Merge FPGA repository back into UHD repository

The FPGA codebase was removed from the UHD repository in 2014 to reduce
the size of the repository. However, over the last half-decade, the
split between the repositories has proven more burdensome than it has
been helpful. By merging the FPGA code back, it will be possible to
create atomic commits that touch both FPGA and UHD codebases. Continuous
integration testing is also simplified by merging the repositories,
because it was previously difficult to automatically derive the correct
UHD branch when testing a feature branch on the FPGA repository.

This commit also updates the license files and paths therein.

We are therefore merging the repositories again. Future development for
FPGA code will happen in the same repository as the UHD host code and
MPM code.

== Original Codebase and Rebasing ==

The original FPGA repository will be hosted for the foreseeable future
at its original local location: https://github.com/EttusResearch/fpga/

It can be used for bisecting, reference, and a more detailed history.

The final commit from said repository to be merged here is
05003794e2da61cabf64dd278c45685a7abad7ec. This commit is tagged as
v4.0.0.0-pre-uhd-merge.

If you have changes in the FPGA repository that you want to rebase onto
the UHD repository, simply run the following commands:

- Create a directory to store patches (this should be an empty
  directory):

    mkdir ~/patches

- Now make sure that your FPGA codebase is based on the same state as
  the code that was merged:

    cd src/fpga # Or wherever your FPGA code is stored
    git rebase v4.0.0.0-pre-uhd-merge

  Note: The rebase command may look slightly different depending on what
  exactly you're trying to rebase.

- Create a patch set for your changes versus v4.0.0.0-pre-uhd-merge:

    git format-patch v4.0.0.0-pre-uhd-merge -o ~/patches

  Note: Make sure that only patches are stored in your output directory.
  It should otherwise be empty. Make sure that you picked the correct
  range of commits, and only commits you wanted to rebase were exported
  as patch files.

- Go to the UHD repository and apply the patches:

    cd src/uhd # Or wherever your UHD repository is stored
    git am --directory fpga ~/patches/*
    rm -rf ~/patches # This is for cleanup

== Contributors ==

The following people have contributed mainly to these files (this list
is not complete):

Co-authored-by: Alex Williams <alex.williams@ni.com>
Co-authored-by: Andrej Rode <andrej.rode@ettus.com>
Co-authored-by: Ashish Chaudhari <ashish@ettus.com>
Co-authored-by: Ben Hilburn <ben.hilburn@ettus.com>
Co-authored-by: Ciro Nishiguchi <ciro.nishiguchi@ni.com>
Co-authored-by: Daniel Jepson <daniel.jepson@ni.com>
Co-authored-by: Derek Kozel <derek.kozel@ettus.com>
Co-authored-by: EJ Kreinar <ej@he360.com>
Co-authored-by: Humberto Jimenez <humberto.jimenez@ni.com>
Co-authored-by: Ian Buckley <ian.buckley@gmail.com>
Co-authored-by: Jörg Hofrichter <joerg.hofrichter@ni.com>
Co-authored-by: Jon Kiser <jon.kiser@ni.com>
Co-authored-by: Josh Blum <josh@joshknows.com>
Co-authored-by: Jonathon Pendlum <jonathan.pendlum@ettus.com>
Co-authored-by: Martin Braun <martin.braun@ettus.com>
Co-authored-by: Matt Ettus <matt@ettus.com>
Co-authored-by: Michael West <michael.west@ettus.com>
Co-authored-by: Moritz Fischer <moritz.fischer@ettus.com>
Co-authored-by: Nick Foster <nick@ettus.com>
Co-authored-by: Nicolas Cuervo <nicolas.cuervo@ettus.com>
Co-authored-by: Paul Butler <paul.butler@ni.com>
Co-authored-by: Paul David <paul.david@ettus.com>
Co-authored-by: Ryan Marlow <ryan.marlow@ettus.com>
Co-authored-by: Sugandha Gupta <sugandha.gupta@ettus.com>
Co-authored-by: Sylvain Munaut <tnt@246tNt.com>
Co-authored-by: Trung Tran <trung.tran@ettus.com>
Co-authored-by: Vidush Vishwanath <vidush.vishwanath@ettus.com>
Co-authored-by: Wade Fife <wade.fife@ettus.com>

1 files changed, 139 insertions, 0 deletions

diff --git a/fpga/usrp3/lib/dsp/small_hb_dec.v b/fpga/usrp3/lib/dsp/small_hb_dec.v
new file mode 100644
index 000000000..25a635bc1
--- /dev/null
+++ b/fpga/usrp3/lib/dsp/small_hb_dec.v
@@ -0,0 +1,139 @@
+//
+// Copyright 2011 Ettus Research LLC
+// Copyright 2018 Ettus Research, a National Instruments Company
+//
+// SPDX-License-Identifier: LGPL-3.0-or-later
+//
+
+// NOTE: This module uses Xilinx IP that is not available in Spartan3 and older FPGA's
+
+// Short halfband decimator (intended to be followed by another stage)
+// Implements impulse responses of the form [A 0 B 0.5 B 0 A]
+//
+// These taps designed by halfgen4 from ldoolittle:
+//   2 * 131072 * halfgen4(.75/8,2)
+module small_hb_dec
+  #(parameter WIDTH=18,
+    parameter DEVICE = "SPARTAN6")
+    (input clk,
+     input rst,
+     input bypass,
+     input run,
+     input stb_in,
+     input [WIDTH-1:0] data_in,
+     output reg stb_out,
+     output reg [WIDTH-1:0] data_out);
+
+   // Round off inputs to 17 bits because of 18 bit multipliers
+   localparam INTWIDTH = 17;
+   wire [INTWIDTH-1:0] 	data_rnd;
+   wire 		stb_rnd;
+
+   round_sd #(.WIDTH_IN(WIDTH),.WIDTH_OUT(INTWIDTH)) round_in
+     (.clk(clk),.reset(rst),.in(data_in),.strobe_in(stb_in),.out(data_rnd),.strobe_out(stb_rnd));
+
+
+   reg 			stb_rnd_d1;
+   reg [INTWIDTH-1:0] 	data_rnd_d1;
+   always @(posedge clk) stb_rnd_d1 <= stb_rnd;
+   always @(posedge clk) data_rnd_d1 <= data_rnd;
+
+   wire 		go;
+   reg 			phase, go_d1, go_d2, go_d3, go_d4;
+   always @(posedge clk)
+     if(rst | ~run)
+       phase <= 0;
+     else if(stb_rnd_d1)
+       phase <= ~phase;
+   assign 		go = stb_rnd_d1 & phase;
+   always @(posedge clk)
+     if(rst | ~run)
+       begin
+	  go_d1 <= 0;
+	  go_d2 <= 0;
+	  go_d3 <= 0;
+	  go_d4 <= 0;
+       end
+     else
+       begin
+	  go_d1 <= go;
+	  go_d2 <= go_d1;
+	  go_d3 <= go_d2;
+	  go_d4 <= go_d3;
+       end
+
+   wire [17:0] 		coeff_a = -10690;
+   wire [17:0] 		coeff_b = 75809;
+
+   reg [INTWIDTH-1:0] 	d1, d2, d3, d4 , d5, d6;
+   always @(posedge clk)
+     if(stb_rnd_d1 | rst)
+       begin
+	  d1 <= data_rnd_d1;
+	  d2 <= d1;
+	  d3 <= d2;
+	  d4 <= d3;
+	  d5 <= d4;
+	  d6 <= d5;
+       end
+
+   reg [17:0] sum_a, sum_b, middle, middle_d1;
+
+   always @(posedge clk)
+     if(go)
+       begin
+	  sum_a <= {data_rnd_d1[INTWIDTH-1],data_rnd_d1} + {d6[INTWIDTH-1],d6};
+	  sum_b <= {d2[INTWIDTH-1],d2} + {d4[INTWIDTH-1],d4};
+	  //middle <= {d3[INTWIDTH-1],d3};
+	  middle <= {d3,1'b0};
+       end
+
+   always @(posedge clk)
+     if(go_d1)
+       middle_d1 <= middle;
+
+   wire [17:0] sum = go_d1 ? sum_b : sum_a;
+   wire [17:0] coeff = go_d1 ? coeff_b : coeff_a;
+   wire [35:0] 	 prod;
+
+    MULT_MACRO #(.DEVICE(DEVICE),  // Target Device: "VIRTEX5", "VIRTEX6", "SPARTAN6","7SERIES"
+		.LATENCY(1),         // Desired clock cycle latency, 0-4
+		.WIDTH_A(18),        // Multiplier A-input bus width, 1-25
+		.WIDTH_B(18))        // Multiplier B-input bus width, 1-18
+      mult (.P(prod),     // Multiplier output bus, width determined by WIDTH_P parameter
+	       .A(coeff),     // Multiplier input A bus, width determined by WIDTH_A parameter
+	       .B(sum),                    // Multiplier input B bus, width determined by WIDTH_B parameter
+	       .CE(go_d1 | go_d2),   // 1-bit active high input clock enable
+	       .CLK(clk),              // 1-bit positive edge clock input
+	       .RST(rst));             // 1-bit input active high reset
+
+   localparam ACCWIDTH = 30;
+   reg [ACCWIDTH-1:0] 	 accum;
+
+   always @(posedge clk)
+     if(rst)
+       accum <= 0;
+     else if(go_d2)
+       accum <= {middle_d1[17],middle_d1[17],middle_d1,{(16+ACCWIDTH-36){1'b0}}} + {prod[35:36-ACCWIDTH]};
+     else if(go_d3)
+       accum <= accum + {prod[35:36-ACCWIDTH]};
+
+   wire [WIDTH:0] 	 accum_rnd;
+   wire [WIDTH-1:0] 	 accum_rnd_clip;
+
+   wire 	 stb_round;
+
+   round_sd #(.WIDTH_IN(ACCWIDTH),.WIDTH_OUT(WIDTH+1)) round_acc
+     (.clk(clk), .reset(rst), .in(accum), .strobe_in(go_d4), .out(accum_rnd), .strobe_out(stb_round));
+
+   clip #(.bits_in(WIDTH+1),.bits_out(WIDTH)) clip (.in(accum_rnd), .out(accum_rnd_clip));
+
+   // Output
+   always @(posedge clk)
+     begin
+	stb_out  <= bypass ? stb_in : stb_round;
+	data_out <= bypass ? data_in : accum_rnd_clip;
+     end
+
+
+endmodule // small_hb_dec