作業系統工程-Device

Table Of Content

tags: 作業系統工程 Operating System Programming note, 110-1, 2021

• 作業系統工程-Device
  • Table Of Content
  • Device 在 rtdef 中的定義

---

Device 在 rtdef 中的定義

struct rt_device
{
    struct rt_object          parent;   /**< inherit from rt_object */

    enum rt_device_class_type type;     /**< device type */
    rt_uint16_t               flag;     /**< device flag */
    rt_uint16_t               open_flag;/**< device open flag */

    rt_uint8_t                ref_count;/**< reference count */
    rt_uint8_t                device_id;/**< 0 - 255 */

    /* device call back */
    rt_err_t (*rx_indicate)(rt_device_t dev, rt_size_t size);
    rt_err_t (*tx_complete)(rt_device_t dev, void *buffer);

    // 操控 device 的 function
#ifdef RT_USING_DEVICE_OPS
    const struct rt_device_ops *ops;
#else
    /* common device interface */
    rt_err_t  (*init)   (rt_device_t dev);
    rt_err_t  (*open)   (rt_device_t dev, rt_uint16_t oflag);
    rt_err_t  (*close)  (rt_device_t dev);
    rt_size_t (*read)   (rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
    rt_size_t (*write)  (rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
    rt_err_t  (*control)(rt_device_t dev, int cmd, void *args);
#endif

#ifdef RT_USING_POSIX_DEVIO
    const struct dfs_file_ops *fops;
    struct rt_wqueue wait_queue;
#endif
    void *user_data; /**< device private data */
};

• 所以在 src 中的 device.c 就會有以下定義

#ifdef RT_USING_DEVICE_OPS // 當 device operation 被定義時
#define device_init     (dev->ops->init)
#define device_open     (dev->ops->open)
#define device_close    (dev->ops->close)
#define device_read     (dev->ops->read)
#define device_write    (dev->ops->write)
#define device_control  (dev->ops->control)
//就將 device 的變數設為 ops 的變數
#else
#define device_init     (dev->init)
#define device_open     (dev->open)
#define device_close    (dev->close)
#define device_read     (dev->read)
#define device_write    (dev->write)
#define device_control  (dev->control)
//否則就設為本來 dev 的變數
#endif /* RT_USING_DEVICE_OPS */