Re: [PATCH v2 4/5] rslib: Improve the performance of encode_rs.c

[Randy Dunlap <rdunlap@infradead.org>]

Hi--

On 6/17/22 07:46, Zhang Boyang wrote:
> Signed-off-by: Zhang Boyang <zhangboyang.id@gmail.com>
> ---
>  include/linux/rslib.h        | 14 +++++++++++++-
>  lib/reed_solomon/encode_rs.c | 21 ++++++++++-----------
>  2 files changed, 23 insertions(+), 12 deletions(-)
> 
> diff --git a/include/linux/rslib.h b/include/linux/rslib.h
> index cd0b5a7a5698..44ec7c6f24b2 100644
> --- a/include/linux/rslib.h
> +++ b/include/linux/rslib.h
> @@ -110,7 +110,7 @@ void free_rs(struct rs_control *rs);
>  /** modulo replacement for galois field arithmetics
>   *
>   *  @rs:	Pointer to the RS codec
> - *  @x:		the value to reduce
> + *  @x:		x >= 0 ; the value to reduce
>   *
>   *  where
>   *  rs->mm = number of bits per symbol
> @@ -127,4 +127,16 @@ static inline int rs_modnn(struct rs_codec *rs, int x)
>  	return x;
>  }
>  
> +/** modulo replacement for galois field arithmetics

/**
 * rs_modnn_fast() - modulo replacement for galois field arithmetics

> + *
> + *  @rs:	Pointer to the RS codec
> + *  @x:		0 <= x < 2*nn ; the value to reduce
> + *
> + *  Same as rs_modnn(x), but faster, at the cost of limited value range of @x
> +*/
> +static inline int rs_modnn_fast(struct rs_codec *rs, int x)
> +{
> +	return x - rs->nn < 0 ? x : x - rs->nn;
> +}
> +
>  #endif

-- 
~Randy