fix #53: add GattClient::onHVX() and GattHVXCallbackParams

ble/GattCallbackParamTypes.h

@@ -75,4 +75,12 @@ struct GattReadAuthCallbackParams {
                                                   * request is to proceed; false otherwise. */
 };
 
+/* For encapsulating handle-value update events (notifications or indications) generated at the remote server. */
+struct GattHVXCallbackParams {
+  GattAttribute::Handle_t  handle; /**< Attribute Handle to which the HVx operation applies. */
+  HVXType_t                type;   /**< Indication or Notification, see @ref HVXType_t. */
+  uint16_t                 len;    /**< Attribute data length. */
+  const uint8_t           *data;   /**< Attribute data, variable length. */
+};
+
 #endif /*__GATT_CALLBACK_PARAM_TYPES_H__*/

ble/GattClient.h

@@ -34,6 +34,8 @@ public:
 
     typedef void (*WriteCallback_t)(const GattWriteCallbackParams *params);
 
+    typedef void (*HVXCallback_t)(const GattHVXCallbackParams *params);
+
     /*
      * The following functions are meant to be overridden in the platform-specific sub-class.
      */
@@ -263,6 +265,15 @@ public:
         /* default implementation; override this API if this capability is supported. */
     }
 
+    /**
+     * Setup a callback for when GattClient receives an update event
+     * corresponding to a change in value of a characteristic on the remote
+     * GattServer.
+     */
+    void onHVX(HVXCallback_t callback) {
+        onHVXCallback = callback;
+    }
+
 protected:
     GattClient() {
         /* empty */
@@ -282,9 +293,16 @@ public:
         }
     }
 
+    void processHVXEvent(const GattHVXCallbackParams *params) {
+        if (onHVXCallback) {
+            onHVXCallback(params);
+        }
+    }
+
 protected:
     ReadCallback_t  onDataReadCallback;
     WriteCallback_t onDataWriteCallback;
+    HVXCallback_t   onHVXCallback;
 
 private:
     /* disallow copy and assignment */

ble/blecommon.h

@@ -129,6 +129,11 @@ enum ble_error_t {
 /** @brief Default MTU size. */
 static const unsigned BLE_GATT_MTU_SIZE_DEFAULT = 23;
 
+enum HVXType_t {
+    BLE_HVX_NOTIFICATION = 0x01,  /**< Handle Value Notification. */
+    BLE_HVX_INDICATION   = 0x02,  /**< Handle Value Indication. */
+};
+
 #ifdef __cplusplus
 }
 #endif