From: "Darrick J. Wong" <djwong@us.ibm.com>
To: Andrew Morton <akpm@linux-foundation.org>,
Herbert Xu <herbert@gondor.apana.org.au>,
"Darrick J. Wong" <djwong@us.ibm.com>
Cc: Theodore Tso <tytso@mit.edu>,
Joakim Tjernlund <joakim.tjernlund@transmode.se>,
Bob Pearson <rpearson@systemfabricworks.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
Andreas Dilger <adilger.kernel@dilger.ca>,
linux-crypto <linux-crypto@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Mingming Cao <cmm@us.ibm.com>,
linux-ext4@vger.kernel.org
Subject: [PATCH 04/14] Replace 2D array references by pointer references in loops.
Date: Mon, 28 Nov 2011 14:37:31 -0800 [thread overview]
Message-ID: <20111128223731.28705.99216.stgit@elm3c44.beaverton.ibm.com> (raw)
In-Reply-To: <20111128223659.28705.56719.stgit@elm3c44.beaverton.ibm.com>
This change has no effect on X86 code but improves PPC
performance.
Signed-off-by: Bob Pearson <rpearson@systemfabricworks.com>
---
lib/crc32.c | 21 +++++++++++----------
1 files changed, 11 insertions(+), 10 deletions(-)
diff --git a/lib/crc32.c b/lib/crc32.c
index 7a0e5a9..c93c9ae 100644
--- a/lib/crc32.c
+++ b/lib/crc32.c
@@ -53,20 +53,21 @@ static inline u32
crc32_body(u32 crc, unsigned char const *buf, size_t len, const u32 (*tab)[256])
{
# ifdef __LITTLE_ENDIAN
-# define DO_CRC(x) crc = tab[0][(crc ^ (x)) & 255] ^ (crc >> 8)
-# define DO_CRC4 crc = tab[3][(crc) & 255] ^ \
- tab[2][(crc >> 8) & 255] ^ \
- tab[1][(crc >> 16) & 255] ^ \
- tab[0][(crc >> 24) & 255]
+# define DO_CRC(x) (crc = t0[(crc ^ (x)) & 255] ^ (crc >> 8))
+# define DO_CRC4 crc = t3[(crc) & 255] ^ \
+ t2[(crc >> 8) & 255] ^ \
+ t1[(crc >> 16) & 255] ^ \
+ t0[(crc >> 24) & 255]
# else
-# define DO_CRC(x) crc = tab[0][((crc >> 24) ^ (x)) & 255] ^ (crc << 8)
-# define DO_CRC4 crc = tab[0][(crc) & 255] ^ \
- tab[1][(crc >> 8) & 255] ^ \
- tab[2][(crc >> 16) & 255] ^ \
- tab[3][(crc >> 24) & 255]
+# define DO_CRC(x) (crc = t0[((crc >> 24) ^ (x)) & 255] ^ (crc << 8))
+# define DO_CRC4 crc = t0[(crc) & 255] ^ \
+ t1[(crc >> 8) & 255] ^ \
+ t2[(crc >> 16) & 255] ^ \
+ t3[(crc >> 24) & 255]
# endif
const u32 *b;
size_t rem_len;
+ const u32 *t0 = tab[0], *t1 = tab[1], *t2 = tab[2], *t3 = tab[3];
/* Align it */
if (unlikely((long)buf & 3 && len)) {
next prev parent reply other threads:[~2011-11-28 22:44 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-28 22:36 [PATCH v5.1 00/14] crc32c: Add faster algorithm and self-test code Darrick J. Wong
2011-11-28 22:37 ` [PATCH 01/14] removed two instances of trailing whitespaces Darrick J. Wong
2011-11-28 22:37 ` [PATCH 02/14] Moved a long comment from lib/crc32.c to Documentation/crc32.txt Darrick J. Wong
2011-11-28 22:37 ` [PATCH 03/14] Replaced the unit test provided in crc32.c, which doesn't have a Darrick J. Wong
2011-11-28 22:37 ` Darrick J. Wong [this message]
2011-11-28 22:37 ` [PATCH 05/14] Misc cleanup of lib/crc32.c and related files Darrick J. Wong
2011-11-28 22:37 ` [PATCH 06/14] crc32.c in its original version freely mixed u32, __le32 and __be32 types Darrick J. Wong
2011-11-28 22:37 ` [PATCH 07/14] crc32.c provides a choice of one of several algorithms for Darrick J. Wong
2011-11-28 22:37 ` [PATCH 08/14] add slicing-by-8 algorithm to the existing Darrick J. Wong
2011-11-28 22:38 ` [PATCH 09/14] Add two changes that improve the performance of x86 systems Darrick J. Wong
2011-11-28 22:38 ` [PATCH 10/14] Some final changes Darrick J. Wong
2011-11-28 22:38 ` [PATCH 11/14] crc32: Bolt on crc32c Darrick J. Wong
2011-11-28 22:38 ` [PATCH 12/14] crypto: crc32c should use library implementation Darrick J. Wong
2011-11-28 22:38 ` [PATCH 13/14] crc32: Add self-test code for crc32c Darrick J. Wong
2011-11-28 22:38 ` [PATCH 14/14] crc32: Select an algorithm via kconfig Darrick J. Wong
2011-11-30 22:29 ` [PATCH v5.1 00/14] crc32c: Add faster algorithm and self-test code Andrew Morton
2011-12-01 20:12 ` Darrick J. Wong
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