[PATCH] small update for strlen, strnlen, use less cpu instructions

[Orestes Leal Rodriguez]

very small update to strlen and strnlen that now use less cpu 
instructions by using a counter to avoid the memory addresses 
substraction to find the length of the string.

Orestes Leal Rodriguez.



--- 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@xxxxxxxxxxxx>,
  *                    Matthew Hawkins <matt@xxxxxxxxxxxxxxxxx>
  * -  Kissed strtok() goodbye
+ *
+ * * Tuesday June 16 2015, Orestes Leal Rodriguez <lukes357@xxxxxxxxx>
+ * - 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