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//////////////////////////////////////////////////////////////////////
//// 																					////
//// MODULE NAME: Data Path of Receive Module   						////
//// 																					////
//// DESCRIPTION: Data path of Receive Engine of 10 Gigabit       ////
////     Ethernet MAC. Used to recognize every field of a         ////
////     frame, including SOF, EOF, Length, Destination Addr    	////
////     , Source Addr and Data field.                            ////
////																					////
//// This file is part of the 10 Gigabit Ethernet IP core project ////
////  http://www.opencores.org/projects/ethmac10g/						////
////																					////
//// AUTHOR(S):																	////
//// Zheng Cao			                                             ////
////							                                    		////
//////////////////////////////////////////////////////////////////////
////																					////
//// Copyright (c) 2005 AUTHORS.  All rights reserved.			   ////
////																					////
//// 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 1.1  2005/12/25 16:43:10  Zheng Cao
// 
// 
//
//////////////////////////////////////////////////////////////////////
 
`include "timescale.v"
`include "xgiga_define.v"
 
module rxDataPath(rxclk, reset, rxd64, rxc8, inband_fcs, receiving, start_da, start_lt, wait_crc_check, get_sfd, 
                  get_terminator, get_error_code, tagged_frame, pause_frame, da_addr, terminator_location, CRC_DATA, 
						rx_data_valid, rx_data,get_terminator_d1, bad_frame_get, good_frame_get,check_reset,rx_good_frame,rx_bad_frame);
//				      fcTxPauseData);
    input rxclk;
    input reset;
    input [63:0] rxd64;
    input [7:0] rxc8;
	 input inband_fcs;
	 input receiving;
	 input start_da;
	 input start_lt;
	 input wait_crc_check;	 
	 input get_terminator_d1;
	 input bad_frame_get;
	 input good_frame_get;
 
	 output get_sfd;
	 output get_terminator; //get T indicator
	 output get_error_code; //get Error indicator
    output tagged_frame;
	 output pause_frame;
	 output[47:0] da_addr;
	 output[2:0] terminator_location;
    output[63:0] CRC_DATA;
	 output[7:0] rx_data_valid;
	 output[63:0] rx_data;
	 output check_reset;
	 output rx_good_frame;
	 output rx_bad_frame;
//	 output [31:0]fcTxPauseData;
 
	 parameter TP = 1;
	 parameter IDLE = 0, READ = 2, WAIT_TMP = 3, WAIT = 1;
 
	 //////////////////////////////////////////////
	 // Pipe Line Stage
	 //////////////////////////////////////////////
	 reg [63:0] rxd64_d1,rxd64_d2,rxd64_d3,CRC_DATA;
	 reg [7:0] rxc8_d1, rxc8_d2, rxc8_d3;
	 reg receiving_d1, receiving_d2;
	 reg wait_crc_check_d1;
 
//	 assign fcTxPauseData = rxd64_d1[31:0];
	 // Data pipeline
	 always@(posedge rxclk or posedge reset) begin
	       if (reset)	begin		
				 rxd64_d1<=#TP 0;
				 rxd64_d2<=#TP 0;
				 rxd64_d3<=#TP 0;
		   	 CRC_DATA<=0;
 
			 end
			 else begin
				 rxd64_d1<=#TP rxd64;
				 rxd64_d2<=#TP rxd64_d1;
				 rxd64_d3<=#TP rxd64_d2;
				 CRC_DATA <={rxd64_d2[0],rxd64_d2[1],rxd64_d2[2],rxd64_d2[3],rxd64_d2[4],rxd64_d2[5],rxd64_d2[6],rxd64_d2[7],
			rxd64_d2[8],rxd64_d2[9],rxd64_d2[10],rxd64_d2[11],rxd64_d2[12],rxd64_d2[13],rxd64_d2[14],rxd64_d2[15],
			rxd64_d2[16],rxd64_d2[17],rxd64_d2[18],rxd64_d2[19],rxd64_d2[20],rxd64_d2[21],rxd64_d2[22],rxd64_d2[23],
			rxd64_d2[24],rxd64_d2[25],rxd64_d2[26],rxd64_d2[27],rxd64_d2[28],rxd64_d2[29],rxd64_d2[30],rxd64_d2[31],
			rxd64_d2[32],rxd64_d2[33],rxd64_d2[34],rxd64_d2[35],rxd64_d2[36],rxd64_d2[37],rxd64_d2[38],rxd64_d2[39],
			rxd64_d2[40],rxd64_d2[41],rxd64_d2[42],rxd64_d2[43],rxd64_d2[44],rxd64_d2[45],rxd64_d2[46],rxd64_d2[47],
			rxd64_d2[48],rxd64_d2[49],rxd64_d2[50],rxd64_d2[51],rxd64_d2[52],rxd64_d2[53],rxd64_d2[54],rxd64_d2[55],
			rxd64_d2[56],rxd64_d2[57],rxd64_d2[58],rxd64_d2[59],rxd64_d2[60],rxd64_d2[61],rxd64_d2[62],rxd64_d2[63]};
			end
	 end
	 //control pipeline
	 always@(posedge rxclk or posedge reset)begin
	      if (reset)	begin		
				 rxc8_d1<=#TP 0;
				 rxc8_d2<=#TP 0;
				 rxc8_d3<=#TP 0;      
			 end
			 else begin
				 rxc8_d1<=#TP rxc8;
				 rxc8_d2<=#TP rxc8_d1;
				 rxc8_d3<=#TP rxc8_d2;
			 end
	 end
 
	 always @(posedge rxclk or posedge reset)begin
	       if (reset) begin
			    receiving_d1 <=#TP 0;
				 receiving_d2 <=#TP 0;
				 wait_crc_check_d1 <=#TP 0;
			 end
			 else	begin
			    receiving_d1 <=#TP receiving;
				 receiving_d2 <=#TP receiving_d1;
				 wait_crc_check_d1 <=#TP wait_crc_check;
			 end
	 end
 
	 ////////////////////////////////////////////
	 // Frame analysis
	 ////////////////////////////////////////////
	 reg get_sfd; //get sfd indicator
	 reg get_terminator; //get T indicator
	 reg get_error_code; //get Error indicator
	 reg[7:0] get_e_chk;
	 reg[7:0] rxc_end_data; //seperate DATA with FCS
	 reg [2:0]terminator_location; //for n*8bits(n<8), get n
	 reg[47:0] da_addr; //get Desetination Address
	 reg tagged_frame;  //Tagged frame indicator(type interpret)
	 reg pause_frame;   //Pause frame indicator(type interpret)
 
	 //1. SFD 
	 always@(posedge rxclk or posedge reset) begin
	       if (reset) 
			    get_sfd <=#TP 0; 
			 else
			    get_sfd <=#TP (rxd64[7:0] ==`START) & (rxd64[63:56]== `SFD) & (rxc8 == 8'h01);
	 end
 
 	 //2. EFD
	 reg this_cycle; 
	 // -----------------------------------------------
	 //|  0  |  1  |  2  |  3  |  4  |  5  |  6  |  7  | 
	 // -----------------------------------------------
	 //|<-------- EFD -------->|<-------- EFD -------->|
	 //|<-- this_cycle = '1' ->|<-- this_cycle = '0' ->|
 
	 always@(posedge rxclk or posedge reset) begin
	       if (reset)	begin
			    get_terminator <=#TP 0;
				 terminator_location <=#TP 0;				 
	 		    this_cycle <=#TP 1'b0;
			    rxc_end_data <=#TP 0;
			 end
			 else begin
			    if (rxc8[0] & (rxd64[7:0]  ==`TERMINATE)) begin
				     get_terminator <=#TP 1'b1;
					  terminator_location <=#TP 0;			 
					  this_cycle <=#TP 1'b1;
					  rxc_end_data <=#TP 8'b00001111;
			    end   
			    else if (rxc8[1] & (rxd64[15:8] ==`TERMINATE)) begin
				     get_terminator <=#TP 1'b1;
					  terminator_location <=#TP 1;
					  this_cycle <=#TP 1'b1;
					  rxc_end_data <=#TP 8'b00011111;
				 end
				 else if (rxc8[2] & (rxd64[23:16]==`TERMINATE)) begin
                 get_terminator <=#TP 1'b1;	
					  terminator_location <=#TP 2;
                 this_cycle <=#TP 1'b1;					  
					  rxc_end_data <=#TP 8'b00111111;
				 end
				 else if (rxc8[3] & (rxd64[31:24]==`TERMINATE)) begin
                 get_terminator <=#TP 1'b1;
					  terminator_location <=#TP 3;	
                 this_cycle <=#TP 1'b1;							  			
					  rxc_end_data <=#TP 8'b01111111;
				 end
             else if (rxc8[4] & (rxd64[39:32]==`TERMINATE)) begin
				     get_terminator <=#TP 1'b1; 
					  terminator_location <=#TP 4;	
                 this_cycle <=#TP 1'b1;							  			
					  rxc_end_data <=#TP 8'b11111111;
				 end
				 else if (rxc8[5] & (rxd64[47:40]==`TERMINATE)) begin		
                 get_terminator <=#TP 1'b1; 
					  terminator_location <=#TP 5;
					  this_cycle <=#TP 1'b0;
					  rxc_end_data <=#TP 8'b00000001;
				 end
				 else if (rxc8[6] & (rxd64[55:48]==`TERMINATE)) begin
                 get_terminator <=#TP 1'b1;	
					  terminator_location <=#TP 6; 
					  this_cycle <=#TP 1'b0;
					  rxc_end_data <=#TP 8'b00000011;
				 end
				 else if (rxc8[7] & (rxd64[63:56]==`TERMINATE))	begin
                 get_terminator <=#TP 1'b1;	
					  terminator_location <=#TP 7;
					  this_cycle <=#TP 1'b0;
					  rxc_end_data <=#TP 8'b00000111;
				 end
				 else	begin
				     get_terminator <=#TP 1'b0;
					  terminator_location <=#TP terminator_location; 
					  this_cycle <=#TP this_cycle;
					  rxc_end_data <=#TP rxc_end_data;
				 end
			 end
	 end
 
	 //3. Error Character
    always@(posedge rxclk or posedge reset) begin
	       if (reset)
			    get_e_chk <=#TP 0;
			 else begin
				 get_e_chk[0] <=#TP rxc8[0] & (rxd64[7:0]  ==`ERROR); 
			    get_e_chk[1] <=#TP rxc8[1] & (rxd64[15:8] ==`ERROR);
             get_e_chk[2] <=#TP rxc8[2] & (rxd64[23:16]==`ERROR);
             get_e_chk[3] <=#TP rxc8[3] & (rxd64[31:24]==`ERROR);
             get_e_chk[4] <=#TP rxc8[4] & (rxd64[39:32]==`ERROR);		
             get_e_chk[5] <=#TP rxc8[5] & (rxd64[47:40]==`ERROR);
             get_e_chk[6] <=#TP rxc8[6] & (rxd64[55:48]==`ERROR);
             get_e_chk[7] <=#TP rxc8[7] & (rxd64[63:56]==`ERROR);
			 end
	 end
 
	 always@(posedge rxclk or posedge reset) begin
	       if (reset) 
			    get_error_code <=#TP 0;
          else
			    get_error_code <=#TP receiving & (| get_e_chk);
	 end
 
	 //////////////////////////////////////
	 // Get Destination Address
	 //////////////////////////////////////
 
	 always@(posedge rxclk or posedge reset)begin
       if (reset) 
	       da_addr <=#TP 0;
   	 else if (start_da) 
	       da_addr <=#TP rxd64_d1[47:0];
		 else	
		    da_addr <=#TP da_addr;
    end
 
	 //////////////////////////////////////
	 // Get Length/Type Field
	 //////////////////////////////////////
 
	 reg[15:0] lt_data; 
	 always@(posedge rxclk or posedge reset)begin
       if (reset) 
	       lt_data <=#TP 0;
   	 else if (start_lt) 
	       lt_data <=#TP rxd64_d1[47:32];
		 else
		    lt_data <=#TP lt_data;
    end
 
    //tagged frame indicator
	 always@(posedge rxclk or posedge reset) begin
	    if (reset)
		    tagged_frame <=#TP 1'b0;
       else	if (start_lt)
		    tagged_frame <=#TP (rxd64[63:32] == `TAG_SIGN); 
		 else								
		    tagged_frame <=#TP tagged_frame;
	 end
	 //pause frame indicator
	 always@(posedge rxclk or posedge reset) begin
	    if (reset)
		    pause_frame <=#TP 1'b0;
       else	if (start_lt)
		    pause_frame <=#TP (rxd64[47:32] == `PAUSE_SIGN); 
		 else 
		    pause_frame <=#TP 1'b0;
	 end
 
    /////////////////////////////////////////////
    // Generate proper rxc to FIFO						
    /////////////////////////////////////////////
 
	 reg [7:0]rxc_final;
	 wire [7:0]rxc_fifo; //rxc send to fifo
 
    always@(posedge rxclk or posedge reset) begin
	       if (reset)
			    rxc_final <=#TP 0;
			 else if (get_terminator & this_cycle)
             rxc_final <=#TP rxc_end_data;
			 else if (get_terminator_d1 & ~this_cycle)
			    rxc_final <=#TP rxc_end_data;
			 else if (get_error_code)
             rxc_final <=#TP 0;			 
          else if (receiving)
             rxc_final <=#TP `ALLONES8;
			 else
			    rxc_final <=#TP 0;			 
    end				 
 
	 assign rxc_fifo = inband_fcs? ~rxc8_d3:rxc_final;
 
    ////////////////////////////////////////////////////////////////
    // FIFO management, to generate rx_good_frame/rx_bad_frame
    // after a frame has been totally received.
    ////////////////////////////////////////////////////////////////
  	 wire rxfifo_full;
	 wire rxfifo_empty;
	 wire fifo_wr_en;
    wire [63:0] rx_data_tmp;
	 wire [7:0] rx_data_valid_tmp;
 
	 reg one_frame_end;
	 always@(posedge rxclk or posedge reset) begin
	        if(reset)
			    one_frame_end <= 1'b0;
			  else if(rx_data_valid_tmp!=8'hff)
			    one_frame_end <= 1'b1;
			  else
             one_frame_end <= 1'b0;				 
	 end			  
 
	 reg fifo_rd_en;
	 reg[1:0] fifo_state;
	 wire rx_good_frame;
	 wire rx_bad_frame;
	 reg check_reset;
	 always@(posedge rxclk or posedge reset) begin
	       if(reset) begin
			   fifo_rd_en <= 1'b0;
			   fifo_state <= IDLE;
				check_reset <= 1'b0;
			 end
			 else
            case (fifo_state) 
              IDLE: begin
						check_reset <= 1'b0;
                  fifo_state <= IDLE;
						fifo_rd_en <= 1'b0;
                  if(~rxfifo_empty) begin 
                    fifo_rd_en <= 1'b1;
                    fifo_state <= WAIT_TMP;
						end  
              end
              READ: begin
				      check_reset <= 1'b0;
                  fifo_rd_en <= 1'b1;
						fifo_state <= READ;
                  if(rx_data_valid_tmp!=8'hff) begin						
                    fifo_state <= WAIT;
						  fifo_rd_en <= 1'b0;
						end
				  end		  
				  WAIT_TMP: begin
                  if(rx_data_valid_tmp == 8'hff)
                     fifo_state <=READ;
						else 
						   fifo_state <=WAIT_TMP;
              end						  
				  WAIT: begin		
                  fifo_state <= WAIT;
                  check_reset <= 1'b0;	
                  fifo_rd_en <= 1'b0;							
                  if(bad_frame_get | good_frame_get)begin
                    fifo_state <= IDLE;
						  check_reset <= 1'b1;
						end  
              end
            endcase
    end
 
	 assign rx_good_frame = good_frame_get & (fifo_state == WAIT);
	 assign rx_bad_frame = bad_frame_get & (fifo_state == WAIT);
 
	 assign fifo_wr_en = receiving_d2;
 
	 rxdatafifo rxdatain(.clk(rxclk),
	                  .sinit(reset),
	                  .din(rxd64_d3),
	       				.wr_en(fifo_wr_en),
                   	.rd_en(fifo_rd_en),
	                  .dout(rx_data_tmp),
	                  .full(rxfifo_full),
	                  .empty(rxfifo_empty));
 
	 rxcntrlfifo rxcntrlin(.clk(rxclk),
	                  .sinit(reset),
	                  .din(rxc_fifo),
	       				.wr_en(fifo_wr_en),
                   	.rd_en(fifo_rd_en),
	                  .dout(rx_data_valid_tmp),
	                  .full(),
	                  .empty());
	 reg [63:0] rx_data;
	 always@(posedge rxclk or posedge reset) begin
	      if (reset) begin
            rx_data <=#TP 0;
			end	
         else begin
            rx_data <=#TP rx_data_tmp;
			end	
    end
 
	 reg [7:0] rx_data_valid;
	 always@(posedge rxclk or posedge reset) begin
	      if (reset)
			  rx_data_valid <=#TP 0;
         else if(fifo_state[1])
           rx_data_valid <=#TP rx_data_valid_tmp;  
			else
			  rx_data_valid <=#TP 0;
    end			
 
endmodule