Merge pull request esp8266#573 from probonopd/patch-2

Example sketch for Espressif ESP8266 SDK functionality

hardware/esp8266com/esp8266/libraries/esp8266/examples/CallSDKFunctions/CallSDKFunctions.ino

@@ -0,0 +1,33 @@
+
+/*
+ * NativeSdk by Simon Peter
+ * Access functionality from the Espressif ESP8266 SDK
+ * This example code is in the public domain
+ * 
+ * This is for advanced users.
+ * Note that this makes your code dependent on the ESP8266, which is generally
+ * a bad idea. So you should try to use esp8266/Arduino functionality
+ * where possible instead, in order to abstract away the hardware dependency.
+ */
+
+// Expose Espressif SDK functionality - wrapped in ifdef so that it still
+// compiles on other platforms
+#ifdef ESP8266
+extern "C" {
+#include "user_interface.h"
+}
+#endif
+
+void setup() {
+  Serial.begin(115200);
+}
+
+void loop() {
+  // Call Espressif SDK functionality - wrapped in ifdef so that it still
+  // compiles on other platforms
+#ifdef ESP8266
+  Serial.print("wifi_station_get_hostname: ");
+  Serial.println(wifi_station_get_hostname());
+#endif
+  delay(1000);
+}