Date: Thu, 4 Dec 2008 14:33:36 +0300 From: Eygene Ryabinkin <rea-fbsd@codelabs.ru> To: Garrett Cooper <yanefbsd@gmail.com> Cc: "current@freebsd.org" <current@freebsd.org>, Maksim Yevmenkin <maksim.yevmenkin@gmail.com> Subject: Re: RFC: small syscons and kbd patch Message-ID: <XyF%2B8oK9MN%2BR7Vvh5BW2XWkYOoE@yY%2BfOhC1VHEMJMRMqdV4xmT5mXM> In-Reply-To: <7d6fde3d0812040324y3bf0901cy1f4a6d961362c314@mail.gmail.com> References: <bb4a86c70812021701i621fdcfjb6a58a7f5cf781d5@mail.gmail.com> <7d6fde3d0812040324y3bf0901cy1f4a6d961362c314@mail.gmail.com>
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Garrett, good day.
Thu, Dec 04, 2008 at 03:24:28AM -0800, Garrett Cooper wrote:
> On Tue, Dec 2, 2008 at 5:01 PM, Maksim Yevmenkin
> Why are you double and triple negating on this line?
> + return (atomic_cmpset_acq_int(&kbd->kb_locked, !!!on, !!on));
Double negation is easy -- !!N = 1 for int N != 0, so it is the way to
turn N != 0 to one. Triple negation? I am out of guesses, because it
seems redundant to me: !0 = 1, !5 = 0, so adding another two negations
is seem to be worthless.
--
Eygene
_ ___ _.--. #
\`.|\..----...-'` `-._.-'_.-'` # Remember that it is hard
/ ' ` , __.--' # to read the on-line manual
)/' _/ \ `-_, / # while single-stepping the kernel.
`-'" `"\_ ,_.-;_.-\_ ', fsc/as #
_.-'_./ {_.' ; / # -- FreeBSD Developers handbook
{_.-``-' {_/ #
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