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Re: [PATCH v4 07/11] xen/arm: bitops: Implement a ffsll function
- To: Rahul Singh <Rahul.Singh@xxxxxxx>
- From: Bertrand Marquis <Bertrand.Marquis@xxxxxxx>
- Date: Tue, 12 Jan 2021 11:35:46 +0000
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- Thread-topic: [PATCH v4 07/11] xen/arm: bitops: Implement a ffsll function
Hi,
> On 8 Jan 2021, at 14:46, Rahul Singh <Rahul.Singh@xxxxxxx> wrote:
>
> Implement the ffsll based on built-in function "__builtin_ffsll()"
>
> ffsll will return one plus the index of the least significant 1-bit in
> doublewords or if doublewords is zero, returns zero.
>
> Signed-off-by: Rahul Singh <rahul.singh@xxxxxxx>
Reviewed-by: Bertrand Marquis <bertrand.marquis@xxxxxxx>
Cheers
Bertrand
> ---
> Changes in V4:
> - This patch is introduce in this verison.
> ---
> xen/include/asm-arm/bitops.h | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/xen/include/asm-arm/bitops.h b/xen/include/asm-arm/bitops.h
> index 71ae14cab3..7f83ee1828 100644
> --- a/xen/include/asm-arm/bitops.h
> +++ b/xen/include/asm-arm/bitops.h
> @@ -170,6 +170,18 @@ static inline unsigned int find_first_set_bit(unsigned
> long word)
> return ffsl(word) - 1;
> }
>
> +/**
> + * ffsll - find the first least significant set bit
> + * @doubleword: double word to search
> + *
> + * Returns one plus the index of the least significant 1-bit in @doubleword
> + * or if doubleword is zero, returns zero.
> + */
> +static inline int ffsll(long long doubleword)
> +{
> + return __builtin_ffsll(doubleword);
> +}
> +
> /**
> * hweightN - returns the hamming weight of a N-bit word
> * @x: the word to weigh
> --
> 2.17.1
>
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