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Subject[PATCH] lib: memmove: Use optimised memcpy if possible
Date
When there is no overlap between src and dst use optimised memcpy if it
is available.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Signed-off-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
---
This change is a small part of a patch [1] from Paul Burton. I have
added his Signed-off by. I do not know whether it is correct. Please let
me know if it has to be changed, I will send a v2.

This patch is boot tested with qemu for MIPS architecture by removing
mips's memmove routine. This patch does not contain MIPS changes. I
will try to find out why [1] was not taken already and figure out what
to do.

1. https://patchwork.linux-mips.org/patch/14517/

lib/string.c | 11 +++++++++++
1 file changed, 11 insertions(+)

diff --git a/lib/string.c b/lib/string.c
index 9921dc2..462ab7b 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -825,6 +825,17 @@ void *memmove(void *dest, const void *src, size_t count)
char *tmp;
const char *s;

+#ifdef __HAVE_ARCH_MEMCPY
+ /* Use optimised memcpy when there is no overlap */
+ const char *s_end = src + count;
+ const char *d = dest;
+ char *d_end = dest + count;
+
+ s = src;
+ if ((d_end <= s) || (s_end <= d))
+ return memcpy(dest, src, count);
+#endif /* __HAVE_ARCH_MEMCPY */
+
if (dest <= src) {
tmp = dest;
s = src;
--
2.10.0
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