linux/arch/x86/lib/memcpy_32.c
Ma, Ling fdf4289679 x86, mem: Don't implement forward memmove() as memcpy()
memmove() allow source and destination address to be overlap, but
there is no such limitation for memcpy().  Therefore, explicitly
implement memmove() in both the forwards and backward directions, to
give us the ability to optimize memcpy().

Signed-off-by: Ma Ling <ling.ma@intel.com>
LKML-Reference: <C10D3FB0CD45994C8A51FEC1227CE22F0E483AD86A@shsmsx502.ccr.corp.intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2010-08-23 14:14:27 -07:00

60 lines
998 B
C

#include <linux/string.h>
#include <linux/module.h>
#undef memcpy
#undef memset
void *memcpy(void *to, const void *from, size_t n)
{
#ifdef CONFIG_X86_USE_3DNOW
return __memcpy3d(to, from, n);
#else
return __memcpy(to, from, n);
#endif
}
EXPORT_SYMBOL(memcpy);
void *memset(void *s, int c, size_t count)
{
return __memset(s, c, count);
}
EXPORT_SYMBOL(memset);
void *memmove(void *dest, const void *src, size_t n)
{
int d0, d1, d2;
if (dest < src) {
if ((dest + n) < src)
return memcpy(dest, src, n);
else
__asm__ __volatile__(
"rep\n\t"
"movsb\n\t"
: "=&c" (d0), "=&S" (d1), "=&D" (d2)
:"0" (n),
"1" (src),
"2" (dest)
:"memory");
} else {
if((src + count) < dest)
return memcpy(dest, src, count);
else
__asm__ __volatile__(
"std\n\t"
"rep\n\t"
"movsb\n\t"
"cld"
: "=&c" (d0), "=&S" (d1), "=&D" (d2)
:"0" (n),
"1" (n-1+src),
"2" (n-1+dest)
:"memory");
}
return dest;
}
EXPORT_SYMBOL(memmove);