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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/x86_64
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/x86_64')
-rw-r--r--src/string/x86_64/memmove.s15
1 files changed, 15 insertions, 0 deletions
diff --git a/src/string/x86_64/memmove.s b/src/string/x86_64/memmove.s
new file mode 100644
index 00000000..247f0ac3
--- /dev/null
+++ b/src/string/x86_64/memmove.s
@@ -0,0 +1,15 @@
+.global memmove
+.type memmove,@function
+memmove:
+	mov %rdi,%rax
+	sub %rsi,%rax
+	cmp %rdx,%rax
+	jae memcpy
+	mov %rdx,%rcx
+	lea -1(%rdi,%rdx),%rdi
+	lea -1(%rsi,%rdx),%rsi
+	std
+	rep movsb
+	cld
+	lea 1(%rdi),%rax
+	ret