Subversion Repositories openarty

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

//

// Filename:    rxehwmac.v

//

// Project:     OpenArty, an entirely open SoC based upon the Arty platform

//

// Purpose:     To remove MACs that aren't our own.  The input is a nibble

//              stream, where the first nibble is the first nibble of the

//      destination MAC (our MAC).  If enabled, this MAC is removed from the

//      stream.  If the MAC matches, the stream is allowed to continue.  If

//      the MAC doesn't match, the packet is thrown away.

//

// Creator:     Dan Gisselquist, Ph.D.

//              Gisselquist Technology, LLC

//

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

//

// Copyright (C) 2016, Gisselquist Technology, LLC

//

// This program is free software (firmware): you can redistribute it and/or

// modify it under the terms of  the GNU General Public License as published

// by the Free Software Foundation, either version 3 of the License, or (at

// your option) any later version.

//

// This program is distributed in the hope that it will be useful, but WITHOUT

// ANY WARRANTY; without even the implied warranty of MERCHANTIBILITY or

// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

// for more details.

//

// You should have received a copy of the GNU General Public License along

// with this program.  (It's in the $(ROOT)/doc directory, run make with no

// target there if the PDF file isn't present.)  If not, see

// <http://www.gnu.org/licenses/> for a copy.

//

// License:     GPL, v3, as defined and found on www.gnu.org,

//              http://www.gnu.org/licenses/gpl.html

//

//

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

//

//

module  rxehwmac(i_clk, i_ce, i_en, i_cancel, i_hwmac, i_v, i_d, o_v, o_d, o_err, o_broadcast);

        input                   i_clk, i_ce, i_en, i_cancel;

        input           [47:0]   i_hwmac;

        input                   i_v;

        input           [3:0]    i_d;

        output  reg             o_v;

        output  reg     [3:0]    o_d;

        output  wire            o_err;

        output  reg             o_broadcast;

        wire    [47:0]   mac_remapped;

        assign  mac_remapped[47:44] = i_hwmac[43:40];

        assign  mac_remapped[43:40] = i_hwmac[47:44];

        assign  mac_remapped[39:36] = i_hwmac[35:32];

        assign  mac_remapped[35:32] = i_hwmac[39:36];

        assign  mac_remapped[31:28] = i_hwmac[27:24];

        assign  mac_remapped[27:24] = i_hwmac[31:28];

        assign  mac_remapped[23:20] = i_hwmac[19:16];

        assign  mac_remapped[19:16] = i_hwmac[23:20];

        assign  mac_remapped[15:12] = i_hwmac[11: 8];

        assign  mac_remapped[11: 8] = i_hwmac[15:12];

        assign  mac_remapped[ 7: 4] = i_hwmac[ 3: 0];

        assign  mac_remapped[ 3: 0] = i_hwmac[ 7: 4];

        reg     [47:0]   r_hwmac;

        reg             r_cancel, r_err, r_hwmatch, r_broadcast;

        reg     [19:0]   r_buf;

        reg     [29:0]   r_p;

        always @(posedge i_clk)

        if (i_ce)

        begin

                if (i_cancel)

                        r_cancel <= 1'b1;

                else if ((!i_v)&&(!o_v))

                        r_cancel <= 1'b0;

                if ((i_en)&&(i_v)&&(r_p[11]))

                begin

                        if (r_hwmac[47:44] != i_d)

                                r_hwmatch <= 1'b0;

                        if (4'hf != i_d)

                                r_broadcast<= 1'b0;

                end

                if ((i_v)&&(r_p[11]))

                        r_hwmac <= { r_hwmac[43:0], 4'h0 };

                r_err <= (i_en)&&(!r_hwmatch)&&(!r_broadcast)&&(i_v);

                o_broadcast <= (r_broadcast)&&(!r_p[11])&&(i_v);

                r_buf <= { r_buf[14:0], i_v, i_d };

                if (((!i_v)&&(!o_v))||(i_cancel))

                begin

                        r_p <= 30'h3fff_ffff;

                        r_hwmac <= mac_remapped;

                        r_hwmatch   <= 1'b1;

                        r_broadcast <= 1'b1;

                        r_buf[ 4] <= 1'b0;

                        r_buf[ 9] <= 1'b0;

                        r_buf[14] <= 1'b0;

                        r_buf[19] <= 1'b0;

                        o_v <= 1'b0;

                        o_d <= i_d;

                end else begin

                        r_p <= { r_p[28:0], 1'b0 };

                        if (i_en)

                        begin

                                // Skip the first 6 bytes, and everything

                                // following if the MAC doesn't match

                                o_v <= (!r_p[11])&&(!r_cancel)&&(i_v);

                                o_d <= i_d;

                        end else begin

                                // In this case, we wish to ignore everything,

                                // but still duplicate the EtherType words

                                if (r_p[27])

                                        { o_v, o_d } <= { (i_v)&&(!r_cancel), i_d };

                                else

                                        { o_v, o_d } <= { (r_buf[19])&&(!r_cancel), r_buf[18:15] };

                        end

                end

                if ((!i_en)&&(r_p[27]))

                begin // Clear out the top half of the EtherType word

                        r_buf[18:15] <= 4'h0;

                        r_buf[13:10] <= 4'h0;

                end

        end

        assign  o_err = r_err;

endmodule