[Openmcl-devel] Structure Alignment of Foreign Double Floats

James Bielman jamesjb at jamesjb.com
Mon Jun 6 00:34:31 UTC 2005


Gary Byers <gb at clozure.com> writes:

> Apple's ABI documentation uses terms like "natural alignment" and
> "embedding alignment", and notes that for some data types (notably
> double-floats) the two are different.  (When embedded in a structure,
> a double is aligned - somewhat unnaturally - on a 32-bit boundary,
> unless it's the first member of the structure; that special case
> affects the overall alignment of the structure.)

[ snip tons of useful information ]

Thanks a lot for this detailed explanation.  For the record, I found
the Apple documentation that describes this at:

http://developer.apple.com/documentation/DeveloperTools/Conceptual/PowerPCRuntime/Data/chapter_2_section_3.html

James



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