Used by the routine at upd_120_to_126.

A rising sweep, one wave per step from a low note upwards. The number of steps comes from the type: four times its bottom three bits, plus three. upd_120_to_126 moves the object on to its next type before calling, so the calls are for types 121 to 127 and each is longer than the last: 7, 11, 15 and so on up to 31 steps.