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From: Andrew Morton <akpm@linux-foundation.org>
To: "John Anthony Kazos Jr." <jakj@j-a-k-j.com>
Cc: James Bottomley <James.Bottomley@SteelEye.com>,
	"Cameron, Steve" <Steve.Cameron@hp.com>,
	"Miller, Mike (OS Dev)" <Mike.Miller@hp.com>,
	Hisashi Hifumi <hifumi.hisashi@oss.ntt.co.jp>,
	jens.axboe@oracle.com, linux-kernel@vger.kernel.org,
	linux-scsi@vger.kernel.org, trivial@kernel.org
Subject: Re: [PATCH] utilities: add helper functions for safe 64-bit integer operations as 32-bit halves
Date: Sat, 21 Apr 2007 03:08:25 -0700	[thread overview]
Message-ID: <20070421030825.bed0b8a9.akpm@linux-foundation.org> (raw)
In-Reply-To: <alpine.DEB.0.98.0704202040150.16687@sigma.j-a-k-j.com>

On Fri, 20 Apr 2007 20:55:49 -0400 (EDT) "John Anthony Kazos Jr." <jakj@j-a-k-j.com> wrote:

> +#define upper_32_bits(n) (sizeof(n) == 8 ? (u64)(n) >> 32 : 0)

It's very unclear what type this returns, in terms of both size and
signedness.  Perhaps it always returns a u64, dunno.  If it does, that will
cause the arithmetic which uses this macro to go 64-bit too.  Casting the
whole return value to u32 would fix all those doubts up.

> +#define lower_32_bits(n) (sizeof(n) == 8 ? (u32)(n) : (n))

n&0xffffffff would be simpler.

Do we actually have any call for this?

  reply	other threads:[~2007-04-21 10:09 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <6.0.0.20.2.20070418160231.043f23c8@172.19.0.2>
2007-04-19 15:09 ` [PATCH] cciss: Fix warnings during compilation under 32bit environment Miller, Mike (OS Dev)
2007-04-19 15:18   ` James Bottomley
2007-04-19 16:12     ` Miller, Mike (OS Dev)
2007-04-19 16:22       ` James Bottomley
2007-04-19 16:26         ` [PATCH] cciss: Fix warnings during compilation under 32bitenvironment Miller, Mike (OS Dev)
2007-04-19 16:27         ` Cameron, Steve
2007-04-20  5:20           ` Andrew Morton
2007-04-20 13:10             ` James Bottomley
2007-04-20 13:36               ` Alan Cox
2007-04-20 18:43               ` Andrew Morton
2007-04-20 18:50                 ` James Bottomley
2007-04-20 19:30                   ` Andrew Morton
2007-04-20 20:20                     ` James Bottomley
2007-04-20 21:12                       ` Andrew Morton
2007-04-20 21:39                         ` John Anthony Kazos Jr.
2007-04-21  0:55                           ` [PATCH] utilities: add helper functions for safe 64-bit integer operations as 32-bit halves John Anthony Kazos Jr.
2007-04-21 10:08                             ` Andrew Morton [this message]
2007-04-21 13:06                               ` John Anthony Kazos Jr.
2007-04-21 21:01                               ` Alan Cox
2007-04-21 21:06                                 ` Andrew Morton
2007-04-22  9:18                                   ` Christoph Hellwig
2007-04-22 12:38                                     ` Alan Cox
2007-04-22 12:35                                       ` Christoph Hellwig

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