1 files changed, 121 insertions, 0 deletions
diff --git a/udp/prot_eng_rx.v b/udp/prot_eng_rx.v
new file mode 100644
index 000000000..5df158b2b
--- /dev/null
+++ b/udp/prot_eng_rx.v
@@ -0,0 +1,121 @@
+
+
+
+// Protocol Engine Receiver
+//  Checks each line (16 bits) against values in setting regs
+//  3 options for each line -- 
+//      Error if mismatch, Slowpath if mismatch, or ignore line
+//  The engine increases the length of each packet by 32 or 48 bits,
+//   bringing the total length to a multiple of 32 bits.  The last line
+//   is entirely new, and contains the results of the matching operation:
+//      16 bits of flags, 16 bits of data.  Flags indicate error or slowpath
+//      Data indicates line that caused mismatch if any.
+
+
+//   Flags[2:0] is {occ, eop, sop}
+//   Protocol word format is:
+//             22   Last Header Line
+//             21   SLOWPATH if mismatch
+//             20   ERROR if mismatch
+//             19   This is the IP checksum
+//             18   This is the UDP checksum
+//             17   Compute IP checksum on this word
+//             16   Compute UDP checksum on this word
+//           15:0   data word to be matched
+
+module prot_eng_rx
+  #(parameter BASE=0)
+   (input clk, input reset, input clear,
+    input set_stb, input [7:0] set_addr, input [31:0] set_data,
+    input [18:0] datain, input src_rdy_i, output dst_rdy_o,
+    output [18:0] dataout, output src_rdy_o, input dst_rdy_i);
+
+   localparam HDR_WIDTH  = 16 + 7;  // 16 bits plus flags
+   localparam HDR_LEN 	 = 32;      // Up to 64 bytes of protocol
+   
+   // Store header values in a small dual-port (distributed) ram
+   reg [HDR_WIDTH-1:0] header_ram[0:HDR_LEN-1];
+   wire [HDR_WIDTH-1:0] header_word;
+   
+   always @(posedge clk)
+     if(set_stb & ((set_addr & 8'hE0) == BASE))
+       header_ram[set_addr[4:0]] <= set_data;
+
+   assign header_word 	= header_ram[state];
+
+   wire consume_input 	= src_rdy_i & dst_rdy_o;
+   wire produce_output 	= src_rdy_o & dst_rdy_i;
+   
+   // Main State Machine
+   reg [15:0] pkt_length, fail_word, dataout_int;
+   
+   reg slowpath, error, sof_o, eof_o, occ_o, odd;
+
+   assign dataout    = {occ_o, eof_o, sof_o, dataout_int};
+
+   wire [15:0] calc_ip_checksum, calc_udp_checksum;
+   reg [15:0] rx_ip_checksum, rx_udp_checksum;
+
+   always @(posedge clk) 
+     if(header_word[19]) 
+       rx_ip_checksum  <= datain[15:0];
+   always @(posedge clk) 
+     if(header_word[18]) 
+       rx_udp_checksum <= datain[15:0];
+   
+   always @(posedge clk)
+     if(reset | clear)
+       begin
+	  slowpath     <= 0;
+	  error        <= 0;
+	  state        <= 0;
+	  fail_word    <= 0;
+	  eof_o        <= 0;
+	  occ_o        <= 0;
+       end
+     else if(src_rdy_i & dst_rdy_i)
+       case (state)
+	 0 :
+	   begin
+	      slowpath 	   <= 0;
+	      error 	   <= 0;
+	      eof_o 	   <= 0;
+	      occ_o 	   <= 0;
+	      state 	   <= 1;
+	   end
+
+	 ST_SLOWPATH :
+	   ;
+	 ST_ERROR :
+	   ;
+	 ST_PAYLOAD :
+	   ;
+	 ST_FILLER :
+	   ;
+	 ST_END1 :
+	   ;
+	 ST_END2 :
+	   ;
+	 default :
+	   if(header_word[21] && mismatch)
+	     state <= ST_SLOWPATH;
+	   else if(header_word[20] && mismatch)
+	     state <= ST_ERROR;
+	   else if(header_word[22])
+	     state <= ST_PAYLOAD;
+	   else
+	     state <= state + 1;
+       endcase // case (state)
+   
+
+
+   // IP + UDP checksum state machines
+   checksum_sm ip_chk
+     (.clk(clk), .reset(reset), .in(datain), 
+      .calc(consume_input & header_word[17]), .clear(state==0), .checksum(ip_checksum));
+   
+   checksum_sm udp_chk
+     (.clk(clk), .reset(reset), .in(datain), 
+      .calc(consume_input & header_word[16]), .clear(state==0), .checksum(udp_checksum));
+   
+endmodule // prot_eng_rx