[alsa-devel] [RFC][PATCH] ELD routines and proc interface

[Takashi Iwai]

At Fri, 14 Nov 2008 15:38:56 +0800,
Wu Fengguang wrote:
> 
> > > > > --- /dev/null
> > > > > +++ sound-2.6/sound/pci/hda/hda_eld.c
> > > > > +static inline unsigned char grab_bits(const unsigned char *buf,
> > > > > +						int byte, int lowbit, int bits)
> > > > > +{
> > > > > +	BUG_ON(lowbit > 7);
> > > > > +	BUG_ON(bits > 8);
> > > > > +	BUG_ON(bits <= 0);
> > > > 
> > > > Can it be rather BUILD_BUG_ON(), BTW?
> > > > Or, hmm, doesn't work if it's an inline function?
> > > 
> > > Yes, converted to BUILD_BUG_ON() and it compiles OK.
> > 
> > The question is whether this really triggers the build error
> > properly.  Could you check it, simply by changing the caller of
> > grab_bits() with some invalid values?  Then you should get a compile
> > error.
> 
> BUILD_BUG_ON() won't emit errors! So use BUG_ON()?

Try to make grab_bits() a macro and check whether BUILD_BUG_ON()
works.  I think it won't be too bad to use a macro for such a pretty
simple case.  If the resultant code looks too ugly, we should switch
back to BUG_ON().

The difference is that BUILD_BUG_ON() would add no real code while
BUG_ON() is a pure run-time check.


thanks,

Takashi