arch/x86/lib/memcpy_32.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);