HAL_DMA_IRQHandler 代码分析

*hdma=&hdma_usart1_tx

void HAL_DMA_IRQHandler(DMA_HandleTypeDef *hdma)
{
  uint32_t flag_it = hdma->DmaBaseAddress->ISR;  // 获取DMA1的ISR
  uint32_t source_it = hdma->Instance->CCR;          //获取UART1的CCR寄存器
  
  /* Half Transfer Complete Interrupt management ******************************/
  if (((flag_it & (DMA_FLAG_HT1 << hdma->ChannelIndex)) != RESET) && ((source_it & DMA_IT_HT) != RESET))
  {
    /* Disable the half transfer interrupt if the DMA mode is not CIRCULAR */
    if((hdma->Instance->CCR & DMA_CCR_CIRC) == 0U)
    {
      /* Disable the half transfer interrupt */
      __HAL_DMA_DISABLE_IT(hdma, DMA_IT_HT);
    }
    /* Clear the half transfer complete flag */
    __HAL_DMA_CLEAR_FLAG(hdma, __HAL_DMA_GET_HT_FLAG_INDEX(hdma));

    /* DMA peripheral state is not updated in Half Transfer */
    /* but in Transfer Complete case */

    if(hdma->XferHalfCpltCallback != NULL)
    {
      /* Half transfer callback */
      hdma->XferHalfCpltCallback(hdma);
    }
  }

  /* Transfer Complete Interrupt management ***********************************/
  else if (((flag_it & (DMA_FLAG_TC1 << hdma->ChannelIndex)) != RESET) && ((source_it & DMA_IT_TC) != RESET))
  {
    if((hdma->Instance->CCR & DMA_CCR_CIRC) == 0U)
    {
      /* Disable the transfer complete and error interrupt */
      __HAL_DMA_DISABLE_IT(hdma, DMA_IT_TE | DMA_IT_TC);  

      /* Change the DMA state */
      hdma->State = HAL_DMA_STATE_READY;
    }
    /* Clear the transfer complete flag */
      __HAL_DMA_CLEAR_FLAG(hdma, __HAL_DMA_GET_TC_FLAG_INDEX(hdma));

    /* Process Unlocked */
    __HAL_UNLOCK(hdma);

    if(hdma->XferCpltCallback != NULL)
    {
      /* Transfer complete callback */
      hdma->XferCpltCallback(hdma);
    }
  }

  /* Transfer Error Interrupt management **************************************/
  else if (( RESET != (flag_it & (DMA_FLAG_TE1 << hdma->ChannelIndex))) && (RESET != (source_it & DMA_IT_TE)))
  {
    /* When a DMA transfer error occurs */
    /* A hardware clear of its EN bits is performed */
    /* Disable ALL DMA IT */
    __HAL_DMA_DISABLE_IT(hdma, (DMA_IT_TC | DMA_IT_HT | DMA_IT_TE));

    /* Clear all flags */
    hdma->DmaBaseAddress->IFCR = (DMA_ISR_GIF1 << hdma->ChannelIndex);

    /* Update error code */
    hdma->ErrorCode = HAL_DMA_ERROR_TE;

    /* Change the DMA state */
    hdma->State = HAL_DMA_STATE_READY;

    /* Process Unlocked */
    __HAL_UNLOCK(hdma);

    if (hdma->XferErrorCallback != NULL)
    {
      /* Transfer error callback */
      hdma->XferErrorCallback(hdma);
    }
  }
  return;
}