STM32Cube_FW_F1_V1.0.0固件库学习（四）外部中断 中

      /*--------------------- EXTI Mode Configuration ------------------------*/
      /* Configure the External Interrupt or event for the current IO */
      if((GPIO_Init->Mode & EXTI_MODE) == EXTI_MODE) 
      {
        /* Enable AFIO Clock */
        __HAL_RCC_AFIO_CLK_ENABLE();
        temp = AFIO->EXTICR[position >> 2];
        CLEAR_BIT(temp, ((uint32_t)0x0F) << (4 * (position & 0x03)));
        SET_BIT(temp, (GPIO_GET_INDEX(GPIOx)) << (4 * (position & 0x03)));
        AFIO->EXTICR[position >> 2] = temp;
        

        /* Configure the interrupt mask */
        if((GPIO_Init->Mode & GPIO_MODE_IT) == GPIO_MODE_IT)
        {
          SET_BIT(EXTI->IMR, iocurrent); 
        } 
        else
        {
          CLEAR_BIT(EXTI->IMR, iocurrent); 
        } 
        
        /* Configure the event mask */
        if((GPIO_Init->Mode & GPIO_MODE_EVT) == GPIO_MODE_EVT)
        {
          SET_BIT(EXTI->EMR, iocurrent); 
        } 
        else
        {
          CLEAR_BIT(EXTI->EMR, iocurrent); 
        }
        
        /* Enable or disable the rising trigger */
        if((GPIO_Init->Mode & RISING_EDGE) == RISING_EDGE)
        {
          SET_BIT(EXTI->RTSR, iocurrent); 
        } 
        else
        {
          CLEAR_BIT(EXTI->RTSR, iocurrent); 
        }
        
        /* Enable or disable the falling trigger */
        if((GPIO_Init->Mode & FALLING_EDGE) == FALLING_EDGE)
        {
          SET_BIT(EXTI->FTSR, iocurrent); 
        } 
        else
        {
          CLEAR_BIT(EXTI->FTSR, iocurrent); 
        }
      }