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

[Paolo Bonzini]

On 14/09/2016 09:33, Michael Tokarev wrote:
> Is this (quite old) patch still relevant?

Yes, I think it's a nice cleanup.  The interesting bit is that it
expands nbits exactly once.

Paolo

> 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 <address@hidden>
>> ---
>>  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);
>>
> 
> 
>