linux-kernel - Re: [PATCH] Make shr to divide by power of 2 (resend)

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Date:	Sat, 15 Aug 2009 15:48:06 +0200
From:	Jiri Slaby <jirislaby@...il.com>
To:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Make shr to divide by power of 2 (resend)

On 08/15/2009 03:43 PM, Sergey Senozhatsky wrote:
> Make an arithmetic right shift to divide by power of 2.

Why? Is out there a compiler not doing that?

Seems like it should be rather converted to DIV_ROUND_UP.

> Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
> ---
> diff --git a/drivers/video/console/bitblit.c b/drivers/video/console/bitblit.c
> index 69864b1..b816151 100644
> --- a/drivers/video/console/bitblit.c
> +++ b/drivers/video/console/bitblit.c
> @@ -144,7 +144,7 @@ static void bit_putcs(struct vc_data *vc, struct fb_info *info,
>  		      int fg, int bg)
>  {
>  	struct fb_image image;
> -	u32 width = (vc->vc_font.width + 7)/8;
> +	u32 width = (vc->vc_font.width + 7) >> 3;
>  	u32 cellsize = width * vc->vc_font.height;
>  	u32 maxcnt = info->pixmap.size/cellsize;
>  	u32 scan_align = info->pixmap.scan_align - 1;

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