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Date: Wed, 12 May 2004 15:29:08 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Gabriel Paubert <paubert@iram.es>
CC: linux-kernel@vger.kernel.org
Subject: Re: [2.6.6-BK] x86_64 has buggy ffs() implementation
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Gabriel Paubert wrote:
> 
> Either I'm asleep or you are emulating bsrl, not bsfl. It
> should rather be:
> 
> 	if ( y & 0x00000001) return 1;
> 	if ( y & 0x00000002) return 2;
> 	if ( y & 0x00000004) return 3;
> 	...
> 	if ( y & 0x80000000) return 32;
> 	return 0;
> 
> No need for the else clauses either because of the return.
> But maybe even __builtin_ffs(y) would work in this case.
> 

If __builtin_ffs() works *AND HAS THE RIGHT SEMANTICS* it's probably the 
best thing to use.

Otherwise, yes, generic_ffs() can clearly be used inside the 
__builtin_constant_p() clause.

	-hpa