关于线程（一）

   主要是怎么监控一个线程正在运行 用if（“线程”！= null）来断定正在运行。

   /// <summary>
        /// 创建循环线程 led_Start
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        static void led_Start()
        {
            int p;
            IntPtr gpiodriver = CreateFile("GIO1:", GENERIC_READ | GENERIC_WRITE, 0, 0, OPEN_EXISTING, 0, 0);
            int bytesReturned = 0;

            while (true)
            {
                for (int i = 0; i < 4; i++)
                {
                    p = 0x01 + i;

                    DeviceIoControl(gpiodriver, p, null, 0, null, 0, ref bytesReturned, IntPtr.Zero);
                    Thread.Sleep(200);
                    DeviceIoControl(gpiodriver, p + 3, null, 0, null, 0, ref bytesReturned, IntPtr.Zero);
                }

            }

        }

        private void button_stop_Click(object sender, EventArgs e)
        {
            IntPtr gpiodriver = CreateFile("GIO1:", GENERIC_READ | GENERIC_WRITE, 0, 0, OPEN_EXISTING, 0, 0);
            if (gpiodriver == (IntPtr)(-1))
            {
                MessageBox.Show("打开GPIO设备失败！");
            }
            else
            {
                if (led_start != null)
                {
                    led_start.Abort();
                    int bytesReturned = 0;
                    DeviceIoControl(gpiodriver, 0x04, null, 0, null, 0, ref bytesReturned, IntPtr.Zero);
                    DeviceIoControl(gpiodriver, 0x05, null, 0, null, 0, ref bytesReturned, IntPtr.Zero);
                    //DeviceIoControl(gpiodriver, 0x06, null, 0, null, 0, ref bytesReturned, IntPtr.Zero);
                    //DeviceIoControl(gpiodriver, 0x07, null, 0, null, 0, ref bytesReturned, IntPtr.Zero);
                }
                else
                {
                    int bytesReturned = 0;
                    DeviceIoControl(gpiodriver, 0x04, null, 0, null, 0, ref bytesReturned, IntPtr.Zero);
                    DeviceIoControl(gpiodriver, 0x05, null, 0, null, 0, ref bytesReturned, IntPtr.Zero);
                   
                }
            }
        }