
433			`reg [14:11] TxStatus;`
434	38	mohor
435	60	mohor	`reg [14:13] RxStatus;`
436	38	mohor
437			`reg TxStartFrm_wb;`
438			`reg TxRetry_wb;`
439	39	mohor	`reg TxAbort_wb;`
440	38	mohor	`reg TxDone_wb;`
441
442			`reg TxDone_wb_q;`
443			`reg TxAbort_wb_q;`
444	39	mohor	`reg TxRetry_wb_q;`
445	219	mohor	`reg TxRetryPacket;`
446	221	mohor	`reg TxRetryPacket_NotCleared;`
447			`reg TxDonePacket;`
448			`reg TxDonePacket_NotCleared;`
449	219	mohor	`reg TxAbortPacket;`
450	221	mohor	`reg TxAbortPacket_NotCleared;`
451	38	mohor	`reg RxBDReady;`
452	166	mohor	`reg RxReady;`
453	38	mohor	`reg TxBDReady;`
454
455			`reg RxBDRead;`
456
457			`reg [31:0] TxDataLatched;`
458			`reg [1:0] TxByteCnt;`
459			`reg LastWord;`
460	39	mohor	`reg ReadTxDataFromFifo_tck;`
461	38	mohor
462			`reg BlockingTxStatusWrite;`
463			`reg BlockingTxBDRead;`
464
465	40	mohor	`reg Flop;`
466	38	mohor
467	329	igorm	`reg [7:1] TxBDAddress;`
468			`reg [7:1] RxBDAddress;`
469	38	mohor
470			`reg TxRetrySync1;`
471			`reg TxAbortSync1;`
472	39	mohor	`reg TxDoneSync1;`
473	38	mohor
474			`reg TxAbort_q;`
475			`reg TxRetry_q;`
476			`reg TxUsedData_q;`
477
478			`reg [31:0] RxDataLatched2;`
479	82	mohor
480			`reg [31:8] RxDataLatched1; // Big Endian Byte Ordering`
481
482	38	mohor	`reg [1:0] RxValidBytes;`
483			`reg [1:0] RxByteCnt;`
484			`reg LastByteIn;`
485			`reg ShiftWillEnd;`
486
487	40	mohor	`reg WriteRxDataToFifo;`
488	42	mohor	`reg [15:0] LatchedRxLength;`
489	64	mohor	`reg RxAbortLatched;`
490	38	mohor
491	40	mohor	`reg ShiftEnded;`
492	60	mohor	`reg RxOverrun;`
493	38	mohor
494	304	tadejm	`reg [3:0] BDWrite; // BD Write Enable for access from WISHBONE side`
495	40	mohor	`reg BDRead; // BD Read access from WISHBONE side`
496	39	mohor	`wire [31:0] RxBDDataIn; // Rx BD data in`
497			`wire [31:0] TxBDDataIn; // Tx BD data in`
498	38	mohor
499	39	mohor	`reg TxEndFrm_wb;`
500	38	mohor

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