blinky/Blinky: a module that blinks a LED every second

Handy as a basic liveness test when you push stuff to an FPGA and
nothing happens.

blinky/Blinky.bsv

@@ -0,0 +1,26 @@
+package Blinky;
+
+import Strobe::*;
+
+(* always_ready *)
+interface Blinky;
+   method Bool led_on();
+endinterface
+
+// mkBlinky returns a module that toggles its output approximately
+// once a second. It's intended to be wired to an LED as a basic "are
+// you alive" indicator.
+module mkBlinky(Integer clock_frequency, Blinky ifc);
+   let strobe <- mkStrobe(clock_frequency, 1);
+
+   Reg#(Bool) out <- mkReg(False);
+
+   (* no_implicit_conditions,fire_when_enabled *)
+   rule increment (strobe);
+      out <= !out;
+   endrule
+
+   method led_on = out._read;
+endmodule
+
+endpackage