1 files changed, 76 insertions, 0 deletions
diff --git a/keyboards/kprepublic/bm40hsrgb/keymaps/dan/features/custom_shift_keys.c b/keyboards/kprepublic/bm40hsrgb/keymaps/dan/features/custom_shift_keys.c
new file mode 100644
index 0000000000..5576612f9a
--- /dev/null
+++ b/keyboards/kprepublic/bm40hsrgb/keymaps/dan/features/custom_shift_keys.c
@@ -0,0 +1,76 @@
+// Copyright 2021-2022 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"
+
+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 mods = get_mods();
+
+#ifndef NO_ACTION_ONESHOT
+    if ((mods | get_weak_mods() | get_oneshot_mods()) & MOD_MASK_SHIFT)
+    {
+#else
+    if ((mods | get_weak_mods()) & MOD_MASK_SHIFT)
+        {  // Shift is held.
+#endif  // NO_ACTION_ONESHOT
+            // Search for a custom key with keycode equal to `keycode`.
+            for (int i = 0; i < NUM_CUSTOM_SHIFT_KEYS; ++i)
+            {
+
+                if (keycode == custom_shift_keys[i].keycode)
+                {
+                    // Continue default handling if this is a tap-hold key being held.
+                    if (((QK_MOD_TAP <= keycode && keycode <= QK_MOD_TAP_MAX) || (QK_LAYER_TAP <= keycode && keycode <= QK_LAYER_TAP_MAX)) && record->tap.count == 0)
+                    {
+                        return true;
+                    }
+
+#ifndef NO_ACTION_ONESHOT
+                del_oneshot_mods(MOD_MASK_SHIFT);
+#endif  // NO_ACTION_ONESHOT
+                del_mods(MOD_MASK_SHIFT);
+                del_weak_mods(MOD_MASK_SHIFT);
+                send_keyboard_report();
+                registered_keycode = custom_shift_keys[i].shifted_keycode;
+                register_code16(registered_keycode);
+                set_mods(mods);  // Restore the mods.
+                return false;
+                }
+            }
+        }
+    }
+
+  return true;  // Continue with default handling.
+}