STM8S105K6使用串口中断发送，如何清发送完成中断TXE呢？

STM8S105K6使用串口中断发送，如何清发送完成中断TXE？找了一个例程
INTERRUPT_HANDLER(UART2_TX_IRQHandler, 20){        // 写操作自动清中断，因此可以不用显式清中断      
       UART2_ClearITPendingBit(UART2_IT_TXE);                 
       // 从写缓冲中写出1字节        UART2_SendData8(writ_buffer[writ_idx++]);        
     // 全部写完、关写中断、置写完成标志（同步化处理）      
      if( writ_idx == writ_len ) {                UART2_ITConfig(UART2_IT_TXE, DISABLE);                writ_ok = 1;        }
}
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这个例程使用UART2_ClearITPendingBit(UART2_IT_TXE); 来清发送完成中断，会导致进入断言while(1)循环void assert_failed(u8* file, u32 line)
查看UART2_ClearITPendingBit函数说明，发现该函数不能请TXE和TC中断，给出的解决方案是UART2_SendData8() or UART2_SendData9()，写数据的方式。单带来的问题是，实际发送数据时，我的最后一个字节发送完了怎么办，没发清中断标志，又无数可发？？
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/**
  * @brief  Clears the UART2 pending flags.
  * @param  UART2_IT specifies the pending bit to clear
  *         This parameter can be one of the following values:
  *         - UART2_IT_LBDF:  LIN Break detection interrupt
  *         - UART2_IT_LHDF:  LIN Header detection interrupt
  *         - UART2_IT_RXNE: Receive Data register not empty interrupt.
  * @note
  *         - PE (Parity error), FE (Framing error), NE (Noise error),
  *           OR (OverRun error) and IDLE (Idle line detected) pending bits are
  *           cleared by software sequence: a read operation to UART2_SR register
  *           (UART2_GetITStatus()) followed by a read operation to UART2_DR register
  *           (UART2_ReceiveData8() or UART2_ReceiveData9()).
  *            
  *         - RXNE pending bit can be also cleared by a read to the UART2_DR
  *           register (UART2_ReceiveData8() or UART2_ReceiveData9()).
  *              
  *         - TC (Transmit complete) pending bit can be cleared by software
  *           sequence: a read operation to UART2_SR register
  *           (UART2_GetITStatus()) followed by a write operation to UART2_DR
  *           register (UART2_SendData8()or UART2_SendData9()).
  *               
  *         - TXE pending bit is cleared only by a write to the UART2_DR register
  *           (UART2_SendData8() or UART2_SendData9()).
  * @retval None
  */
void UART2_ClearITPendingBit(UART2_IT_TypeDef UART2_IT)