Merge commit 'v3.3.0' into upstream

[debian/gnuradio] / gr-sounder / src / fpga / lib / lfsr.v

diff --git a/gr-sounder/src/fpga/lib/lfsr.v b/gr-sounder/src/fpga/lib/lfsr.v
new file mode 100644 (file)
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+++ b/gr-sounder/src/fpga/lib/lfsr.v
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+// -*- verilog -*-
+//
+//  USRP - Universal Software Radio Peripheral
+//
+//  Copyright (C) 2007 Corgan Enterprises LLC
+//
+//  This program is free software; 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 2 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
+//  MERCHANTABILITY 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; if not, write to the Free Software
+//  Foundation, Inc., 51 Franklin Street, Boston, MA  02110-1301  USA
+//
+
+module lfsr(clk_i,rst_i,ena_i,strobe_i,mask_i,pn_o);
+   parameter width = 16;
+
+   input clk_i;
+   input rst_i;
+   input ena_i;
+   input strobe_i;
+   input [width-1:0] mask_i;
+   
+   output pn_o;
+
+   reg  [width-1:0] shifter;
+
+   wire parity = ^(shifter & mask_i);
+   
+   always @(posedge clk_i)
+     if (rst_i | ~ena_i)
+       shifter <= #5 1;
+     else
+       if (strobe_i)
+        shifter <= #5 {shifter[width-2:0],parity};
+
+   assign pn_o = shifter[0];
+   
+endmodule // lfsr