Endian-ness

[brians@Aureal.com (Brian Sassone)]

Hello,

Does a PCI bus master designed for an Intel based system need to perform
byte swapping when running on a PowerPC?

I realize that the PCI bus is defined to be little-endian and that the MacOS
is big-endian, so it would seem logical that the PowerPC PCI bridge chip
would perform the necessary byte swapping.  This would certainly be a
problem for pixel formats since they are non-byte wide fields, but it seems
things would be cool for audio formats, right?

The Apple document "Designing PCI Cards and Drivers for Power Macintosh
Computers" (1995) seems to contradict itself in numerous places.  In one
place it says byte swapping is done by the bridge chip (pp. 24) and then in
another it states that the bridge chip performs no byte swapping (pp. 398).
There also seems to be contradictory references in regards as to whether 
drivers must handle byte swapping or not.

Can anybody clarify these issues for me or point be to an appropriate
reference that can?

Thanks,
Brian

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Brian Sassone (brians@aureal.com)                Aureal Semiconductor
Senior Design Engineer                           4245 Technology Drive
510-252-4225                                     Fremont, California 94538
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