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

[Pat Kane]

What the deal with the "!!" operator?  I read it as a double logical negation.
A NOOP,  does it have some useful side effect?

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
>
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