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authorH. Peter Anvin <hpa@zytor.com>2008-02-13 17:49:38 -0800
committerH. Peter Anvin <hpa@zytor.com>2008-02-13 17:49:38 -0800
commit4d36df22fcb042a595300fb7d61b64b58caf018d (patch)
treef747ee070b3adf8ec76dac1345b8373b57770ae1
parent42cb21a4063c39feeb900e0441b96efea19159c5 (diff)
downloadsyslinux.git-4d36df22fcb042a595300fb7d61b64b58caf018d.tar.gz
syslinux.git-4d36df22fcb042a595300fb7d61b64b58caf018d.tar.xz
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Replace C version of memmove() with slightly optimized assembly
Replace the C version of memmove() with a slightly more optimized assembly version that at least can do dword-sized rep moves.
-rw-r--r--com32/lib/memmove.S79
-rw-r--r--com32/lib/memmove.c34
2 files changed, 79 insertions, 34 deletions
diff --git a/com32/lib/memmove.S b/com32/lib/memmove.S
new file mode 100644
index 00000000..e39f884b
--- /dev/null
+++ b/com32/lib/memmove.S
@@ -0,0 +1,79 @@
+/* ----------------------------------------------------------------------- *
+ *
+ * Copyright 2008 rPath, Inc. - All Rights Reserved
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom
+ * the Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall
+ * be included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * memmove.S
+ *
+ * Reasonably efficient memmove
+ */
+
+ .globl memmove
+ .type memmove,@function
+ .text
+memmove:
+ pushl %esi
+ pushl %edi
+
+ movl %eax,%edi
+ movl %edx,%esi
+
+ cmpl %edi,%esi
+ jb 1f
+
+ /* source >= dest, forwards move */
+ movl %ecx,%edx
+ shrl $2,%ecx
+ andl $3,%edx
+
+ rep; movsl
+ movl %edx,%ecx
+ rep; movsb
+
+ jmp 2f
+1:
+ /* source < dest, backwards move */
+ leal -4(%ecx,%esi),%esi
+ leal -4(%ecx,%edi),%edi
+
+ movl %ecx,%edx
+ shrl $2,%ecx
+ andl $3,%edx
+
+ std
+ rep; movsl
+ movl %edx,%ecx
+ addl $3,%esi
+ addl $3,%edi
+ rep; movsb
+ cld
+
+2:
+ popl %edi
+ popl %esi
+ ret
+
+ .size memmove, .-memmove
diff --git a/com32/lib/memmove.c b/com32/lib/memmove.c
deleted file mode 100644
index c1f042af..00000000
--- a/com32/lib/memmove.c
+++ /dev/null
@@ -1,34 +0,0 @@
-/*
- * memmove.c
- */
-
-#include <string.h>
-
-void *memmove(void *dst, const void *src, size_t n)
-{
- const char *p = src;
- char *q = dst;
-#if defined(__i386__) || defined(__x86_64__)
- if ( q < p ) {
- asm volatile("cld ; rep ; movsb" : "+c" (n), "+S" (p), "+D" (q));
- } else {
- p += (n-1);
- q += (n-1);
- asm volatile("std ; rep ; movsb" : "+c" (n), "+S" (p), "+D" (q));
- }
-#else
- if ( q < p ) {
- while ( n-- ) {
- *q++ = *p++;
- }
- } else {
- p += n;
- q += n;
- while ( n-- ) {
- *--q = *--p;
- }
- }
-#endif
-
- return dst;
-}