1 files changed, 42 insertions, 0 deletions
diff --git a/fpga/usrp2/control_lib/wb_semaphore.v b/fpga/usrp2/control_lib/wb_semaphore.v
new file mode 100644
index 000000000..a9208e6a1
--- /dev/null
+++ b/fpga/usrp2/control_lib/wb_semaphore.v
@@ -0,0 +1,42 @@
+
+// up to 8 semaphores
+
+// After a read operation, the semaphore is always locked
+//  If it was already locked before the read (meaning someone else holds the lock)
+//    then a 1 is returned
+//  If it was not already locked (meaning the reader now holds the lock)
+//    then a 0 is returned
+
+// A write operation clears the lock
+
+module wb_semaphore 
+  #(parameter count=8, DBUS_WIDTH=32)
+    (input wb_clk_i,
+     input wb_rst_i,
+     input [DBUS_WIDTH-1:0] wb_dat_i,
+     input [2:0] wb_adr_i,
+     input wb_cyc_i,
+     input wb_stb_i,
+     input wb_we_i,
+     output wb_ack_o,
+     output [DBUS_WIDTH-1:0] wb_dat_o);
+
+   reg [count-1:0] locked;
+
+   always @(posedge clock)
+     if(wb_rst_i)
+       locked <= {count{1'b0}};
+     else if(wb_stb_i)
+       if(wb_we_i)
+	 locked[adr_i] <= 1'b0;
+       else
+	 locked[adr_i] <= 1'b1;
+
+   assign 	   wb_dat_o[DBUS_WIDTH-1:1] = {(DBUS_WIDTH-1){1'b0}};
+   assign 	   wb_dat_o[0] = locked[adr_i];
+   assign 	   wb_ack_o = wb_stb_i;
+   
+
+endmodule // wb_semaphore
+
+