-uint8_t layer_switch_get_layer(void);
-
-/* switch off all layers */
-void layer_switch_clear(void);
-/* set layer status */
-void layer_switch_set(uint16_t stat);
-/* move to layer */
-void layer_switch_move(uint8_t layer);
-/* switch on layer */
-void layer_switch_on(uint8_t layer);
-/* switch off layer */
-void layer_switch_off(uint8_t layer);
-/* switch state of layer */
-void layer_switch_invert(uint8_t layer);
-
-/* bitwise operation against layer status */
-void layer_switch_or(uint16_t stat);
-void layer_switch_and(uint16_t stat);
-void layer_switch_xor(uint16_t stat);
-
-void layer_switch_debug(void);
+uint8_t overlay_get_layer(void);
+void overlay_clear(void);
+void overlay_set(uint16_t stat);
+void overlay_move(uint8_t layer);
+void overlay_on(uint8_t layer);
+void overlay_off(uint8_t layer);
+void overlay_invert(uint8_t layer);
+/* bitwise operation */
+void overlay_or(uint16_t stat);
+void overlay_and(uint16_t stat);
+void overlay_xor(uint16_t stat);
+void overlay_debug(void);
+
+