Merge branch 'uhd_fpga_merge' into pre_merge

1 files changed, 168 insertions, 0 deletions

diff --git a/fpga/usrp2/fifo/buffer_int.v b/fpga/usrp2/fifo/buffer_int.v
new file mode 100644
index 000000000..b45ed3532
--- /dev/null
+++ b/fpga/usrp2/fifo/buffer_int.v
@@ -0,0 +1,168 @@
+
+// FIFO Interface to the 2K buffer RAMs
+// Read port is read-acknowledge
+// FIXME do we want to be able to interleave reads and writes?
+
+module buffer_int
+  #(parameter BUF_NUM = 0,
+    parameter BUF_SIZE = 9)
+    (// Control Interface
+     input clk,
+     input rst,
+     input [31:0] ctrl_word,
+     input go,
+     output done,
+     output error,
+     output idle,
+     output [1:0] flag,
+     
+     // Buffer Interface
+     output en_o,
+     output we_o,
+     output reg [BUF_SIZE-1:0] addr_o,
+     output [31:0] dat_to_buf,
+     input [31:0] dat_from_buf,
+     
+     // Write FIFO Interface
+     input [31:0] wr_data_i,
+     input [3:0] wr_flags_i,
+     input wr_ready_i,
+     output wr_ready_o,
+     
+     // Read FIFO Interface
+     output [31:0] rd_data_o,
+     output [3:0] rd_flags_o,
+     output rd_ready_o,
+     input rd_ready_i
+     );
+   
+   reg [31:0] ctrl_reg;
+   reg 	      go_reg;
+   
+   always @(posedge clk)
+     go_reg <= go;
+   
+   always @(posedge clk)
+     if(rst)
+       ctrl_reg <= 0;
+     else
+       if(go & (ctrl_word[31:28] == BUF_NUM))
+	 ctrl_reg <= ctrl_word;
+   
+   wire [BUF_SIZE-1:0] firstline = ctrl_reg[BUF_SIZE-1:0];
+   wire [BUF_SIZE-1:0] lastline = ctrl_reg[2*BUF_SIZE-1:BUF_SIZE];
+
+   wire       read = ctrl_reg[22];
+   wire       write = ctrl_reg[23];
+   wire       clear = ctrl_reg[24];
+   //wire [2:0] port = ctrl_reg[27:25];  // Ignored in this block
+   //wire [3:0] buff_num = ctrl_reg[31:28];  // Ignored here ?
+   
+   localparam IDLE = 3'd0;
+   localparam PRE_READ = 3'd1;
+   localparam READING = 3'd2;
+   localparam WRITING = 3'd3;
+   localparam ERROR = 3'd4;
+   localparam DONE = 3'd5;
+   
+   reg [2:0]  state;
+   reg 	      rd_sop, rd_eop;
+   wire       wr_sop, wr_eop, wr_error;
+   reg [1:0]  rd_occ;
+   wire [1:0] wr_occ;
+   
+   always @(posedge clk)
+     if(rst)
+       begin
+	  state <= IDLE;
+	  rd_sop <= 0;
+	  rd_eop <= 0;
+	  rd_occ <= 0;
+       end
+     else
+       if(clear)
+	 begin
+	    state <= IDLE;
+	    rd_sop <= 0;
+	    rd_eop <= 0;
+	    rd_occ <= 0;
+	 end
+       else 
+	 case(state)
+	   IDLE :
+	     if(go_reg & read)
+	       begin
+		  addr_o <= firstline;
+		  state <= PRE_READ;
+	       end
+	     else if(go_reg & write)
+	       begin
+		  addr_o <= firstline;
+		  state <= WRITING;
+	       end
+	   
+	   PRE_READ :
+	     begin
+		state <= READING;
+		addr_o <= addr_o + 1;
+		rd_occ <= 2'b00;
+		rd_sop <= 1;
+		rd_eop <= 0;
+	     end
+	   
+	   READING :
+	     if(rd_ready_i)
+	       begin
+		  rd_sop <= 0;
+		  addr_o <= addr_o + 1;
+		  if(addr_o == lastline)
+		    begin
+		       rd_eop <= 1;
+		       // FIXME assign occ here
+		       rd_occ <= 0;
+		    end
+		  else
+		    rd_eop <= 0;
+		  if(rd_eop)
+		    state <= DONE;
+	       end
+	   
+	   WRITING :
+	     begin
+		if(wr_ready_i)
+		  begin
+		     addr_o <= addr_o + 1;
+		     if(wr_error)
+		       begin
+			  state <= ERROR;
+			  // Save OCC flags here
+		       end
+		     else if((addr_o == lastline)||wr_eop)
+		       state <= DONE;
+		  end // if (wr_ready_i)
+	     end // case: WRITING
+	   
+	 endcase // case(state)
+   
+   assign     dat_to_buf = wr_data_i;
+   assign     rd_data_o = dat_from_buf;
+
+   assign     rd_flags_o = { rd_occ[1:0], rd_eop, rd_sop };
+   assign     rd_ready_o = (state == READING);
+   
+   assign     wr_sop = wr_flags_i[0];
+   assign     wr_eop = wr_flags_i[1];
+   assign     wr_occ = wr_flags_i[3:2];
+   assign     wr_error = wr_sop & wr_eop;
+   assign     wr_ready_o = (state == WRITING);
+
+   assign     we_o = (state == WRITING);
+   //assign     we_o = (state == WRITING) && wr_ready_i;  // always write to avoid timing issue
+
+   assign     en_o = ~((state==READING)& ~rd_ready_i);   // FIXME potential critical path
+   
+   assign     done = (state == DONE);
+   assign     error = (state == ERROR);
+   assign     idle = (state == IDLE);
+
+endmodule // buffer_int