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//////////////////////////////////////////////////////////////////////
//// ////
//// eth_shiftreg.v ////
//// ////
//// This file is part of the Ethernet IP core project ////
//// http://www.opencores.org/projects/ethmac/ ////
//// ////
//// Author(s): ////
//// - Igor Mohor (igorM@opencores.org) ////
//// ////
//// All additional information is avaliable in the Readme.txt ////
//// file. ////
//// ////
//////////////////////////////////////////////////////////////////////
//// ////
//// Copyright (C) 2001 Authors ////
//// ////
//// This source file may be used and distributed without ////
//// restriction provided that this copyright statement is not ////
//// removed from the file and that any derivative work contains ////
//// the original copyright notice and the associated disclaimer. ////
//// ////
//// This source file is free software; you can redistribute it ////
//// and/or modify it under the terms of the GNU Lesser General ////
//// Public License as published by the Free Software Foundation; ////
//// either version 2.1 of the License, or (at your option) any ////
//// later version. ////
//// ////
//// This source is distributed in the hope that it will be ////
//// useful, but WITHOUT ANY WARRANTY; without even the implied ////
//// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR ////
//// PURPOSE. See the GNU Lesser General Public License for more ////
//// details. ////
//// ////
//// You should have received a copy of the GNU Lesser General ////
//// Public License along with this source; if not, download it ////
//// from http://www.opencores.org/lgpl.shtml ////
//// ////
//////////////////////////////////////////////////////////////////////
//
// CVS Revision History
//
// $Log: eth_shiftreg.v,v $
// Revision 1.2 2005/12/13 12:54:49 maverickist
// first simulation passed
//
// Revision 1.1.1.1 2005/12/13 01:51:45 Administrator
// no message
//
// Revision 1.2 2005/04/27 15:58:47 Administrator
// no message
//
// Revision 1.1.1.1 2004/12/15 06:38:54 Administrator
// no message
//
// Revision 1.5 2002/08/14 18:16:59 mohor
// LinkFail signal was not latching appropriate bit.
//
// Revision 1.4 2002/03/02 21:06:01 mohor
// LinkFail signal was not latching appropriate bit.
//
// Revision 1.3 2002/01/23 10:28:16 mohor
// Link in the header changed.
//
// Revision 1.2 2001/10/19 08:43:51 mohor
// eth_timescale.v changed to timescale.v This is done because of the
// simulation of the few cores in a one joined project.
//
// Revision 1.1 2001/08/06 14:44:29 mohor
// A define FPGA added to select between Artisan RAM (for ASIC) and Block Ram (For Virtex).
// Include files fixed to contain no path.
// File names and module names changed ta have a eth_ prologue in the name.
// File eth_timescale.v is used to define timescale
// All pin names on the top module are changed to contain _I, _O or _OE at the end.
// Bidirectional signal MDIO is changed to three signals (Mdc_O, Mdi_I, Mdo_O
// and Mdo_OE. The bidirectional signal must be created on the top level. This
// is done due to the ASIC tools.
//
// Revision 1.1 2001/07/30 21:23:42 mohor
// Directory structure changed. Files checked and joind together.
//
// Revision 1.3 2001/06/01 22:28:56 mohor
// This files (MIIM) are fully working. They were thoroughly tested. The testbench is not updated.
//
//
module eth_shiftreg(Clk, Reset, MdcEn_n, Mdi, Fiad, Rgad, CtrlData, WriteOp, ByteSelect,
LatchByte, ShiftedBit, Prsd, LinkFail);
input Clk; // Input clock (Host clock)
input Reset; // Reset signal
input MdcEn_n; // Enable signal is asserted for one Clk period before Mdc falls.
input Mdi; // MII input data
input [4:0] Fiad; // PHY address
input [4:0] Rgad; // Register address (within the selected PHY)
input [15:0]CtrlData; // Control data (data to be written to the PHY)
input WriteOp; // The current operation is a PHY register write operation
input [3:0] ByteSelect; // Byte select
input [1:0] LatchByte; // Byte select for latching (read operation)
output ShiftedBit; // Bit shifted out of the shift register
output[15:0]Prsd; // Read Status Data (data read from the PHY)
output LinkFail; // Link Integrity Signal
reg [7:0] ShiftReg; // Shift register for shifting the data in and out
reg [15:0]Prsd;
reg LinkFail;
// ShiftReg[7:0] :: Shift Register Data
always @ (posedge Clk or posedge Reset)
begin
if(Reset)
begin
ShiftReg[7:0] <= 8'h0;
Prsd[15:0] <= 16'h0;
LinkFail <= 1'b0;
end
else
begin
if(MdcEn_n)
begin
if(|ByteSelect)
begin
case (ByteSelect[3:0])
4'h1 : ShiftReg[7:0] <= {2'b01, ~WriteOp, WriteOp, Fiad[4:1]};
4'h2 : ShiftReg[7:0] <= {Fiad[0], Rgad[4:0], 2'b10};
4'h4 : ShiftReg[7:0] <= CtrlData[15:8];
4'h8 : ShiftReg[7:0] <= CtrlData[7:0];
default : ShiftReg[7:0] <= 8'h0;
endcase
end
else
begin
ShiftReg[7:0] <= {ShiftReg[6:0], Mdi};
if(LatchByte[0])
begin
Prsd[7:0] <= {ShiftReg[6:0], Mdi};
if(Rgad == 5'h01)
LinkFail <= ~ShiftReg[1]; // this is bit [2], because it is not shifted yet
end
else
begin
if(LatchByte[1])
Prsd[15:8] <= {ShiftReg[6:0], Mdi};
end
end
end
end
end
assign ShiftedBit = ShiftReg[7];
endmodule
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