Hi guys. There is something I still don't understand about ImageSegment hahaha. But each time there is less :)

There is a place in ImageSegment >> copyObj: oop toSegment: segmentWordArray addr: lastSeg stopAt: stopAddr saveOopAt: oopPtr headerAt: hdrPtr
where it does this:

    self forward: oop to: (lastSeg+BytesPerWord + extraSize - segmentWordArray)
        savingOopAt: oopPtr andHeaderAt: hdrPtr.

Basically, it forwards oop to another address which is actually the offset inside the segment. And it backups the original oop and the hader, as you can see here:

Interpreter >> forward: oop to: newOop savingOopAt: oopPtr andHeaderAt: hdrPtr

    "Make a new entry in the table of saved oops."
    self longAt: oopPtr put: oop.                    "Save the oop"
    self longAt: hdrPtr put: (self longAt: oop).    "Save the old header word"

    "Put a forwarding pointer in the old object, flagged with forbidden header type"
    self longAt: oop put: newOop + HeaderTypeFree.

Now....the line I don't understand is this:

    self longAt: oop put: newOop + HeaderTypeFree.

Because 'self longAt: oop'
will answer the object header of oop. And there, it stores a number (the offset). Is this possible?

In addition, it not only stores the offset, by it plus the flag HeaderTypeFree.

I really don't understand how you can plus an offset and the flag. What is the result? how should I interpret that?

Thanks for any hint you can give me.

Mariano