4 files changed, 48 insertions, 29 deletions
diff --git a/control_lib/newfifo/.gitignore b/control_lib/newfifo/.gitignore
new file mode 100644
index 000000000..cba7efc8e
--- /dev/null
+++ b/control_lib/newfifo/.gitignore
@@ -0,0 +1 @@
+a.out
diff --git a/control_lib/newfifo/fifo_2clock.v b/control_lib/newfifo/fifo_2clock.v
index 23a6f693c..40c479db7 100644
--- a/control_lib/newfifo/fifo_2clock.v
+++ b/control_lib/newfifo/fifo_2clock.v
@@ -1,23 +1,31 @@
 
-module newfifo_2clock
-  #(parameter DWIDTH=32, AWIDTH=9)
-  (input wclk, input [DWIDTH-1:0] datain, input src_rdy_i, output dst_rdy_o, output reg [AWIDTH-1:0] level_wclk,
-   input rclk, output [DWIDTH-1:0] dataout, output src_rdy_o, input dst_rdy_i, output reg [AWIDTH-1:0] level_rclk,
-   input arst);
+// FIXME ignores the AWIDTH (fifo size) parameter
 
-   wire full, empty, write, read;
+module fifo_2clock
+  #(parameter WIDTH=32, SIZE=9)
+   (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-1:0] level_rclk, level_wclk;
+   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;
-
-//`define USE_XLNX_FIFO 1
-`ifdef USE_XLNX_FIFO
+   
    fifo_xlnx_512x36_2clk mac_tx_fifo_2clk
      (.rst(rst),
-      .wr_clk(wclk),.din(datain),.full(full),.wr_en(write),.wr_data_count(fifo_occupied[8:0]),
-      .rd_clk(rclk),.dout(dataout),.empty(empty),.rd_en(read),.rd_data_count() );   
+      .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) );
+
+   assign occupied  = {{(16-SIZE){1'b0}},level_rclk};
+   assign space = ((1<<SIZE)-1)-level_wclk;
+   
+endmodule // fifo_2clock
+
+/*
 `else
    // ISE sucks, so the following doesn't work properly
 
@@ -80,3 +88,5 @@ module newfifo_2clock
      level_rclk <= wr_addr_rclk - rd_addr;
 `endif
 endmodule // fifo_2clock
+
+*/
diff --git a/control_lib/newfifo/fifo_2clock_cascade.v b/control_lib/newfifo/fifo_2clock_cascade.v
index 2abbbf3b5..8d8a47954 100644
--- a/control_lib/newfifo/fifo_2clock_cascade.v
+++ b/control_lib/newfifo/fifo_2clock_cascade.v
@@ -1,27 +1,35 @@
 
-module cascadefifo_2clock
-  #(parameter DWIDTH=32, AWIDTH=9)
-    (input wclk, input [DWIDTH-1:0] datain, input src_rdy_i, output dst_rdy_o, output [AWIDTH-1:0] level_wclk,
-     input rclk, output [DWIDTH-1:0] dataout, output src_rdy_o, input dst_rdy_i, output [AWIDTH-1:0] level_rclk,
-     input arst);
-
-   wire [DWIDTH-1:0] data_int1, data_int2;
-   wire src_rdy_int1, src_rdy_int2, dst_rdy_int1, dst_rdy_int2;
+module fifo_2clock_cascade
+  #(parameter WIDTH=32, SIZE=9)
+   (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 [WIDTH-1:0] data_int1, data_int2;
+   wire 	    src_rdy_int1, src_rdy_int2, dst_rdy_int1, dst_rdy_int2;
+   wire [SIZE-1:0]  level_wclk, level_rclk;
+   wire [4:0] 	    s1_space, s1_occupied, s2_space, s2_occupied;
+   wire [15:0] 	    l_space, l_occupied;
    
-   fifo_short #(.WIDTH(DWIDTH)) shortfifo
+   fifo_short #(.WIDTH(WIDTH)) shortfifo
      (.clk(wclk), .reset(arst), .clear(0),
       .datain(datain), .src_rdy_i(src_rdy_i), .dst_rdy_o(dst_rdy_o),
-      .dataout(data_int1), .src_rdy_o(src_rdy_int1), .dst_rdy_i(dst_rdy_int1) );
+      .dataout(data_int1), .src_rdy_o(src_rdy_int1), .dst_rdy_i(dst_rdy_int1),
+      .space(s1_space), .occupied(s1_occupied) );
    
-   newfifo_2clock #(.DWIDTH(DWIDTH),.AWIDTH(AWIDTH)) fifo_2clock
-     (.wclk(wclk), .datain(data_int1), .src_rdy_i(src_rdy_int1), .dst_rdy_o(dst_rdy_int1), .level_wclk(level_wclk),
-      .rclk(rclk), .dataout(data_int2), .src_rdy_o(src_rdy_int2), .dst_rdy_i(dst_rdy_int2), .level_rclk(level_rclk),
+   fifo_2clock #(.DWIDTH(WIDTH),.SIZE(SIZE)) fifo_2clock
+     (.wclk(wclk), .datain(data_int1), .src_rdy_i(src_rdy_int1), .dst_rdy_o(dst_rdy_int1), .space(l_space),
+      .rclk(rclk), .dataout(data_int2), .src_rdy_o(src_rdy_int2), .dst_rdy_i(dst_rdy_int2), .occupied(l_occupied),
       .arst(arst) );
-
-   fifo_short #(.WIDTH(DWIDTH)) shortfifo2
+   
+   fifo_short #(.WIDTH(WIDTH)) shortfifo2
      (.clk(rclk), .reset(arst), .clear(0),
       .datain(data_int2), .src_rdy_i(src_rdy_int2), .dst_rdy_o(dst_rdy_int2),
-      .dataout(dataout), .src_rdy_o(src_rdy_o), .dst_rdy_i(dst_rdy_i) );
-   
-endmodule // fifo_2clock_casc
+      .dataout(dataout), .src_rdy_o(src_rdy_o), .dst_rdy_i(dst_rdy_i),
+      .space(s2_space), .occupied(s2_occupied));
 
+   // Be conservative -- Only advertise space from input side of fifo, occupied from output side
+   assign 	    space = {11'b0,s1_space} + l_space;
+   assign 	    occupied = {11'b0,s2_occupied} + l_occupied;
+   
+endmodule // fifo_2clock_cascade
diff --git a/control_lib/newfifo/fifo_new_tb.v b/control_lib/newfifo/fifo_tb.v
index f561df7fa..f561df7fa 100644
--- a/control_lib/newfifo/fifo_new_tb.v
+++ b/control_lib/newfifo/fifo_tb.v