Re: [Qemu-devel] [PATCH] bitmap: refine and move BITMAP_{FIRST/LAST}_WORD_MASK

From: Michael Tokarev <mjt@tls.msk.ru>
To: Wei Yang <richard.weiyang@gmail.com>, corentincj@iksaif.net
Cc: qemu-trivial@nongnu.org, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH] bitmap: refine and move BITMAP_{FIRST/LAST}_WORD_MASK
Date: Wed, 14 Sep 2016 10:33:38 +0300	[thread overview]
Message-ID: <b31417a0-f1ff-32ce-1893-bb7576333469@msgid.tls.msk.ru> (raw)
In-Reply-To: <1457185628-23304-1-git-send-email-richard.weiyang@gmail.com>

Is this (quite old) patch still relevant?

Thanks,

/mjt

05.03.2016 16:47, Wei Yang wrote:
> According to linux kernel commit <89c1e79eb30> ("linux/bitmap.h: improve
> BITMAP_{LAST,FIRST}_WORD_MASK"), these two macro could be improved.
>
> This patch takes this change and also move them all in header file.
>
> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
> ---
>  include/qemu/bitmap.h | 7 ++-----
>  util/bitmap.c         | 2 --
>  2 files changed, 2 insertions(+), 7 deletions(-)
>
> diff --git a/include/qemu/bitmap.h b/include/qemu/bitmap.h
> index 0e33fa5..864982d 100644
> --- a/include/qemu/bitmap.h
> +++ b/include/qemu/bitmap.h
> @@ -58,11 +58,8 @@
>   * find_next_bit(addr, nbits, bit)	Position next set bit in *addr >= bit
>   */
>
> -#define BITMAP_LAST_WORD_MASK(nbits)                                    \
> -    (                                                                   \
> -        ((nbits) % BITS_PER_LONG) ?                                     \
> -        (1UL<<((nbits) % BITS_PER_LONG))-1 : ~0UL                       \
> -        )
> +#define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) & (BITS_PER_LONG - 1)))
> +#define BITMAP_LAST_WORD_MASK(nbits) (~0UL >> (-(nbits) & (BITS_PER_LONG - 1)))
>
>  #define DECLARE_BITMAP(name,bits)                  \
>          unsigned long name[BITS_TO_LONGS(bits)]
> diff --git a/util/bitmap.c b/util/bitmap.c
> index 40aadfb..43ed011 100644
> --- a/util/bitmap.c
> +++ b/util/bitmap.c
> @@ -157,8 +157,6 @@ int slow_bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
>      return result != 0;
>  }
>
> -#define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) % BITS_PER_LONG))
> -
>  void bitmap_set(unsigned long *map, long start, long nr)
>  {
>      unsigned long *p = map + BIT_WORD(start);
>