From: Bob Pearson <rpearson@systemfabricworks.com>
To: linux-kernel@vger.kernel.org
Cc: fzago@systemfabricworks.com, rpearson@systemfabricworks.com,
Joakim Tjernlund <joakim.tjernlund@transmode.se>,
George Spelvin <linux@horizon.com>,
akpm@linux-foundation.org
Subject: [PATCH v6 04/10] crc32-add-pointer-to-tab.diff
Date: Wed, 31 Aug 2011 17:30:06 -0500 [thread overview]
Message-ID: <4E5EB5EE.806@systemfabricworks.com> (raw)
In-Reply-To: <20110831213729.395283830@systemfabricworks.com>
Replace 2D array references by pointer references in loops.
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 file changed, 11 insertions(+), 10 deletions(-)
Index: for-next/lib/crc32.c
===================================================================
--- for-next.orig/lib/crc32.c
+++ for-next/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:[~2011-08-31 22:30 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20110831213729.395283830@systemfabricworks.com>
2011-08-31 22:29 ` [PATCH v6 01/10] crc32-remove-trailing-whitespace.diff Bob Pearson
2011-08-31 22:29 ` [PATCH v6 02/10] crc32-move-to-documentation.diff Bob Pearson
2011-08-31 22:29 ` [PATCH v6 03/10] crc32-replace-self-test.diff Bob Pearson
2011-09-02 23:51 ` Andrew Morton
2011-09-06 16:14 ` Bob Pearson
2011-08-31 22:30 ` Bob Pearson [this message]
2011-09-01 8:16 ` [PATCH v6 04/10] crc32-add-pointer-to-tab.diff Joakim Tjernlund
2011-08-31 22:30 ` [PATCH v6 05/10] crc32-misc-cleanup.diff Bob Pearson
2011-09-02 23:50 ` Andrew Morton
2011-09-03 1:44 ` Stephen Rothwell
2011-09-06 13:40 ` Joakim Tjernlund
2011-09-06 14:50 ` Stephen Rothwell
2011-09-06 19:38 ` Andrew Morton
2011-09-06 20:18 ` Bob Pearson
2011-09-07 7:39 ` Joakim Tjernlund
2011-09-07 16:30 ` Bob Pearson
2011-09-07 17:51 ` Joakim Tjernlund
2011-09-06 16:05 ` Bob Pearson
2011-08-31 22:30 ` [PATCH v6 06/10] crc32-fix-check-endian-warnings.diff Bob Pearson
2011-08-31 22:30 ` [PATCH v6 07/10] crc32-add-real-8-bit.diff Bob Pearson
2011-08-31 22:30 ` [PATCH v6 08/10] crc32-add-slicing-by-8.diff Bob Pearson
2011-09-07 7:31 ` Joakim Tjernlund
2011-09-07 19:44 ` Bob Pearson
[not found] ` <OF3D37A60B.7A33B855-ONC1257904.00276B5B-C1257904.002951AF@LocalDomain>
2011-09-07 8:30 ` Joakim Tjernlund
2011-08-31 22:30 ` [PATCH v6 09/10] crc32-optimize-loops-for-x86.diff Bob Pearson
2011-08-31 22:30 ` [PATCH v6 10/10] crc32-final.diff Bob Pearson
2011-09-01 3:03 ` [PATCH v6 08/10] crc32-add-slicing-by-8.diff Bob Pearson
2011-09-07 7:32 ` Joakim Tjernlund
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