BLE协议栈入门三（Server端读写属性表）

以TI BLE协议栈为例，Server端对自己的属性表进行读写操作的函数Simple Profile Service Callbacks如下，下面两个回调是有GATT层的Lib调用：

Server端读属性表的回调函数

/*********************************************************************
 * @fn          simpleProfile_ReadAttrCB
 *
 * @brief       Read an attribute.
 *
 * @param       connHandle - connection message was received on
 * @param       pAttr - pointer to attribute
 * @param       pValue - pointer to data to be read
 * @param       pLen - length of data to be read
 * @param       offset - offset of the first octet to be read
 * @param       maxLen - maximum length of data to be read
 *
 * @return      Success or Failure
 */
static uint8 simpleProfile_ReadAttrCB( uint16 connHandle, gattAttribute_t *pAttr,
                            uint8 *pValue, uint8 *pLen, uint16 offset, uint8 maxLen )
{
  bStatus_t status = SUCCESS;

  // If attribute permissions require authorization to read, return error
  if ( gattPermitAuthorRead( pAttr->permissions ) )
  {
    // Insufficient authorization
    return ( ATT_ERR_INSUFFICIENT_AUTHOR );
  }

  // Make sure it's not a blob operation (no attributes in the profile are long)
  if ( offset > 0 )
  {
    return ( ATT_ERR_ATTR_NOT_LONG );
  }

  if ( pAttr->type.len == ATT_BT_UUID_SIZE )
  {
    // 16-bit UUID
    uint16 uuid = BUILD_UINT16( pAttr->type.uuid[0], pAttr->type.uuid[1]);
    switch ( uuid )
    {
      // No need for "GATT_SERVICE_UUID" or "GATT_CLIENT_CHAR_CFG_UUID" cases;
      // gattserverapp handles those reads

      // characteristics 1 and 2 have read permissions
      // characteritisc 3 does not have read permissions; therefore it is not
      //   included here
      // characteristic 4 does not have read permissions, but because it
      //   can be sent as a notification, it is included here
      case SIMPLEPROFILE_CHAR1_UUID:
        *pLen = 1;
        pValue[0] = *pAttr->pValue;
        break;
        
      default:
        // Should never get here! (characteristics 3 and 4 do not have read permissions)
        *pLen = 0;
        status = ATT_ERR_ATTR_NOT_FOUND;
        break;
    }
  }
  else
  {
    // 128-bit UUID
    *pLen = 0;
    status = ATT_ERR_INVALID_HANDLE;
  }

  return ( status );
}

Server端写属性表的回调函数

/*********************************************************************
* @fn      simpleProfile_WriteAttrCB
*
* @brief   Validate attribute data prior to a write operation
*
* @param   connHandle - connection message was received on
* @param   pAttr - pointer to attribute
* @param   pValue - pointer to data to be written
* @param   len - length of data
* @param   offset - offset of the first octet to be written
*
* @return  Success or Failure
*/
static bStatus_t simpleProfile_WriteAttrCB( uint16 connHandle, gattAttribute_t *pAttr,
                                uint8 *pValue, uint8 len, uint16 offset )
{
 bStatus_t status = SUCCESS;
 uint8 notifyApp = 0xFF;

 // If attribute permissions require authorization to write, return error
 if ( gattPermitAuthorWrite( pAttr->permissions ) )
 {
   // Insufficient authorization
   return ( ATT_ERR_INSUFFICIENT_AUTHOR );
 }

 if ( pAttr->type.len == ATT_BT_UUID_SIZE )
 {
   // 16-bit UUID
   uint16 uuid = BUILD_UINT16( pAttr->type.uuid[0], pAttr->type.uuid[1]);
   switch ( uuid )
   {
     case SIMPLEPROFILE_CHAR1_UUID:
       //Validate the value
       // Make sure it's not a blob oper
       if ( offset ==0 )
       {
         if ( len != 1 )
         {
           status = ATT_ERR_INVALID_VALUE_SIZE;
         }
       }
       else
       {
         status = ATT_ERR_ATTR_NOT_LONG;
       }

       //Write the value
       if ( status == SUCCESS )
       {
         uint8 *pCurValue = (uint8 *)pAttr->pValue;
         *pCurValue = pValue[0];

         if( pAttr->pValue == &simpleProfileChar1 )
         {
           notifyApp = SIMPLEPROFILE_CHAR1;
         }
       }

       break;

     case GATT_CLIENT_CHAR_CFG_UUID:
     	//处理给定客户端的客户端特性配置写入请求
       status = GATTServApp_ProcessCCCWriteReq( connHandle, pAttr, pValue, len,
                                                offset, GATT_CLIENT_CFG_NOTIFY );
       break;

     default:
       // Should never get here! (characteristics 2 and 4 do not have write permissions)
       status = ATT_ERR_ATTR_NOT_FOUND;
       break;
   }
 }
 else
 {
   // 128-bit UUID
   status = ATT_ERR_INVALID_HANDLE;
 }

 // If a charactersitic value changed then callback function to notify application of change
 // 写了属性表之后，调用simpleProfile的应用层回调函数，通知应用层
 if ( (notifyApp != 0xFF ) && simpleProfile_AppCBs && simpleProfile_AppCBs->pfnSimpleProfileChange )
 {
   simpleProfile_AppCBs->pfnSimpleProfileChange( notifyApp );
 }

 return ( status );
}

应用层写特征值变量的函数

/*********************************************************************
* @fn      SimpleProfile_SetParameter
*
* @brief   Set a Simple Profile parameter.
*
* @param   param - Profile parameter ID
* @param   len - length of data to right
* @param   value - pointer to data to write.  This is dependent on
*          the parameter ID and WILL be cast to the appropriate
*          data type (example: data type of uint16 will be cast to
*          uint16 pointer).
*
* @return  bStatus_t
*/
bStatus_t SimpleProfile_SetParameter( uint8 param, uint8 len, void *value )
{
 bStatus_t ret = SUCCESS;
 switch ( param )
 {
   case SIMPLEPROFILE_CHAR1:
     if ( len == sizeof ( uint8 ) )
     {
       simpleProfileChar1 = *((uint8*)value);
     }
     else
     {
       ret = bleInvalidRange;
     }
     break;

   case SIMPLEPROFILE_CHAR4:
     if ( len == sizeof ( uint8 ) )
     {
       simpleProfileChar4 = *((uint8*)value);

       // See if Notification has been enabled
       // 通常，默认情况下不会启用特征通知。客户端可以写入客户端特征配置描述符（CCCD）以启用/禁用通知。该调用（GATT_writeReq）被转换为服务器端的GATTServApp_ProcessCharCfg，以更改通知设置。
       GATTServApp_ProcessCharCfg( simpleProfileChar4Config, &simpleProfileChar4, FALSE,
                                   simpleProfileAttrTbl, GATT_NUM_ATTRS( simpleProfileAttrTbl ),
                                   INVALID_TASK_ID );
     }
     else
     {
       ret = bleInvalidRange;
     }
     break;

   case SIMPLEPROFILE_CHAR5:
     if ( len == SIMPLEPROFILE_CHAR5_LEN )
     {
       VOID osal_memcpy( simpleProfileChar5, value, SIMPLEPROFILE_CHAR5_LEN );
     }
     else
     {
       ret = bleInvalidRange;
     }
     break;

   default:
     ret = INVALIDPARAMETER;
     break;
 }

 return ( ret );
}

应用层读特征值变量的函数

/*********************************************************************
* @fn      SimpleProfile_GetParameter
*
* @brief   Get a Simple Profile parameter.
*
* @param   param - Profile parameter ID
* @param   value - pointer to data to put.  This is dependent on
*          the parameter ID and WILL be cast to the appropriate
*          data type (example: data type of uint16 will be cast to
*          uint16 pointer).
*
* @return  bStatus_t
*/
bStatus_t SimpleProfile_GetParameter( uint8 param, void *value )
{
bStatus_t ret = SUCCESS;
switch ( param )
{
  case SIMPLEPROFILE_CHAR1:
    *((uint8*)value) = simpleProfileChar1;
    break;

  case SIMPLEPROFILE_CHAR2:
    *((uint8*)value) = simpleProfileChar2;
    break;

  case SIMPLEPROFILE_CHAR3:
    *((uint8*)value) = simpleProfileChar3;
    break;

  case SIMPLEPROFILE_CHAR4:
    *((uint8*)value) = simpleProfileChar4;
    break;

  case SIMPLEPROFILE_CHAR5:
    VOID osal_memcpy( value, simpleProfileChar5, SIMPLEPROFILE_CHAR5_LEN );
    break;

  case SIMPLEPROFILE_CHAR6:
    VOID osal_memcpy( value, simpleProfileChar6, SIMPLEPROFILE_CHAR6_LEN );
    break;

  default:
    ret = INVALIDPARAMETER;
    break;
}

return ( ret );
}