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

////                                                              ////

//// hostSlaveMuxBI.v                                             ////

////                                                              ////

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

//// <http://www.opencores.org/cores//>                           ////

////                                                              ////

//// 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>                   ////

////                                                              ////

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

//

`include "timescale.v"

`include "usbhostslave_hostslave_h.v"

module hostSlaveMuxBI (dataIn, dataOut, address, writeEn, strobe_i, busClk, usbClk,

  hostMode, hostSlaveMuxSel, rstFromWire, rstSyncToBusClkOut, rstSyncToUsbClkOut);

input [7:0] dataIn;

input address;

input writeEn;

input strobe_i;

input busClk;

input usbClk;

output [7:0] dataOut;

input hostSlaveMuxSel;

output hostMode;

input rstFromWire;

output rstSyncToBusClkOut;

output rstSyncToUsbClkOut;

wire [7:0] dataIn;

wire address;

wire writeEn;

wire strobe_i;

wire busClk;

wire usbClk;

reg [7:0] dataOut;

wire hostSlaveMuxSel;

reg hostMode;

wire rstFromWire;

reg rstSyncToBusClkOut;

reg rstSyncToUsbClkOut;

//internal wire and regs

reg [5:0] rstShift;

reg rstFromBus;

reg rstSyncToUsbClkFirst;

//sync write demux

always @(posedge busClk)

begin

  if (rstSyncToBusClkOut == 1'b1)

    hostMode <= 1'b0;

  else begin

    if (writeEn == 1'b1 && hostSlaveMuxSel == 1'b1 && strobe_i == 1'b1 && address == `HOST_SLAVE_CONTROL_REG )

      hostMode <= dataIn[0];

    end

    if (writeEn == 1'b1 && hostSlaveMuxSel == 1'b1 && strobe_i == 1'b1 && address == `HOST_SLAVE_CONTROL_REG && dataIn[1] == 1'b1 )

      rstFromBus <= 1'b1;

    else

      rstFromBus <= 1'b0;

end

// async read mux

always @(address or hostMode)

begin

  case (address)

    `HOST_SLAVE_CONTROL_REG: dataOut <= {7'h0, hostMode};

    `HOST_SLAVE_VERSION_REG: dataOut <= `USBHOSTSLAVE_VERSION_NUM;

  endcase

end

// reset control

//generate 'rstSyncToBusClk'

//assuming that 'busClk' < 5 * 'usbClk'. ie 'busClk' < 240MHz

always @(posedge busClk) begin

  if (rstFromWire == 1'b1 || rstFromBus == 1'b1)

    rstShift <= 6'b111111;

  else

    rstShift <= {1'b0, rstShift[5:1]};

end

always @(rstShift)

  rstSyncToBusClkOut <= rstShift[0];

// double sync across clock domains to generate 'forceEmptySyncToWrClk'

always @(posedge usbClk) begin

    rstSyncToUsbClkFirst <= rstSyncToBusClkOut;

    rstSyncToUsbClkOut <= rstSyncToUsbClkFirst;

end

endmodule