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

////                                                              ////

////  File name "rx_enqueue.v"                                    ////

////                                                              ////

////  This file is part of the "10GE MAC" project                 ////

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

////                                                              ////

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

////      - A. Tanguay (antanguay@opencores.org)                  ////

////                                                              ////

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

////                                                              ////

//// Copyright (C) 2008 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                     ////

////                                                              ////

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

`include "defines.v"

module rx_enqueue(/*AUTOARG*/

  // Outputs

  rxdfifo_wdata, rxdfifo_wstatus, rxdfifo_wen, rxhfifo_ren,

  rxhfifo_wdata, rxhfifo_wstatus, rxhfifo_wen, local_fault_msg_det,

  remote_fault_msg_det, status_crc_error_tog,

  status_fragment_error_tog, status_rxdfifo_ovflow_tog,

  status_pause_frame_rx_tog, rxsfifo_wen, rxsfifo_wdata,

  // Inputs

  clk_xgmii_rx, reset_xgmii_rx_n, xgmii_rxd, xgmii_rxc, rxdfifo_wfull,

  rxhfifo_rdata, rxhfifo_rstatus, rxhfifo_rempty,

  rxhfifo_ralmost_empty

  );

`include "CRC32_D64.v"

`include "CRC32_D8.v"

`include "utils.v"

input         clk_xgmii_rx;

input         reset_xgmii_rx_n;

input  [63:0] xgmii_rxd;

input  [7:0]  xgmii_rxc;

input         rxdfifo_wfull;

input  [63:0] rxhfifo_rdata;

input  [7:0]  rxhfifo_rstatus;

input         rxhfifo_rempty;

input         rxhfifo_ralmost_empty;

output [63:0] rxdfifo_wdata;

output [7:0]  rxdfifo_wstatus;

output        rxdfifo_wen;

output        rxhfifo_ren;

output [63:0] rxhfifo_wdata;

output [7:0]  rxhfifo_wstatus;

output        rxhfifo_wen;

output [1:0]  local_fault_msg_det;

output [1:0]  remote_fault_msg_det;

output        status_crc_error_tog;

output        status_fragment_error_tog;

output        status_rxdfifo_ovflow_tog;

output        status_pause_frame_rx_tog;

output        rxsfifo_wen;

output [13:0] rxsfifo_wdata;

/*AUTOREG*/

// Beginning of automatic regs (for this module's undeclared outputs)

reg [1:0]               local_fault_msg_det;

reg [1:0]               remote_fault_msg_det;

reg [63:0]              rxdfifo_wdata;

reg                     rxdfifo_wen;

reg [7:0]               rxdfifo_wstatus;

reg                     rxhfifo_ren;

reg [63:0]              rxhfifo_wdata;

reg                     rxhfifo_wen;

reg [7:0]               rxhfifo_wstatus;

reg [13:0]              rxsfifo_wdata;

reg                     rxsfifo_wen;

reg                     status_crc_error_tog;

reg                     status_fragment_error_tog;

reg                     status_pause_frame_rx_tog;

reg                     status_rxdfifo_ovflow_tog;

// End of automatics

/*AUTOWIRE*/

reg [63:32]   xgmii_rxd_d1;

reg [7:4]     xgmii_rxc_d1;

reg [63:0]    xgxs_rxd_barrel;

reg [7:0]     xgxs_rxc_barrel;

reg [63:0]    xgxs_rxd_barrel_d1;

reg [7:0]     xgxs_rxc_barrel_d1;

reg           barrel_shift;

reg [31:0]    crc32_d64;

reg [31:0]    crc32_d8;

reg [3:0]     crc_bytes;

reg [3:0]     next_crc_bytes;

reg [63:0]    crc_shift_data;

reg           crc_start_8b;

reg           crc_done;

reg           crc_good;

reg           crc_clear;

reg [31:0]    crc_rx;

reg [31:0]    next_crc_rx;

reg [2:0]     curr_state;

reg [2:0]     next_state;

reg [13:0]    curr_byte_cnt;

reg [13:0]    next_byte_cnt;

reg           frame_end_flag;

reg           next_frame_end_flag;

reg [2:0]     frame_end_bytes;

reg [2:0]     next_frame_end_bytes;

reg           fragment_error;

reg           rxd_ovflow_error;

reg           coding_error;

reg           next_coding_error;

reg [7:0]     addmask;

reg [7:0]     datamask;

reg           pause_frame;

reg           next_pause_frame;

reg           pause_frame_hold;

reg           good_pause_frame;

reg           drop_data;

reg           next_drop_data;

reg           pkt_pending;

reg           rxhfifo_ren_d1;

reg           rxhfifo_ralmost_empty_d1;

parameter [2:0]

             SM_IDLE = 3'd0,

             SM_RX = 3'd1;

// count the number of set bits in a nibble

function [2:0] bit_cnt4;

input   [3:0]   bits;

    begin

    case (bits)

    0:  bit_cnt4 = 0;

    1:  bit_cnt4 = 1;

    2:  bit_cnt4 = 1;

    3:  bit_cnt4 = 2;

    4:  bit_cnt4 = 1;

    5:  bit_cnt4 = 2;

    6:  bit_cnt4 = 2;

    7:  bit_cnt4 = 3;

    8:  bit_cnt4 = 1;

    9:  bit_cnt4 = 2;

    10: bit_cnt4 = 2;

    11: bit_cnt4 = 3;

    12: bit_cnt4 = 2;

    13: bit_cnt4 = 3;

    14: bit_cnt4 = 3;

    15: bit_cnt4 = 4;

    endcase

    end

endfunction

function [3:0] bit_cnt8;

input   [7:0]   bits;

    begin

    bit_cnt8 = bit_cnt4(bits[3:0]) + bit_cnt4(bits[7:4]);

    end

endfunction

always @(posedge clk_xgmii_rx or negedge reset_xgmii_rx_n) begin

    if (reset_xgmii_rx_n == 1'b0) begin

        xgmii_rxd_d1 <= 32'b0;

        xgmii_rxc_d1 <= 4'b0;

        xgxs_rxd_barrel <= 64'b0;

        xgxs_rxc_barrel <= 8'b0;

        xgxs_rxd_barrel_d1 <= 64'b0;

        xgxs_rxc_barrel_d1 <= 8'b0;

        barrel_shift <= 1'b0;

        local_fault_msg_det <= 2'b0;

        remote_fault_msg_det <= 2'b0;

        crc32_d64 <= 32'b0;

        crc32_d8 <= 32'b0;

        crc_bytes <= 4'b0;

        crc_shift_data <= 64'b0;

        crc_done <= 1'b0;

        crc_rx <= 32'b0;

        pause_frame_hold <= 1'b0;

        status_crc_error_tog <= 1'b0;

        status_fragment_error_tog <= 1'b0;

        status_rxdfifo_ovflow_tog <= 1'b0;

        status_pause_frame_rx_tog <= 1'b0;

        rxsfifo_wen <= 1'b0;

        rxsfifo_wdata <= 14'b0;

        datamask <= 8'b0;

    end

    else begin

        rxsfifo_wen <= 1'b0;

        rxsfifo_wdata <= curr_byte_cnt + {11'b0, frame_end_bytes};

        //---

        // Link status RC layer

        // Look for local/remote messages on lower 4 lanes and upper

        // 4 lanes. This is a 64-bit interface but look at each 32-bit

        // independantly.

        local_fault_msg_det[1] <= (xgmii_rxd[63:32] ==

                                   {`LOCAL_FAULT, 8'h0, 8'h0, `SEQUENCE} &&

                                   xgmii_rxc[7:4] == 4'b0001);

        local_fault_msg_det[0] <= (xgmii_rxd[31:0] ==

                                   {`LOCAL_FAULT, 8'h0, 8'h0, `SEQUENCE} &&

                                   xgmii_rxc[3:0] == 4'b0001);

        remote_fault_msg_det[1] <= (xgmii_rxd[63:32] ==

                                    {`REMOTE_FAULT, 8'h0, 8'h0, `SEQUENCE} &&

                                    xgmii_rxc[7:4] == 4'b0001);

        remote_fault_msg_det[0] <= (xgmii_rxd[31:0] ==

                                    {`REMOTE_FAULT, 8'h0, 8'h0, `SEQUENCE} &&

                                    xgmii_rxc[3:0] == 4'b0001);

        //---

        // Rotating barrel. This function allow us to always align the start of

        // a frame with LANE0. If frame starts in LANE4, it will be shifted 4 bytes

        // to LANE0, thus reducing the amount of logic needed at the next stage.

        xgmii_rxd_d1[63:32] <= xgmii_rxd[63:32];

        xgmii_rxc_d1[7:4] <= xgmii_rxc[7:4];

        if (xgmii_rxd[`LANE0] == `START && xgmii_rxc[0]) begin

            xgxs_rxd_barrel <= xgmii_rxd;

            xgxs_rxc_barrel <= xgmii_rxc;

            barrel_shift <= 1'b0;

        end

        else if (xgmii_rxd[`LANE4] == `START && xgmii_rxc[4]) begin

            xgxs_rxd_barrel <= {xgmii_rxd[31:0], xgmii_rxd_d1[63:32]};

            xgxs_rxc_barrel <= {xgmii_rxc[3:0], xgmii_rxc_d1[7:4]};

            barrel_shift <= 1'b1;

        end

        else if (barrel_shift) begin

            xgxs_rxd_barrel <= {xgmii_rxd[31:0], xgmii_rxd_d1[63:32]};

            xgxs_rxc_barrel <= {xgmii_rxc[3:0], xgmii_rxc_d1[7:4]};

        end

        else begin

            xgxs_rxd_barrel <= xgmii_rxd;

            xgxs_rxc_barrel <= xgmii_rxc;

        end

        xgxs_rxd_barrel_d1 <= xgxs_rxd_barrel;

        xgxs_rxc_barrel_d1 <= xgxs_rxc_barrel;

        //---

        // Mask for end-of-frame

        datamask[0] <= addmask[0];

        datamask[1] <= &addmask[1:0];

        datamask[2] <= &addmask[2:0];

        datamask[3] <= &addmask[3:0];

        datamask[4] <= &addmask[4:0];

        datamask[5] <= &addmask[5:0];

        datamask[6] <= &addmask[6:0];

        datamask[7] <= &addmask[7:0];

        //---

        // When final CRC calculation begins we capture info relevant to

        // current frame CRC claculation continues while next frame is

        // being received.

        if (crc_start_8b) begin

            pause_frame_hold <= pause_frame;

        end

        //---

        // CRC Checking

        crc_rx <= next_crc_rx;

        if (crc_clear) begin

            // CRC is cleared at the beginning of the frame, calculate

            // 64-bit at a time otherwise

            crc32_d64 <= 32'hffffffff;

        end

        else begin

            crc32_d64 <= nextCRC32_D64(reverse_64b(xgxs_rxd_barrel_d1), crc32_d64);

        end

        if (crc_bytes != 4'b0) begin

            // When reaching the end of the frame we switch from 64-bit mode

            // to 8-bit mode to accomodate odd number of bytes in the frame.

            // crc_bytes indicated the number of remaining payload byte to

            // compute CRC on. Calculate and decrement until it reaches 0.

            if (crc_bytes == 4'b1) begin

                crc_done <= 1'b1;

            end

            crc32_d8 <= nextCRC32_D8(reverse_8b(crc_shift_data[7:0]), crc32_d8);

            crc_shift_data <= {8'h00, crc_shift_data[63:8]};

            crc_bytes <= crc_bytes - 4'b1;

        end

        else if (crc_bytes == 4'b0) begin

            // Per Clause 46. Control code during data must be reported

            // as a CRC error. Indicated here by coding_error. Corrupt CRC

            // if coding error is detected.

            if (coding_error || next_coding_error) begin

                crc32_d8 <= ~crc32_d64;

            end

            else begin

                crc32_d8 <= crc32_d64;

            end

            crc_done <= 1'b0;

            crc_shift_data <= xgxs_rxd_barrel_d1;

            crc_bytes <= next_crc_bytes;

        end

        //---

        // Error detection

        if (crc_done && !crc_good) begin

            status_crc_error_tog <= ~status_crc_error_tog;

        end

        if (fragment_error) begin

            status_fragment_error_tog <= ~status_fragment_error_tog;

        end

        if (rxd_ovflow_error) begin

            status_rxdfifo_ovflow_tog <= ~status_rxdfifo_ovflow_tog;

        end

        //---

        // Frame receive indication

        if (good_pause_frame) begin

            status_pause_frame_rx_tog <= ~status_pause_frame_rx_tog;

        end

        if (frame_end_flag) begin

            rxsfifo_wen <= 1'b1;

        end

    end

end

always @(/*AS*/crc32_d8 or crc_done or crc_rx or pause_frame_hold) begin

    crc_good = 1'b0;

    good_pause_frame = 1'b0;

    if (crc_done) begin

        // Check CRC. If this is a pause frame, report it to cpu.

        if (crc_rx == ~reverse_32b(crc32_d8)) begin

            crc_good = 1'b1;

            good_pause_frame = pause_frame_hold;

        end

    end

end

always @(posedge clk_xgmii_rx or negedge reset_xgmii_rx_n) begin

    if (reset_xgmii_rx_n == 1'b0) begin

        curr_state <= SM_IDLE;

        curr_byte_cnt <= 14'b0;

        frame_end_flag <= 1'b0;

        frame_end_bytes <= 3'b0;

        coding_error <= 1'b0;

        pause_frame <= 1'b0;

    end

    else begin

        curr_state <= next_state;

        curr_byte_cnt <= next_byte_cnt;

        frame_end_flag <= next_frame_end_flag;

        frame_end_bytes <= next_frame_end_bytes;

        coding_error <= next_coding_error;

        pause_frame <= next_pause_frame;

    end

end

always @(/*AS*/coding_error or crc_rx or curr_byte_cnt or curr_state

         or datamask or pause_frame or xgxs_rxc_barrel

         or xgxs_rxc_barrel_d1 or xgxs_rxd_barrel

         or xgxs_rxd_barrel_d1) begin

    next_state = curr_state;

    rxhfifo_wdata = xgxs_rxd_barrel_d1;

    rxhfifo_wstatus = `RXSTATUS_NONE;

    rxhfifo_wen = 1'b0;

    next_crc_bytes = 4'b0;

    next_crc_rx = crc_rx;

    crc_start_8b = 1'b0;

    crc_clear = 1'b0;

    next_byte_cnt = curr_byte_cnt;

    next_frame_end_flag = 1'b0;

    next_frame_end_bytes = 3'b0;

    fragment_error = 1'b0;

    next_coding_error = coding_error;

    next_pause_frame = pause_frame;

    addmask[0] = !(xgxs_rxd_barrel[`LANE0] == `TERMINATE && xgxs_rxc_barrel[0]);

    addmask[1] = !(xgxs_rxd_barrel[`LANE1] == `TERMINATE && xgxs_rxc_barrel[1]);

    addmask[2] = !(xgxs_rxd_barrel[`LANE2] == `TERMINATE && xgxs_rxc_barrel[2]);

    addmask[3] = !(xgxs_rxd_barrel[`LANE3] == `TERMINATE && xgxs_rxc_barrel[3]);

    addmask[4] = !(xgxs_rxd_barrel[`LANE4] == `TERMINATE && xgxs_rxc_barrel[4]);

    addmask[5] = !(xgxs_rxd_barrel[`LANE5] == `TERMINATE && xgxs_rxc_barrel[5]);

    addmask[6] = !(xgxs_rxd_barrel[`LANE6] == `TERMINATE && xgxs_rxc_barrel[6]);

    addmask[7] = !(xgxs_rxd_barrel[`LANE7] == `TERMINATE && xgxs_rxc_barrel[7]);

    case (curr_state)

        SM_IDLE:

          begin

              next_byte_cnt = 14'b0;

              crc_clear = 1'b1;

              next_coding_error = 1'b0;

              next_pause_frame = 1'b0;

              // Detect the start of a frame

              if (xgxs_rxd_barrel_d1[`LANE0] == `START && xgxs_rxc_barrel_d1[0] &&

                  xgxs_rxd_barrel_d1[`LANE1] == `PREAMBLE && !xgxs_rxc_barrel_d1[1] &&

                  xgxs_rxd_barrel_d1[`LANE2] == `PREAMBLE && !xgxs_rxc_barrel_d1[2] &&

                  xgxs_rxd_barrel_d1[`LANE3] == `PREAMBLE && !xgxs_rxc_barrel_d1[3] &&

                  xgxs_rxd_barrel_d1[`LANE4] == `PREAMBLE && !xgxs_rxc_barrel_d1[4] &&

                  xgxs_rxd_barrel_d1[`LANE5] == `PREAMBLE && !xgxs_rxc_barrel_d1[5] &&

                  xgxs_rxd_barrel_d1[`LANE6] == `PREAMBLE && !xgxs_rxc_barrel_d1[6] &&

                  xgxs_rxd_barrel_d1[`LANE7] == `SFD && !xgxs_rxc_barrel_d1[7]) begin

                  next_state = SM_RX;

              end

          end

        SM_RX:

          begin

              // Pause frames are filtered

              rxhfifo_wen = !pause_frame;

              if (xgxs_rxd_barrel_d1[`LANE0] == `START && xgxs_rxc_barrel_d1[0] &&

                  xgxs_rxd_barrel_d1[`LANE7] == `SFD && !xgxs_rxc_barrel_d1[7]) begin

                  // Fragment received, if we are still at SOP stage don't store

                  // the frame. If not, write a fake EOP and flag frame as bad.

                  next_byte_cnt = 14'b0;

                  crc_clear = 1'b1;

                  next_coding_error = 1'b0;

                  fragment_error = 1'b1;

                  rxhfifo_wstatus[`RXSTATUS_ERR] = 1'b1;

                  if (curr_byte_cnt == 14'b0) begin

                      rxhfifo_wen = 1'b0;

                  end

                  else begin

                      rxhfifo_wstatus[`RXSTATUS_EOP] = 1'b1;

                  end

              end

              else if (curr_byte_cnt > 14'd9900) begin

                  // Frame too long, TERMMINATE must have been corrupted.

                  // Abort transfer, write a fake EOP, report as fragment.

                  fragment_error = 1'b1;

                  rxhfifo_wstatus[`RXSTATUS_ERR] = 1'b1;

                  rxhfifo_wstatus[`RXSTATUS_EOP] = 1'b1;

                  next_state = SM_IDLE;

              end

              else begin

                  // Pause frame receive, these frame will be filtered

                  if (curr_byte_cnt == 14'd0 &&

                      xgxs_rxd_barrel_d1[47:0] == `PAUSE_FRAME) begin

                      rxhfifo_wen = 1'b0;

                      next_pause_frame = 1'b1;

                  end

                  // Control character during data phase, force CRC error

                  if (|(xgxs_rxc_barrel_d1 & datamask)) begin

                      next_coding_error = 1'b1;

                  end

                  // Write SOP to status bits during first byte

                  if (curr_byte_cnt == 14'b0) begin

                      rxhfifo_wstatus[`RXSTATUS_SOP] = 1'b1;

                  end

                  /* verilator lint_off WIDTH */

                  //next_byte_cnt = curr_byte_cnt +

                  //                addmask[0] + addmask[1] + addmask[2] + addmask[3] +

                  //                addmask[4] + addmask[5] + addmask[6] + addmask[7];

                  /* verilator lint_on WIDTH */

                  // don't infer a chain of adders

                  next_byte_cnt = curr_byte_cnt + {10'b0, bit_cnt8(datamask[7:0])};

                  // We will not write to the fifo if all is left

                  // are four or less bytes of crc. We also strip off the

                  // crc, which requires looking one cycle ahead

                  // wstatus:

                  //   [2:0] modulus of packet length

                  // Look one cycle ahead for TERMINATE in lanes 0 to 4

                  if (xgxs_rxd_barrel[`LANE4] == `TERMINATE && xgxs_rxc_barrel[4]) begin

                      rxhfifo_wstatus[`RXSTATUS_EOP] = 1'b1;

                      rxhfifo_wstatus[2:0] = 3'd0;

                      crc_start_8b = 1'b1;

                      next_crc_bytes = 4'd8;

                      next_crc_rx = xgxs_rxd_barrel[31:0];

                      next_frame_end_flag = 1'b1;

                      next_frame_end_bytes = 3'd4;

                      next_state = SM_IDLE;

                  end

                  if (xgxs_rxd_barrel[`LANE3] == `TERMINATE && xgxs_rxc_barrel[3]) begin

                      rxhfifo_wstatus[`RXSTATUS_EOP] = 1'b1;

                      rxhfifo_wstatus[2:0] = 3'd7;

                      crc_start_8b = 1'b1;

                      next_crc_bytes = 4'd7;

                      next_crc_rx = {xgxs_rxd_barrel[23:0], xgxs_rxd_barrel_d1[63:56]};

                      next_frame_end_flag = 1'b1;

                      next_frame_end_bytes = 3'd3;

                      next_state = SM_IDLE;

                  end