19-bit fifo handling for receive side of eth/udp system

2 files changed, 83 insertions, 45 deletions

diff --git a/control_lib/newfifo/fifo19_rxrealign.v b/control_lib/newfifo/fifo19_rxrealign.v
new file mode 100644
index 000000000..35ad90951
--- /dev/null
+++ b/control_lib/newfifo/fifo19_rxrealign.v
@@ -0,0 +1,42 @@
+
+
+//  Adds a junk line at the beginning of every packet, which the
+//   following stages should ignore.  This gives us proper alignment due
+//   to the 14 byte ethernet header
+
+// Bit 18 -- odd length
+// Bit 17 -- eof
+// Bit 16 -- sof
+// Bit 15:0 -- data
+
+module fifo19_rxrealign
+  (input clk, input reset, input clear,
+   input [18:0] datain, input src_rdy_i, output dst_rdy_o,
+   output [18:0] dataout, output src_rdy_o, input dst_rdy_i);
+   
+   reg 	rxre_state;
+   localparam RXRE_DUMMY  = 0;
+   localparam RXRE_PKT 	  = 1;
+   
+   assign dataout[18] 	  = datain[18];
+   assign dataout[17] 	  = datain[17];
+   assign dataout[16] 	  = (rxre_state==RXRE_DUMMY) | (datain[17] & datain[16]);  // allows for passing error signal
+   assign dataout[15:0] = datain[15:0];
+   
+   always @(posedge clk)
+     if(reset | clear)
+       rxre_state <= RXRE_DUMMY;
+     else if(src_rdy_i & dst_rdy_i)
+       case(rxre_state)
+	 RXRE_DUMMY :
+	   rxre_state <= RXRE_PKT;
+	 RXRE_PKT :
+	   if(datain[17])   // if eof or error
+	     rxre_state <= RXRE_DUMMY;
+       endcase // case (rxre_state)
+
+   assign src_rdy_o 	 = src_rdy_i & dst_rdy_i;   // Send anytime both sides are ready
+   assign dst_rdy_o = src_rdy_i & dst_rdy_i & (rxre_state == RXRE_PKT);  // Only consume after the dummy
+   
+endmodule // fifo19_rxrealign
+
diff --git a/control_lib/newfifo/ll8_to_fifo19.v b/control_lib/newfifo/ll8_to_fifo19.v
index c65be5136..af3b91afb 100644
--- a/control_lib/newfifo/ll8_to_fifo19.v
+++ b/control_lib/newfifo/ll8_to_fifo19.v
@@ -10,68 +10,64 @@ module ll8_to_fifo19
    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;   Not needed
    
-   reg 	 f19_sof, f19_eof, f19_occ;
+   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] dat0, dat1;
-
-   always @(posedge clk)
-     if(ll_src_rdy & ((state==0)|xfer_out))
-       f19_sof <= ll_sof;
-
+   reg [7:0] hold_reg;
+   
    always @(posedge clk)
-     if(ll_src_rdy & ((state != 2)|xfer_out))
-       f19_eof <= ll_eof;
-
+     if(ll_src_rdy & (state==XFER_EMPTY))
+       hold_reg 	      <= ll_data;
+   
    always @(posedge clk)
-     if(ll_eof)
-       f19_occ <= ~state[0];
-     else
-       f19_occ <= 0;
+     if(ll_sof & (state==XFER_EMPTY))
+       hold_sof 	      <= 1;
+     else if(xfer_out)
+       hold_sof 	      <= 0;
    
    always @(posedge clk)
-     if(reset)
-       state   <= 0;
+     if(reset | clear)
+       state 		      <= XFER_EMPTY;
      else
-       if(ll_src_rdy)
-	 case(state)
-	   0 : 
+       case(state)
+	 XFER_EMPTY :
+	   if(ll_src_rdy)
 	     if(ll_eof)
-	       state <= 2;
+	       state 	      <= XFER_HALF_WRITE;
 	     else
-	       state <= 1;
-	   1 : 
-	     state <= 2;
-	   2 : 
-	     if(xfer_out)
-	       state 	   <= 1;
-	 endcase // case(state)
-       else
-	 if(xfer_out)
-	   state 	   <= 0;
-
-   always @(posedge clk)
-     if(ll_src_rdy & (state==1))
-       dat1 		   <= ll_data;
-
-   always @(posedge clk)
-     if(ll_src_rdy & ((state==0) | xfer_out))
-       dat0 		   <= ll_data;
+	       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    ll_dst_rdy     = xfer_out | (state != 2);
-   assign    f19_data 	    = {f19_occ,f19_eof,f19_sof,dat0,dat1};
-   assign    f19_src_rdy_o  = (state == 2);
+   assign f19_data 	 = {f19_occ,f19_eof,f19_sof,hold_reg,ll_data};
       
 endmodule // ll8_to_fifo19