////////////////////////////////////////////////////////////////////////////////
//
// 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
// 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;
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
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 <= i_hwmac;
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
