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static inline void __constant_memcpy_fromfs(void * to, const void * from, unsigned long n)
{
	switch (n) {
		case 0:
			return;
		case 1:
			*(char *)to = get_user_byte((const char *) from);
			return;
		case 2:
			*(short *)to = get_user_word((const short *) from);
			return;
		case 3:
			*(short *) to = get_user_word((const short *) from);
			*(char *) to = get_user_byte(2+(const char *) from);
			return;
		case 4:
			*(int *) to = get_user_long((const int *) from);
			return;
	}
#define COMMON(x) \
	__asm__("cld\n\t" \
	"rep ; fs ; movsl\n\t" \
	x \
	: /* no outputs*/  \
	:"c" (n/4),"D" ((long) to),"S" ((long) from) \
	:"cx","di","si","memory")

	switch (n % 4) {
		case 0:
			COMMON("");
			return;
		case 1:
			COMMON("fs ; movsb");
			return;
		case 2:
			COMMON("fs ; movsw");
			return;
		case 3:
			COMMON("fs ; movsw\n\tfs ; movsb");
			return;
	}
#undef COMMON
}

Code: Select all

short d0, d1, d2;
   __asm__("cld\n\t" \
   "rep ; fs ; movsl\n\t" \
   x \
   :"=&c" (d0), "=&D" (d1), "=&S" (d2)  \
   :"0" (n/4),"1" ((long) to),"2" ((long) from) \
   :"memory")