DllImport on c#

Question

How do I access the functions of a C++ DLL in C#

Here are the prototypes from the DLL:

NOMANGLE int CCONV SSPSendCommand (SSP_COMMAND * cmd, SSP_COMMAND_INFO * sspInfo);
NOMANGLE int CCONV OpenSSPComPort (SSP_COMMAND * cmd);
NOMANGLE int CCONV OpenSSPComPort2 (SSP_COMMAND * cmd);
NOMANGLE int CCONV OpenSSPComPortUSB (SSP_COMMAND * cmd);
NOMANGLE int CCONV CloseSSPComPort (void);
NOMANGLE int CCONV CloseSSPComPort2 (void);
NOMANGLE int CCONV CloseSSPComPortUSB (void);
NOMANGLE int CCONV DownloadFileToTarget (char * szFilename, int cPort, unsigned char sspAddress);
NOMANGLE long CCONV GetRamDownloadStatus (RAM_UPDATE_STATUS * rmData);
NOMANGLE int CCONV SetPortCloseOption (unsigned int md);
NOMANGLE int CCONV OpenCCTComPort (int PortNumber);
NOMANGLE int CCONV CloseCCTComPort (void);
NOMANGLE int CCONV CCTSendPacket (unsigned char * pkt, unsigned char * length);

In C# I am attempting this:

[DllImport ("ITLSSPProc.dll")]
private extern static IntPtr SSP_COMMAND ();

[DllImport ("ITLSSPProc.dll")]
private static extern int OpenSSPComPort (SSP_COMMAND smd);

But it is giving me an error. What am I doing wrong? Thanks in advance

Answer 1

At least one error is SSP_COMMAND isn't a function. It's a type. [DllImport] only imports functions. Either treat it as an opaque IntPtr or create an appropriate struct representation of it.

Using it as an opaque IntPtr :

[DllImport ("ITLSSPProc.dll")]
private static extern int OpenSSPComPort (IntPtr smd);

For using a structure, see Passing Structures from MSDN and define a struct SSP_COMMAND in C#. (This link contains everything required to get started, including relevant samples).

Happy coding.

Answer 2

try so:

public unsafe struct SSP_FULL_KEY
{
    System.Int64 FixedKey;
    System.Int64 EncryptKey;
    public SSP_FULL_KEY(System.Int64 fix, System.Int64 encr)
    {
        FixedKey = fix;
        EncryptKey = encr;
    }

}
public unsafe struct SSP_COMMAND
{
    //string PortNumber; 
    SSP_FULL_KEY key;
    System.Int32 BaudRate; // baud rate of the packet 
    System.Int32 Timeout; // how long in ms to wait for a reply from the slave 
    char PortNumber; // the serial com port number of the host 
    char SSPAddress; // the SSP address of the slave 
    char RetryLevel; // how many retries to the slave for non-response 
    char EncryptionStatus; // is this an encrypted command 0 - No, 1 - Yes 
    char CommandDataLength; // Number of bytes in the command 
    fixed char CommandData[255]; // Array containing the command bytes 
    char ResponseStatus; // Response Status (PORT_STATUS enum) 
    char ResponseDataLength; // how many bytes in the response 
    fixed char ResponseData[255]; // an array of response data 
    char IgnoreError; // flag to suppress error box (0 - display,1- suppress) 

    public SSP_COMMAND(Byte comport)
    {
        BaudRate = 9600;
        Timeout = 500;
        PortNumber = (char)comport;
        RetryLevel = '5';
        IgnoreError = '0';
        EncryptionStatus = '0';
        ResponseStatus = '0';
        ResponseDataLength = '0';
        SSPAddress = '0';
        CommandDataLength = '0';
        key = new SSP_FULL_KEY(0123456701234567, 0123456701234567);

    }
} 


class Program
{
    //NOMANGLE int CCONV OpenSSPComPort (SSP_COMMAND * cmd); 
    [DllImport("ITLSSPProc.dll")]
    private static extern int OpenSSPComPort(ref SSP_COMMAND cmd);

    //NOMANGLE int CCONV CloseSSPComPort (void);
    [DllImport("ITLSSPProc.dll")]
    private static extern int CloseSSPComPort();

    static void Main(string[] args)
    {
        SSP_COMMAND cmd = new SSP_COMMAND(3);
        /* IntPtr.BaudRate = 9600; 
        IntPtr.PortName = "COM0"; 
        IntPtr.Parity = Parity.None; 
        IntPtr.StopBits = StopBits.One; 
        */
        Console.WriteLine("open {0}", OpenSSPComPort(ref cmd));
        Console.WriteLine("close {0}", CloseSSPComPort());
        Console.ReadKey();
    }
}