From d07aed31e95fb596d452aaa96b3c9c3c28bd98f8 Mon Sep 17 00:00:00 2001
From: stefan <stefan@315a16e6-25f9-4109-90ae-ca3045a26c18>
Date: Tue, 10 Aug 2010 20:16:09 +0000
Subject: [PATCH] - add optimized assembler code for strlen

git-svn-id: http://svn.lfbs.rwth-aachen.de/svn/scc/trunk/MetalSVM@61 315a16e6-25f9-4109-90ae-ca3045a26c18
---
 arch/x86/include/asm/string.h | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/string.h b/arch/x86/include/asm/string.h
index 4ef4f3b5..67d89da6 100644
--- a/arch/x86/include/asm/string.h
+++ b/arch/x86/include/asm/string.h
@@ -35,7 +35,7 @@ inline static void *memcpy(void *dest, const void *src, size_t count)
 		return dest;
 
 	asm volatile (
-		"rep ; movsl\n\t"
+		"cld; rep ; movsl\n\t"
 		"movl %4, %%ecx\n\t" 
 		"andl $3, %%ecx\n\t"
 		"rep ; movsb\n\t" 
@@ -54,12 +54,32 @@ inline static void *memset(void *dest, int val, size_t count)
 	if (BUILTIN_EXPECT(!dest, 0))
 		return dest;
 
-	asm volatile ("rep ; stosb" : "=&c"(i), "=&D"(j) : "a"(val), "1"(dest), "0"(count) : "memory");
+	asm volatile ("cld; rep ; stosb" 
+		: "=&c"(i), "=&D"(j)
+		: "a"(val), "1"(dest), "0"(count) : "memory");
 
 	return dest;
 }
 #endif
 
+#ifdef HAVE_ARCH_STRLEN
+inline static size_t strlen(const char *str)
+{
+	size_t len = 0;
+	uint32_t i, j = 0;
+
+	if (BUILTIN_EXPECT(!str, 0))
+		return len;
+
+	asm volatile("not %%ecx; cld; repne ; scasb; not %%ecx; dec %%ecx"
+		: "=&c"(len), "=&D"(i), "=&a"(j)
+		: "2"(j), "1"(str), "0"(len)
+		: "memory");
+
+	return len;
+}
+#endif
+
 #ifdef __cplusplus
 }
 #endif