rwlocks revisited

[Tigran Aivazian]

Hi David,

You asked:

> This instruction (or perhaps I should say intruction family) is 
> "cmpxchg*". I've known about a similar one on the m68k ("cas" & "cas2")
> for a  while. I was wondering why the writelock code was done using
> "subl" rather than "cmpxchgl":

One reason may be because it is not present on 386 but only 486+ see page
3-100 of Volume II of Pentium III Manuals.

Regards,
------
Tigran A. Aivazian           | http://www.sco.com
Escalations Research Group   | tel: +44-(0)1923-813796
Santa Cruz Operation Ltd     | http://www.ocston.org/~tigran


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