Add mozc dial version.

Co-authored-by: Takashi Toyoshima <toyoshim@google.com>
Co-authored-by: Shun Ikejima <ikejima@google.com>

mozc-dial/firmware/common/dial_controller.h

@@ -0,0 +1,28 @@
+// Copyright 2025 Google Inc.
+// Use of this source code is governed by an Apache License that can be found
+// in the LICENSE file.
+
+#ifndef COMMON_DIAL_CONTROLLER_H
+#define COMMON_DIAL_CONTROLLER_H
+
+#include <cstdint>
+#include <optional>
+
+class DialController {
+ public:
+  DialController();
+  DialController(const DialController&) = delete;
+  DialController& operator=(const DialController&) = delete;
+  ~DialController() = default;
+
+  void Update(uint8_t sensor_gray_code);
+  bool IsBasePosition() const;
+  std::optional<uint8_t> PopDecidedPosition();
+
+ private:
+  uint8_t position_ = 0u;
+  uint8_t max_position_ = 0u;
+  std::optional<uint8_t> decided_position_;
+};
+
+#endif  // COMMON_DIAL_CONTROLLER_H