Moved usrp2 fpga files into usrp2 subdir.

15 files changed, 892 insertions, 0 deletions

diff --git a/usrp2/sdr_lib/hb/acc.v b/usrp2/sdr_lib/hb/acc.v
new file mode 100644
index 000000000..195d5ea94
--- /dev/null
+++ b/usrp2/sdr_lib/hb/acc.v
@@ -0,0 +1,22 @@
+
+
+module acc (input clock, input reset, input clear, input enable_in, output reg enable_out,
+	    input signed [30:0] addend, output reg signed [33:0] sum );
+
+   always @(posedge clock)
+     if(reset)
+       sum <= #1 34'd0;
+     //else if(clear & enable_in)
+     //  sum <= #1 addend;
+     //else if(clear)
+     //  sum <= #1 34'd0;
+     else if(clear)
+       sum <= #1 addend;
+     else if(enable_in)
+       sum <= #1 sum + addend;
+
+   always @(posedge clock)
+     enable_out <= #1 enable_in;
+   
+endmodule // acc
+
diff --git a/usrp2/sdr_lib/hb/coeff_ram.v b/usrp2/sdr_lib/hb/coeff_ram.v
new file mode 100644
index 000000000..65460822f
--- /dev/null
+++ b/usrp2/sdr_lib/hb/coeff_ram.v
@@ -0,0 +1,26 @@
+
+
+module coeff_ram (input clock, input [3:0] rd_addr, output reg [15:0] rd_data);
+
+   always @(posedge clock)
+     case (rd_addr)
+       4'd0 : rd_data <= #1 -16'd16;
+       4'd1 : rd_data <= #1 16'd74;
+       4'd2 : rd_data <= #1 -16'd254;
+       4'd3 : rd_data <= #1 16'd669;
+       4'd4 : rd_data <= #1 -16'd1468;
+       4'd5 : rd_data <= #1 16'd2950;
+       4'd6 : rd_data <= #1 -16'd6158;
+       4'd7 : rd_data <= #1 16'd20585;
+       4'd8 : rd_data <= #1 16'd20585;
+       4'd9 : rd_data <= #1 -16'd6158;
+       4'd10 : rd_data <= #1 16'd2950;
+       4'd11 : rd_data <= #1 -16'd1468;
+       4'd12 : rd_data <= #1 16'd669;
+       4'd13 : rd_data <= #1 -16'd254;
+       4'd14 : rd_data <= #1 16'd74;
+       4'd15 : rd_data <= #1 -16'd16;
+       default : rd_data <= #1 16'd0;
+     endcase // case(rd_addr)
+   
+endmodule // ram
diff --git a/usrp2/sdr_lib/hb/coeff_rom.v b/usrp2/sdr_lib/hb/coeff_rom.v
new file mode 100644
index 000000000..7f8886b4e
--- /dev/null
+++ b/usrp2/sdr_lib/hb/coeff_rom.v
@@ -0,0 +1,19 @@
+
+
+module coeff_rom (input clock, input [2:0] addr, output reg [15:0] data);
+
+   always @(posedge clock)
+     case (addr)
+       3'd0 : data <= #1 -16'd49;
+       3'd1 : data <= #1 16'd165;
+       3'd2 : data <= #1 -16'd412;
+       3'd3 : data <= #1 16'd873;
+       3'd4 : data <= #1 -16'd1681;
+       3'd5 : data <= #1 16'd3135;
+       3'd6 : data <= #1 -16'd6282;
+       3'd7 : data <= #1 16'd20628;
+     endcase // case(addr)
+      
+endmodule // coeff_rom
+
+
diff --git a/usrp2/sdr_lib/hb/halfband_decim.v b/usrp2/sdr_lib/hb/halfband_decim.v
new file mode 100644
index 000000000..dff4d902c
--- /dev/null
+++ b/usrp2/sdr_lib/hb/halfband_decim.v
@@ -0,0 +1,163 @@
+/* -*- verilog -*-
+ * 
+ *  USRP - Universal Software Radio Peripheral
+ * 
+ *  Copyright (C) 2005 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
+ */
+
+/*
+ * This implements a 31-tap halfband filter that decimates by two.
+ * The coefficients are symmetric, and with the exception of the middle tap,
+ * every other coefficient is zero.  The middle section of taps looks like this:
+ *
+ *  ..., -1468, 0, 2950, 0, -6158, 0, 20585, 32768, 20585, 0, -6158, 0, 2950, 0, -1468, ...
+ *                                             |
+ *                           middle tap -------+
+ *
+ * See coeff_rom.v for the full set.  The taps are scaled relative to 32768,
+ * thus the middle tap equals 1.0.  Not counting the middle tap, there are 8
+ * non-zero taps on each side, and they are symmetric.  A naive implementation
+ * requires a mulitply for each non-zero tap.  Because of symmetry, we can
+ * replace 2 multiplies with 1 add and 1 multiply.  Thus, to compute each output
+ * sample, we need to perform 8 multiplications.  Since the middle tap is 1.0,
+ * we just add the corresponding delay line value.
+ *
+ * About timing: We implement this with a single multiplier, so it takes
+ * 8 cycles to compute a single output.  However, since we're decimating by two 
+ * we can accept a new input value every 4 cycles.  strobe_in is asserted when
+ * there's a new input sample available.  Depending on the overall decimation
+ * rate, strobe_in may be asserted less frequently than once every 4 clocks.
+ * On the output side, we assert strobe_out when output contains a new sample.
+ *
+ * Implementation: Every time strobe_in is asserted we store the new data into
+ * the delay line.  We split the delay line into two components, one for the
+ * even samples, and one for the odd samples.  ram16_odd is the delay line for
+ * the odd samples.  This ram is written on each odd assertion of strobe_in, and
+ * is read on each clock when we're computing the dot product.  ram16_even is
+ * similar, although because it holds the even samples we must be able to read
+ * two samples from different addresses at the same time, while writing the incoming
+ * even samples. Thus it's "triple-ported".
+ */
+
+module halfband_decim
+  (input clock, input reset, input enable, input strobe_in, output wire strobe_out,
+   input wire [15:0] data_in, output reg [15:0] data_out,output wire [15:0] debugctrl);
+
+   reg [3:0] rd_addr1;
+   reg [3:0] rd_addr2;
+   reg [3:0] phase;
+   reg [3:0] base_addr;
+
+   wire      signed [15:0] mac_out,middle_data, sum, coeff;
+   wire      signed [30:0] product;
+   wire      signed [33:0] sum_even;
+   wire      clear;
+   reg 	     store_odd;
+   
+   always @(posedge clock)
+     if(reset)
+       store_odd <= #1 1'b0;
+     else
+       if(strobe_in)
+	 store_odd <= #1 ~store_odd;
+
+   wire      start = strobe_in & store_odd;
+   always @(posedge clock)
+     if(reset)
+       base_addr <= #1 4'd0;
+     else if(start)
+       base_addr <= #1 base_addr + 4'd1;
+
+   always @(posedge clock)
+     if(reset)
+       phase <= #1 4'd8;
+     else if (start)
+       phase <= #1 4'd0;
+     else if(phase != 4'd8)
+       phase <= #1 phase + 4'd1;
+
+   reg 	     start_d1,start_d2,start_d3,start_d4,start_d5,start_d6,start_d7,start_d8,start_d9,start_dA,start_dB,start_dC,start_dD;
+   always @(posedge clock)
+     begin
+	start_d1 <= #1 start;
+	start_d2 <= #1 start_d1;
+	start_d3 <= #1 start_d2;
+	start_d4 <= #1 start_d3;
+	start_d5 <= #1 start_d4;
+	start_d6 <= #1 start_d5;
+	start_d7 <= #1 start_d6;
+	start_d8 <= #1 start_d7;
+	start_d9 <= #1 start_d8;
+	start_dA <= #1 start_d9;
+	start_dB <= #1 start_dA;
+	start_dC <= #1 start_dB;
+	start_dD <= #1 start_dC;
+     end // always @ (posedge clock)
+   
+   reg 	  mult_en, mult_en_pre;
+   always @(posedge clock)
+     begin
+	mult_en_pre <= #1 phase!=8;
+	mult_en <= #1 mult_en_pre;
+     end
+   
+   assign clear = start_d4; // was dC
+   wire   latch_result = start_d4; // was dC
+   assign strobe_out = start_d5; // was dD
+   wire   acc_en;
+   
+   always @*
+     case(phase[2:0])
+       3'd0 : begin rd_addr1 = base_addr + 4'd0; rd_addr2 = base_addr + 4'd15; end
+       3'd1 : begin rd_addr1 = base_addr + 4'd1; rd_addr2 = base_addr + 4'd14; end
+       3'd2 : begin rd_addr1 = base_addr + 4'd2; rd_addr2 = base_addr + 4'd13; end
+       3'd3 : begin rd_addr1 = base_addr + 4'd3; rd_addr2 = base_addr + 4'd12; end
+       3'd4 : begin rd_addr1 = base_addr + 4'd4; rd_addr2 = base_addr + 4'd11; end
+       3'd5 : begin rd_addr1 = base_addr + 4'd5; rd_addr2 = base_addr + 4'd10; end
+       3'd6 : begin rd_addr1 = base_addr + 4'd6; rd_addr2 = base_addr + 4'd9; end
+       3'd7 : begin rd_addr1 = base_addr + 4'd7; rd_addr2 = base_addr + 4'd8; end
+       default: begin rd_addr1 = base_addr + 4'd0; rd_addr2 = base_addr + 4'd15; end
+     endcase // case(phase)
+   
+   coeff_rom coeff_rom (.clock(clock),.addr(phase[2:0]-3'd1),.data(coeff));
+   
+   ram16_2sum ram16_even (.clock(clock),.write(strobe_in & ~store_odd),
+			  .wr_addr(base_addr),.wr_data(data_in),
+			  .rd_addr1(rd_addr1),.rd_addr2(rd_addr2),
+			  .sum(sum));
+
+   ram16 ram16_odd (.clock(clock),.write(strobe_in & store_odd),  // Holds middle items
+		    .wr_addr(base_addr),.wr_data(data_in),
+		    //.rd_addr(base_addr+4'd7),.rd_data(middle_data));
+		    .rd_addr(base_addr+4'd6),.rd_data(middle_data));
+
+   mult mult(.clock(clock),.x(coeff),.y(sum),.product(product),.enable_in(mult_en),.enable_out(acc_en));
+
+   acc acc(.clock(clock),.reset(reset),.enable_in(acc_en),.enable_out(),
+	   .clear(clear),.addend(product),.sum(sum_even));
+
+   wire signed [33:0] dout = sum_even + {{4{middle_data[15]}},middle_data,14'b0}; // We already divided product by 2!!!!
+
+   always @(posedge clock)
+     if(reset)
+       data_out <= #1 16'd0;
+     else if(latch_result)
+       data_out <= #1 dout[30:15] + (dout[33]& |dout[14:0]);
+
+   assign  debugctrl = { clock,reset,acc_en,mult_en,clear,latch_result,store_odd,strobe_in,strobe_out,phase};
+   
+endmodule // halfband_decim
diff --git a/usrp2/sdr_lib/hb/halfband_interp.v b/usrp2/sdr_lib/hb/halfband_interp.v
new file mode 100644
index 000000000..cdb11c1f6
--- /dev/null
+++ b/usrp2/sdr_lib/hb/halfband_interp.v
@@ -0,0 +1,121 @@
+
+
+module halfband_interp 
+  (input clock, input reset, input enable,
+   input strobe_in, input strobe_out,
+   input [15:0] signal_in_i, input [15:0] signal_in_q, 
+   output reg [15:0] signal_out_i, output reg [15:0] signal_out_q,
+   output wire [12:0] debug);
+   
+   wire [15:0] 	coeff_ram_out;
+   wire [15:0] 	data_ram_out_i;
+   wire [15:0] 	data_ram_out_q;
+
+   wire [3:0] 	data_rd_addr;
+   reg [3:0] 	data_wr_addr;
+   reg [2:0] 	coeff_rd_addr;
+
+   wire 		filt_done;
+   
+   wire [15:0] 	mac_out_i;
+   wire [15:0] 	mac_out_q;
+   reg [15:0] 	delayed_middle_i, delayed_middle_q;
+   wire [7:0] 	shift = 8'd9;
+
+   reg 		stb_out_happened;
+
+   wire [15:0] 	data_ram_out_i_b;
+   
+   always @(posedge clock)
+     if(strobe_in)
+       stb_out_happened <= #1 1'b0;
+     else if(strobe_out)
+       stb_out_happened <= #1 1'b1;
+   
+assign debug = {filt_done,data_rd_addr,data_wr_addr,coeff_rd_addr};
+
+   wire [15:0] 	signal_out_i = stb_out_happened ? mac_out_i : delayed_middle_i;
+   wire [15:0] 	signal_out_q = stb_out_happened ? mac_out_q : delayed_middle_q;
+
+/*   always @(posedge clock)
+     if(reset)
+       begin
+	  signal_out_i <= #1 16'd0;
+	  signal_out_q <= #1 16'd0;
+       end
+     else if(strobe_in)
+       begin
+	  signal_out_i <= #1 delayed_middle_i; // Multiply by 1 for middle coeff
+	  signal_out_q <= #1 delayed_middle_q;
+       end
+     //else if(filt_done&stb_out_happened)
+     else if(stb_out_happened)
+       begin
+	  signal_out_i <= #1 mac_out_i;
+	  signal_out_q <= #1 mac_out_q;
+       end
+*/
+   
+   always @(posedge clock)
+     if(reset)
+       coeff_rd_addr <= #1 3'd0;
+     else if(coeff_rd_addr != 3'd0)
+       coeff_rd_addr <= #1 coeff_rd_addr + 3'd1;
+     else if(strobe_in)
+       coeff_rd_addr <= #1 3'd1;
+
+   reg filt_done_d1;
+   always@(posedge clock)
+     filt_done_d1 <= #1 filt_done;
+   
+   always @(posedge clock)
+     if(reset)
+       data_wr_addr <= #1 4'd0;
+   //else if(strobe_in)
+     else if(filt_done & ~filt_done_d1)
+       data_wr_addr <= #1 data_wr_addr + 4'd1;
+
+   always @(posedge clock)
+     if(coeff_rd_addr == 3'd7)
+       begin
+	  delayed_middle_i <= #1 data_ram_out_i_b;
+	//  delayed_middle_q <= #1 data_ram_out_q_b;
+       end
+   
+//   always @(posedge clock)
+//     if(reset)
+//       data_rd_addr <= #1 4'd0;
+//     else if(strobe_in)
+//       data_rd_addr <= #1 data_wr_addr + 4'd1;
+//     else if(!filt_done)
+//       data_rd_addr <= #1 data_rd_addr + 4'd1;
+//     else
+//       data_rd_addr <= #1 data_wr_addr;
+  
+   wire [3:0] data_rd_addr1 = data_wr_addr + {1'b0,coeff_rd_addr};
+   wire [3:0] data_rd_addr2 = data_wr_addr + 15 - {1'b0,coeff_rd_addr};
+//   always @(posedge clock)
+//     if(reset)
+//       filt_done <= #1 1'b1;
+//     else if(strobe_in)
+ //      filt_done <= #1 1'b0;
+//     else if(coeff_rd_addr == 4'd0)
+//       filt_done <= #1 1'b1;
+
+   assign filt_done = (coeff_rd_addr == 3'd0);
+   
+   coeff_ram coeff_ram ( .clock(clock),.rd_addr({1'b0,coeff_rd_addr}),.rd_data(coeff_ram_out) );
+   
+   ram16_2sum data_ram_i ( .clock(clock),.write(strobe_in),.wr_addr(data_wr_addr),.wr_data(signal_in_i),
+		      .rd_addr1(data_rd_addr1),.rd_addr2(data_rd_addr2),.rd_data(data_ram_out_i_b),.sum(data_ram_out_i));
+   
+   ram16_2sum data_ram_q ( .clock(clock),.write(strobe_in),.wr_addr(data_wr_addr),.wr_data(signal_in_q),
+		      .rd_addr1(data_rd_addr1),.rd_addr2(data_rd_addr2),.rd_data(data_ram_out_q));
+   
+   mac mac_i (.clock(clock),.reset(reset),.enable(~filt_done),.clear(strobe_in),
+	      .x(data_ram_out_i),.y(coeff_ram_out),.shift(shift),.z(mac_out_i) );
+   
+   mac mac_q (.clock(clock),.reset(reset),.enable(~filt_done),.clear(strobe_in),
+	      .x(data_ram_out_q),.y(coeff_ram_out),.shift(shift),.z(mac_out_q) );
+
+endmodule // halfband_interp
diff --git a/usrp2/sdr_lib/hb/hbd_tb/HBD b/usrp2/sdr_lib/hb/hbd_tb/HBD
new file mode 100644
index 000000000..574fbba91
--- /dev/null
+++ b/usrp2/sdr_lib/hb/hbd_tb/HBD
@@ -0,0 +1,80 @@
+*-6.432683 5736 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
+@28
+test_hbd.clock
+test_hbd.reset
+@420
+test_hbd.halfband_decim.middle_data[15:0]
+@22
+test_hbd.halfband_decim.sum_even[33:0]
+test_hbd.halfband_decim.base_addr[3:0]
+@420
+test_hbd.i_in[15:0]
+@24
+test_hbd.halfband_decim.phase[3:0]
+test_hbd.halfband_decim.ram16_even.rd_addr1[3:0]
+test_hbd.halfband_decim.ram16_even.rd_addr2[3:0]
+test_hbd.halfband_decim.ram16_even.wr_addr[3:0]
+test_hbd.halfband_decim.ram16_even.wr_data[15:0]
+@28
+test_hbd.halfband_decim.ram16_even.write
+@420
+test_hbd.halfband_decim.sum[15:0]
+test_hbd.halfband_decim.product[30:0]
+test_hbd.halfband_decim.dout[33:0]
+test_hbd.halfband_decim.sum_even[33:0]
+@22
+test_hbd.halfband_decim.acc.addend[30:0]
+@28
+test_hbd.halfband_decim.acc.reset
+@420
+test_hbd.halfband_decim.acc.sum[33:0]
+test_hbd.halfband_decim.mult.x[15:0]
+test_hbd.halfband_decim.mult.y[15:0]
+@28
+test_hbd.halfband_decim.acc.clear
+test_hbd.strobe_in
+test_hbd.strobe_out
+test_hbd.halfband_decim.acc_en
+@420
+test_hbd.i_out[15:0]
+@28
+test_hbd.halfband_decim.mult_en
+test_hbd.halfband_decim.latch_result
+@420
+test_hbd.halfband_decim.sum[15:0]
+test_hbd.halfband_decim.sum_even[33:0]
+test_hbd.halfband_decim.dout[33:0]
+test_hbd.halfband_decim.data_out[15:0]
+@22
+test_hbd.halfband_decim.data_out[15:0]
+@28
+test_hbd.halfband_decim.dout[33:0]
+@29
+test_hbd.halfband_decim.acc_en
+@22
+test_hbd.halfband_decim.base_addr[3:0]
+@28
+test_hbd.halfband_decim.clear
+test_hbd.halfband_decim.latch_result
+test_hbd.halfband_decim.mult_en
+test_hbd.halfband_decim.mult_en_pre
+@22
+test_hbd.halfband_decim.phase[3:0]
+@28
+test_hbd.halfband_decim.start
+test_hbd.halfband_decim.start_d1
+test_hbd.halfband_decim.start_d2
+test_hbd.halfband_decim.start_d3
+test_hbd.halfband_decim.start_d4
+test_hbd.halfband_decim.start_d5
+test_hbd.halfband_decim.start_d6
+test_hbd.halfband_decim.start_d7
+test_hbd.halfband_decim.start_d8
+test_hbd.halfband_decim.start_d9
+test_hbd.halfband_decim.start_dA
+test_hbd.halfband_decim.start_dB
+test_hbd.halfband_decim.start_dC
+test_hbd.halfband_decim.start_dD
+test_hbd.halfband_decim.store_odd
+test_hbd.halfband_decim.strobe_in
+test_hbd.halfband_decim.strobe_out
diff --git a/usrp2/sdr_lib/hb/hbd_tb/really_golden b/usrp2/sdr_lib/hb/hbd_tb/really_golden
new file mode 100644
index 000000000..2d24a9e14
--- /dev/null
+++ b/usrp2/sdr_lib/hb/hbd_tb/really_golden
@@ -0,0 +1,142 @@
+VCD info: dumpfile test_hbd.vcd opened for output.
+    x
+    x
+    x
+    x
+    x
+    x
+    x
+    x
+    x
+    x
+    x
+    x
+    x
+    x
+    x
+    x
+    0
+    0
+    0
+    0
+    0
+    0
+    0
+    0
+    0
+    0
+    0
+ 8192
+    0
+    0
+    0
+    0
+    0
+    0
+    0
+    0
+    0
+    0
+    0
+    0
+    0
+-     4
+   18
+-    63
+  167
+-   367
+  737
+-  1539
+ 5146
+ 5146
+-  1539
+  737
+-   367
+  167
+-    63
+   18
+-     4
+    0
+    0
+    0
+    0
+    0
+-     4
+   14
+-    49
+  118
+-   249
+  488
+ 7141
+12287
+17433
+15894
+16631
+16264
+16432
+16368
+16387
+16383
+16383
+16383
+16383
+16383
+16387
+16368
+16432
+16264
+16631
+15894
+ 9241
+ 4095
+-  1051
+  488
+-   249
+  118
+-    49
+   14
+-     4
+    0
+    0
+    0
+    0
+    0
+-     4
+   14
+-    49
+  118
+-   249
+  488
+-  1051
+12287
+17433
+15894
+16631
+16264
+16432
+16368
+16387
+16383
+16383
+16383
+16383
+16383
+16387
+16368
+16432
+16264
+16631
+15894
+17433
+ 4095
+-  1051
+  488
+-   249
+  118
+-    49
+   14
+-     4
+    0
+    0
+    0
+    0
diff --git a/usrp2/sdr_lib/hb/hbd_tb/regression b/usrp2/sdr_lib/hb/hbd_tb/regression
new file mode 100644
index 000000000..fc279c2f2
--- /dev/null
+++ b/usrp2/sdr_lib/hb/hbd_tb/regression
@@ -0,0 +1,95 @@
+echo "Baseline 1000"
+iverilog -y .. -o test_hbd -DRATE=1000 test_hbd.v  ; ./test_hbd >golden
+diff golden really_golden
+
+echo
+echo "Test 100"
+iverilog -y .. -o test_hbd -DRATE=100 test_hbd.v  ; ./test_hbd >output ; diff output golden
+
+echo
+echo "Test 50"
+iverilog -y .. -o test_hbd -DRATE=50 test_hbd.v  ; ./test_hbd >output ; diff output golden
+
+echo
+echo "Test 40"
+iverilog -y .. -o test_hbd -DRATE=40 test_hbd.v  ; ./test_hbd >output ; diff output golden
+
+echo
+echo "Test 30"
+iverilog -y .. -o test_hbd -DRATE=30 test_hbd.v  ; ./test_hbd >output ; diff output golden
+
+echo
+echo "Test 25"
+iverilog -y .. -o test_hbd -DRATE=25 test_hbd.v  ; ./test_hbd >output ; diff output golden
+
+echo
+echo "Test 20"
+iverilog -y .. -o test_hbd -DRATE=20 test_hbd.v  ; ./test_hbd >output ; diff output golden
+
+echo
+echo "Test 19"
+iverilog -y .. -o test_hbd -DRATE=19 test_hbd.v  ; ./test_hbd >output ; diff output golden
+
+echo
+echo "Test 18"
+iverilog -y .. -o test_hbd -DRATE=18 test_hbd.v  ; ./test_hbd >output ; diff output golden
+
+echo
+echo "Test 17"
+iverilog -y .. -o test_hbd -DRATE=17 test_hbd.v  ; ./test_hbd >output ; diff output golden
+
+echo
+echo "Test 16"
+iverilog -y .. -o test_hbd -DRATE=16 test_hbd.v  ; ./test_hbd >output ; diff output golden
+
+echo
+echo "Test 15"
+iverilog -y .. -o test_hbd -DRATE=15 test_hbd.v  ; ./test_hbd >output ; diff output golden
+
+echo
+echo "Test 14"
+iverilog -y .. -o test_hbd -DRATE=14 test_hbd.v  ; ./test_hbd >output ; diff output golden
+
+echo
+echo "Test 13"
+iverilog -y .. -o test_hbd -DRATE=13 test_hbd.v  ; ./test_hbd >output ; diff output golden
+
+echo
+echo "Test 12"
+iverilog -y .. -o test_hbd -DRATE=12 test_hbd.v  ; ./test_hbd >output ; diff output golden
+
+echo
+echo "Test 11"
+iverilog -y .. -o test_hbd -DRATE=11 test_hbd.v  ; ./test_hbd >output ; diff output golden
+
+echo
+echo "Test 10"
+iverilog -y .. -o test_hbd -DRATE=10 test_hbd.v  ; ./test_hbd >output ; diff output golden
+
+echo
+echo "Test 9"
+iverilog -y .. -o test_hbd -DRATE=9 test_hbd.v  ; ./test_hbd >output ; diff output golden
+
+echo
+echo "Test 8"
+iverilog -y .. -o test_hbd -DRATE=8 test_hbd.v  ; ./test_hbd >output ; diff output golden
+
+echo
+echo "Test 7"
+iverilog -y .. -o test_hbd -DRATE=7 test_hbd.v  ; ./test_hbd >output ; diff output golden
+
+echo
+echo "Test 6"
+iverilog -y .. -o test_hbd -DRATE=6 test_hbd.v  ; ./test_hbd >output ; diff output golden
+
+echo
+echo "Test 5"
+iverilog -y .. -o test_hbd -DRATE=5 test_hbd.v  ; ./test_hbd >output ; diff output golden
+
+echo
+echo "Test 4"
+iverilog -y .. -o test_hbd -DRATE=4 test_hbd.v  ; ./test_hbd >output ; diff output golden
+
+echo
+echo "Test 3"
+iverilog -y .. -o test_hbd -DRATE=3 test_hbd.v  ; ./test_hbd >output ; diff output golden
diff --git a/usrp2/sdr_lib/hb/hbd_tb/run_hbd b/usrp2/sdr_lib/hb/hbd_tb/run_hbd
new file mode 100755
index 000000000..b8aec7574
--- /dev/null
+++ b/usrp2/sdr_lib/hb/hbd_tb/run_hbd
@@ -0,0 +1,4 @@
+#!/bin/sh
+
+iverilog -y .. -o test_hbd test_hbd.v
+./test_hbd
diff --git a/usrp2/sdr_lib/hb/hbd_tb/test_hbd.v b/usrp2/sdr_lib/hb/hbd_tb/test_hbd.v
new file mode 100644
index 000000000..01ab5e7e0
--- /dev/null
+++ b/usrp2/sdr_lib/hb/hbd_tb/test_hbd.v
@@ -0,0 +1,75 @@
+
+
+module test_hbd();
+
+   reg clock;
+   initial clock = 1'b0;
+   always #5 clock <= ~clock;
+
+   reg reset;
+   initial reset = 1'b1;
+   initial #1000 reset = 1'b0;
+   
+   initial $dumpfile("test_hbd.vcd");
+   initial $dumpvars(0,test_hbd);
+
+   reg [15:0] i_in, q_in;
+   wire [15:0] i_out, q_out;
+
+   reg 	       strobe_in;
+   wire        strobe_out;
+   reg 	       coeff_write;
+   reg [15:0]  coeff_data;
+   reg [4:0]   coeff_addr;
+   
+   halfband_decim halfband_decim 
+     ( .clock(clock),.reset(reset),.enable(),.strobe_in(strobe_in),.strobe_out(strobe_out),
+       .data_in(i_in),.data_out(i_out) );
+   
+   always @(posedge strobe_out)
+     if(i_out[15])
+       $display("-%d",65536-i_out);
+     else
+       $display("%d",i_out);
+
+   initial
+     begin
+	strobe_in = 1'b0;
+	@(negedge reset);
+	@(posedge clock);
+	while(1)
+	  begin
+	     strobe_in <= #1 1'b1;
+	     @(posedge clock);
+	     strobe_in <= #1 1'b0;
+	     repeat (`RATE)
+	       @(posedge clock);
+	  end
+     end
+
+   initial #10000000 $finish;    // Just in case...
+
+   initial
+     begin
+	i_in <= #1 16'd0;
+	repeat (40) @(posedge strobe_in);
+	i_in <= #1 16'd16384;
+	@(posedge strobe_in);
+	i_in <= #1 16'd0;
+	repeat (40) @(posedge strobe_in);
+	i_in <= #1 16'd16384;
+	@(posedge strobe_in);
+	i_in <= #1 16'd0;
+	repeat (40) @(posedge strobe_in);
+	i_in <= #1 16'd16384;
+	repeat (40) @(posedge strobe_in);
+	i_in <= #1 16'd0;
+	repeat (41) @(posedge strobe_in);
+	i_in <= #1 16'd16384;
+	repeat (40) @(posedge strobe_in);
+	i_in <= #1 16'd0;
+	repeat (40) @(posedge strobe_in);
+	repeat (7) @(posedge clock);
+	$finish;
+     end // initial begin
+endmodule // test_hb
diff --git a/usrp2/sdr_lib/hb/mac.v b/usrp2/sdr_lib/hb/mac.v
new file mode 100644
index 000000000..5a270bc73
--- /dev/null
+++ b/usrp2/sdr_lib/hb/mac.v
@@ -0,0 +1,58 @@
+
+
+module mac (input clock, input reset, input enable, input clear,
+	    input signed [15:0] x, input signed [15:0] y,
+	    input [7:0] shift, output [15:0] z );
+
+   reg signed [30:0] product;
+   reg signed [39:0] z_int;
+   reg signed [15:0] z_shift;
+
+   reg enable_d1;
+   always @(posedge clock)
+     enable_d1 <= #1 enable;
+   
+   always @(posedge clock)
+     if(reset | clear)
+       z_int <= #1 40'd0;
+     else if(enable_d1)
+       z_int <= #1 z_int + {{9{product[30]}},product};
+
+   always @(posedge clock)
+     product <= #1 x*y;
+
+   always @*   // FIXME full case? parallel case?
+     case(shift)
+       //8'd0 : z_shift <= z_int[39:24];
+       //8'd1 : z_shift <= z_int[38:23];
+       //8'd2 : z_shift <= z_int[37:22];
+       //8'd3 : z_shift <= z_int[36:21];
+       //8'd4 : z_shift <= z_int[35:20];
+       //8'd5 : z_shift <= z_int[34:19];
+       8'd6 : z_shift <= z_int[33:18];
+       8'd7 : z_shift <= z_int[32:17];
+       8'd8 : z_shift <= z_int[31:16];
+       8'd9 : z_shift <= z_int[30:15];
+       8'd10 : z_shift <= z_int[29:14];
+       8'd11 : z_shift <= z_int[28:13];
+       //8'd12 : z_shift <= z_int[27:12];
+       //8'd13 : z_shift <= z_int[26:11];
+       //8'd14 : z_shift <= z_int[25:10];
+       //8'd15 : z_shift <= z_int[24:9];
+       //8'd16 : z_shift <= z_int[23:8];
+       //8'd17 : z_shift <= z_int[22:7];
+       //8'd18 : z_shift <= z_int[21:6];
+       //8'd19 : z_shift <= z_int[20:5];
+       //8'd20 : z_shift <= z_int[19:4];
+       //8'd21 : z_shift <= z_int[18:3];
+       //8'd22 : z_shift <= z_int[17:2];
+       //8'd23 : z_shift <= z_int[16:1];
+       //8'd24 : z_shift <= z_int[15:0];
+       default : z_shift <= z_int[15:0];
+     endcase // case(shift)
+   
+   // FIXME do we need to saturate?
+   //assign z = z_shift;
+   assign z = z_int[15:0];
+   
+endmodule // mac
diff --git a/usrp2/sdr_lib/hb/mult.v b/usrp2/sdr_lib/hb/mult.v
new file mode 100644
index 000000000..a8d4cb1b7
--- /dev/null
+++ b/usrp2/sdr_lib/hb/mult.v
@@ -0,0 +1,16 @@
+
+
+module mult (input clock, input signed [15:0] x, input signed [15:0] y, output reg signed [30:0] product,
+	     input enable_in, output reg enable_out );
+
+   always @(posedge clock)
+     if(enable_in)
+       product <= #1 x*y;
+     else
+       product <= #1 31'd0;
+   
+   always @(posedge clock)
+     enable_out <= #1 enable_in;
+   
+endmodule // mult
+
diff --git a/usrp2/sdr_lib/hb/ram16_2port.v b/usrp2/sdr_lib/hb/ram16_2port.v
new file mode 100644
index 000000000..e1761a926
--- /dev/null
+++ b/usrp2/sdr_lib/hb/ram16_2port.v
@@ -0,0 +1,22 @@
+
+
+module ram16_2port (input clock, input write, 
+		    input [3:0] wr_addr, input [15:0] wr_data,
+		    input [3:0] rd_addr1, output reg [15:0] rd_data1,
+		    input [3:0] rd_addr2, output reg [15:0] rd_data2);
+   
+   reg [15:0] 			ram_array [0:31];
+   
+   always @(posedge clock)
+     rd_data1 <= #1 ram_array[rd_addr1];
+   
+   always @(posedge clock)
+     rd_data2 <= #1 ram_array[rd_addr2];
+   
+   always @(posedge clock)
+     if(write)
+       ram_array[wr_addr] <= #1 wr_data;
+   
+endmodule // ram16_2port
+
+
diff --git a/usrp2/sdr_lib/hb/ram16_2sum.v b/usrp2/sdr_lib/hb/ram16_2sum.v
new file mode 100644
index 000000000..559b06fd5
--- /dev/null
+++ b/usrp2/sdr_lib/hb/ram16_2sum.v
@@ -0,0 +1,27 @@
+
+
+module ram16_2sum (input clock, input write, 
+		   input [3:0] wr_addr, input [15:0] wr_data,
+		   input [3:0] rd_addr1, input [3:0] rd_addr2,
+                   output reg [15:0] sum);
+   
+   reg signed [15:0] 	  ram_array [0:15];
+   reg signed [15:0] 	  a,b;
+   wire signed [16:0] 	  sum_int;
+   
+   always @(posedge clock)
+     if(write)
+       ram_array[wr_addr] <= #1 wr_data;
+      
+   always @(posedge clock)
+     begin
+	a <= #1 ram_array[rd_addr1];
+	b <= #1 ram_array[rd_addr2];
+     end
+   
+   assign sum_int = {a[15],a} + {b[15],b};
+   
+   always @(posedge clock)
+     sum <= #1 sum_int[16:1] + (sum_int[16]&sum_int[0]);
+     
+endmodule // ram16_2sum
diff --git a/usrp2/sdr_lib/hb/ram32_2sum.v b/usrp2/sdr_lib/hb/ram32_2sum.v
new file mode 100644
index 000000000..d1f55b7d0
--- /dev/null
+++ b/usrp2/sdr_lib/hb/ram32_2sum.v
@@ -0,0 +1,22 @@
+
+
+module ram32_2sum (input clock, input write, 
+		   input [4:0] wr_addr, input [15:0] wr_data,
+		   input [4:0] rd_addr1, input [4:0] rd_addr2,
+		   output reg [15:0] sum);
+   
+   reg [15:0] 			ram_array [0:31];
+   wire [16:0] 			sum_int;
+   
+   always @(posedge clock)
+     if(write)
+       ram_array[wr_addr] <= #1 wr_data;
+
+   assign sum_int = ram_array[rd_addr1] + ram_array[rd_addr2];
+
+   always @(posedge clock)
+     sum <= #1 sum_int[16:1] + (sum_int[16]&sum_int[0]);
+
+   
+endmodule // ram32_2sum
+