linux-kernel - [PATCH] rtc: Modify leap year test for more simpler way

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Message-id: <1360149775-19606-1-git-send-email-jonghwa3.lee@samsung.com>
Date:	Wed, 06 Feb 2013 20:22:55 +0900
From:	Jonghwa Lee <jonghwa3.lee@...sung.com>
To:	linux-kernel@...r.kernel.org
Cc:	a.zummo@...ertech.it, Andrew Morton <akpm@...ux-foundation.org>,
	rtc-linux@...glegroups.com, Jonghwa Lee <jonghwa3.lee@...sung.com>
Subject: [PATCH] rtc: Modify leap year test for more simpler way

Leap year which is multiple of 4, just needed 2 LSB for verifying.
A year with zero for all thease two bits means that it is leap year.

Signed-off-by: Jonghwa Lee <jonghwa3.lee@...sung.com>
---
 include/linux/rtc.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/rtc.h b/include/linux/rtc.h
index 9531845..d662b8d 100644
--- a/include/linux/rtc.h
+++ b/include/linux/rtc.h
@@ -181,7 +181,7 @@ void rtc_timer_do_work(struct work_struct *work);
 
 static inline bool is_leap_year(unsigned int year)
 {
-	return (!(year % 4) && (year % 100)) || !(year % 400);
+	return !(year & 0x3);
 }
 
 #ifdef CONFIG_RTC_HCTOSYS_DEVICE
-- 
1.7.9.5

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