Re: [Corelinux-public] Endianess

[Thomas M. <t.r...@wo...>]

I think an approach that encodes the ordering in the beginning of data files
and source files is an appropriate approach.  This would be akin to the
UNICODE non spacing non breaking code <0xfffe> used in the beginning of
unicode files to tell the reader the ordering.

----- Original Message -----
From: Jim Koontz <jrk...@at...>
To: <cor...@ma...>
Sent: Thursday, December 09, 1999 10:29 AM
Subject: Re: [Corelinux-public] Endianess


>
>
> On Thu, 9 Dec 1999, Frank V. Castellucci wrote:
>
> > > Is endian-ness an issue in Linux?  If a data file is created by a
> > > Linux/Intel application, can it be read by the Linux/PowerPC version
of
> > > that application?
> > >
> > > Should CoreLinux provide some facility for conversion of endian-ness
in
> > > cross-platform data?
> > >
> > > Jim Koontz
> > > jrk...@us...
> >
> > Data Files
> > --------------
> > There is an issue that has to be addressed by the applications
persistence
> > implementation or any persistence that the library provides. From a
numeric
> > stand point using network byte order consistently should avoid that, or
of
> > course characters.
> >
> > Source Files
> > ------------------
> > There is an issue, I know bitfields and unions may be targets for
analysis,
> > there may be more (I have been corrupted for too long by
little-endianess)
> > but avoiding bit manipulation and unions is part of the CoreLinux
standards.
> >
> > Binary Libraries and Apps
> > ------------------------------------
> > Big issue, I don't know of solutions.
> >
> >
> > I'm hoping there are some who are running on both type of Linux
> > implementations (big and little) that we can test/verify against early
on in
> > the development stages.
> >
> As far as the binary libraries and apps go, I think the only solution is
> to build them on each platform.
>
> The way that I have seen endian-ness resolved in other operating systems
> is to either save in one format, and provide code that does bit flipping
> if the platform reading is opposite-endian, or to save in a canonical
> format, that contains a flag field indicating the source platform.  If the
> platform reading is opposite-endian from the platform that saved the data,
> the bit flipping takes place.  In either case, macros that test for
> endian-ness and perform the bit-flipping are provided as part of the
> API.
>
> Jim Koontz
> jrk...@so...
>
>
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