Add generic mechanism for background protocols (e.g. ARP, IGMP)

src/core/background.c

@@ -0,0 +1,47 @@
+#include "background.h"
+
+static struct background backgrounds[0] __table_start ( background );
+static struct background backgrounds_end[0] __table_end ( background );
+
+/** @file */
+
+/**
+ * Call send method of all background protocols
+ *
+ * @v timestamp		Current time
+ * @ret None		-
+ * @err None		-
+ *
+ * This calls each background protocol's background::send() method.
+ */
+void background_send ( unsigned long timestamp ) {
+	struct background *background;
+
+	for ( background = backgrounds ; background < backgrounds_end ;
+	      background++ ) {
+		if ( background->send )
+			background->send ( timestamp );
+	}
+}
+
+/**
+ * Call process method of all background protocols
+ *
+ * @v timestamp		Current time
+ * @v ptype		Packet type
+ * @v ip		IP header, if present
+ * @ret None		-
+ * @err None		-
+ *
+ * This calls each background protocol's background::process() method.
+ */
+void background_process ( unsigned long timestamp, unsigned short ptype,
+			  struct iphdr *ip ) {
+	struct background *background;
+
+	for ( background = backgrounds ; background < backgrounds_end ;
+	      background++ ) {
+		if ( background->process )
+			background->process ( timestamp, ptype, ip );
+	}
+}