在Linux内核驱动中，构建一个存放如下结构体的队列： struct msg { u16 module_id; u16 cmd_id; u16 cmd_subid; u16 complete; u8 data[128]; }; 这个队列结构体为struct ring_buffer { int head; int tail; struct msg *data; int size; unsigned int capacity; };。 请给出操作这个队列的函数，包括初始化，入队，出队，注销等。 再构建两个函数，在函数中使用操作队列的函数完成如下功能： 函数一初始化msg结构体，将msg所有成员设置为常数（其中msg的complete成员设置为0），向msg的data数组内放置两个unsigned int 类型数据a和b，之后将msg结构体放入队列中，触发函数二，使用usleep_range()函数等待函数二将msg的complete成员设置为1后，获取函数二放入的c并还原成unsigned int 类型。 函数二需要从队列中取出msg，并进行解析：判断msg的module_id是否为0x1，如果不是，报错，如果是0x1,使用switch函数解析msg的cmd_id，再根据不同的cmd_id解析cmd_subid，具体解析内容为，取出在函数一向msg的data数组中放入的a和b，还原成unsigned int 类型数据，再将一个unsigned int 类型数据c=1000，放到msg的data数组内，之后，再将msg中的complete置1；请在驱动的probe函数中注册这个队列，在remove函数中注销队列，使用移位的方式放置和还原unsigned int类型数据。注意，全部的函数都需使用msg结构体指针修改msg成员，不要产生复制数据。

以下是操作队列的函数实现：

#include <linux/slab.h> // kmalloc, kfree
#include <linux/delay.h> // usleep_range

struct ring_buffer {
    int head;
    int tail;
    struct msg *data;
    int size;
    unsigned int capacity;
};

void init_ring_buffer(struct ring_buffer *buffer, int size) {
    buffer->head = 0;
    buffer->tail = 0;
    buffer->data = kmalloc(sizeof(struct msg) * size, GFP_KERNEL);
    buffer->size = size;
    buffer->capacity = size - 1;
}

void destroy_ring_buffer(struct ring_buffer *buffer) {
    kfree(buffer->data);
}

int is_ring_buffer_empty(struct ring_buffer *buffer) {
    return buffer->head == buffer->tail;
}

int is_ring_buffer_full(struct ring_buffer *buffer) {
    return ((buffer->tail + 1) & buffer->capacity) == buffer->head;
}

void ring_buffer_enqueue(struct ring_buffer *buffer, struct msg *msg) {
    buffer->data[buffer->tail] = *msg;
    buffer->tail = (buffer->tail + 1) & buffer->capacity;
}

void ring_buffer_dequeue(struct ring_buffer *buffer, struct msg *msg) {
    *msg = buffer->data[buffer->head];
    buffer->head = (buffer->head + 1) & buffer->capacity;
}

void wait_for_msg_complete(struct msg *msg) {
    while (!msg->complete) {
        usleep_range(1000, 2000);
    }
}

void set_msg_data(struct msg *msg, unsigned int a, unsigned int b) {
    msg->module_id = 0;
    msg->cmd_id = 0;
    msg->cmd_subid = 0;
    msg->complete = 0;
    *(unsigned int *)(msg->data) = a;
    *(unsigned int *)(msg->data + sizeof(unsigned int)) = b;
}

void process_msg(struct msg *msg) {
    if (msg->module_id != 0x1) {
        printk(KERN_ERR "Invalid module_id\n");
        return;
    }

    switch (msg->cmd_id) {
        case 1:
            switch (msg->cmd_subid) {
                case 1: {
                    unsigned int a = *(unsigned int *)(msg->data);
                    unsigned int b = *(unsigned int *)(msg->data + sizeof(unsigned int));
                    *(unsigned int *)(msg->data) = 1000;
                    msg->complete = 1;
                    break;
                }
                default:
                    printk(KERN_ERR "Invalid cmd_subid\n");
                    break;
            }
            break;
        default:
            printk(KERN_ERR "Invalid cmd_id\n");
            break;
    }
}

函数一和函数二如下：

void function_one(struct ring_buffer *buffer) {
    struct msg msg;
    set_msg_data(&msg, 1, 2);
    ring_buffer_enqueue(buffer, &msg);
}

void function_two(struct ring_buffer *buffer) {
    struct msg msg;
    ring_buffer_dequeue(buffer, &msg);
    process_msg(&msg);
}

在驱动的probe函数中注册这个队列：

struct ring_buffer buffer;

static int my_driver_probe(struct platform_device *pdev)
{
    init_ring_buffer(&buffer, 16);
    return 0;
}

static int my_driver_remove(struct platform_device *pdev)
{
    destroy_ring_buffer(&buffer);
    return 0;
}

static const struct of_device_id my_driver_of_match[] = {
    { .compatible = "my_driver", },
    {},
};
MODULE_DEVICE_TABLE(of, my_driver_of_match);

static struct platform_driver my_driver = {
    .probe  = my_driver_probe,
    .remove = my_driver_remove,
    .driver = {
        .name           = "my_driver",
        .of_match_table = my_driver_of_match,
        .owner          = THIS_MODULE,
    },
};
module_platform_driver(my_driver);

使用移位的方式放置和还原unsigned int类型数据，可以直接调用 `set_msg_data` 和 `process_msg` 函数中的代码实现。