refactor: Rework repository structure

Using this structure, only the keymap itself is bound to a specific
board. Everything else (configuration, rules) can be shared across
multiple boards.

features/layer_lock.c

@@ -0,0 +1,147 @@
+// Copyright 2022-2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+/**
+ * @file layer_lock.c
+ * @brief Layer Lock implementation
+ *
+ * For full documentation, see
+ * <https://getreuer.info/posts/keyboards/layer-lock>
+ */
+
+#include "layer_lock.h"
+
+// The current lock state. The kth bit is on if layer k is locked.
+static layer_state_t locked_layers = 0;
+
+// Layer Lock timer to disable layer lock after X seconds inactivity
+#if LAYER_LOCK_IDLE_TIMEOUT > 0
+static uint32_t layer_lock_timer = 0;
+
+void layer_lock_task(void) {
+  if (locked_layers &&
+      timer_elapsed32(layer_lock_timer) > LAYER_LOCK_IDLE_TIMEOUT) {
+    layer_lock_all_off();
+    layer_lock_timer = timer_read32();
+  }
+}
+#endif  // LAYER_LOCK_IDLE_TIMEOUT > 0
+
+// Handles an event on an `MO` or `TT` layer switch key.
+static bool handle_mo_or_tt(uint8_t layer, keyrecord_t* record) {
+  if (is_layer_locked(layer)) {
+    if (record->event.pressed) {  // On press, unlock the layer.
+      layer_lock_invert(layer);
+    }
+    return false;  // Skip default handling.
+  }
+  return true;
+}
+
+bool process_layer_lock(uint16_t keycode, keyrecord_t* record,
+                        uint16_t lock_keycode) {
+#if LAYER_LOCK_IDLE_TIMEOUT > 0
+  layer_lock_timer = timer_read32();
+#endif  // LAYER_LOCK_IDLE_TIMEOUT > 0
+
+  // The intention is that locked layers remain on. If something outside of
+  // this feature turned any locked layers off, unlock them.
+  if ((locked_layers & ~layer_state) != 0) {
+    layer_lock_set_user(locked_layers &= layer_state);
+  }
+
+  if (keycode == lock_keycode) {
+    if (record->event.pressed) {  // The layer lock key was pressed.
+      layer_lock_invert(get_highest_layer(layer_state));
+    }
+    return false;
+  }
+
+  switch (keycode) {
+    case QK_MOMENTARY ... QK_MOMENTARY_MAX:  // `MO(layer)` keys.
+      return handle_mo_or_tt(QK_MOMENTARY_GET_LAYER(keycode), record);
+
+    case QK_LAYER_TAP_TOGGLE ... QK_LAYER_TAP_TOGGLE_MAX:  // `TT(layer)`.
+      return handle_mo_or_tt(QK_LAYER_TAP_TOGGLE_GET_LAYER(keycode), record);
+
+    case QK_LAYER_MOD ... QK_LAYER_MOD_MAX: {  // `LM(layer, mod)`.
+      uint8_t layer = QK_LAYER_MOD_GET_LAYER(keycode);
+      if (is_layer_locked(layer)) {
+        if (record->event.pressed) {  // On press, unlock the layer.
+          layer_lock_invert(layer);
+        } else {  // On release, clear the mods.
+          clear_mods();
+          send_keyboard_report();
+        }
+        return false;  // Skip default handling.
+      }
+    } break;
+
+#ifndef NO_ACTION_TAPPING
+    case QK_LAYER_TAP ... QK_LAYER_TAP_MAX:  // `LT(layer, key)` keys.
+      if (record->tap.count == 0 && !record->event.pressed &&
+          is_layer_locked(QK_LAYER_TAP_GET_LAYER(keycode))) {
+        // Release event on a held layer-tap key where the layer is locked.
+        return false;  // Skip default handling so that layer stays on.
+      }
+      break;
+#endif  // NO_ACTION_TAPPING
+  }
+
+  return true;
+}
+
+bool is_layer_locked(uint8_t layer) {
+  return locked_layers & ((layer_state_t)1 << layer);
+}
+
+void layer_lock_invert(uint8_t layer) {
+  const layer_state_t mask = (layer_state_t)1 << layer;
+  if ((locked_layers & mask) == 0) {  // Layer is being locked.
+#ifndef NO_ACTION_ONESHOT
+    if (layer == get_oneshot_layer()) {
+      reset_oneshot_layer();  // Reset so that OSL doesn't turn layer off.
+    }
+#endif  // NO_ACTION_ONESHOT
+    layer_on(layer);
+#if LAYER_LOCK_IDLE_TIMEOUT > 0
+    layer_lock_timer = timer_read32();
+#endif  // LAYER_LOCK_IDLE_TIMEOUT > 0
+  } else {  // Layer is being unlocked.
+    layer_off(layer);
+  }
+  layer_lock_set_user(locked_layers ^= mask);
+}
+
+// Implement layer_lock_on/off by deferring to layer_lock_invert.
+void layer_lock_on(uint8_t layer) {
+  if (!is_layer_locked(layer)) {
+    layer_lock_invert(layer);
+  }
+}
+
+void layer_lock_off(uint8_t layer) {
+  if (is_layer_locked(layer)) {
+    layer_lock_invert(layer);
+  }
+}
+
+void layer_lock_all_off(void) {
+  layer_and(~locked_layers);
+  locked_layers = 0;
+  layer_lock_set_user(locked_layers);
+}
+
+__attribute__((weak)) void layer_lock_set_user(layer_state_t locked_layers) {}
+