[fpc-pascal] return 8 byte of return as function result via register

[Dennis Poon]

I am trying to use an external C++ dll and also privide call back 
functions to this dll to call back.
However, the dll requires my functions to return 8 byte of 'struct' via 
register and the dll author said it is not possible with Delphi.
Is that possible with fpc?

Dennis