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, 94 insertions, 0 deletions

diff --git a/fpga/usrp3/lib/control/map/cam_priority_encoder.v b/fpga/usrp3/lib/control/map/cam_priority_encoder.v
new file mode 100644
index 000000000..5125134f6
--- /dev/null
+++ b/fpga/usrp3/lib/control/map/cam_priority_encoder.v
@@ -0,0 +1,94 @@
+/*
+
+Copyright (c) 2014-2016 Alex Forencich
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+
+*/
+
+// Language: Verilog 2001
+
+`timescale 1ns / 1ps
+
+/*
+ * Priority encoder module
+ */
+module cam_priority_encoder #
+(
+    parameter WIDTH = 4,
+    // LSB priority: "LOW", "HIGH"
+    parameter LSB_PRIORITY = "LOW"
+)
+(
+    input  wire [WIDTH-1:0]         input_unencoded,
+    output wire                     output_valid,
+    output wire [$clog2(WIDTH)-1:0] output_encoded,
+    output wire [WIDTH-1:0]         output_unencoded
+);
+
+// power-of-two width
+parameter W1 = 2**$clog2(WIDTH);
+parameter W2 = W1/2;
+
+generate
+    if (WIDTH == 2) begin
+        // two inputs - just an OR gate
+        assign output_valid = |input_unencoded;
+        if (LSB_PRIORITY == "LOW") begin
+            assign output_encoded = input_unencoded[1];
+        end else begin
+            assign output_encoded = ~input_unencoded[0];
+        end
+    end else begin
+        // more than two inputs - split into two parts and recurse
+        // also pad input to correct power-of-two width
+        wire [$clog2(W2)-1:0] out1, out2;
+        wire valid1, valid2;
+        cam_priority_encoder #(
+            .WIDTH(W2),
+            .LSB_PRIORITY(LSB_PRIORITY)
+        )
+        priority_encoder_inst1 (
+            .input_unencoded(input_unencoded[W2-1:0]),
+            .output_valid(valid1),
+            .output_encoded(out1)
+        );
+        cam_priority_encoder #(
+            .WIDTH(W2),
+            .LSB_PRIORITY(LSB_PRIORITY)
+        )
+        priority_encoder_inst2 (
+            .input_unencoded({{W1-WIDTH{1'b0}}, input_unencoded[WIDTH-1:W2]}),
+            .output_valid(valid2),
+            .output_encoded(out2)
+        );
+        // multiplexer to select part
+        assign output_valid = valid1 | valid2;
+        if (LSB_PRIORITY == "LOW") begin
+            assign output_encoded = valid2 ? {1'b1, out2} : {1'b0, out1};
+        end else begin
+            assign output_encoded = valid1 ? {1'b0, out1} : {1'b1, out2};
+        end
+    end
+endgenerate
+
+// unencoded output
+assign output_unencoded = 1 << output_encoded;
+
+endmodule