Duff’s device

“This code forms some sort of argument (…), but I’m not sure whether it’s for or against.”

	send(to, from, count)
	register short *to, *from;
	register count;
	{
		register n = (count + 7) / 8;
		switch (count % 8) {
		case 0: do { *to = *from++;
		case 7:      *to = *from++;
		case 6:      *to = *from++;
		case 5:      *to = *from++;
		case 4:      *to = *from++;
		case 3:      *to = *from++;
		case 2:      *to = *from++;
		case 1:      *to = *from++;
			    } while (--n > 0);
		}
	}