+#if (__GNUC__ >= 4)
+# ifdef SD_EXPORT_SYMBOLS
+/* Export symbols */
+# define _sd_export_ __attribute__ ((visibility("default")))
+# else
+/* Don't export the symbols */
+# define _sd_export_ __attribute__ ((visibility("hidden")))
+# endif
+#else
+# define _sd_export_
+#endif
+