using System;
using System.Runtime.InteropServices;

namespace NativeDll
{
/// <summary>
/// SerialPort 的摘要说明。
/// </summary>
public class SerialPort
{
#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;
public int ReadTotalTimeoutConstant;
public int WriteTotalTimeoutMultiplier;
public int WriteTotalTimeoutConstant;
}

[StructLayout(LayoutKind.Sequential)]
private struct OVERLAPPED
{
public int Internal;
public int InternalHigh;
public int Offset;
public int OffsetHigh;
public int hEvent;
}

[StructLayout(LayoutKind.Sequential)]
private struct COMSTAT
{
/*public int fCtsHold;
public int fDsrHold;
public int fRlsdHold;
public int fXoffHold;
public int fXoffSent;
public int fEof;
public int fTxim;
public int fReserved;
p