ryancerium

Does anyone know why there's a size limit on the struct you can pass
to a C dll as a ref? Assuming you have a C function that takes a
pointer to a BigType, this will throw:

System.Runtime.InteropServices.MarshalDirectiveExc eption: Internal
limitation: structure is too complex or too large.

///////////////////////////////////////////////////////////////////////////////
in C#

[StructLayout(LayoutKind.Sequential)]
public struct BigType
{
public int a;
public int b;
public int c;
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 65536)]
public int[] d;
}

[DllImport("my_dll.dll")]
public static extern int GetBigType(ref BigType bt);

main()
{
BigType bt = new BigType();
GetBigType(ref bt);
}
///////////////////////////////////////////////////////////////////////////////
in C:

typedef struct tagBigType
{
int a;
int b;
int c;
int d[65536];
} BigType;

MY_DLL_API int RequestImage(BigType * const bt);