From: Luke Skywalker <lukes357@gmail.com>
To: linux-kernel@vger.kernel.org
Subject: [PATCH] small update for strlen, strnlen, use less cpu instructions
Date: Tue, 16 Jun 2015 04:26:45 -0500 [thread overview]
Message-ID: <557FEBD5.5010902@gmail.com> (raw)
[-- Attachment #1: Type: text/plain, Size: 199 bytes --]
very small update to strlen and strnlen that now use less cpu
instructions by
using a counter avoiding the memory addresses substraction to find the
length
of the string,
Orestes Leal Rodriguez.
[-- Attachment #2: string.c.patch --]
[-- Type: text/plain, Size: 1140 bytes --]
--- lib/string.c.orig 2015-06-15 23:59:32.768346193 -0400
+++ lib/string.c 2015-06-16 00:11:45.791381539 -0400
@@ -17,6 +17,10 @@
* * Sat Feb 09 2002, Jason Thomas <jason@topic.com.au>,
* Matthew Hawkins <matt@mh.dropbear.id.au>
* - Kissed strtok() goodbye
+ *
+ * * Tuesday June 16 2015, Orestes Leal Rodriguez <lukes357@gmail.com>
+ * - strlen, strnlen: by using a single counter we use less cpu instructions
+ * by avoiding substracting the memory addresses before return
*/
#include <linux/types.h>
@@ -401,11 +405,11 @@ EXPORT_SYMBOL(strim);
*/
size_t strlen(const char *s)
{
- const char *sc;
+ size_t sz = 0;
- for (sc = s; *sc != '\0'; ++sc)
- /* nothing */;
- return sc - s;
+ for (; *s++ != '\0'; sz++)
+ /*empty */;
+ return sz;
}
EXPORT_SYMBOL(strlen);
#endif
@@ -418,12 +422,13 @@ EXPORT_SYMBOL(strlen);
*/
size_t strnlen(const char *s, size_t count)
{
- const char *sc;
+ size_t sz = 0;
- for (sc = s; count-- && *sc != '\0'; ++sc)
- /* nothing */;
- return sc - s;
+ for (; count-- && *s++ != '\0'; sz++)
+ /* empty */;
+ return sz;
}
+
EXPORT_SYMBOL(strnlen);
#endif
next reply other threads:[~2015-06-16 8:57 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-16 9:26 Luke Skywalker [this message]
-- strict thread matches above, loose matches on Subject: below --
2015-06-16 9:28 [PATCH] small update for strlen, strnlen, use less cpu instructions Orestes Leal Rodriguez
2015-06-16 10:37 ` Richard Weinberger
2015-06-16 18:56 ` Luke Skywalker
2015-06-16 19:06 ` Darth Vader
2015-06-16 9:36 Orestes Leal Rodriguez
2015-06-16 9:40 Orestes Leal Rodriguez
2015-06-16 10:03 ` Mihai Donțu
2015-06-16 11:41 Alexey Dobriyan
2015-06-16 11:43 ` Richard Weinberger
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