[U-Boot] [PATCH V2] memcpy/memmove: Do not copy to same address

Matthias Weisser
2011-05-23T09:03:55Z

In some cases (e.g. bootm with a elf payload which is already at the right
position) there is a in place copy of data to the same address. Catching this
saves some ms while booting.

Signed-off-by: Matthias Weisser <weisserm@arcor.de>
---
Changes since V1:
- Made subject more informative
- Removed the optimization from bcopy as bcopy is not used anywhere

lib/string.c | 6 ++++++
1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/lib/string.c b/lib/string.c
index b375b81..2c4f0ec 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -467,6 +467,9 @@ void * memcpy(void *dest, const void *src, size_t count)
unsigned long *dl = (unsigned long *)dest, *sl = (unsigned long *)src;
char *d8, *s8;

+ if (src == dest)
+ return dest;
+
/* while all data is aligned (common case), copy a word at a time */
if ( (((ulong)dest | (ulong)src) & (sizeof(*dl) - 1)) == 0) {
while (count >= sizeof(*dl)) {
@@ -497,6 +500,9 @@ void * memmove(void * dest,const void *src,size_t count)
{
char *tmp, *s;

+ if (src == dest)
+ return dest;
+
if (dest <= src) {
tmp = (char *) dest;
s = (char *) src;
--
1.7.0.4