[PATCH 08/12] ipa: rkisp1: agc: Simplify predivider calculation

[Paul Elder]

On Sun, Jun 16, 2024 at 07:39:06PM +0300, Laurent Pinchart wrote:
> The condition
> 
> 	if (std::pow(std::floor(root), 2) < factor)
> 		predivider = static_cast<uint8_t>(std::ceil(root));
> 	else
> 		predivider = static_cast<uint8_t>(std::floor(root));
> 
> can only be false when the factor's root is an integer. In that case,
> std::ceil(root) and std::floor(root) will be equal. The computation can
> thus be simplified by always rounding up.
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

Reviewed-by: Paul Elder <paul.elder at ideasonboard.com>

> ---
>  src/ipa/rkisp1/algorithms/agc.cpp | 7 +------
>  1 file changed, 1 insertion(+), 6 deletions(-)
> 
> diff --git a/src/ipa/rkisp1/algorithms/agc.cpp b/src/ipa/rkisp1/algorithms/agc.cpp
> index 9f3b59b45f95..a61201bb05c9 100644
> --- a/src/ipa/rkisp1/algorithms/agc.cpp
> +++ b/src/ipa/rkisp1/algorithms/agc.cpp
> @@ -115,12 +115,7 @@ uint8_t Agc::computeHistogramPredivider(const Size &size,
>  	int count = mode == RKISP1_CIF_ISP_HISTOGRAM_MODE_RGB_COMBINED ? 3 : 1;
>  	double factor = size.width * size.height * count / 65536.0;
>  	double root = std::sqrt(factor);
> -	uint8_t predivider;
> -
> -	if (std::pow(std::floor(root), 2) < factor)
> -		predivider = static_cast<uint8_t>(std::ceil(root));
> -	else
> -		predivider = static_cast<uint8_t>(std::floor(root));
> +	uint8_t predivider = static_cast<uint8_t>(std::ceil(root));
>  
>  	return std::clamp<uint8_t>(predivider, 3, 127);
>  }