Re: deprecated FOUR_CHAR_CODE and macintel
Re: deprecated FOUR_CHAR_CODE and macintel
- Subject: Re: deprecated FOUR_CHAR_CODE and macintel
- From: Eric Albert <email@hidden>
- Date: Thu, 12 Jan 2006 15:21:48 -0800
On Jan 12, 2006, at 1:28 PM, Lawrence Gold wrote:
On Jan 12, 2006, at 11:46 AM, Eric Albert wrote:
This is a very common misconception. FOUR_CHAR_CODE has never
done anything useful on the Mac at all. If you look carefully at
ConditionalMacros.h (or whichever header defines it), you'll see
that it only does anything on MIPS or something like that -- some
architecture for which Apple has no products. I don't even know
why the macro exists.
In other words, everything that you write as FOUR_CHAR_CODE
('ABCD') is exactly equivalent to 'ABCD', and has always been that
way. And that's just a 32-bit integer. We've worked hard to make
nearly all APIs in the system take native-endian arguments, so in
just about every case you don't need to byte-swap four-char
codes. The exceptions to this are documented in the Universal
Binary Programming Guidelines, as are the APIs you can use to byte-
swap 32-bit integers.
This is somewhat off-topic, but also somewhat related: We've made
liberal use of such four-character constants in our code, which
assumes that 'ABCD' is represented in big-endian order on a Mac and
little-endian order on a Windows PC. This assumption has worked
fine for CodeWarrior and Xcode, but we've begun transitioning to
Visual C++ for our Windows builds, and that compiler represents
such constants in big-endian order.
Are you sure that's right? I hate to doubt you here, but this is the
first I've heard of this. Presumably anyone working with QuickTime
for Windows would've hit this a long time ago, but I haven't heard
the QuickTime team or any developers using QT on Windows mention it.
Maybe I'm just not talking to the right developers....
-Eric
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