Keep unicode's input_mode through a power cycle

quantum/process_keycode/process_unicode.c

@@ -1,6 +1,7 @@
 #include "process_unicode.h"
 
 static uint8_t input_mode;
+static uint8_t first_flag = 0;
 
 __attribute__((weak))
 uint16_t hex_to_keycode(uint8_t hex)
@@ -17,6 +18,7 @@ uint16_t hex_to_keycode(uint8_t hex)
 void set_unicode_input_mode(uint8_t os_target)
 {
   input_mode = os_target;
+  eeprom_update_byte(EECONFIG_UNICODEMODE, os_target);
 }
 
 uint8_t get_unicode_input_mode(void) {
@@ -75,6 +77,10 @@ void register_hex(uint16_t hex) {
 
 bool process_unicode(uint16_t keycode, keyrecord_t *record) {
   if (keycode > QK_UNICODE && record->event.pressed) {
+    if (first_flag == 0) {
+      set_unicode_input_mode(eeprom_read_byte(EECONFIG_UNICODEMODE));
+      first_flag = 1;
+    }
     uint16_t unicode = keycode & 0x7FFF;
     unicode_input_start();
     register_hex(unicode);

tmk_core/common/eeconfig.h

@@ -33,6 +33,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #define EECONFIG_BACKLIGHT                          (uint8_t *)6
 #define EECONFIG_AUDIO                              (uint8_t *)7
 #define EECONFIG_RGBLIGHT                           (uint32_t *)8
+#define EECONFIG_UNICODEMODE                        (uint8_t *)12
 
 
 /* debug bit */