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From: Bob Friesenhahn <bfriesen@simple.dallas.tx.us>
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Cc: Tiff List <tiff@lists.maptools.org>
Subject: Re: [Tiff] Wrong Native Bit Order on Intel x86_64
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On Wed, 7 Oct 2009, Toby Thain wrote:
>
> As I understand it, the problem is not in the reading and writing code or 
> runtime behaviour, but relates to determination of the built default (May not 
> match platform's "actual" machine default.)
>
> The 'bug' would be at build-time, but it seems relatively unimportant to get 
> right, esp. for a C library.

I hope that you don't mind that I am Cc:ing this response to the list 
since it is an important issue to correct properly.

If the default is wrong, then the best-case penalty is that CPU is 
wasted executing TIFFReverseBits() when writing and reading files on 
the same system and the user explicitly specified the fill-order tag 
correctly for the CPU.  The worst-case penalty is that the files can't 
be read by some other host.  Since it took three years for this issue 
to be reported, the worst-case penalty seems unlikely since 
interoperability issues are noticed right away, and because no one has 
reported fill-order issues on unusual CPUs.

Bob
--
Bob Friesenhahn
bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/
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