Re: Byte Alignment question with Change User Space Attributes API (QUSCUSAT) -- RPG400-L

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Now for example, the Initial value key has a data field that is only 1 byte long. Does this mean that you should add 3 bytes of filler so that the next key is on a 4 byte boundary?


Yes, that's what it means.

    d t_InitialValueAttr...
    d                 ds                  qualified
    d  key                          10I 0 inz(2)
    d  dataLength                   10I 0 inz(%sizeof(data))
    d  data
    d   initialValue                 1a   overlay( data : *NEXT )
    d                                3a   overlay( data : *NEXT )

Hard to say how they're aligned when you only show one key! The point is, if you're specifying 2 or more keys, they have to be an even multiple of 4 bytes apart.

So, if the data structure above were an array (you added the DIM keyword to the DS line) it would be correct. Each 'key' element of the array would be an even multiple of 4 bytes apart because the filler pads your DS out to make it 12 bytes long (instead of being 9 bytes)

Likewise, if you based it on a pointer, and used %size(t_InitialValueAttr) to increment the pointer, they'd be 12 bytes apart which is a multiple of 4, and that's what you want.

Make sense?

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