HAL_Empty: fixed I2CDriver for use in Linux subtypes

libraries/AP_HAL_Empty/I2CDriver.cpp

@@ -35,4 +35,14 @@ uint8_t I2CDriver::readRegisters(uint8_t addr, uint8_t reg,
     return 1;
 }
 
+#if CONFIG_HAL_BOARD == HAL_BOARD_LINUX
+uint8_t I2CDriver::readRegistersMultiple(uint8_t addr, uint8_t reg,
+                                         uint8_t len, uint8_t count, 
+                                         uint8_t* data)
+{
+    memset(data, 0, len*count);
+    return 1;
+}
+#endif
+
 uint8_t I2CDriver::lockup_count() {return 0;}

libraries/AP_HAL_Empty/I2CDriver.h

@@ -7,29 +7,41 @@
 class Empty::I2CDriver : public AP_HAL::I2CDriver {
 public:
     I2CDriver(AP_HAL::Semaphore* semaphore) : _semaphore(semaphore) {}
-    void begin();
-    void end();
-    void setTimeout(uint16_t ms);
-    void setHighSpeed(bool active);
+    void begin() override;
+    void end() override;
+    void setTimeout(uint16_t ms) override;
+    void setHighSpeed(bool active) override;
 
     /* write: for i2c devices which do not obey register conventions */
-    uint8_t write(uint8_t addr, uint8_t len, uint8_t* data);
+    uint8_t write(uint8_t addr, uint8_t len, uint8_t* data) override;
+    
     /* writeRegister: write a single 8-bit value to a register */
-    uint8_t writeRegister(uint8_t addr, uint8_t reg, uint8_t val);
+    uint8_t writeRegister(uint8_t addr, uint8_t reg, uint8_t val) override;
+    
     /* writeRegisters: write bytes to contigious registers */
     uint8_t writeRegisters(uint8_t addr, uint8_t reg,
-                                   uint8_t len, uint8_t* data);
+                           uint8_t len, uint8_t* data) override;
 
     /* read: for i2c devices which do not obey register conventions */
-    uint8_t read(uint8_t addr, uint8_t len, uint8_t* data);
+    uint8_t read(uint8_t addr, uint8_t len, uint8_t* data) override;
+    
     /* readRegister: read from a device register - writes the register,
      * then reads back an 8-bit value. */
-    uint8_t readRegister(uint8_t addr, uint8_t reg, uint8_t* data);
+    uint8_t readRegister(uint8_t addr, uint8_t reg, uint8_t* data) override;
+    
     /* readRegister: read contigious device registers - writes the first 
      * register, then reads back multiple bytes */
     uint8_t readRegisters(uint8_t addr, uint8_t reg,
-                                  uint8_t len, uint8_t* data);
-
+                          uint8_t len, uint8_t* data) override;
+
+#if CONFIG_HAL_BOARD == HAL_BOARD_LINUX
+    /* readRegistersMultiple: read contigious device registers. 
+       Equivalent to count calls to readRegisters() */
+    virtual uint8_t readRegistersMultiple(uint8_t addr, uint8_t reg,
+                                          uint8_t len, uint8_t count, 
+                                          uint8_t* data) override;
+#endif
+    
     uint8_t lockup_count();
 
     AP_HAL::Semaphore* get_semaphore() { return _semaphore; }