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diff --git a/fpga/usrp2/fifo/crossbar36.v b/fpga/usrp2/fifo/crossbar36.v
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+++ b/fpga/usrp2/fifo/crossbar36.v
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+//
+// 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 crossbar36
+  (input clk, input reset, input clear,
+   input cross,
+   input [35:0] data0_i, input src0_rdy_i, output dst0_rdy_o,
+   input [35:0] data1_i, input src1_rdy_i, output dst1_rdy_o,
+   output [35:0] data0_o, output src0_rdy_o, input dst0_rdy_i,
+   output [35:0] data1_o, output src1_rdy_o, input dst1_rdy_i);
+
+   reg 		 cross_int, active0, active1;
+   wire active0_next = (src0_rdy_i & dst0_rdy_o)? ~data0_i[33] : active0;
+   wire active1_next = (src1_rdy_i & dst1_rdy_o)? ~data1_i[33] : active1;
+
+   assign data0_o = cross_int ? data1_i : data0_i;
+   assign data1_o = cross_int ? data0_i : data1_i;
+
+   assign src0_rdy_o = cross_int ? src1_rdy_i : src0_rdy_i;
+   assign src1_rdy_o = cross_int ? src0_rdy_i : src1_rdy_i;
+
+   assign dst0_rdy_o = cross_int ? dst1_rdy_i : dst0_rdy_i;
+   assign dst1_rdy_o = cross_int ? dst0_rdy_i : dst1_rdy_i;
+   
+   always @(posedge clk)
+     if(reset | clear)
+       active0 <= 0;
+     else
+       active0 <= active0_next;
+   
+   always @(posedge clk)
+     if(reset | clear)
+       active1 <= 0;
+     else
+       active1 <= active1_next;
+
+   always @(posedge clk)
+     if(reset | clear)
+       cross_int <= 0;
+     else if(~active0_next & ~active1_next)
+       cross_int <= cross;
+   
+endmodule // crossbar36