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

////                                                              ////

//// usbTxWireArbiter

////                                                              ////

//// This file is part of the usbhostslave opencores effort.

//// http://www.opencores.org/cores/usbhostslave/                 ////

////                                                              ////

//// Module Description:                                          ////

//// 

////                                                              ////

//// To Do:                                                       ////

//// 

////                                                              ////

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

//// - Steve Fielding, sfielding@base2designs.com                 ////

////                                                              ////

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

////                                                              ////

//// Copyright (C) 2004 Steve Fielding and OPENCORES.ORG          ////

////                                                              ////

//// This source file may be used and distributed without         ////

//// restriction provided that this copyright statement is not    ////

//// removed from the file and that any derivative work contains  ////

//// the original copyright notice and the associated disclaimer. ////

////                                                              ////

//// This source file is free software; you can redistribute it   ////

//// and/or modify it under the terms of the GNU Lesser General   ////

//// Public License as published by the Free Software Foundation; ////

//// either version 2.1 of the License, or (at your option) any   ////

//// later version.                                               ////

////                                                              ////

//// This source is distributed in the hope that it will be       ////

//// useful, but WITHOUT ANY WARRANTY; without even the implied   ////

//// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR      ////

//// PURPOSE. See the GNU Lesser General Public License for more  ////

//// details.                                                     ////

////                                                              ////

//// You should have received a copy of the GNU Lesser General    ////

//// Public License along with this source; if not, download it   ////

//// from http://www.opencores.org/lgpl.shtml                     ////

////                                                              ////

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

//

// $Id: usbTxWireArbiter.v,v 1.2 2004-12-18 14:36:16 sfielding Exp $

//

// CVS Revision History

//

// $Log: not supported by cvs2svn $

//

`timescale 1ns / 1ps

`include "usbConstants_h.v"

`include "usbSerialInterfaceEngine_h.v"

module USBWireTxArbiter (clk, prcTxByteCtrl, prcTxByteData, prcTxByteGnt, prcTxByteReq, prcTxByteWEn, rst, SIETxCtrl, SIETxData, SIETxGnt, SIETxReq, SIETxWEn, TxBits, TxCtl, USBWireRdyIn, USBWireRdyOut, USBWireWEn);

input   clk;

input   prcTxByteCtrl;

input   [1:0]prcTxByteData;

input   prcTxByteReq;

input   prcTxByteWEn;

input   rst;

input   SIETxCtrl;

input   [1:0]SIETxData;

input   SIETxReq;

input   SIETxWEn;

input   USBWireRdyIn;

output  prcTxByteGnt;

output  SIETxGnt;

output  [1:0]TxBits;

output  TxCtl;

output  USBWireRdyOut;

output  USBWireWEn;

wire    clk;

wire    prcTxByteCtrl;

wire    [1:0]prcTxByteData;

reg     prcTxByteGnt, next_prcTxByteGnt;

wire    prcTxByteReq;

wire    prcTxByteWEn;

wire    rst;

wire    SIETxCtrl;

wire    [1:0]SIETxData;

reg     SIETxGnt, next_SIETxGnt;

wire    SIETxReq;

wire    SIETxWEn;

reg     [1:0]TxBits, next_TxBits;

reg     TxCtl, next_TxCtl;

wire    USBWireRdyIn;

reg     USBWireRdyOut, next_USBWireRdyOut;

reg     USBWireWEn, next_USBWireWEn;

// diagram signals declarations

reg muxSIENotPTXB, next_muxSIENotPTXB;

// BINARY ENCODED state machine: txWireArb

// State codes definitions:

`define START_TARB 2'b00

`define TARB_WAIT_REQ 2'b01

`define PTXB_ACT 2'b10

`define SIE_TX_ACT 2'b11

reg [1:0]CurrState_txWireArb, NextState_txWireArb;

// Diagram actions (continuous assignments allowed only: assign ...)

// processTxByte/SIETransmitter mux

always @(USBWireRdyIn)

begin

USBWireRdyOut <= USBWireRdyIn;

end

always @(muxSIENotPTXB or SIETxWEn or SIETxData or

SIETxCtrl or prcTxByteWEn or prcTxByteData or prcTxByteCtrl)

begin

if (muxSIENotPTXB  == 1'b1)

begin

USBWireWEn <= SIETxWEn;

TxBits <= SIETxData;

TxCtl <= SIETxCtrl;

end

else

begin

USBWireWEn <= prcTxByteWEn;

TxBits <= prcTxByteData;

TxCtl <= prcTxByteCtrl;

end

end

// Machine: txWireArb

// NextState logic (combinatorial)

always @ (prcTxByteReq or SIETxReq or prcTxByteGnt or SIETxGnt or muxSIENotPTXB or CurrState_txWireArb)

begin

  NextState_txWireArb <= CurrState_txWireArb;

  // Set default values for outputs and signals

  next_prcTxByteGnt <= prcTxByteGnt;

  next_SIETxGnt <= SIETxGnt;

  next_muxSIENotPTXB <= muxSIENotPTXB;

  case (CurrState_txWireArb)  // synopsys parallel_case full_case

    `START_TARB:

    begin

      NextState_txWireArb <= `TARB_WAIT_REQ;

    end

    `TARB_WAIT_REQ:

    begin

      if (prcTxByteReq == 1'b1)

      begin

        NextState_txWireArb <= `PTXB_ACT;

        next_prcTxByteGnt <= 1'b1;

        next_muxSIENotPTXB <= 1'b0;

      end

      else if (SIETxReq == 1'b1)

      begin

        NextState_txWireArb <= `SIE_TX_ACT;

        next_SIETxGnt <= 1'b1;

        next_muxSIENotPTXB <= 1'b1;

      end

    end

    `PTXB_ACT:

    begin

      if (prcTxByteReq == 1'b0)

      begin

        NextState_txWireArb <= `TARB_WAIT_REQ;

        next_prcTxByteGnt <= 1'b0;

      end

    end

    `SIE_TX_ACT:

    begin

      if (SIETxReq == 1'b0)

      begin

        NextState_txWireArb <= `TARB_WAIT_REQ;

        next_SIETxGnt <= 1'b0;

      end

    end

  endcase

end

// Current State Logic (sequential)

always @ (posedge clk)

begin

  if (rst)

    CurrState_txWireArb <= `START_TARB;

  else

    CurrState_txWireArb <= NextState_txWireArb;

end

// Registered outputs logic

always @ (posedge clk)

begin

  if (rst)

  begin

    prcTxByteGnt <= 1'b0;

    SIETxGnt <= 1'b0;

    muxSIENotPTXB <= 1'b0;

  end

  else

  begin

    prcTxByteGnt <= next_prcTxByteGnt;

    SIETxGnt <= next_SIETxGnt;

    muxSIENotPTXB <= next_muxSIENotPTXB;

  end

end

endmodule