kpneal@pobox.com writes:

>> An immediate drawback is that not all architectures support the cmpxchg
>> instruction. What are others? Is the possible performance gain negligible
>> compared to the required effort of recoding a large volume of code?

>I think the Amiga documentation forbids use of the m68k CAS instruction...

The instructions like CAS are only necessary for shared data
among multiple bus masters. For a single processor you can
simply use read-modify-write instructions like BSET/BCLR.