RT-Thread ---- 控制台功能的实现

一、准备

1.1 、 安装putty终端，将其配置为使用 com 串口，配置方法：https://blog.csdn.net/Galdys/article/details/23922531。

二、实现

2.1、rt_kprintf()函数的实现

其实现的源码如下：

/**
 * This function will print a formatted string on system console
 *
 * @param fmt the format
 */
void rt_kprintf(const char *fmt, ...)   //c语言中的可变参数列表
{
    va_list args;
    rt_size_t length;
    static char rt_log_buf[RT_CONSOLEBUF_SIZE];

    va_start(args, fmt);
    /* the return value of vsnprintf is the number of bytes that would be
     * written to buffer had if the size of the buffer been sufficiently
     * large excluding the terminating null byte. If the output string
     * would be larger than the rt_log_buf, we have to adjust the output
     * length. */
    length = rt_vsnprintf(rt_log_buf, sizeof(rt_log_buf) - 1, fmt, args);
    if (length > RT_CONSOLEBUF_SIZE - 1)
        length = RT_CONSOLEBUF_SIZE - 1;
#ifdef RT_USING_DEVICE
    if (_console_device == RT_NULL)
    {
        rt_hw_console_output(rt_log_buf);
    }
    else
    {
        rt_uint16_t old_flag = _console_device->open_flag;

        _console_device->open_flag |= RT_DEVICE_FLAG_STREAM;
        rt_device_write(_console_device, 0, rt_log_buf, length);
        _console_device->open_flag = old_flag;
    }
#else
    rt_hw_console_output(rt_log_buf);
#endif
    va_end(args);
}
RTM_EXPORT(rt_kprintf);
#endif

2.11、