From: Andreas Dilger <adilger@clusterfs.com>
To: Dave <dave.jiang@gmail.com>
Cc: akpm@osdl.org, torvalds@osdl.org, linux-kernel@vger.kernel.org,
smaurer@teja.com, linux@arm.linux.org.uk, dsaxena@plexity.net,
drew.moseley@intel.com, mporter@kernel.crashing.org
Subject: Re: [PATCH 2/5] Convert resource to u64 from unsigned long
Date: Thu, 13 Jan 2005 22:48:03 -0700 [thread overview]
Message-ID: <20050114054803.GA22715@schnapps.adilger.int> (raw)
In-Reply-To: <8746466a050113152843f32a2f@mail.gmail.com>
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On Jan 13, 2005 16:28 -0700, Dave wrote:
> Fixed some of the drivers as example just to get working on i386.
> + /*
> + * FIXME: apparently ia32 does not have u64 divide implementation
> + * we cast the pci_resource_len to u32 for the time being
> + * this probably should be fixed to support u64 for ia32
> + * and other archs that do not have u64 divide
> + */
> +#if BIS_PER_LONG == 64
> maxnr = (pci_resource_len(dev, bar) - board->first_offset) /
> (8 << board->reg_shift);
> +#else
> + maxnr = ((u32)pci_resource_len(dev, bar) - board->first_offset) /
> + (8 << board->reg_shift);
> +#endif
One of the reasons that ia32 doesn't support 64-bit divide directly is
because it is a big red flag that you are probably doing something wrong.
This is a prime example - why do a divide when you could do a shift:
maxnr = (pci_resource_len(dev, bar) - board->first_offset) >>
(board->reg_shift + 3);
Cheers, Andreas
--
Andreas Dilger
http://sourceforge.net/projects/ext2resize/
http://members.shaw.ca/adilger/ http://members.shaw.ca/golinux/
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prev parent reply other threads:[~2005-01-14 5:48 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-01-13 23:28 [PATCH 2/5] Convert resource to u64 from unsigned long Dave
2005-01-14 5:48 ` Andreas Dilger [this message]
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