使用STM8L101F3P芯片，用iar库函数，想实现最简单的按键中断，在库里有一函数
void EXTI_SetHalfPortSelection(EXTI_HalfPort_TypeDef EXTI_HalfPort,
                               FunctionalState NewState)
如图所示，
在使用这个函数的时候，EXTI_HalfPort_TypeDef EXTI_HalfPort可以使用上面提供的组合，
例如EXTI_HalfPort_B_LSB
可是FunctionalState NewState这个应该填什么进去呢，说明没有提供，直接填上十六进制数上去也不行，请教大家一下，谢谢...！
 
下面贴上直接在库里复制出的原函数
 
/**
  * @brief  Configure the half port interrupt selection.
  * @note   This function must be called once the port sensitivity is configured,
  *          otherwise this function call won't have any effect on the port external interrupt.
  * @param  EXTI_HalfPort The port part  to access (MSB or LSB).
  *          This parameter can be any combination of the following values:
  *            @arg EXTI_HalfPort_B_LSB:     Interrupt selector PB(3:0)
  *            @arg EXTI_HalfPort_B_MSB:     Interrupt selector PB(7:4)
  *            @arg EXTI_HalfPort_D_LSB:     Interrupt selector PE(3:0)
  *            @arg EXTI_HalfPort_D_MSB:     Interrupt selector PE(7:4)
  * @param  NewState  The external interrupt new state.
  * @retval None
  */
void EXTI_SetHalfPortSelection(EXTI_HalfPort_TypeDef EXTI_HalfPort,
                               FunctionalState NewState)
{
  /* Check function parameters */
  assert_param(IS_EXTI_HALFPORT(EXTI_HalfPort));
  assert_param(IS_FUNCTIONAL_STATE(NewState));


  if (NewState != DISABLE)
  {
    EXTI->CONF |= (uint8_t)EXTI_HalfPort; /* Enable port interrupt selector */
  }
  else /*NewState == DISABLE */
  {
    EXTI->CONF &= (uint8_t)(~(uint8_t)EXTI_HalfPort); /* Disable port interrupt selector */
  }
}