dwm-flexipatch/patch/shiftview.c

void
shiftview(const Arg *arg)
{
	Arg shifted;

	if (arg->i > 0) // left circular shift
		shifted.ui = (selmon->tagset[selmon->seltags] << arg->i)
		   | (selmon->tagset[selmon->seltags] >> (LENGTH(tags) - arg->i));

	else // right circular shift
		shifted.ui = selmon->tagset[selmon->seltags] >> (- arg->i)
		   | selmon->tagset[selmon->seltags] << (LENGTH(tags) + arg->i);

	view(&shifted);
}