Re: [PATCH v4 07/11] xen/arm: bitops: Implement a ffsll function

[Julien Grall <julien@xxxxxxx>]

Hi Rahul,

On 08/01/2021 14:46, Rahul Singh 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>
> ---
> 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)
If I am not mistaken, we already have an helper doing exactly the same 
(see ffs64() in xen/bitops.h).
Can you check if it is effectively the case and use it?

Cheers,

--
Julien Grall