[alsa-devel] [PATCH] ASoC: nau8825: jack connection decision with different insertion logic

[Mark Brown]

On Thu, Jun 30, 2016 at 03:51:51PM +0800, John Hsu wrote:

> Yes, it'll be more readable. I have a question. Why to add !! in
> front of bit wise operation? What does it mean?

It's redundant in almost all cases.  It translates an integer value
into a 0/1 value (so if you've got a value of 2 it'll end up as 1) by
doing a double not.  This very rarely matters unless you're storing the
value in an integer and comparing it to 1 to check for truth, otherwise
C will translate any non-zero value into true in any logic context.
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