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authorRich Felker <dalias@aerifal.cx>2012-09-10 19:04:24 -0400
committerRich Felker <dalias@aerifal.cx>2012-09-10 19:04:24 -0400
commit2bf469310de6793228c103691859ed4d3158b117 (patch)
treeb292372faf231031dbe9404efb081fdf341ff719 /src/string/i386
parenta9555a995cea8aa67da571c95af61109140f2c8d (diff)
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asm for memmove on i386 and x86_64
for the sake of simplicity, I've only used rep movsb rather than
breaking up the copy for using rep movsd/q. on all modern cpus, this
seems to be fine, but if there are performance problems, there might
be a need to go back and add support for rep movsd/q.
Diffstat (limited to 'src/string/i386')
-rw-r--r--src/string/i386/memmove.s21
1 files changed, 21 insertions, 0 deletions
diff --git a/src/string/i386/memmove.s b/src/string/i386/memmove.s
new file mode 100644
index 00000000..6e6cc8e3
--- /dev/null
+++ b/src/string/i386/memmove.s
@@ -0,0 +1,21 @@
+.global memmove
+.type memmove,@function
+memmove:
+	mov 4(%esp),%eax
+	sub 8(%esp),%eax
+	cmp 12(%esp),%eax
+	jae memcpy
+	push %esi
+	push %edi
+	mov 12(%esp),%edi
+	mov 16(%esp),%esi
+	mov 20(%esp),%ecx
+	lea -1(%edi,%ecx),%edi
+	lea -1(%esi,%ecx),%esi
+	std
+	rep movsb
+	cld
+	lea 1(%edi),%eax
+	pop %edi
+	pop %esi
+	ret