有关多sensor设备的module定义结构体自调用的疑惑

发布于 2021-03-24 11:23:14 浏览：1316 订阅该版

module 的结构体定义如下
```c
struct rt_sensor_module
{
    rt_mutex_t            lock;                      /* The module lock */

rt_sensor_t           sen[RT_SENSOR_MODULE_MAX]; /* The module contains a list of sensors */
    rt_uint8_t            sen_num;                   /* Number of sensors contained in the module */
};
```
Sensor 设备的结构体如下所示：
```c
struct rt_sensor_device
{
    struct rt_device             parent;    /* The standard device */

struct rt_sensor_info        info;      /* The sensor info data */
    struct rt_sensor_config      config;    /* The sensor config data */

void                        *data_buf;  /* The buf of the data received */
    rt_size_t                    data_len;  /* The size of the data received */

const struct rt_sensor_ops  *ops;       /* The sensor ops */

struct rt_sensor_module     *module;    /* The sensor module */

rt_err_t (*irq_handle)(rt_sensor_t sensor);  /* Called when an interrupt is generated, registered by the driver */
};
typedef struct rt_sensor_device *rt_sensor_t;      //标记1
```
以上是教程提供的sensor设备定义，
我疑惑的是sensor结构体定义的`struct rt_sensor_module`型指针它的定义里又包含了结构体指针类型`rt_sensor_t`，
这个指针类型不是在`struct rt_sensor_device`完成定义后定义的吗？

（标记1）为什么可以提前引用呢？还有这两个结构体的定义顺序怎么排都觉得有问题。
有点罗生门啊！