implement accel and gyro backend

src/common/emu_window.h

@@ -120,6 +120,54 @@ public:
         return std::make_tuple(touch_x, touch_y, touch_pressed);
     }
 
+    /**
+     * Gets the current accelerometer state (acceleration along each three axis).
+     * Axis explained:
+     *   +x is the same direction as LEFT on D-pad.
+     *   +y is normal to the touch screen, pointing outward.
+     *   +z is the same direction as UP on D-pad.
+     * Units:
+     *   1 unit of return value = 1/512 g (measured by hw test),
+     *   where g is the gravitational acceleration (9.8 m/sec2).
+     * @note This should be called by the core emu thread to get a state set by the window thread.
+     * @todo Implement accelerometer input in front-end.
+     * @return std::tuple of (x, y, z)
+     */
+    std::tuple<s16, s16, s16> GetAccelerometerState() const {
+        // stubbed
+        return std::make_tuple(0, -512, 0);
+    }
+
+    /**
+     * Gets the current gyroscope state (angular rates about each three axis).
+     * Axis explained:
+     *   +x is the same direction as LEFT on D-pad.
+     *   +y is normal to the touch screen, pointing outward.
+     *   +z is the same direction as UP on D-pad.
+     * Orientation is determined by right-hand rule.
+     * Units:
+     *   1 unit of return value = (1/coef) deg/sec,
+     *   where coef is the return value of GetGyroscopeRawToDpsCoefficient().
+     * @note This should be called by the core emu thread to get a state set by the window thread.
+     * @todo Implement gyroscope input in front-end.
+     * @return std::tuple of (x, y, z)
+     */
+    std::tuple<s16, s16, s16> GetGyroscopeState() const {
+        // stubbed
+        return std::make_tuple(0, 0, 0);
+    }
+
+    /**
+     * Gets the coefficient for units conversion of gyroscope state.
+     * The conversion formula is r = coefficient * v,
+     * where v is angular rate in deg/sec,
+     * and r is the gyroscope state.
+     * @return float-type coefficient
+     */
+    f32 GetGyroscopeRawToDpsCoefficient() const {
+        return 14.375f; // taken from hw test, and gyroscope's document
+    }
+
     /**
      * Returns currently active configuration.
      * @note Accesses to the returned object need not be consistent because it may be modified in another thread