Re: [Qemu-devel] [PATCH] bitops: unify bitops_flsl with host-utils.h, call it bitops_clzl

[Eric Blake]

On 02/04/2013 11:26 AM, Richard Henderson wrote:
> Similar to the bitops_ctz change just made.
> 
> Signed-off-by: Richard Henderson <address@hidden>
> ---
>  include/qemu/bitops.h  | 44 +++++++++++++++-----------------------------
>  target-i386/topology.h |  2 +-
>  util/bitops.c          |  2 +-
>  3 files changed, 17 insertions(+), 31 deletions(-)

Reviewed-by: Eric Blake <address@hidden>

> 
> diff --git a/include/qemu/bitops.h b/include/qemu/bitops.h
> index 8b88791..07ada63 100644
> --- a/include/qemu/bitops.h
> +++ b/include/qemu/bitops.h
> @@ -50,41 +50,27 @@ static unsigned long bitops_ctzl(unsigned long word)
>  }
>  
>  /**
> - * bitops_fls - find last (most-significant) set bit in a long word
> + * bitops_clzl - find last (most-significant) set bit in a long word
>   * @word: the word to search
>   *
>   * Undefined if no set bit exists, so code should check against 0 first.

Interesting that you chose to leave 0 undefined here, even though
bitops_ctzl specifically defines that case, but not a show-stopper.  Per
Paolo's arguments in the other thread, if we did decide to define
bitops_clzl(0), setting it to the word size would be a reasonable choice
(bitops_clzl(2)=>62, bitops_clzl(1)=>63, bitops_clzl(0)=>64), but that
can be done later if it turns out to be useful.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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