Allow QMK to save a single default layers in the full range of 0-31

docs/feature_layers.md

@@ -53,6 +53,8 @@ Layers stack on top of each other in numerical order. When determining what a ke
 
 Sometimes, you might want to switch between layers in a macro or as part of a tap dance routine. `layer_on` activates a layer, and `layer_off` deactivates it. More layer-related functions can be found in [action_layer.h](https://github.com/qmk/qmk_firmware/blob/master/quantum/action_layer.h).
 
+If you want to save multiple persistent default layers, you will want to avoid using the `set_single_persistent_default_layer` function which only supports one default persistent layer at a time. Instead, you can `#define DEFAULT_LAYER_BITMASK_ENABLE` and call the `eeconfig_update_default_layer` function directly, passing it an 8-bit wide bitfield representing the least significant byte of a layer_state_t variable. Note that this approach is limited to storing persistent default layers only between layers 0 and 7.
+
 ## Functions :id=functions
 
 There are a number of functions (and variables) related to how you can use or manipulate the layers.

keyboards/satt/comet46/keymaps/default-rgbled/keymap.c

@@ -174,7 +174,11 @@ void matrix_init_user(void) {
 
 void matrix_scan_user(void) {
   uint8_t layer = get_highest_layer(layer_state);
-  uint8_t default_layer = biton32(eeconfig_read_default_layer());
+#ifdef DEFAULT_LAYER_BITMASK_ENABLE
+  uint8_t default_layer = get_highest_layer(eeconfig_read_default_layer());
+#else
+  uint8_t default_layer = eeconfig_read_default_layer();
+#endif
   switch (layer) {
     case _LOWER:
       set_led_red;

keyboards/satt/comet46/keymaps/default/keymap.c

@@ -158,7 +158,11 @@ bool oled_task_user(void) {
   char layer_str[22];
   oled_write_P(PSTR("Layer: "), false);
   uint8_t layer = get_highest_layer(layer_state);
+#ifdef DEFAULT_LAYER_BITMASK_ENABLE
   uint8_t default_layer = get_highest_layer(eeconfig_read_default_layer());
+#else
+  uint8_t default_layer = eeconfig_read_default_layer();
+#endif
   switch (layer) {
     case _QWERTY:
       switch (default_layer) {

quantum/eeconfig.c

@@ -51,7 +51,11 @@ void eeconfig_init_quantum(void) {
 
     eeprom_update_word(EECONFIG_MAGIC, EECONFIG_MAGIC_NUMBER);
     eeprom_update_byte(EECONFIG_DEBUG, 0);
+#if defined(DEFAULT_LAYER_BITMASK_ENABLE)
     default_layer_state = (layer_state_t)1 << 0;
+#else
+    default_layer_state = 0;
+#endif
     eeprom_update_byte(EECONFIG_DEFAULT_LAYER, default_layer_state);
     // Enable oneshot and autocorrect by default: 0b0001 0100 0000 0000
     eeprom_update_word(EECONFIG_KEYMAP, 0x1400);

quantum/keyboard.c

@@ -394,7 +394,13 @@ void quantum_init(void) {
 #endif
 
     /* read here just incase bootmagic process changed its value */
+#if defined(DEFAULT_LAYER_BITMASK_ENABLE)
+    /* stored as 8-bit-wide bitmask, so write the value directly to default_layer */
     layer_state_t default_layer = (layer_state_t)eeconfig_read_default_layer();
+#else
+    /* stored as a layer number, so left shift 1 by the stored value */
+    layer_state_t default_layer = (layer_state_t)(1UL << eeconfig_read_default_layer());
+#endif
     default_layer_set(default_layer);
 
     /* Also initialize layer state to trigger callback functions for layer_state */

quantum/quantum.c

@@ -483,7 +483,11 @@ void set_single_persistent_default_layer(uint8_t default_layer) {
 #if defined(AUDIO_ENABLE) && defined(DEFAULT_LAYER_SONGS)
     PLAY_SONG(default_layer_songs[default_layer]);
 #endif
+#if defined(DEFAULT_LAYER_BITMASK_ENABLE)
     eeconfig_update_default_layer((layer_state_t)1 << default_layer);
+#else
+    eeconfig_update_default_layer(default_layer);
+#endif
     default_layer_set((layer_state_t)1 << default_layer);
 }