From: Jeremy Fitzhardinge <jeremy@goop.org>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@elte.hu>, LKML <linux-kernel@vger.kernel.org>,
Arnaldo Carvalho de Melo <acme@redhat.com>,
Paul Mackerras <paulus@samba.org>
Subject: Re: [PATCH] perf tools: Prevent from BITS_PER_LONG redefinition
Date: Sat, 19 Dec 2009 21:11:20 -0800 [thread overview]
Message-ID: <4B2DB1F8.2070006@goop.org> (raw)
In-Reply-To: <20091219143425.GA5003@nowhere>
On 12/19/2009 06:34 AM, Frederic Weisbecker wrote:
> Yeah but we need it from the CPP level.
> We include such code located in kernel headers:
>
> static __always_inline unsigned long __fls(unsigned long word)
> {
> int num = BITS_PER_LONG - 1;
>
> #if BITS_PER_LONG == 64
> if (!(word& (~0ul<< 32))) {
> num -= 32;
> word<<= 32;
> }
> #endif
> if (!(word& (~0ul<< (BITS_PER_LONG-16)))) {
> num -= 16;
> word<<= 16;
> }
>
>
> And sizeof() is not defined :)
>
You can use if() with a constant expression instead of #if.
J
next prev parent reply other threads:[~2009-12-20 5:11 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-18 22:05 [PATCH] perf tools: Prevent from BITS_PER_LONG redefinition Frederic Weisbecker
2009-12-19 9:26 ` Peter Zijlstra
2009-12-19 14:34 ` Frederic Weisbecker
2009-12-20 5:11 ` Jeremy Fitzhardinge [this message]
2009-12-30 21:45 ` Frederic Weisbecker
2009-12-31 11:09 ` Jeremy Fitzhardinge
2010-01-02 17:01 ` Frederic Weisbecker
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