Packed structures

[Phil Prentice <philp dot cheer at btinternet dot com>]

Hi

  I'm using a gnu X-compiler (2.95.3) (Linux to VxWorks Intel).  I have a 
device driver that maps memory to a device.  It uses packed structures to aid 
this, in that the packed structures maps exactly to what the hardware 
expects.  The only way I can attempt to mimic this using the X-compiler is to 
use the -fpack-struct compiler option.  But this I assume would affect all 
structures in the file being compiled.  It's turns out to be a lot of work to 
try and split the structures out of the files in question.

Is there any way of making the compiler only pack the structures that require 
packing?

I think that my only option at the moment is to access the hardware registers 
directly (by offsets).  The other way is clever but not very portable???


Thanks
   Phil