-#define AT32_GPIOF_PULLUP 0x00000001 /* Enable pull-up */
-#define AT32_GPIOF_OUTPUT 0x00000002 /* Enable output driver */
-#define AT32_GPIOF_HIGH 0x00000004 /* Set output high */
+#define AT32_GPIOF_PULLUP 0x00000001 /* (not-OUT) Enable pull-up */
+#define AT32_GPIOF_OUTPUT 0x00000002 /* (OUT) Enable output driver */
+#define AT32_GPIOF_HIGH 0x00000004 /* (OUT) Set output high */
+#define AT32_GPIOF_DEGLITCH 0x00000008 /* (IN) Filter glitches */