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Date: Sat, 03 Feb 2007 15:59:28 +0100
From: Gautier <gautier@fakeaddress.nil>
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Subject: Re: Reading Float Data from a binary file into ada
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Date: 2007-02-03T15:59:28+01:00
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Simon Wright:

> And endianness-handling isn't easy and (on GNAT) isn't on by default.
> 
> You can build your own GNAT RTL with XDR support on streaming by
> replacing s-stratt.adb with the supplied s-strxdr.adb -- and then
> streams Just Work across platforms. Well, all the platforms I'm
> interested in.
> 
> We need to stream betweem PowerPC and x86, and would much prefer to
> work with AdaCore's supplied RTL than one we rebuilt ourselves, so we
> shall be using the standard RTL on the deliverable PPC target and a
> modified one on the Intel host (we can't use AdaCore's, because it
> streams one data type (Wide_Character???) in 4 bytes where the native
> code streams in 2).

It seems complicated, depends on GNAT and furthermore needs modifying its RTL.
What about a deterministic way where data is sliced into bytes in the Ada code ?
You can take a look at GLOBE_3D-IO.adb in GLOBE_3D
( http://www.mysunrise.ch/users/gdm/g3d.htm ), it's working fine: a .g3d 
object can be written on a PowerPC machine with a GLOBE_3D engine compiled by 
GNAT, then read on a PC with a GLOBE_3D compiled by ObjectAda (succesfully 
tested). A single source, no tweak, no compiler dependence...
BTW, there is also a portable way (single-source) of transferring Floats use 
by GLOBE_3D.IO.

G.