I've been working with C++ for years and am strugling at C#.  I am trying to
reuse a COM object that I wrote that takes a chacter buffer and a size of
the buffer.  I am having a problem "filling" in the memory buffer to pass to
my COM object.  An example might be more explanatory.

public struct Data
{
   ushort data_id;
   ushort data_size;
}

Data my_data;
sbyte buf = new sbyte[8];

How do I copy the data structure into the buf array.  Note that my data
structure can be any structure and can be variable length, thats why I can't
just to a simple ushort array.  In C++ I would do something like this,
memcpy( buf, my_data, my_data.data_size ).  I really can't seem to get my
mind around how to do this in C#.

Any help would be greatly appreciated.

Mike