【小白求助】RT_USING_POSIX_STDIO这个宏是什么意思？

发布于 2022-09-18 09:31:06 浏览：713 订阅该版

![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20220918/9c9e7aab0baa0c8461ddf2afdde19dff.png)
最近在使用segger_rtt软件包的时候对接到瑞萨console，在控制台输入命令没有反应，然后使用潘多拉板没什么问题，并且debug定位到在`finsh_getchar()`这个函数这，瑞萨和潘多拉的设计略有不同，代码如下：

```c
// 潘多拉STM32L475开发板

static int finsh_getchar(void)
{
#ifdef RT_USING_DEVICE
#ifdef RT_USING_POSIX
    return getchar();
#else
    char ch = 0;

RT_ASSERT(shell != RT_NULL);
    while (rt_device_read(shell->device, -1, &ch, 1) != 1)
        rt_sem_take(&shell->rx_sem, RT_WAITING_FOREVER);

return (int)ch;
#endif
#else
    extern char rt_hw_console_getchar(void);
    return rt_hw_console_getchar();
#endif
}
```

```c
// 瑞萨RA6M4
int finsh_getchar(void)
{
#ifdef RT_USING_DEVICE
    char ch = 0;
#ifdef RT_USING_POSIX_STDIO
    if(read(STDIN_FILENO, &ch, 1) > 0)
    {
        return ch;
    }
    else
    {
        return -1; /* EOF */
    }
#else
    rt_device_t device;

RT_ASSERT(shell != RT_NULL);

device = shell->device;
    if (device == RT_NULL)
    {
        return -1; /* EOF */
    }

while (rt_device_read(device, -1, &ch, 1) != 1)
    {
        rt_sem_take(&shell->rx_sem, RT_WAITING_FOREVER);
        if (shell->device != device)
        {
            device = shell->device;
            if (device == RT_NULL)
            {
                return -1;
            }
        }
    }
    return ch;
#endif /* RT_USING_POSIX_STDIO */
#else
    extern char rt_hw_console_getchar(void);
    return rt_hw_console_getchar();
#endif /* RT_USING_DEVICE */
}
```

求教：`RT_USING_POSIX_STDIO`和`RT_USING_POSIX`这两个宏有什么区别，主要是对`RT_USING_POSIX_STDIO`这个宏进行解释，麻烦各位大佬了