1 files changed, 59 insertions, 0 deletions
diff --git a/fpga/usrp2/fifo/fifo36_to_ll8.v b/fpga/usrp2/fifo/fifo36_to_ll8.v
new file mode 100644
index 000000000..9604d0e38
--- /dev/null
+++ b/fpga/usrp2/fifo/fifo36_to_ll8.v
@@ -0,0 +1,59 @@
+
+module fifo36_to_ll8
+  (input clk, input reset, input clear,
+   input [35:0] f36_data,
+   input f36_src_rdy_i,
+   output f36_dst_rdy_o,
+
+   output reg [7:0] ll_data,
+   output ll_sof_n,
+   output ll_eof_n,
+   output ll_src_rdy_n,
+   input ll_dst_rdy_n,
+
+   output [31:0] debug);
+
+   wire  ll_sof, ll_eof, ll_src_rdy;
+   assign ll_sof_n = ~ll_sof;
+   assign ll_eof_n = ~ll_eof;
+   assign ll_src_rdy_n = ~ll_src_rdy;
+   wire ll_dst_rdy = ~ll_dst_rdy_n;
+
+   wire   f36_sof = f36_data[32];
+   wire   f36_eof = f36_data[33];
+   wire   f36_occ = f36_data[35:34];
+   wire advance, end_early;
+   reg [1:0] state;
+   assign debug    = {29'b0,state};
+
+   always @(posedge clk)
+     if(reset)
+       state 	  <= 0;
+     else
+       if(advance)
+	 if(ll_eof)
+	   state  <= 0;
+	 else
+	   state  <= state + 1;
+
+   always @*
+     case(state)
+       0 : ll_data = f36_data[31:24];
+       1 : ll_data = f36_data[23:16];
+       2 : ll_data = f36_data[15:8];
+       3 : ll_data = f36_data[7:0];
+       default : ll_data = f36_data[31:24];
+       endcase // case (state)
+   
+   assign ll_sof 	 = (state==0) & f36_sof;
+   assign ll_eof 	 = f36_eof & (((state==0)&(f36_occ==1)) |
+			       ((state==1)&(f36_occ==2)) |
+			       ((state==2)&(f36_occ==3)) |
+			       (state==3));
+   
+   assign ll_src_rdy 	 = f36_src_rdy_i;
+
+   assign advance 	 = ll_src_rdy & ll_dst_rdy;
+   assign f36_dst_rdy_o  = advance & ((state==3)|ll_eof);
+   
+endmodule // ll8_to_fifo36