STM32 USB CDC program transfer "integer multiple" problems occur when the size of the data packet

Program transfer using USB CDC generated Stm32CubeMX 5.4 "integral multiple" packet size (usbd_cdc.h has: #define USB_HS_MAX_PACKET_SIZE 512U) problems when data.

main (), if used are:

while (1)
{
    /* USER CODE END WHILE */
    while(CDC_Transmit_HS(UserTxBuffer,49*1024) != USBD_OK);//49K
｝

Because 49K = 512Bytes * 98, so libusb-win32 will not be able to receive, so it changes the original function, that is, the statement is sent to remove the empty package:

usbd_cdc.c natively function:

//USBD_CDC_DataIn()发送完成中断的回调函数
static uint8_t  USBD_CDC_DataIn (USBD_HandleTypeDef *pdev, uint8_t epnum)
{
  USBD_CDC_HandleTypeDef *hcdc = (USBD_CDC_HandleTypeDef*)pdev->pClassData;
  PCD_HandleTypeDef *hpcd = pdev->pData;

  if(pdev->pClassData != NULL)
  { 
    if((pdev->ep_in[epnum].total_length > 0U) && ((pdev->ep_in[epnum].total_length % hpcd->IN_ep[epnum].maxpacket) == 0U))
    {
      /* Update the packet total length */
      pdev->ep_in[epnum].total_length = 0U;

      /* Send ZLP *///发送空包
      USBD_LL_Transmit (pdev, epnum, NULL, 0U);
	}
    else
    {
      hcdc->TxState = 0U;
    }
    return USBD_OK;
  }
  else
  {
    return USBD_FAIL;
  }
}

Modified:

//USBD_CDC_DataIn()发送完成中断的回调函数
static uint8_t  USBD_CDC_DataIn (USBD_HandleTypeDef *pdev, uint8_t epnum)
{
  USBD_CDC_HandleTypeDef *hcdc = (USBD_CDC_HandleTypeDef*)pdev->pClassData;
  PCD_HandleTypeDef *hpcd = pdev->pData;

  if(pdev->pClassData != NULL)
  { //stm32的原生函数中已经做了整数倍MAX_PACKET_SIZE的处理了
	//但好象并不需要额外再发送一个空包表示本次发送结束标志,发送了空包后,libusb-win反而认为是接收到了一个新的包
	//所以做了以下的修改
    if((pdev->ep_in[epnum].total_length > 0U) && ((pdev->ep_in[epnum].total_length % hpcd->IN_ep[epnum].maxpacket) == 0U))
    {
//      /* Update the packet total length */
//      pdev->ep_in[epnum].total_length = 0U;//这语句注释掉

//      /* Send ZLP *///发送空包
//      USBD_LL_Transmit (pdev, epnum, NULL, 0U);//这语句注释掉
		hcdc->TxState = 0U; //添加这语句
    }
    else
    {
      hcdc->TxState = 0U;
    }
    return USBD_OK;
  }
  else
  {
    return USBD_FAIL;
  }
}