linux-kernel - Re: [PATCH 22/37] move round

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Message-ID: <4B57675E.7070309@kernel.org>
Date:	Wed, 20 Jan 2010 12:28:14 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	Christoph Lameter <cl@...ux-foundation.org>,
	"H. Peter Anvin" <hpa@...or.com>
CC:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org
Subject: Re: [PATCH 22/37] move round_up/down to kernel.h

On 01/19/2010 09:57 AM, Christoph Lameter wrote:
> On Fri, 15 Jan 2010, Yinghai Lu wrote:
> 
>>
>>  #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))
>>
>> +/*
>> + * This looks more complex than it should be. But we need to
>> + * get the type for the ~ right in round_down (it needs to be
>> + * as wide as the result!), and we want to evaluate the macro
>> + * arguments just once each.
>> + */
>> +#define __round_mask(x,y) ((__typeof__(x))((y)-1))
>> +#define round_up(x,y) ((((x)-1) | __round_mask(x,y))+1)
>> +#define round_down(x,y) ((x) & ~__round_mask(x,y))
>> +
>>  #define FIELD_SIZEOF(t, f) (sizeof(((t*)0)->f))
>>  #define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))
>>  #define roundup(x, y) ((((x) + ((y) - 1)) / (y)) * (y))
> 
> Note the last two lines! We already have roundup(), DIV_ROUND_UP and
> DIV_ROUND_CLOSEST. Please integrate them properly. Maybe extract
> __round_mask() from all of them.

like this, using DIVIDE for all ?

---
 include/linux/kernel.h |   14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

Index: linux-2.6/include/linux/kernel.h
===================================================================
--- linux-2.6.orig/include/linux/kernel.h
+++ linux-2.6/include/linux/kernel.h
@@ -44,19 +44,13 @@ extern const char linux_proc_banner[];
 
 #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))
 
-/*
- * This looks more complex than it should be. But we need to
- * get the type for the ~ right in round_down (it needs to be
- * as wide as the result!), and we want to evaluate the macro
- * arguments just once each.
- */
-#define __round_mask(x,y) ((__typeof__(x))((y)-1))
-#define round_up(x,y) ((((x)-1) | __round_mask(x,y))+1)
-#define round_down(x,y) ((x) & ~__round_mask(x,y))
+#define roundup(x, y) ((((x) + ((y) - 1)) / (y)) * (y))
+#define rounddown(x, y) (((x) / (y)) * (y))
+#define round_up(x,y) roundup(x,y)
+#define round_down(x,y) rounddown(x,y)
 
 #define FIELD_SIZEOF(t, f) (sizeof(((t*)0)->f))
 #define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))
-#define roundup(x, y) ((((x) + ((y) - 1)) / (y)) * (y))
 #define DIV_ROUND_CLOSEST(x, divisor)(			\
 {							\
 	typeof(divisor) __divisor = divisor;		\
--
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