From mboxrd@z Thu Jan  1 00:00:00 1970
From: =?utf-8?B?SsO2cm4=?= Engel <joern@logfs.org>
Subject: Re: [PATCH 1/2] Make cramfs little endian only
Date: Wed, 5 Dec 2007 23:41:03 +0100
Message-ID: <20071205224102.GA32330@lazybastard.org>
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Cc: Andi Drebes <lists-receive@programmierforen.de>,
	Jeff Garzik <jeff@garzik.org>, J?rn Engel <joern@logfs.org>,
	linux-fsdevel@vger.kernel.org, Karel Zak <kzak@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Christoph Hellwig <hch@infradead.org>,
	Phillip Lougher <phillip@lougher.demon.co.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
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On Wed, 5 December 2007 14:21:02 -0800, Linus Torvalds wrote:
>=20
> No, no, what I meant about not having any #ifdef __LITTLE_ENDIAN was =
to do=20
> the code do the same thing *regardless* of endianness. In other words=
, a=20
> simple:
>=20
> 	struct cramfs_inode {
> 		__le32 mode_uid;	/* CRAMFS_MODE_WIDTH:CRAMFS_UID_WIDTH */
> 		__le32 size_gid;	/* CRAMFS_SIZE_WIDTH:CRAMFS_GID_WIDTH */
> 		__le32 namelen_offset;	/* CRAMFS_NAMELEN_WIDTH:CRAMFS_OFFSET_WIDTH =
*/
> 	};

Mode and uid are both 16bit.  So maybe we can change the structure:

	struct cramfs_inode {
		__le16 uid;
		__le16 mode;
		__le32 size_gid;	/* CRAMFS_SIZE_WIDTH:CRAMFS_GID_WIDTH */
		__le32 namelen_offset;	/* CRAMFS_NAMELEN_WIDTH:CRAMFS_OFFSET_WIDTH */
	};

That way masks and shifts are only needed for the remaining two shared
variables.

> (No, the above is not tested in any way, shape, or form, and no, I di=
dn't=20
> double-check that I actually extracted the right bits, but you get th=
e=20
> idea).

Same warning applies to my code as well.

J=C3=B6rn

--=20
Rules of Optimization:
Rule 1: Don't do it.
Rule 2 (for experts only): Don't do it yet.
-- M.A. Jackson
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