The design of the slab in the short direction will be the same as that of the walls in the vertical direction, #8 bars @ 6″ top and bottom faces of the slab. Also note that the shear is considerably less than in the walls, thus the 14″ thick slab is adequate for the shear strength.
The slab in the long span direction is mainly taking moment from the bottom of the short exterior walls. The same design will be used in this direction as the vertical reinforcing for the short exterior walls, #6 bars @ 8″ top and bottom faces