e100: squashed work on bus implementation on GPMC

1 files changed, 42 insertions, 0 deletions

diff --git a/usrp2/gpmc/cross_clock_reader.v b/usrp2/gpmc/cross_clock_reader.v
new file mode 100644
index 000000000..a30e0385f
--- /dev/null
+++ b/usrp2/gpmc/cross_clock_reader.v
@@ -0,0 +1,42 @@
+//
+// Copyright 2011 Ettus Research LLC
+//
+// 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 3 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, see <http://www.gnu.org/licenses/>.
+//
+
+module cross_clock_reader
+    #(
+        parameter WIDTH = 1,
+        parameter DEFAULT = 0
+    )
+    (
+        input clk, input rst,
+        input [WIDTH-1:0] in,
+        output reg [WIDTH-1:0] out
+    );
+
+    reg [WIDTH-1:0] shadow;
+
+    always @(posedge clk) begin
+        if (rst) begin
+            out <= DEFAULT;
+            shadow <= DEFAULT;
+        end
+        else if (shadow == in) begin
+            out <= shadow;
+        end
+        shadow <= in;
+    end
+
+endmodule //cross_clock_reader