1 files changed, 87 insertions, 0 deletions
diff --git a/keyboards/orbekk_dactyl/keymaps/default/features/custom_shift_keys.c b/keyboards/orbekk_dactyl/keymaps/default/features/custom_shift_keys.c
new file mode 100644
index 0000000000..cb371ae339
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+++ b/keyboards/orbekk_dactyl/keymaps/default/features/custom_shift_keys.c
@@ -0,0 +1,87 @@
+// Copyright 2021-2024 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 custom_shift_keys.c
+ * @brief Custom Shift Keys implementation
+ *
+ * For full documentation, see
+ * <https://getreuer.info/posts/keyboards/custom-shift-keys>
+ */
+
+#include "custom_shift_keys.h"
+
+#if !defined(IS_QK_MOD_TAP)
+// Attempt to detect out-of-date QMK installation, which would fail with
+// implicit-function-declaration errors in the code below.
+#error "custom_shift_keys: QMK version is too old to build. Please update QMK."
+#else
+
+bool process_custom_shift_keys(uint16_t keycode, keyrecord_t *record) {
+  static uint16_t registered_keycode = KC_NO;
+
+  // If a custom shift key is registered, then this event is either releasing
+  // it or manipulating another key at the same time. Either way, we release
+  // the currently registered key.
+  if (registered_keycode != KC_NO) {
+    unregister_code16(registered_keycode);
+    registered_keycode = KC_NO;
+  }
+
+  if (record->event.pressed) {  // Press event.
+    const uint8_t saved_mods = get_mods();
+#ifndef NO_ACTION_ONESHOT
+    const uint8_t mods = saved_mods | get_weak_mods() | get_oneshot_mods();
+#else
+    const uint8_t mods = saved_mods | get_weak_mods();
+#endif  // NO_ACTION_ONESHOT
+    if ((mods & MOD_MASK_SHIFT) != 0  // Shift is held.
+#if CUSTOM_SHIFT_KEYS_NEGMODS != 0
+        // Nothing in CUSTOM_SHIFT_KEYS_NEGMODS is held.
+        && (mods & (CUSTOM_SHIFT_KEYS_NEGMODS)) == 0
+#endif  // CUSTOM_SHIFT_KEYS_NEGMODS != 0
+          ) {
+      // Continue default handling if this is a tap-hold key being held.
+      if ((IS_QK_MOD_TAP(keycode) || IS_QK_LAYER_TAP(keycode)) &&
+          record->tap.count == 0) {
+        return true;
+      }
+
+      // Search for a custom shift key whose keycode is `keycode`.
+      for (int i = 0; i < NUM_CUSTOM_SHIFT_KEYS; ++i) {
+        if (keycode == custom_shift_keys[i].keycode) {
+          registered_keycode = custom_shift_keys[i].shifted_keycode;
+          if (IS_QK_MODS(registered_keycode) &&  // Should keycode be shifted?
+              (QK_MODS_GET_MODS(registered_keycode) & MOD_LSFT) != 0) {
+            register_code16(registered_keycode);  // If so, press it directly.
+          } else {
+            // Otherwise cancel shift mods, press the key, and restore mods.
+            del_weak_mods(MOD_MASK_SHIFT);
+#ifndef NO_ACTION_ONESHOT
+            del_oneshot_mods(MOD_MASK_SHIFT);
+#endif  // NO_ACTION_ONESHOT
+            unregister_mods(MOD_MASK_SHIFT);
+            register_code16(registered_keycode);
+            set_mods(saved_mods);
+          }
+          return false;
+        }
+      }
+    }
+  }
+
+  return true;  // Continue with default handling.
+}
+
+#endif  // version check