[PATCH] include: let BitIsOn() return a boolean value.

[Peter Hutterer]

On Wed, Nov 24, 2010 at 12:18:16PM -0600, Pat Kane wrote:
> What the deal with the "!!" operator?  I read it as a double logical negation.
> A NOOP,  does it have some useful side effect?

http://stackoverflow.com/questions/1406604/what-does-the-operator-double-exclamation-point-mean-in-javascript
is the first link I found.

yes, I used to think it was dirty too, but I've grown to like it.

Cheers,
  Peter
> 
> On Wed, Nov 24, 2010 at 10:30 AM, walter harms <wharms at bfs.de> wrote:
> >
> >
> > Am 24.11.2010 07:25, schrieb Keith Packard:
> >> On Wed, 24 Nov 2010 14:40:11 +1000, Peter Hutterer <peter.hutterer at who-t.net> wrote:
> >>
> >>> -#define BitIsOn(ptr, bit) (((BYTE *) (ptr))[(bit)>>3] & (1 << ((bit) & 7)))
> >>> +#define BitIsOn(ptr, bit) !!(((BYTE *) (ptr))[(bit)>>3] & (1 << ((bit) & 7)))
> >>
> >
> > bit is checked to be less than 8 with "(bit) & 7" but only in the second statement.
> > the linux kernel specifies them as inline code. maybe this is the way to go here also.
> >
> > re,
> >  wh