Re: Patch to 2.6.8.1-mm2 to allow multiple NMI handlers to be registered

[Mikael Pettersson <mikpe@csd.uu.se>]

Corey Minyard writes:
 > > > +	/* 
 > > > +	 * If the timer has overflowed, this is certainly a watchdog
 > > > +	 * source
 > > > +	 */
 > > > +	source = (low & (1 << 31)) == 0;
 > > > +	if (source)
 > >
 > >Why not "if ((int)low >= 0)"?
 > >  
 > >
 > IIRC, the docs state that timer goes off if the high bit is cleared in 
 > the register.  I was just going with the documentation description.  Not 
 > a big deal either way, I don't think.

Which is the same as saying it occurs on the negative-to-non-negative
transition. The "if ((int)low >= 0)" test is just a test and branch
on sign, while your original requires either a (microcoded?) bit op,
or constructing a large-magnitude mask, followed by some tests.

Yes this is a micro-optimisation, but I find it actually simplifies the code.

/Mikael