Used by the routine at MOVE_PLAYER.

Called by MOVE_PLAYER once the move has been cut short and before it is made. A room is left only through a doorway, and only walking the way the robot faces: a doorway's first pillar sets bit 0 of the legs' flags while he is in it (CHK_PLYR_NEAR_ARCH), which also lets him past the line of the wall (ADJ_DU_FOR_OUT_OF_BOUNDS, ADJ_DV_FOR_OUT_OF_BOUNDS). This clears the bit -- it is used once, and the pillar sets it again on its next update if he is still there -- and jumps through SCREEN_MOVE_TBL by the facing; each of the four decides whether this turn's move takes him wholly past the wall he faces.

Knight Lore's, instruction for instruction. The room's half-sizes are pushed for the four, because the dispatch uses HL.