Need Help With UNION TYPES

[Wildman]

I am not clear on the order that the "part" elements
are stored in a UNION. Below is an example:

TYPE SegOff
Segment AS WORD
Offset AS WORD
END TYPE

UNION Address
Whole AS DWORD
Part AS SegOff
END UNION

DIM A AS Address
A.Whole = VARPTR(SomeVariable)

My question is does A.Part.Segment contain the segment of
SomeVariable and does A.Part.Offset contain the offset?
I have seem examples where the high order word is stored
first, like my example and I seen an example where the
low order word is stored first like this:

TYPE SegOff
Offset AS WORD
Segment AS WORD
END TYPE

Which way is correct? Some clarification would be
appreciated.

[WangoTango]

In article <Soq1s.401$pl4...@newsfe12.iad>, best...@yahoo.com says...

Is this suppose to be a holder for a X86 segmented (1MB) architecture
SEG:OFF addressing scheme? If that is the case, the SEG:OFF may be 2 16
bit values, but it does *NOT* mean that you can concatenate the two
values and get a 32 bit absolute address. Which means that your
"Whole" should have an absolute address in it and your "SegOff" is just
two parts of that absolute address. Remember, multiple segment:offset
pairs can map into the same linear/absolute address. I think of the
segment as page number, and those pages are just 16 bytes long.
Naturally, if you may be referring to something else entirely, and I am
wasting your time. Also, if you are in a flat memory addressing scheme
you are correct and I am just wasting your time again. :)

[Wildman]

On Tue, 04 Sep 2012 19:04:51 -0400, WangoTango wrote:

> <snip>

Yes, I am talking about a flat memory scheme or real mode an in PB/DOS.
Perhaps I should have used VARPTR32 in my example.

Thanks for the reply tho. That did answer my question.