Function bintime_off

freebsd/kern/kern_tc.c:213–241

 */

static __inline void
bintime_off(struct bintime *bt, u_int off)
{
	struct timehands *th;
	struct bintime *btp;
	uint64_t scale, x;
	u_int delta, gen, large_delta;

	do {
		th = timehands;
		gen = atomic_load_acq_int(&th->th_generation);
		btp = (struct bintime *)((vm_offset_t)th + off);
		*bt = *btp;
		scale = th->th_scale;
		delta = tc_delta(th);
		large_delta = th->th_large_delta;
		atomic_thread_fence_acq();
	} while (gen == 0 || gen != th->th_generation);

	if (__predict_false(delta >= large_delta)) {
		/* Avoid overflow for scale * delta. */
		x = (scale >> 32) * delta;
		bt->sec += x >> 32;
		bintime_addx(bt, x << 32);
		bintime_addx(bt, (scale & 0xffffffff) * delta);
	} else {
		bintime_addx(bt, scale * delta);
	}
}
#define	GETTHBINTIME(dst, member)					\
do {									\
	bintime_off(dst, __offsetof(struct timehands, member));		\