linux-kernel - [PATCH 1/2] div64

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Message-ID: <20070321131532.66e7f0e1@freekitty>
Date:	Wed, 21 Mar 2007 13:15:32 -0700
From:	Stephen Hemminger <shemminger@...ux-foundation.org>
To:	Willy Tarreau <w@....eu>, David Miller <davem@...emloft.net>
Cc:	rkuhn@....physik.tu-muenchen.de, andi@...stfloor.org,
	dada1@...mosbay.com, jengelh@...ux01.gwdg.de,
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH 1/2] div64_64 optimization

Minor optimization of div64_64.  do_div() already does optimization
for the case of 32 by 32 divide, so no need to do it here.

Signed-off-by: Stephen Hemminger <shemminger@...ux-foundation.org>

--- net-2.6.22.orig/lib/div64.c	2007-03-21 12:03:59.000000000 -0700
+++ net-2.6.22/lib/div64.c	2007-03-21 12:04:46.000000000 -0700
@@ -61,20 +61,18 @@
 /* 64bit divisor, dividend and result. dynamic precision */
 uint64_t div64_64(uint64_t dividend, uint64_t divisor)
 {
-	uint32_t d = divisor;
+	uint32_t high, d;
 
-	if (divisor > 0xffffffffULL) {
-		unsigned int shift = fls(divisor >> 32);
+	high = divisor >> 32;
+	if (high) {
+		unsigned int shift = fls(high);
 
 		d = divisor >> shift;
 		dividend >>= shift;
-	}
+	} else
+		d = divisor;
 
-	/* avoid 64 bit division if possible */
-	if (dividend >> 32)
-		do_div(dividend, d);
-	else
-		dividend = (uint32_t) dividend / d;
+	do_div(dividend, d);
 
 	return dividend;
 }
-
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