关于ST库函数的assert_param

只看该作者 · 2011-6-4 21:12

不少人问在ST官方的STM32的库函数里有很多assert_param是什么作用
比如下面的
assert_param(IS_ADC_ALL_PERIPH(ADCx));
assert_param(IS_ADC_IT(ADC_IT));
assert_param(IS_GPIO_ALL_PERIPH(GPIOx));
assert_param(IS_GPIO_MODE(GPIO_InitStruct->GPIO_Mode));assert_param(IS_GPIO_PIN(GPIO_InitStruct->GPIO_Pin));
这样的函数，几乎是带参数的函数前面都有调用assert_param
实际这是个调试函数，当你在调试程序时打开DEBUG参数assert_param才起作用。
assert_param是反映参数你在调用库函数传递的参数是错误的。
assert_param的原型定义在stm32f10x_conf.h 文件里
定义如下：
/* Exported macro ------------------------------------------------------------*/
#ifdef  DEBUG
/*******************************************************************************
* Macro Name    : assert_param
* Description : The assert_param macro is used for function's parameters check.
*                It is used only if the library is compiled in DEBUG mode.
* Input       : - expr: If expr is false, it calls assert_failed function
*                   which reports the name of the source file and the source
*                   line number of the call that failed.
*                   If expr is true, it returns no value.
* Return       : None
*******************************************************************************/
  #define assert_param(expr) ((expr) ? (void)0 : assert_failed((u8 *)__FILE__, __LINE__))
/* Exported functions ------------------------------------------------------- */
  void assert_failed(u8* file, u32 line);
#else
  #define assert_param(expr) ((void)0)
#endif /* DEBUG */
#endif /* __STM32F10x_CONF_H */

可以看到assert_param实际在DEBUG打开时就是assert_failed，关闭DEBUG时是空函数

assert_failed函数如下
#ifdef  DEBUG
/*******************************************************************************
* Function Name  : assert_failed
* Description : Reports the name of the source file and the source line number
*                where the assert_param error has occurred.
* Input       : - file: pointer to the source file name
*                - line: assert_param error line source number
* Output       : None
* Return       : None
*******************************************************************************/
void assert_failed(u8* file, u32 line)
{
  /* User can add his own implementation to report the file name and line number,
   ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
  //用户可以在这里添加错误信息:比如打印出出错的文件名和行号
  /* Infinite loop */
  while (1)
  {
  }
}
#endif