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Date: Mon, 17 Aug 2009 09:15:20 +0200 From: Jiri Slaby <jirislaby@...il.com> To: Sergey Senozhatsky <sergey.senozhatsky@...il.com> CC: Andi Kleen <andi@...stfloor.org>, "Robert P. J. Day" <rpjday@...shcourse.ca>, Andrew Morton <akpm@...ux-foundation.org>, linux-kernel@...r.kernel.org Subject: Re: [PATCH] Make shr to divide by power of 2 (resend) On 08/16/2009 11:14 AM, Sergey Senozhatsky wrote: > There are different shr/shl operations in bitblit.c. Like, > #1 > cur_height = vc->vc_font.height >> 1 > cur_height = (vc->vc_font.height << 1)/3; > c |= c >> 1; > u32 idx = vc->vc_font.width >> 3; > etc. > > So, should I convert it to something like: Not at all. I was writing about about (X + 7) / 8 [or >> 3] which is DIV_ROUND_UP(X, 8). > #2 > cur_height = DIV_XXX(vc->vc_font.height, 2) > cur_height = DIV_XXX( MUL_XXX(vc->vc_font.height, 2), 3); or cur_height = DIV_XXX( (vc->vc_font.height * 2), 3); > c |= DIV_XXX(c, 1); > u32 idx = DIV_XXX(vc->vc_font.width, 8); > > #1 is better-looking I think. Agreed. I would write it without shifts though. But we were talking about the roundup case not about the shifts all over the code. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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