[PATCH] Improve memccpy performance

[Wilco Dijkstra]

Improve memccpy performance by using memchr/memcpy rather than a byte loop. 
Overall performance on bench-memccpy is > 2x faster when using the C 
implementation of memchr and an optimized memcpy.

ChangeLog:

2015-01-14  Wilco Dijkstra  wdijkstr@arm.com

    * string/memccpy.c (memccpy): Improve performance using memchr/memcpy.

---
 string/memccpy.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/string/memccpy.c b/string/memccpy.c
index 70ee2ae..d4146f9 100644
--- a/string/memccpy.c
+++ b/string/memccpy.c
@@ -26,15 +26,15 @@
 void *
 __memccpy (void *dest, const void *src, int c, size_t n)
 {
-  const char *s = src;
-  char *d = dest;
-  const char x = c;
-  size_t i = n;
+  void *p = memchr (src, c, n);
 
-  while (i-- > 0)
-    if ((*d++ = *s++) == x)
-      return d;
+  if (p != NULL)
+    {
+      n = p - src + 1;
+      return memcpy (dest, src, n) + n;
+    }
 
+  memcpy (dest, src, n);
   return NULL;
 }
 
-- 
1.9.1