Labview type conversion to C#

I am just hoping for somebody out there who might have an answer. I am posting here eventually after fruitless dealing with Labview and the Device company.

开发者_JAVA百科I am currently making an application to control a device, which is provided with Labview compiled DLL. The dll is compiled with missing some necessary Labview functions not included. So I have to call functions directly using Labview Run Time Engine. The Labview website replied me that I have to deal directly with the device company, which has no solution for me.

There is a labview function called FCreate (Labview Manager Function) which is defined as:

MgErr FCreate(File* fdp, Path path, int32 permissions, int32 openMode, int32 denyMode, PStr group);

If this function creates the file, the resulting file descriptor is stored in the address referred to by fdp.

And the there is another function called FNewRefNum:

FNewRefNum(Path path, File fd, LVRefNum* refNumPtr)

This function creates a new file refnum for an open file with file descriptor fd.

The refNumPtr is the one that I have to create and pass in to the dll, which doesn't have above functions compiled with.

I need to know exact type conversions in C# for those two labview functions. Or at least to C++ then I might able to convert them to C#.

The function calls were tested with Labview runtime engine and the engine seems recognizing. The error currently I am having is "AccessViolationException was unhandled"

ErroMessage: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

Thanks in advance for anyone trying to help.

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You need to look in extcode.h to see the definitions of the various types. I found an instance online here:

typedef int32   MgErr; 

#define LV_PRIVATE(T)   typedef struct T##_t { void *p; } *T 

/** @struct File 
Opaque type used by the file manager. See filemgr.cpp */ 
LV_PRIVATE(File); 

/** @struct Path 
Opaque type used by the path manager. See pathmgr.cpp 
declared here for use in constant table */ 

typedef struct PATHREF PathRef;
typedef PathRef*        Path;

typedef uChar       *PStr, **PStrHandle, *CStr; 

/** MagicCookie 
Opaque type used by the cookie manager. */ 
typedef uInt32 MagicCookie; 

typedef MagicCookie LVRefNum; 

To summarize, all of your types are either int or IntPtr:

MgErr: int
File: IntPtr
Path: IntPtr
int32: int
PStr: IntPtr
LVRefNum: int

Here's how you might declare the functions:

int FCreate(IntPtr* fdp, IntPtr path, int permissions,
            int openMode, int denyMode, IntPtr group);
int FNewRefNum(IntPtr path, IntPtr fd, int* refNumPtr);