Add hulk.time and msleep()

src/hulk/time.d

@@ -0,0 +1,42 @@
+/**
+ * Time functionality.
+ */
+module hulk.time;
+
+import core.volatile;
+
+struct Time
+{
+    /** System uptime (ms). */
+    private static __gshared ulong s_uptime;
+
+    /**
+     * Millisecond ISR.
+     */
+    public static void ms_isr()
+    {
+        s_uptime++;
+    }
+
+    /**
+     * Get system uptime (ms).
+     */
+    public static @property ulong uptime()
+    {
+        return s_uptime;
+    }
+
+    /**
+     * Sleep for the given amount of time (ms).
+     *
+     * @param count
+     *   Number of milliseconds to sleep for.
+     */
+    public static void msleep(ulong count)
+    {
+        ulong wait_for = s_uptime + count + 1;
+        while (volatileLoad(&s_uptime) < wait_for)
+        {
+        }
+    }
+}