Nightshade: Routine at DC43

DC43: Turn a stick's directions round with the town

Used by the routine at TURN_KNIGHT.

With the town turned round the stick's directions are swapped end for end -- left for right, up for down -- so that pushing it still means the same way on the screen. Fire is kept; the town-turning bit is dropped, having been used.

Input
E	The controls

Output
E	The same, turned round

SWAP_STICK

DC43

LD A,E

Keep fire

DC44

AND $08

DC46

BIT 0,E

Left becomes right

DC48

JR Z,SWAP_STICK_0

DC4A

SET 1,A

SWAP_STICK_0

DC4C

BIT 1,E

Right becomes left

DC4E

JR Z,SWAP_STICK_1

DC50

SET 0,A

SWAP_STICK_1

DC52

BIT 2,E

Up becomes down

DC54

JR Z,SWAP_STICK_2

DC56

SET 4,A

SWAP_STICK_2

DC58

BIT 4,E

Down becomes up

DC5A

JR Z,SWAP_STICK_3

DC5C

SET 2,A

SWAP_STICK_3

DC5E

LD E,A

The new controls

DC5F

RET