串口中断接收数据，缓冲区

//应用层获取数据
int tf_luna_get_originaldata(rt_device_t device, int *dist, int *amp)
{
    #if 1
    int ret;
    uint8_t buf[9] = {0};
    //rt_device_write(device, 0, "11", 2);//新雷达不需要发指令，就可以接收数据
    rt_device_control(device, RT_DEVICE_CTRL_CLEAN_BUF, 0);
    rt_thread_mdelay(20);
    for (size_t i = 0; i < 3; i++)
    {
        rt_device_control(device, RT_DEVICE_CTRL_GET_BUF_LEN, &ret);
        if (ret == sizeof(buf))
            break;
        rt_thread_mdelay(10);
    }
    ret = rt_device_read(device, 0, buf, sizeof(buf));//这个位置
    rt_kprintf("ret = %d\n", ret);
    rt_kprintf("buf = %x %x %x %x %x %x %x %x %x\n", buf[0], buf[1], buf[2], buf[3], buf[4], buf[5], buf[6], buf[7], buf[8]);
    if (ret == 9)
    {
        if (buf[0] == 0x59 && buf[1] == 0x59) // 简单校验头部
        {
            *dist = buf[3] << 8;
            *dist |= buf[2];
            rt_kprintf("hua_dist: %d\n", *dist);
            *amp = buf[5] << 8;
            *amp |= buf[4];
              rt_kprintf("hua_amp: %d\n", *amp);
            return 0;
        }
    }
 }

//串口中断
rt_inline int _serial_int_rx(struct rt_serial_device *serial, rt_uint8_t *data, int length)
{
    //length 初始值为9
    int size;
    struct rt_serial_rx_fifo* rx_fifo;
    RT_ASSERT(serial != RT_NULL);
    size = length;
    rx_fifo = (struct rt_serial_rx_fifo*) serial->serial_rx;
    RT_ASSERT(rx_fifo != RT_NULL);
    /* read from software FIFO */
    while (length)
    {
        int ch;
        rt_base_t level;
        /* disable interrupt  没有数据*/
        level = rt_hw_interrupt_disable();
        /* there's no data: */
        if ((rx_fifo->get_index == rx_fifo->put_index) && (rx_fifo->is_full == RT_FALSE)) //这个判断没有成立，所以返回的是0，没用数据
        {
            /* no data, enable interrupt and break out */
            rt_hw_interrupt_enable(level);
            break;
        }
        /* otherwise there's the data:  有数据 */
        ch = rx_fifo->buffer[rx_fifo->get_index];
        rx_fifo->get_index += 1;
        if (rx_fifo->get_index >= serial->config.bufsz) rx_fifo->get_index = 0;
        if (rx_fifo->is_full == RT_TRUE)
        {
            rx_fifo->is_full = RT_FALSE;
        }
        /* enable interrupt */
        rt_hw_interrupt_enable(level);
        *data = ch & 0xff;
        data ++; length --;
    }
    return size - length;
}