使用宏来简化，在Nordic52832 的sdk17.0.2中添加自定义Service和attribute

sdk17.0.2附带的example中，各种类型和函数等都过度包装了，一个很简单的东西，定义了一层又一层，很容易让人看的头皮发麻。
为了降低添加Service和处理各种handler的难度，使用宏来简化添加自定义Service和attribute

typedef struct ble_bas_s ble_bas_t;

typedef struct
{
    ble_bas_evt_handler_t        evt_handler;                    
    bool                         support_notification;         
    ble_srv_report_ref_t       * p_report_ref;                 
    uint8_t                      initial_batt_level;             
    ble_srv_cccd_security_mode_t battery_level_char_attr_md;     
    ble_gap_conn_sec_mode_t      battery_level_report_read_perm; 
} ble_bas_init_t;

struct ble_bas_s
{
    ble_bas_evt_handler_t    evt_handler;            /**< Event handler to be called for handling events in the Battery Service. */
    uint16_t                 service_handle;            /**< Handle of Battery Service (as provided by the BLE stack). */
    ble_gatts_char_handles_t battery_level_handles;     /**< Handles related to the Battery Level characteristic. */
    uint16_t                 report_ref_handle;         /**< Handle of the Report Reference descriptor. */
    uint8_t                  battery_level_last;        /**< Last Battery Level measurement passed to the Battery Service. */
    bool                     is_notification_supported; /**< TRUE if notification of Battery Level is supported. */
};

typedef struct
{
    ble_bas_evt_type_t evt_type;    /**< Type of event. */
    uint16_t           conn_handle; /**< Connection handle. */
} ble_bas_evt_t;

typedef enum
{
    BLE_BAS_EVT_NOTIFICATION_ENABLED, /**< Battery value notification enabled event. */
    BLE_BAS_EVT_NOTIFICATION_DISABLED /**< Battery value notification disabled event. */
} ble_bas_evt_type_t;

static void services_init(void)

memset(&bas_init_obj, 0, sizeof(bas_init_obj));
//BLE_BAS_DEF(m_bas);                                     /**< Battery service instance. */
err_code = pvt_ble_bas_init(&m_bas, &bas_init_obj);
APP_ERROR_CHECK(err_code);//需要调用pvt_ble_bas_init返回值,pvt_ble_bas_init必须加入return err_code。

uint32_t pvt_ble_bas_init(ble_bas_t * p_bas, const ble_bas_init_t * p_bas_init)

ble_bas_init_t          bas_init_obj;
bas_init_obj.support_notification = true;
bas_init_obj.p_report_ref         = NULL;
bas_init_obj.initial_batt_level   = 100;
bas_init_obj.evt_handler          = on_bas_evt;//在services_init加上这行代码,不会有bas实时数据
err_code = msy_ble_bas_init(&m_bas, &bas_init_obj);
// APP_ERROR_CHECK(err_code);
return err_code;//尤为重要

ret_code_t msy_ble_bas_init(ble_bas_t * p_bas, const ble_bas_init_t * p_bas_init)

// Initialize service structure
p_bas->evt_handler               = p_bas_init->evt_handler;
p_bas->is_notification_supported = p_bas_init->support_notification;
p_bas->battery_level_last        = INVALID_BATTERY_LEVEL;
// Add service
BLE_UUID_BLE_ASSIGN(ble_uuid, BLE_UUID_BATTERY_SERVICE);
err_code = sd_ble_gatts_service_add(BLE_GATTS_SRVC_TYPE_PRIMARY, 
                                    &ble_uuid, 
                                    &p_bas->service_handle);
VERIFY_SUCCESS(err_code);
// Add battery level characteristic
err_code = battery_level_char_add(p_bas, p_bas_init);
return err_code;

static ret_code_t battery_level_char_add(ble_bas_t * p_bas, const ble_bas_init_t * p_bas_init)

    ble_gatts_char_md_t char_md;
    ble_gatts_attr_md_t cccd_md;
    ble_gatts_attr_t    attr_char_value;
    ble_uuid_t          ble_uuid;
    ble_gatts_attr_md_t attr_md;
   
    // Add Battery Level characteristic
    if (p_bas->is_notification_supported)
        memset(&cccd_md, 0, sizeof(cccd_md));
        
    memset(&char_md, 0, sizeof(char_md));
    BLE_UUID_BLE_ASSIGN(ble_uuid, BLE_UUID_BATTERY_LEVEL_CHAR);
    
    memset(&attr_md, 0, sizeof(attr_md));
   initial_battery_level = p_bas_init->initial_batt_level;
   
   memset(&attr_char_value, 0, sizeof(attr_char_value));
   err_code = sd_ble_gatts_characteristic_add(p_bas->service_handle, &char_md,
                                               &attr_char_value,
                                               &p_bas->battery_level_handles);
  
  if (p_bas_init->p_report_ref != NULL)
        // Add Report Reference descriptor
        BLE_UUID_BLE_ASSIGN(ble_uuid, BLE_UUID_REPORT_REF_DESCR);
        memset(&attr_md, 0, sizeof(attr_md));
       
        init_len = ble_srv_report_ref_encode(encoded_report_ref, p_bas_init->p_report_ref);
        memset(&attr_char_value, 0, sizeof(attr_char_value));
        err_code = sd_ble_gatts_descriptor_add(p_bas->battery_level_handles.value_handle,
                                              &attr_char_value,
                                              &p_bas->report_ref_handle);