__asm__ __volatile__()

in include/asm/uaccess.h [222:278]

• 49 lines of code
• 1 McCabe index (conditional complexity)

__asm__ __volatile__("1: stq %r2,%1\n"				\
	"2:\n"							\
	EXC(1b,2b,$31,%0)					\
		: "=r"(__pu_err)				\
		: "m" (__m(addr)), "rJ" (x), "0"(__pu_err))

#define __put_user_32(x, addr)					\
__asm__ __volatile__("1: stl %r2,%1\n"				\
	"2:\n"							\
	EXC(1b,2b,$31,%0)					\
		: "=r"(__pu_err)				\
		: "m"(__m(addr)), "rJ"(x), "0"(__pu_err))

#ifdef __alpha_bwx__
/* Those lucky bastards with ev56 and later CPUs can do byte/word moves.  */

#define __put_user_16(x, addr)					\
__asm__ __volatile__("1: stw %r2,%1\n"				\
	"2:\n"							\
	EXC(1b,2b,$31,%0)					\
		: "=r"(__pu_err)				\
		: "m"(__m(addr)), "rJ"(x), "0"(__pu_err))

#define __put_user_8(x, addr)					\
__asm__ __volatile__("1: stb %r2,%1\n"				\
	"2:\n"							\
	EXC(1b,2b,$31,%0)					\
		: "=r"(__pu_err)				\
		: "m"(__m(addr)), "rJ"(x), "0"(__pu_err))
#else
/* Unfortunately, we can't get an unaligned access trap for the sub-word
   write, so we have to do a general unaligned operation.  */

#define __put_user_16(x, addr)					\
{								\
	long __pu_tmp1, __pu_tmp2, __pu_tmp3, __pu_tmp4;	\
	__asm__ __volatile__(					\
	"1:	ldq_u %2,1(%5)\n"				\
	"2:	ldq_u %1,0(%5)\n"				\
	"	inswh %6,%5,%4\n"				\
	"	inswl %6,%5,%3\n"				\
	"	mskwh %2,%5,%2\n"				\
	"	mskwl %1,%5,%1\n"				\
	"	or %2,%4,%2\n"					\
	"	or %1,%3,%1\n"					\
	"3:	stq_u %2,1(%5)\n"				\
	"4:	stq_u %1,0(%5)\n"				\
	"5:\n"							\
	EXC(1b,5b,$31,%0)					\
	EXC(2b,5b,$31,%0)					\
	EXC(3b,5b,$31,%0)					\
	EXC(4b,5b,$31,%0)					\
		: "=r"(__pu_err), "=&r"(__pu_tmp1), 		\
		  "=&r"(__pu_tmp2), "=&r"(__pu_tmp3), 		\
		  "=&r"(__pu_tmp4)				\
		: "r"(addr), "r"((unsigned long)(x)), "0"(__pu_err)); \
}