Used by the routine at PLAYER_LEGS.

Called from the legs' update routine (PLAYER_LEGS) every turn. One press does one thing: pick up a valve he is on or beside; failing that, put down the last of the things he carries (CARRIED_LAST), under himself, so that he stands on it; and if there is nothing in that slot, move what he carries one slot along towards it. TAKE_HELD latches the press, so holding the key does nothing more, and every press that gets past the tests below beeps (PLAIN_BEEP). Knight Lore's handle_pickup_drop and the routines after it, joined into one, as in Pentagram.

Nothing happens unless he is inside the room's walls (CHK_PLYR_OOB, not in a doorway), not jumping (bit 3 of +$0C) and standing on something (bit 2). Before anything else it looks for an object in the space he would fill if he were lifted 12 units (DO_ANY_OBJS_INTERSECT): if there is one, NO_HEADROOM is set and nothing is put down, because putting something down lifts him 12 units onto it.

Only the two records at VALVES are looked at, for a thing to pick up and for a record to put one down in: the records that hold what lies in the room from the table of places (PLACES). So only a valve that lies in its place can be picked up, and a thing can be put down only while one of the two is empty: a room holds at most two valves.

He carries up to three things, in the four-byte slots CARRIED (the newest), the one after, and CARRIED_LAST (the oldest, put down next): the graphic, the flags from +7, and the address of the thing's place (PLACES). CARRIED_NEW is a fourth slot in front of them, where a thing just picked up waits for the slots to be moved along. They behave as a queue, and a press that puts nothing down moves them along: one thing carried takes three presses to reach CARRIED_LAST and a fourth to be put down (measured by the build's sessions: see the notes' driving recipe).