linux-kernel - [PATCH] lib: string.c: A speed optimized for strncpy

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Message-Id: <1412515757-19689-2-git-send-email-rickard_strandqvist@spectrumdigital.se>
Date:	Sun,  5 Oct 2014 15:29:16 +0200
From:	Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>
To:	Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>,
	Grant Likely <grant.likely@...aro.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Andi Kleen <ak@...ux.intel.com>,
	Dan Carpenter <dan.carpenter@...cle.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] lib: string.c:  A speed optimized for strncpy

This variant is in my tests about 7-10% faster, and also think
it is perhaps even clearer code than before.

Signed-off-by: Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>
---
 lib/string.c |   12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/lib/string.c b/lib/string.c
index f3c6ff5..6961229 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -123,12 +123,12 @@ char *strncpy(char *dest, const char *src, size_t count)
 {
 	char *tmp = dest;
 
-	while (count) {
-		if ((*tmp = *src) != 0)
-			src++;
-		tmp++;
-		count--;
-	}
+	while (count && (*tmp++ = *src++))
+		--count;
+
+	while (count--)
+		*tmp++ = '\0';
+
 	return dest;
 }
 EXPORT_SYMBOL(strncpy);
-- 
1.7.10.4

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