Imported Upstream version 3.2.2

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

diff --git a/gr-sounder/src/fpga/lib/sounder_rx.v b/gr-sounder/src/fpga/lib/sounder_rx.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 sounder_rx(clk_i,rst_i,ena_i,sum_strobe_i,ref_strobe_i,
+                 mask_i,degree_i,rx_in_i_i,rx_in_q_i,rx_i_o,rx_q_o);
+   
+   input         clk_i;                // Master clock
+   input         rst_i;         // Subsystem reset
+   input         ena_i;                // Subsystem enable
+   input         sum_strobe_i;  // Strobe on last sample per period
+   input         ref_strobe_i;  // PN code reference retarded one sample per period
+    
+   input  [15:0] mask_i;       // PN code LFSR mask
+   input  [4:0]  degree_i;     // PN code LFSR sequency degree
+   
+   input  [15:0] rx_in_i_i;    // I channel on receive
+   input  [15:0] rx_in_q_i;    // Q channel on receive
+
+   output [15:0] rx_i_o;       // I channel of impulse response
+   output [15:0] rx_q_o;       // Q channel of impulse response
+
+   reg  [31:0] sum_i, sum_q;
+   reg  [31:0] total_i, total_q;
+   wire [31:0] i_ext, q_ext;
+
+   sign_extend #(16,32) i_extender(rx_in_i_i, i_ext);
+   sign_extend #(16,32) q_extender(rx_in_q_i, q_ext);
+
+   wire pn_ref;
+   lfsr ref_code
+     ( .clk_i(clk_i),.rst_i(rst_i),.ena_i(ena_i),.strobe_i(ref_strobe_i),.mask_i(mask_i),.pn_o(pn_ref) );
+
+   wire [31:0] prod_i = pn_ref ? i_ext : -i_ext;
+   wire [31:0] prod_q = pn_ref ? q_ext : -q_ext;
+
+   always @(posedge clk_i)
+     if (rst_i | ~ena_i)
+       begin
+         sum_i <= #5 0;
+         sum_q <= #5 0;
+         total_i <= #5 0;
+         total_q <= #5 0;
+       end
+     else
+       if (sum_strobe_i)
+        begin
+           total_i <= #5 sum_i;
+           total_q <= #5 sum_q;
+           sum_i <= #5 prod_i;
+           sum_q <= #5 prod_q;
+        end
+       else
+        begin
+           sum_i <= #5 sum_i + prod_i;
+           sum_q <= #5 sum_q + prod_q;
+        end
+
+   wire [5:0]  offset = (5'd16-degree_i);
+   wire [31:0] scaled_i = total_i << offset;
+   wire [31:0] scaled_q = total_q << offset;
+   assign rx_i_o = scaled_i[31:16];
+   assign rx_q_o = scaled_q[31:16];
+   
+endmodule // sounder_rx
+