From: Joe Perches <joe@perches.com>
To: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: netdev@vger.kernel.org, "David S. Miller" <davem@davemloft.net>
Subject: [PATCH] - trivial - Improve appletalk checksum calculation
Date: Mon, 22 Oct 2007 12:36:19 -0700 [thread overview]
Message-ID: <1193081779.5132.24.camel@localhost> (raw)
It's a bit after 2.6.1 now...
Removes unnecessary if, uses 16 bit rotate left.
Performance improves ~30%
Signed-off-by: Joe Perches <joe@perches.com>
diff --git a/net/appletalk/ddp.c b/net/appletalk/ddp.c
index 7c0b515..1c50f4c 100644
--- a/net/appletalk/ddp.c
+++ b/net/appletalk/ddp.c
@@ -925,15 +925,9 @@ static int atrtr_ioctl(unsigned int cmd, void __user *arg)
static unsigned long atalk_sum_partial(const unsigned char *data,
int len, unsigned long sum)
{
- /* This ought to be unwrapped neatly. I'll trust gcc for now */
while (len--) {
- sum += *data;
- sum <<= 1;
- if (sum & 0x10000) {
- sum++;
- sum &= 0xffff;
- }
- data++;
+ sum += *data++;
+ sum = ((sum & 0x8000)>>15) | ((sum & 0x7fff)<<1);
}
return sum;
}
next reply other threads:[~2007-10-22 19:36 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-22 19:36 Joe Perches [this message]
2007-10-23 0:35 ` [PATCH] - trivial - Improve appletalk checksum calculation David Miller
2007-10-23 1:36 ` Joe Perches
2007-10-23 1:43 ` David Miller
2007-10-23 1:53 ` Joe Perches
2007-10-23 3:51 ` Herbert Xu
2007-10-28 20:18 ` Urs Thuermann
2007-10-28 21:01 ` Joe Perches
2007-10-29 2:40 ` Joe Perches
2007-10-23 3:30 ` Stephen Hemminger
2007-10-23 3:39 ` Joe Perches
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