Update store_or_get_action to cache keycode on key press, return cached keycode on key release

docs/config_options.md

@@ -144,6 +144,8 @@ If you define these options you will enable the associated feature, which may in
   * NKRO by default requires to be turned on, this forces it on during keyboard startup regardless of EEPROM setting. NKRO can still be turned off but will be turned on again if the keyboard reboots.
 * `#define STRICT_LAYER_RELEASE`
   * force a key release to be evaluated using the current layer stack instead of remembering which layer it came from (used for advanced cases)
+* `#define KEYCODE_CACHE_ENABLE`
+  * Cache keycode for pressed keys, to be used on key release, across entire physical keyboard layout.
 
 ## Behaviors That Can Be Configured
 

quantum/action_layer.c

@@ -287,6 +287,64 @@ uint8_t read_source_layers_cache(keypos_t key) {
 #    endif // ENCODER_MAP_ENABLE
     return 0;
 }
+
+#    ifdef KEYCODE_CACHE_ENABLE
+uint16_t keycode_map[((MATRIX_ROWS * MATRIX_COLS) + (CHAR_BIT)-1) / (CHAR_BIT)][16] = {{KC_NO}};
+#        ifdef ENCODER_MAP_ENABLE
+uint16_t encoder_keycode_map[(NUM_ENCODERS + (CHAR_BIT)-1) / (CHAR_BIT)][16] = {{KC_NO}};
+#        endif // ENCODER_MAP_ENABLE
+
+/** \brief update keycode map
+ *
+ * Updates map of keycodes when a key is pressed down
+ */
+void update_keycode_map_impl(uint16_t entry_number, uint16_t keycode, uint16_t cache[][16]) {
+    cache[entry_number / 16][entry_number % 16] = keycode;
+}
+
+/** \brief read keycode map
+ *
+ * reads from map of keycodes when a key is released
+ */
+uint16_t read_keycode_map_impl(uint16_t entry_number, uint16_t cache[][16]) {
+    return cache[entry_number / 16][entry_number % 16];
+}
+
+/** \brief update keycode map
+ *
+ * Updates map of keycodes when a key is pressed down
+ */
+void update_keycode_map(keypos_t key, uint16_t keycode) {
+    if (key.row < MATRIX_ROWS && key.col < MATRIX_COLS) {
+        const uint16_t entry_number = (uint16_t)(key.row * MATRIX_COLS) + key.col;
+        update_keycode_map_impl(entry_number, keycode, keycode_map);
+    }
+#        ifdef ENCODER_MAP_ENABLE
+    else if (key.row == KEYLOC_ENCODER_CW || key.row == KEYLOC_ENCODER_CCW) {
+        const uint16_t entry_number = key.col;
+        update_keycode_map_impl(entry_number, keycode, encoder_keycode_map);
+    }
+#        endif // ENCODER_MAP_ENABLE
+}
+
+/** \brief read keycode map
+ *
+ * reads from map of keycodes when a key is released
+ */
+uint16_t read_keycode_map(keypos_t key) {
+    if (key.row < MATRIX_ROWS && key.col < MATRIX_COLS) {
+        const uint16_t entry_number = (uint16_t)(key.row * MATRIX_COLS) + key.col;
+        return read_keycode_map_impl(entry_number, keycode_map);
+    }
+#        ifdef ENCODER_MAP_ENABLE
+    else if (key.row == KEYLOC_ENCODER_CW || key.row == KEYLOC_ENCODER_CCW) {
+        const uint16_t entry_number = key.col;
+        return read_keycode_map_impl(entry_number, encoder_keycode_map);
+    }
+#        endif // ENCODER_MAP_ENABLE
+    return KC_NO;
+}
+#    endif
 #endif
 
 /** \brief Store or get action (FIXME: Needs better summary)
@@ -303,14 +361,27 @@ action_t store_or_get_action(bool pressed, keypos_t key) {
     }
 
     uint8_t layer;
-
+#    ifdef KEYCODE_CACHE_ENABLE
+    uint16_t keycode;
+#    endif
     if (pressed) {
         layer = layer_switch_get_layer(key);
         update_source_layers_cache(key, layer);
+#    ifdef KEYCODE_CACHE_ENABLE
+        keycode = keymap_key_to_keycode(layer, key);
+        update_keycode_map(key, keycode);
+#    endif
     } else {
         layer = read_source_layers_cache(key);
+#    ifdef KEYCODE_CACHE_ENABLE
+        keycode = read_keycode_map(key);
+#    endif
     }
+#    ifndef KEYCODE_CACHE_ENABLE
     return action_for_key(layer, key);
+#    else
+    return action_for_keycode(keycode);
+#    endif
 #else
     return layer_switch_get_action(key);
 #endif

quantum/action_layer.h

@@ -160,6 +160,11 @@ layer_state_t update_tri_layer_state(layer_state_t state, uint8_t layer1, uint8_
 
 void    update_source_layers_cache(keypos_t key, uint8_t layer);
 uint8_t read_source_layers_cache(keypos_t key);
+#    ifdef KEYCODE_CACHE_ENABLE
+void     update_keycode_map(keypos_t key, uint16_t keycode);
+uint16_t read_keycode_map(keypos_t key);
+uint16_t keymap_key_to_keycode(uint8_t layer, keypos_t key);
+#    endif
 #endif
 action_t store_or_get_action(bool pressed, keypos_t key);