RE: Prototyping printf()

 >> So getting back to the original premise: copying pointers to a string
then back to pointers.  It appears that it would work if at all points you
could guarantee that the pointers would always be intact and always on a
16-byte boundary.

I think that is probably a good summary.  If you think about it, it has to
be able to do that or even a structure (DS, array, whatever) which
consisted of nothing but pointers could never be moved from point a to
point b other than by moving a pointer at a time.  The tag bit gets turned
off when (as you have noted) any attempt is made to mess with anything less
than the whole pointer.  I can recall architecture discussions when
pointers were being added to COBOL and considered for RPG.  I believe the
result was that the compilers actually check to determine if any structure
being moved includes a (whole) pointer and if so flags it so that a "move
bytes with pointer" is done rather than a "move bytes".

The net of it is that the architecture protects you from people messing
with pointers (by defining them as char fields or ints) while still
allowing structures containing pointers to be manipulated safely.


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