Re: GNAT.Sockets

[Simon Wright <simon.j.wright@mac.com>]

Maciej Sobczak <see.my.homepage@gmail.com> writes:

> On 9 Pa , 17:10, a...@anon.org (anon) wrote:
>
>>          -- Get message length
>>
>>          Integer'Read ( Channel, Length_Message ) ;
>
> How does it deal with endianness issues?
> Or in general with different representation on two communicating
> platforms?

AdaCore supply an alternate body for System.Stream_Attributes
(s-stratt.adb) in s-strxdr.adb. This converts to/from XDR
representation on the fly.

One way to deal with this is to copy s-strxdr.adb to s-stratt.adb in
your source path and use gnatmake -a.

Another is to rebuild the RTS (there's a makefile in adalib or
adainclude, forget which) and use the --RTS= switch (I think in GPR
package Builder).

As a matter of interest, we found that the PowerPC (G4)'s native
representation is the same as XDR except for Wide_Character, which is
2 bytes natively and 4 via s-strxdr.adb. That's 3.16a1, not sure about
the latest releases. We don't use Wide_Character, so we can use the
native RTS on VxWorks/PPC and XDR on the host (intel) side; the XDR
conversions for floats look complex & possibly loady, not measured,
but more important is reducing the need to modify third-party tools
and code.