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, 129 insertions, 0 deletions

diff --git a/fpga/usrp3/lib/gpif2/gpif2_error_checker.v b/fpga/usrp3/lib/gpif2/gpif2_error_checker.v
new file mode 100644
index 000000000..412253213
--- /dev/null
+++ b/fpga/usrp3/lib/gpif2/gpif2_error_checker.v
@@ -0,0 +1,129 @@
+
+// Copyright 2013 Ettus Research LLC
+// Copyright 2018 Ettus Research, a National Instruments Company
+//
+// SPDX-License-Identifier: LGPL-3.0-or-later
+
+// inspect the input for invalid conditions
+// when bad - drain input, flag error, and insert error msg packet
+//
+// Packets alignment errors are searched for in two different ways:
+// 1) Blatently illegal values in what is assumed to be the PACKET_LENGTH field
+// in the CHDR header
+// (We could probably improve this by looking at other fields of the header that 
+// have a limited range of values)
+// 2) Packet length indicating an EOF word that doesn't have TLAST set in the FIFO.
+// (Upstream can howvever legally insert TLAST in the FIFO for words that are not EOF)
+// 
+// Packet allignment recovery strategy is to wait for TLAST asserted and then decode the 
+// following data assuming it is the start of new CHDR headers.
+//
+//TODO - insert bad packet
+
+module gpif2_error_checker
+  #(parameter SIZE = 9)
+  (input clk, input reset, input clear,
+   input [31:0] i_tdata, input i_tlast, input i_tvalid, output i_tready,
+   output [31:0] o_tdata, output o_tlast, output o_tvalid, input o_tready,
+   output bus_error, output [63:0] debug);
+
+    wire [31:0] gate_tdata;
+    wire gate_tlast, gate_terror;
+    wire gate_tvalid, gate_tready;
+
+    localparam STATE_HDR = 0;
+    localparam STATE_FWD = 1;
+    localparam STATE_EOF = 2;
+    localparam STATE_WAIT = 3;
+    reg [1:0] state;
+
+    reg [15:0] lines32;
+    reg [11:0] seq_id_ref;
+    reg        seq_id_bad;
+    reg        seq_id_wayoff;
+   
+
+    wire [15:0] hdr_bytes = i_tdata[15:0] + 3; //round up to multiple of 4
+    wire [15:0] hdr_lines32 = {2'b0, hdr_bytes[15:2]}; //convert to lines32 count
+    wire [11:0] seq_id_actual = i_tdata[27:16];
+   
+   
+    wire obviously_bad_hdr = (hdr_lines32 == 16'h0) || (hdr_lines32 > (1 << SIZE));
+
+    always @(posedge clk) begin
+        if (reset | clear) begin
+            state <= STATE_HDR;
+            lines32 <= 16'b0;
+	    seq_id_ref <= 12'h0;
+	    seq_id_bad <= 0;
+	    seq_id_wayoff <= 0;
+	   
+	   
+        end
+        else case (state)
+
+        STATE_HDR: begin //forward header and grab vita length
+            if (i_tvalid && i_tready) begin
+                if (obviously_bad_hdr)           state <= STATE_WAIT;
+                else if (hdr_lines32 == 16'h1)  state <= STATE_HDR;
+                else if (hdr_lines32 == 16'h2)  state <= STATE_EOF;
+                else                            state <= STATE_FWD;
+	        seq_id_bad <= (seq_id_actual != seq_id_ref);
+	        seq_id_wayoff <= (seq_id_actual != seq_id_ref) |
+				(seq_id_actual != seq_id_ref+1) |
+				(seq_id_actual != seq_id_ref+2) |
+				(seq_id_actual != seq_id_ref+3);
+	        if (seq_id_actual != seq_id_ref)
+		 seq_id_ref <= seq_id_actual + 1;
+	        else
+		 seq_id_ref <= seq_id_ref + 1;
+            end
+            lines32 <= hdr_lines32;
+	    
+        end
+
+        STATE_FWD: begin //forward the rest of vita packet
+            if (i_tvalid && i_tready) begin
+                if (lines32 == 16'h3) state <= STATE_EOF;
+                lines32 <= lines32 - 1'b1;
+            end
+        end
+
+        STATE_EOF: begin //do last line of vita frame + eof
+	   if (i_tvalid && i_tready) 
+	     if (gate_tlast) state <= STATE_HDR;
+	     else state <= STATE_WAIT; // Try somehow to get synchronized again.
+        end
+
+        STATE_WAIT: begin //drop until idle
+            if (i_tvalid && i_tready && i_tlast) state <= STATE_HDR;
+        end
+
+        endcase //state
+    end
+
+    assign bus_error = (gate_terror && gate_tvalid && gate_tready) || ((state == STATE_HDR) && i_tvalid && i_tready && obviously_bad_hdr);
+    assign gate_tlast = (state == STATE_HDR)? (hdr_lines32 == 16'h1) : (state == STATE_EOF);
+    assign gate_tdata = i_tdata;
+    assign gate_tvalid = i_tvalid && ((state == STATE_HDR)? !obviously_bad_hdr : (state != STATE_WAIT));
+    assign i_tready = gate_tready;
+
+    axi_packet_gate #(.WIDTH(32), .SIZE(SIZE), .USE_AS_BUFF(0)) gate_xfer
+    (
+        .clk(clk), .reset(reset), .clear(clear),
+        .i_tdata(gate_tdata), .i_tlast(gate_tlast), .i_terror(1'b0), .i_tvalid(gate_tvalid), .i_tready(gate_tready),
+        .o_tdata(o_tdata), .o_tlast(o_tlast), .o_tvalid(o_tvalid), .o_tready(o_tready)
+    );
+   assign  debug = {13'b0,
+		    seq_id_wayoff, //[50]      [114]
+		    gate_terror,  // [49]      [113]
+		    obviously_bad_hdr, // [48] [112]
+		    seq_id_bad,   // [47]      [111]
+		    seq_id_ref,   // [46:35]   [110:99]
+		    i_tlast,      // [34]      [98]
+		    i_tready,     // [33]      [97]
+		    i_tvalid,     // [32]      [96]
+		    i_tdata};     // [31:0]    [95:64]
+   
+
+endmodule // gpif2_error_checker