linux-kernel - [PATCH] drivers/sbus/char: Micro-optimization in display7seg.c

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Message-Id: <1403181112-12018-1-git-send-email-linux@rasmusvillemoes.dk>
Date:	Thu, 19 Jun 2014 14:31:52 +0200
From:	Rasmus Villemoes <linux@...musvillemoes.dk>
To:	"David S. Miller" <davem@...emloft.net>,
	Paul Gortmaker <paul.gortmaker@...driver.com>
Cc:	sparclinux@...r.kernel.org, linux-kernel@...r.kernel.org,
	Rasmus Villemoes <linux@...musvillemoes.dk>
Subject: [PATCH] drivers/sbus/char: Micro-optimization in display7seg.c

Flipping a bit doesn't need four lines of code; and gcc seems to
actually generate two branches.

Signed-off-by: Rasmus Villemoes <linux@...musvillemoes.dk>
---
 drivers/sbus/char/display7seg.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/sbus/char/display7seg.c b/drivers/sbus/char/display7seg.c
index 7c71e7b..3221dff 100644
--- a/drivers/sbus/char/display7seg.c
+++ b/drivers/sbus/char/display7seg.c
@@ -143,10 +143,7 @@ static long d7s_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 
 	case D7SIOCTM:
 		/* toggle device mode-- flip display orientation */
-		if (regs & D7S_FLIP)
-			regs &= ~D7S_FLIP;
-		else
-			regs |= D7S_FLIP;
+		regs ^= D7S_FLIP;
 		writeb(regs, p->regs);
 		break;
 	}
-- 
1.9.2

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