Z80-Pacman/moveLibs.asm at master · yarbsemaj/Z80-Pacman · GitHub

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move:
				CP		'W'
				JR		Z,moveU
				CP		'A'
				JR		Z,moveL
				CP		'S'
				JR		Z,moveD
				JR		moveR

moveU:
				LD		A, (BC)
				DEC		A
				AND		00011111B
				LD		(BC),A
				RET
moveD:
				LD		A, (BC)
				INC		A
				AND		00011111B
				LD		(BC),A
				RET
moveL:
				LD		A, (DE)
				DEC		A
				AND		00011111B
				LD		(DE),A
				RET
moveR:
				LD		A, (DE)
				INC		A
				AND		00011111B
				LD		(DE),A
				RET
isMoveValid:
				CP		'W'
				JR		Z,moveUValid
				CP		'A'
				JR		Z,moveLValid
				CP		'S'
				JR		Z,moveDValid
				JR		moveRValid
moveUValid:
				BIT		upBit,D
				RET
moveDValid:
				BIT		downBit,D
				RET
moveLValid:
				BIT		leftBit,D
				RET
moveRValid:
				BIT		rightBit,D
				RET