From e0fcbaee124d3e8c4c11bdda662f88e082352058 Mon Sep 17 00:00:00 2001
From: jcorgan
Date: Mon, 8 Sep 2008 01:00:12 +0000
Subject: Merged r9433:9527 from features/gr-usrp2 into trunk.  Adds usrp2 and
 gr-usrp2 top-level components.  Trunk passes distcheck with mb-gcc installed,
 but currently not without them.  The key issue is that when mb-gcc is not
 installed, the build system skips over the usrp2/firmware directory, and the
 firmware include files don't get put into the dist tarball.  But we can't do
 the usual DIST_SUBDIRS method as the firmware is a subpackage.

git-svn-id: http://gnuradio.org/svn/gnuradio/trunk@9528 221aa14e-8319-0410-a670-987f0aec2ac5
---
 usrp2/fpga/sdr_lib/cic_interp.v | 87 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 87 insertions(+)
 create mode 100755 usrp2/fpga/sdr_lib/cic_interp.v

(limited to 'usrp2/fpga/sdr_lib/cic_interp.v')

diff --git a/usrp2/fpga/sdr_lib/cic_interp.v b/usrp2/fpga/sdr_lib/cic_interp.v
new file mode 100755
index 000000000..9b6928aa1
--- /dev/null
+++ b/usrp2/fpga/sdr_lib/cic_interp.v
@@ -0,0 +1,87 @@
+// -*- verilog -*-
+//
+//  USRP - Universal Software Radio Peripheral
+//
+//  Copyright (C) 2003 Matt Ettus
+//
+//  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 cic_interp
+  #(parameter bw = 16, parameter N = 4, parameter log2_of_max_rate = 7)
+    (input clock,
+     input reset,
+     input enable,
+     input [7:0] rate,
+     input strobe_in,
+     input strobe_out,
+     input [bw-1:0] signal_in,
+     output reg [bw-1:0] signal_out);
+   
+   integer 	     i;
+   localparam 	     maxbitgain = (N-1)*log2_of_max_rate;
+
+   wire [bw+maxbitgain-1:0] signal_in_ext;
+   reg [bw+maxbitgain-1:0]  integrator [0:N-1];
+   reg [bw+maxbitgain-1:0]  differentiator [0:N-1];
+   reg [bw+maxbitgain-1:0]  pipeline [0:N-1];
+   
+   sign_extend #(bw,bw+maxbitgain) 
+     ext_input (.in(signal_in),.out(signal_in_ext));
+   
+   //FIXME Note that this section has pipe and diff reversed
+   // It still works, but is confusing
+   always @(posedge clock)
+     if(reset | ~enable)
+       for(i=0;i<N;i=i+1)
+	 integrator[i] <= 0;
+     else if (enable & strobe_out)
+       begin
+	  if(strobe_in)
+	    integrator[0] <= integrator[0] + pipeline[N-1];
+	  for(i=1;i<N;i=i+1)
+	    integrator[i] <= integrator[i] + integrator[i-1];
+       end
+   
+   always @(posedge clock)
+     if(reset | ~enable)
+       begin
+	  for(i=0;i<N;i=i+1)
+	    begin
+	       differentiator[i] <= 0;
+	       pipeline[i] <= 0;
+ 	    end
+       end
+     else if (enable && strobe_in)
+       begin
+	  differentiator[0] <= signal_in_ext;
+	  pipeline[0] <= signal_in_ext - differentiator[0];
+	  for(i=1;i<N;i=i+1)
+	    begin
+	       differentiator[i] <= pipeline[i-1];
+	       pipeline[i] <= pipeline[i-1] - differentiator[i];
+	    end
+       end
+
+   wire [bw-1:0] signal_out_unreg;
+   cic_int_shifter #(bw)
+     cic_int_shifter(rate,integrator[N-1],signal_out_unreg);
+   
+   always @(posedge clock)
+     signal_out <= signal_out_unreg;
+   
+endmodule // cic_interp
+
-- 
cgit