I am calling a method from C# to an unmanaged dll that includes two callback
methods, one for reading from a buffer and one for writing to a buffer.  The
callback methods have 3 parameters, all IntPtrs.  The first callback to each
method works fine, but the second time the read callback is called, the 3rd
parameter is now the second and the second parameter is now the first.  I'm
sure I'm defining something wrong but I can't seem to figure it out.  I've
tried all CallingConvention types without any success.   Any help would be
appreciated