linux/arch/x86/boot/compressed/string.c

#include "misc.h"
#include "../string.c"

/* misc.h might pull in string_32.h which has a macro for memcpy. undef that */
#undef memcpy

#ifdef CONFIG_X86_32
void *memcpy(void *dest, const void *src, size_t n)
{
	int d0, d1, d2;
	asm volatile(
		"rep ; movsl\n\t"
		"movl %4,%%ecx\n\t"
		"rep ; movsb\n\t"
		: "=&c" (d0), "=&D" (d1), "=&S" (d2)
		: "0" (n >> 2), "g" (n & 3), "1" (dest), "2" (src)
		: "memory");

	return dest;
}
#else
void *memcpy(void *dest, const void *src, size_t n)
{
	long d0, d1, d2;
	asm volatile(
		"rep ; movsq\n\t"
		"movq %4,%%rcx\n\t"
		"rep ; movsb\n\t"
		: "=&c" (d0), "=&D" (d1), "=&S" (d2)
		: "0" (n >> 3), "g" (n & 7), "1" (dest), "2" (src)
		: "memory");

	return dest;
}
#endif