From 7bf8a6df381a667134b55701993c6770d32bc76b Mon Sep 17 00:00:00 2001
From: Josh Blum <josh@joshknows.com>
Date: Fri, 22 Jan 2010 11:56:55 -0800
Subject: Moved usrp2 fpga files into usrp2 subdir.

---
 usrp2/control_lib/newfifo/fifo_2clock.v | 117 ++++++++++++++++++++++++++++++++
 1 file changed, 117 insertions(+)
 create mode 100644 usrp2/control_lib/newfifo/fifo_2clock.v

(limited to 'usrp2/control_lib/newfifo/fifo_2clock.v')

diff --git a/usrp2/control_lib/newfifo/fifo_2clock.v b/usrp2/control_lib/newfifo/fifo_2clock.v
new file mode 100644
index 000000000..34c85ccb4
--- /dev/null
+++ b/usrp2/control_lib/newfifo/fifo_2clock.v
@@ -0,0 +1,117 @@
+
+// FIXME ignores the AWIDTH (fifo size) parameter
+
+module fifo_2clock
+  #(parameter WIDTH=36, SIZE=6)
+   (input wclk, input [WIDTH-1:0] datain, input src_rdy_i, output dst_rdy_o, output [15:0] space,
+    input rclk, output [WIDTH-1:0] dataout, output src_rdy_o, input dst_rdy_i, output [15:0] occupied,
+    input arst);
+   
+   wire [SIZE:0] level_rclk, level_wclk; // xilinx adds an extra bit if you ask for accurate levels
+   wire 	 full, empty, write, read;
+
+   assign dst_rdy_o  = ~full;
+   assign src_rdy_o  = ~empty;
+   assign write      = src_rdy_i & dst_rdy_o;
+   assign read 	     = src_rdy_o & dst_rdy_i;
+
+   generate
+      if(WIDTH==36)
+	if(SIZE==9)
+	  fifo_xlnx_512x36_2clk fifo_xlnx_512x36_2clk
+	       (.rst(arst),
+		.wr_clk(wclk),.din(datain),.full(full),.wr_en(write),.wr_data_count(level_wclk),
+		.rd_clk(rclk),.dout(dataout),.empty(empty),.rd_en(read),.rd_data_count(level_rclk) );
+	else if(SIZE==11)
+	  fifo_xlnx_2Kx36_2clk fifo_xlnx_2Kx36_2clk 
+		     (.rst(arst),
+		      .wr_clk(wclk),.din(datain),.full(full),.wr_en(write),.wr_data_count(level_wclk),
+		      .rd_clk(rclk),.dout(dataout),.empty(empty),.rd_en(read),.rd_data_count(level_rclk) );
+	else if(SIZE==6)
+	  fifo_xlnx_64x36_2clk fifo_xlnx_64x36_2clk 
+		     (.rst(arst),
+		      .wr_clk(wclk),.din(datain),.full(full),.wr_en(write),.wr_data_count(level_wclk),
+		      .rd_clk(rclk),.dout(dataout),.empty(empty),.rd_en(read),.rd_data_count(level_rclk) );
+	else
+	  fifo_xlnx_512x36_2clk fifo_xlnx_512x36_2clk
+	       (.rst(arst),
+		.wr_clk(wclk),.din(datain),.full(full),.wr_en(write),.wr_data_count(level_wclk),
+		.rd_clk(rclk),.dout(dataout),.empty(empty),.rd_en(read),.rd_data_count(level_rclk) );
+      else if((WIDTH==19)|(WIDTH==18))
+	if(SIZE==4)
+	  fifo_xlnx_16x19_2clk fifo_xlnx_16x19_2clk
+		     (.rst(arst),
+		      .wr_clk(wclk),.din(datain),.full(full),.wr_en(write),.wr_data_count(level_wclk),
+		      .rd_clk(rclk),.dout(dataout),.empty(empty),.rd_en(read),.rd_data_count(level_rclk) );
+   endgenerate
+   
+   assign occupied  = {{(16-SIZE-1){1'b0}},level_rclk};
+   assign space     = ((1<<SIZE)+1)-level_wclk;
+   
+endmodule // fifo_2clock
+
+/*
+`else
+   // ISE sucks, so the following doesn't work properly
+
+   reg [AWIDTH-1:0] wr_addr, rd_addr;
+   wire [AWIDTH-1:0] wr_addr_rclk, rd_addr_wclk;
+   wire [AWIDTH-1:0] next_rd_addr;
+   wire 	    enb_read;
+   
+   // Write side management
+   wire [AWIDTH-1:0] next_wr_addr = wr_addr + 1;
+   always @(posedge wclk or posedge arst)
+     if(arst)
+       wr_addr <= 0;
+     else if(write)
+       wr_addr <= next_wr_addr;
+   assign 	    full = (next_wr_addr == rd_addr_wclk);
+
+   //  RAM for data storage.  Data out is registered, complicating the
+   //     read side logic
+   ram_2port #(.DWIDTH(DWIDTH),.AWIDTH(AWIDTH)) mac_rx_ff_ram
+     (.clka(wclk),.ena(1'b1),.wea(write),.addra(wr_addr),.dia(datain),.doa(),
+      .clkb(rclk),.enb(enb_read),.web(1'b0),.addrb(next_rd_addr),.dib(0),.dob(dataout) );
+
+   // Read side management
+   reg 		    data_valid;
+   assign 	    empty = ~data_valid;
+   assign 	    next_rd_addr = rd_addr + data_valid;
+   assign 	    enb_read = read | ~data_valid;
+
+   always @(posedge rclk or posedge arst)
+     if(arst)
+       rd_addr <= 0;
+     else if(read)
+       rd_addr <= rd_addr + 1;
+
+   always @(posedge rclk or posedge arst)
+     if(arst)
+       data_valid <= 0;
+     else
+       if(read & (next_rd_addr == wr_addr_rclk))
+	 data_valid <= 0;
+       else if(next_rd_addr != wr_addr_rclk)
+	 data_valid <= 1;
+	 
+   // Send pointers across clock domains via gray code
+   gray_send #(.WIDTH(AWIDTH)) send_wr_addr
+     (.clk_in(wclk),.addr_in(wr_addr),
+      .clk_out(rclk),.addr_out(wr_addr_rclk) );
+   
+   gray_send #(.WIDTH(AWIDTH)) send_rd_addr
+     (.clk_in(rclk),.addr_in(rd_addr),
+      .clk_out(wclk),.addr_out(rd_addr_wclk) );
+
+   // Generate fullness info, these are approximate and may be delayed 
+   // and are only for higher-level flow control.  
+   // Only full and empty are guaranteed exact.
+   always @(posedge wclk) 
+     level_wclk <= wr_addr - rd_addr_wclk;
+   always @(posedge rclk) 
+     level_rclk <= wr_addr_rclk - rd_addr;
+`endif
+endmodule // fifo_2clock
+
+*/
-- 
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