C#编程：运用DllImport驱动COM接口与Win32 API

using System;
using System.Runtime.InteropServices;
using System.IO;
using System.Reflection;
namespace testComApp
{
/// <summary>
/// SeriaCls 的摘要说明。
/// </summary>
public class clsCom
{
#region 申明要引用的和串口调用有关的API
//win32 api constants 
private const uint GENERIC_READ = 0x80000000;
private const uint GENERIC_WRITE = 0x40000000;
private const int OPEN_EXISTING = 3;
private const int INVALID_HANDLE_VALUE = -1;
private const int MAXBLOCK = 4096;
private const uint PURGE_TXABORT = 0x0001; // Kill the pending/current writes to the comm port. 
private const uint PURGE_RXABORT = 0x0002; // Kill the pending/current reads to the comm port. 
private const uint PURGE_TXCLEAR = 0x0004; // Kill the transmit queue if there. 
private const uint PURGE_RXCLEAR = 0x0008; // Kill the typeahead buffer if there. 
[StructLayout(LayoutKind.Sequential)]
private struct DCB
{
//taken from c struct in platform sdk 
public int DCBlength; // sizeof(DCB) 
public int BaudRate; // current baud rate 
public int fBinary; // binary mode, no EOF check 
public int fParity; // enable parity checking 

public int fOutxCtsFlow; // CTS output flow control 
public int fOutxDsrFlow; // DSR output flow control 
public int fDtrControl; // DTR flow control type 
public int fDsrSensitivity; // DSR sensitivity 
public int fTXContinueOnXoff; // XOFF continues Tx 
public int fOutX; // XON/XOFF out flow control 
public int fInX; // XON/XOFF in flow control 
public int fErrorChar; // enable error replacement 
public int fNull; // enable null stripping 
public int fRtsControl; // RTS flow control 
public int fAbortOnError; // abort on error 
public int fDummy2; // reserved 
public ushort wReserved; // not currently used 
public ushort XonLim; // transmit XON threshold 
public ushort XoffLim; // transmit XOFF threshold 
public byte ByteSize; // number of bits/byte, 4-8 
public byte Parity; // 0-4=no,odd,even,mark,space 
public byte StopBits; // 0,1,2 = 1, 1.5, 2 
public char XonChar; // Tx and Rx XON character 
public char XoffChar; // Tx and Rx XOFF character 
public char ErrorChar; // error replacement character 
public char EofChar; // end of input character 
public char EvtChar; // received event character 
public ushort wReserved1; // reserved; do not use 
}
[StructLayout(LayoutKind.Sequential)]
private struct COMMTIMEOUTS
{
public int ReadIntervalTimeout;
public int ReadTotalTimeoutMultiplier;