1 files changed, 73 insertions, 0 deletions
diff --git a/fpga/usrp2/fifo/ll8_to_fifo19.v b/fpga/usrp2/fifo/ll8_to_fifo19.v
new file mode 100644
index 000000000..af3b91afb
--- /dev/null
+++ b/fpga/usrp2/fifo/ll8_to_fifo19.v
@@ -0,0 +1,73 @@
+
+module ll8_to_fifo19
+  (input clk, input reset, input clear,
+   input [7:0] ll_data,
+   input ll_sof_n,
+   input ll_eof_n,
+   input ll_src_rdy_n,
+   output ll_dst_rdy_n,
+
+   output [18:0] f19_data,
+   output f19_src_rdy_o,
+   input f19_dst_rdy_i );
+   
+   localparam XFER_EMPTY       = 0;
+   localparam XFER_HALF        = 1;
+   localparam XFER_HALF_WRITE  = 3;
+   
+   // Why anybody would use active low in an FPGA is beyond me...
+   wire  ll_sof      = ~ll_sof_n;
+   wire  ll_eof      = ~ll_eof_n;
+   wire  ll_src_rdy  = ~ll_src_rdy_n;
+   wire  ll_dst_rdy;
+   assign    ll_dst_rdy_n  = ~ll_dst_rdy;
+   
+   wire  xfer_out 	   = f19_src_rdy_o & f19_dst_rdy_i;
+   wire  xfer_in 	   = ll_src_rdy & ll_dst_rdy; 
+   
+   reg 	 hold_sof;
+   wire  f19_sof, f19_eof, f19_occ;
+   
+   reg [1:0] state;
+   reg [7:0] hold_reg;
+   
+   always @(posedge clk)
+     if(ll_src_rdy & (state==XFER_EMPTY))
+       hold_reg 	      <= ll_data;
+   
+   always @(posedge clk)
+     if(ll_sof & (state==XFER_EMPTY))
+       hold_sof 	      <= 1;
+     else if(xfer_out)
+       hold_sof 	      <= 0;
+   
+   always @(posedge clk)
+     if(reset | clear)
+       state 		      <= XFER_EMPTY;
+     else
+       case(state)
+	 XFER_EMPTY :
+	   if(ll_src_rdy)
+	     if(ll_eof)
+	       state 	      <= XFER_HALF_WRITE;
+	     else
+	       state 	      <= XFER_HALF;
+	 XFER_HALF :
+	   if(ll_src_rdy & f19_dst_rdy_i)
+	       state 	      <= XFER_EMPTY;
+         XFER_HALF_WRITE :
+	   if(f19_dst_rdy_i)
+	     state 	<= XFER_EMPTY;
+       endcase // case (state)
+      
+   assign ll_dst_rdy 	 = (state==XFER_EMPTY) | ((state==XFER_HALF)&f19_dst_rdy_i);
+   assign f19_src_rdy_o  = (state==XFER_HALF_WRITE) | ((state==XFER_HALF)&ll_src_rdy);
+   
+   assign f19_sof 	 = hold_sof | (ll_sof & (state==XFER_HALF));
+   assign f19_eof 	 = (state == XFER_HALF_WRITE) | ll_eof;
+   assign f19_occ 	 = (state == XFER_HALF_WRITE);
+   
+   assign f19_data 	 = {f19_occ,f19_eof,f19_sof,hold_reg,ll_data};
+      
+endmodule // ll8_to_fifo19
+