Optimization for scanning less layers. (#8311)

* Optimization for scanning less layers.

* Rename NUM_LAYERS to MAX_LAYER.

2 files changed, 14 insertions, 3 deletions

diff --git a/tmk_core/common/action_layer.c b/tmk_core/common/action_layer.c
index 81f86f0f3..af2d7d964 100644
--- a/tmk_core/common/action_layer.c
+++ b/tmk_core/common/action_layer.c
@@ -257,7 +257,7 @@ uint8_t layer_switch_get_layer(keypos_t key) {
 
     layer_state_t layers = layer_state | default_layer_state;
     /* check top layer first */
-    for (int8_t i = sizeof(layer_state_t) * 8 - 1; i >= 0; i--) {
+    for (int8_t i = MAX_LAYER - 1; i >= 0; i--) {
         if (layers & (1UL << i)) {
             action = action_for_key(i, key);
             if (action.code != ACTION_TRANSPARENT) {
diff --git a/tmk_core/common/action_layer.h b/tmk_core/common/action_layer.h
index c283d2623..16922c1ff 100644
--- a/tmk_core/common/action_layer.h
+++ b/tmk_core/common/action_layer.h
@@ -23,12 +23,24 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 #if defined(LAYER_STATE_8BIT)
 typedef uint8_t layer_state_t;
+#    define MAX_LAYER_BITS 3
+#    ifndef MAX_LAYER
+#        define MAX_LAYER 8
+#    endif
 #    define get_highest_layer(state) biton(state)
 #elif defined(LAYER_STATE_16BIT)
 typedef uint16_t layer_state_t;
+#    define MAX_LAYER_BITS 4
+#    ifndef MAX_LAYER
+#        define MAX_LAYER 16
+#    endif
 #    define get_highest_layer(state) biton16(state)
 #else
 typedef uint32_t layer_state_t;
+#    define MAX_LAYER_BITS 5
+#    ifndef MAX_LAYER
+#        define MAX_LAYER 32
+#    endif
 #    define get_highest_layer(state) biton32(state)
 #endif
 
@@ -96,8 +108,7 @@ layer_state_t layer_state_set_kb(layer_state_t state);
 
 /* pressed actions cache */
 #if !defined(NO_ACTION_LAYER) && !defined(STRICT_LAYER_RELEASE)
-/* The number of bits needed to represent the layer number: log2(32). */
-#    define MAX_LAYER_BITS 5
+
 void    update_source_layers_cache(keypos_t key, uint8_t layer);
 uint8_t read_source_layers_cache(keypos_t key);
 #endif