Re: DS alignment (was RE: Prototyping printf())

>Date: Tue, 10 Oct 2000 10:47:09 -0400
>From: Jon.Paris@hal.it
>
> >> The ALIGN keyword insures that float, signed, and unsigned integers
are
>aligned on the appropriate boundaries
>
>I'll have to leave it to Barbara or Hans to confirm but I believe that a
DS
>will always be 16 byte aligned.  Try coding a DS where the first field is
a
>single character and the second is a pointer and if the compiler generates
>a 15 byte "filler" the you know it is assuming that the DS was on a
>boundary.

Jon, you're partly right.  The whole DS is aligned according to the
largest required alignment, so if you have a pointer, the whole DS
will indeed be 16-byte aligned.  But if you only have a 4-byte int, the
DS will be 4-byte aligned.

Try an aligned multiple occurrence DS with a 10i 0 followed by a 1a.  The
occurrences will be further apart than 5 because of alignment.  To see the
actual distance between occurrences, divide %size(ds:*all) by the number
of occurrences (a different answer from %size(ds)).

All that's guaranteed is the minimum alignment.

Barbara Morris

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