Date: Wed, 27 Jan 1999 16:37:35 -0800 (PST) From: John Polstra <jdp@polstra.com> To: dillon@apollo.backplane.com Cc: current@FreeBSD.ORG Subject: Re: btokup() macro in sys/malloc.h Message-ID: <199901280037.QAA27694@vashon.polstra.com> In-Reply-To: <199901272128.NAA56542@apollo.backplane.com>
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In article <199901272128.NAA56542@apollo.backplane.com>,
Matthew Dillon <dillon@apollo.backplane.com> wrote:
> Is this parenthesization correct ?
>
> OLD
>
> #define btokup(addr) (&kmemusage[(caddr_t)(addr) - kmembase >> PAGE_SHIFT])
>
> NEW
>
> #define btokup(addr) (&kmemusage[((caddr_t)(addr) - kmembase) >> PAGE_SHIFT])
The added parentheses don't make any difference, semantically. This
change probably wouldn't meet the criteria spelled out in style(9):
Unary operators don't require spaces, binary operators do. Don't use
parentheses unless they're required for precedence, or the statement is
really confusing without them.
a = b->c[0] + ~d == (e || f) || g && h ? i : j >> 1;
k = !(l & FLAGS);
John
--
John Polstra jdp@polstra.com
John D. Polstra & Co., Inc. Seattle, Washington USA
"Nobody ever went broke underestimating the taste of the American public."
-- H. L. Mencken
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