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Re: [Qemu-trivial] [PATCH] bitmap: refine and move BITMAP_{FIRST/LAST}_W
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-trivial] [PATCH] bitmap: refine and move BITMAP_{FIRST/LAST}_WORD_MASK |
Date: |
Wed, 14 Sep 2016 11:01:31 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 |
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);
>>
>
>
>