1 files changed, 80 insertions, 0 deletions
diff --git a/fpga/usrp2/fifo/fifo72_to_fifo36.v b/fpga/usrp2/fifo/fifo72_to_fifo36.v
new file mode 100644
index 000000000..c365f0196
--- /dev/null
+++ b/fpga/usrp2/fifo/fifo72_to_fifo36.v
@@ -0,0 +1,80 @@
+//
+// 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/>.
+//
+
+
+// Parameter LE tells us if we are little-endian.  
+// Little-endian means send lower 16 bits first.
+// Default is big endian (network order), send upper bits first.
+
+module fifo72_to_fifo36
+  #(parameter LE=0)
+   (input clk, input reset, input clear,
+    input [71:0] f72_datain,
+    input f72_src_rdy_i,
+    output f72_dst_rdy_o,
+    
+    output [35:0] f36_dataout,
+    output f36_src_rdy_o,
+    input f36_dst_rdy_i );
+      
+   wire [35:0] f36_data_int;
+   wire        f36_src_rdy_int, f36_dst_rdy_int;
+   wire [71:0] f72_data_int;
+   wire        f72_src_rdy_int, f72_dst_rdy_int;
+   
+   // Shortfifo on input to guarantee no deadlock
+   fifo_short #(.WIDTH(72)) head_fifo
+     (.clk(clk),.reset(reset),.clear(clear),
+      .datain(f72_datain), .src_rdy_i(f72_src_rdy_i), .dst_rdy_o(f72_dst_rdy_o),
+      .dataout(f72_data_int), .src_rdy_o(f72_src_rdy_int), .dst_rdy_i(f72_dst_rdy_int),
+      .space(),.occupied() );
+
+   // Main fifo72_to_fifo36, needs shortfifos to guarantee no deadlock
+   wire [2:0]  f72_occ_int  = f72_data_int[68:66];
+   wire        f72_sof_int  = f72_data_int[64];
+   wire        f72_eof_int  = f72_data_int[65];
+   
+   reg 	  phase;
+   wire   half_line 	   = f72_eof_int & ( (f72_occ_int==1)|(f72_occ_int==2)|(f72_occ_int==3)|(f72_occ_int==4) );
+      
+   assign f36_data_int[31:0]   = (LE ^ phase) ? f72_data_int[31:0] : f72_data_int[63:32];
+   assign f36_data_int[32]     = phase ? 0 : f72_sof_int;
+   assign f36_data_int[33]     = phase ? f72_eof_int : half_line;
+   assign f36_data_int[35:34]  = f36_data_int[33] ? f72_occ_int[1:0] : 2'b00;
+      
+   assign f36_src_rdy_int    = f72_src_rdy_int;
+   assign f72_dst_rdy_int    = (phase | half_line) & f36_dst_rdy_int;
+   
+   wire   f36_xfer 	   = f36_src_rdy_int & f36_dst_rdy_int;
+   wire   f72_xfer 	   = f72_src_rdy_int & f72_dst_rdy_int;
+   
+   always @(posedge clk)
+     if(reset)
+       phase 		  <= 0;
+     else if(f72_xfer)
+       phase 		  <= 0;
+     else if(f36_xfer)
+       phase 		  <= 1;
+   
+   // Shortfifo on output to guarantee no deadlock
+   fifo_short #(.WIDTH(36)) tail_fifo
+     (.clk(clk),.reset(reset),.clear(clear),
+      .datain(f36_data_int), .src_rdy_i(f36_src_rdy_int), .dst_rdy_o(f36_dst_rdy_int),
+      .dataout(f36_dataout), .src_rdy_o(f36_src_rdy_o), .dst_rdy_i(f36_dst_rdy_i),
+      .space(),.occupied() );
+
+endmodule // fifo72_to_fifo36