[RESOLVED] Marshalling Structure to kernel32.dll

[RaleTheBlade]

Very simple example but I cant seem to get it to work accurately, I have created a managed version of the DCB structure within the Windows.h header file:

    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto, Pack = 8, Size = 28)]
    internal struct DCB
    {
        public DWORD DCBlength; // sizeof(DCB)
        public DWORD BaudRate; // current baud rate
        public DWORD fBinary; // binary mode, no EOF check
        public DWORD fParity; // enable parity checking
        public DWORD fOutxCtsFlow; // CTS output flow control
        public DWORD fOutxDsrFlow; // DSR output flow control
        public DWORD fDtrControl; // DTR flow control type
        public DWORD fDsrSensitivity; // DSR sensitivity
        public DWORD fTXContinueOnXoff; // XOFF continues Tx
        public DWORD fOutX; // XON/XOFF out flow control
        public DWORD fInX; // XON/XOFF in flow control
        public DWORD fErrorChar; // enable error replacement
        public DWORD fNull; // enable null stripping
        public DWORD fRtsControl; // RTS flow control
        public DWORD fAbortOnError; // abort on error
        public DWORD fDummy2; // reserved
        public WORD wReserved; // not currently used
        public WORD XonLim; // transmit XON threshold
        public WORD 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 WORD wReserved1; // reserved; do not use
    }

The datatypes have been coerced with "using" statements to be as close to the Win32 data types Microsoft has been using when developing Win32 C++ application. ex. DWORD = System.UInt32 and CHAR = System.SByte.

Here is my function "prototype" for the function I am attempting to use:

        [DllImport("kernel32.dll", SetLastError = true)]
        private static unsafe extern bool GetCommState(SafeFileHandle hFile, DCB* lpDCB);

Seems ok to me... But when you call the GetCommState function passing in a handle to an open serial port, you end up getting back a DCB structure which has the first few fields properly set (BaudRate, DCBlength) but a few of the fields are really odd. For example:

fBinary = 6161
fParity = 134217728
fOutxCtsFlow = 524800

At first I thought it may have been a data misalignment problem. But I set the LayoutKind to Explicit and went through the structure and set the FieldOffset attribute for each member manually and it STILL was messed up. I cant seem to set the Parity, StopBits, and some of the other fields using the function SetCommState either since my DCB structure is messed up. Anyone got anyone ideas?