AP_HAL_Empty: add support for OpticalFlow

Void driver

libraries/AP_HAL_Empty/AP_HAL_Empty_Namespace.h

@@ -6,6 +6,7 @@ namespace Empty {
     class DigitalSource;
     class GPIO;
     class I2CDriver;
+    class OpticalFlow;
     class PrivateMember;
     class RCInput;
     class RCOutput;

libraries/AP_HAL_Empty/AP_HAL_Empty_Private.h

@@ -17,6 +17,7 @@
 #include "Semaphores.h"
 #include "Scheduler.h"
 #include "Util.h"
+#include "OpticalFlow.h"
 #include "PrivateMember.h"
 
 #endif // __AP_HAL_EMPTY_PRIVATE_H__

libraries/AP_HAL_Empty/HAL_Empty_Class.cpp

@@ -22,6 +22,7 @@ static RCInput rcinDriver;
 static RCOutput rcoutDriver;
 static Scheduler schedulerInstance;
 static Util utilInstance;
+static OpticalFlow opticalFlowDriver;
 
 HAL_Empty::HAL_Empty() :
     AP_HAL::HAL(
@@ -41,8 +42,9 @@ HAL_Empty::HAL_Empty() :
         &rcinDriver,
         &rcoutDriver,
         &schedulerInstance,
-        &utilInstance),
+        &utilInstance,
-    _member(new PrivateMember(123))
+        &opticalFlowDriver),
+    _member(new EmptyPrivateMember(123))
 {}
 
 void HAL_Empty::run(int argc, char* const argv[], Callbacks* callbacks) const

libraries/AP_HAL_Empty/OpticalFlow.h

@@ -0,0 +1,24 @@
+/*
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef __AP_HAL_EMPTY_OPTICALFLOW_H__
+#define __AP_HAL_EMPTY_OPTICALFLOW_H__
+
+class Empty::OpticalFlow : public AP_HAL::OpticalFlow {
+public:
+    void init(AP_HAL::OpticalFlow::Gyro_Cb) {return;};
+    bool read(Data_Frame& frame) {return false;};
+};
+
+#endif