From 31409617a46c5ac6ef1a893d3c478f76ce4d7d3d Mon Sep 17 00:00:00 2001 From: Stefan Reinauer Date: Wed, 22 Aug 2012 17:01:08 -0700 Subject: [PATCH] x86 memcpy: Copy 4 bytes at once This is a slight improvement over the rep movsb loop Change-Id: Id71d9bfe5330b154a5c62fac85ce3955ae89b057 Signed-off-by: Stefan Reinauer Reviewed-on: http://review.coreboot.org/1742 Tested-by: build bot (Jenkins) Reviewed-by: Stefan Reinauer --- src/arch/x86/lib/memcpy.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/src/arch/x86/lib/memcpy.c b/src/arch/x86/lib/memcpy.c index f8607cfc50..7f079ce9d6 100644 --- a/src/arch/x86/lib/memcpy.c +++ b/src/arch/x86/lib/memcpy.c @@ -5,11 +5,13 @@ void *memcpy(void *dest, const void *src, size_t n) unsigned long d0, d1, d2; asm volatile( - "rep movsb" - : "=S"(d0), "=D"(d1), "=c"(d2) - : "0"(src), "1"(dest), "2"(n) + "rep ; movsl\n\t" + "movl %4,%%ecx\n\t" + "rep ; movsb\n\t" + : "=&c" (d0), "=&D" (d1), "=&S" (d2) + : "0" (n >> 2), "g" (n & 3), "1" (dest), "2" (src) : "memory" - ); + ); return dest; }