Re: Prototyping printf()

["Simon Coulter" <shc@xxxxxxxxxxxxxxxxx>]

E
Hello Anton,

You wrote:
>Sigh, and i thought it had to be invalid all the time, due to "the extra 
>bit" Frank Soltis is talking about in his "Inside the AS/400"...
>Seems to be a fairy tale... *sniff*

In addition to what Barabara wrote -- why would this be a fairy tale?  Even if 
you could 
successfully store a pointer in a 16-byte aligned char field and then copy it 
back to a 
pointer why would that, in itself, be a problem?  The only problem is that you 
could 
potentially modify the character version of the pointer before copying it back 
and in 
that case I guarantee you will have an invalid pointer.  The tag bits will be 
reset and 
you'll get an exception (probably MCH3601 or MCH3602).

There is a possible problem (loophole) if an authorised pointer is stored for 
later 
retrieval but storing authority in a pointer is only available to system state 
programs 
so that limits the usefulness (and regardless of what Uncle Frank says -- if 
authorities 
can be stored in pointers then the AS/400 is STILL a capability-based machine).

Regards,
Simon Coulter.

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