Re: Endianness independance

["Warren W. Gay VE3WWG" <ve3wwg@cogeco.ca>]

Simon Wright wrote:
> "David C. Hoos, Sr." <david.c.hoos.sr@ada95.com> writes:
> 
>>If all you want is platform-independence, then replace the file
>>s-stratt.adb in your standard gnat distribution with the one from
>>the same version of glade, and re-compile and rebuild the library
>>files (.a), and you have what you want.  Now, as long as your types
>>are declared the same on both platforms (with no representation
>>clauses) you will have platform- independence.
> 
> You can certainly use the 3.14 GLADE file with 3.15 (and I think
> GCC-3, too). Not a huge amount of change.
> 
> I suspect you'd be well advised to have the same release at both ends,
> even so!

If you look carefully at GLADE, you will notice that all that is
being done there is "byte swapping". There is more to independent
network formats than that (it just happens to work with _most_
modern platforms at the moment).

The problem that XDR solved was that they specified a network
independent format for floating point types. If you try to use
GLADE on hosts that use different floating point formats, then
no amount of byte swapping is going to make them compatible!

I would have preferred to see GLADE make use of the XDR facilities
that are available on any Linux/UNIX platform, and I am certain
that XDR exists in some form on any Windows platform that
supports DCOM.  XDR would give you true compatibility at the
floating point type level, in addition to the less difficult
types like integers.

Perhaps someone can take on that XDR project for the NG Glade? ;-)

-- 
Warren W. Gay VE3WWG
http://home.cogeco.ca/~ve3wwg