> > #define write() do {                            \
> >                 if (readsp) asm("mb");          \
> >                 else asm("wmb");                \
> >                 readsp = 0;                     \
> >                 asm("write");                   \
> >         } while (0)
> > 
> > 
> > #define read() do {                             \
> >                 asm("mb");                      \
> >                 asm("read");                    \
> >                 readsp = 1;                     \
> >         } while (0)
> 
> except, in truly generic macros like this, you cannot reasonably use
> 'extern int' unless you know that the macros will be used without any
> possibility of taking an interrupt or exception.  you really should be
> using volatile int, and in that case, because if you do not you
> _might_ lose.  (actually, even if you do, you might lose, since
> there's no atomicity of access.)

.. and then there's also the minor matter of MP..

					- Bill