Nightshade: Routine at D727

D727: Update Speed Bonus

The routine for objects of type 02, the bonuses that make the player move faster. A bonus vanishes when the player is more than four cells away. When the player touches it, the bonus turns into a burst and the player's speed is raised for FF frames.
Vanish if the player is too far away.
UpdateSpeedBonus	D727	LD C,$04	Set the distance to 04 cells and check whether the bonus is that close to the player.
	D729	CALL CheckPlayerClose
	D72C	JR C,UpdateSpeedBonus_Close	Jump to UpdateSpeedBonus_Close if it is.
	D72E	LD (IX+$00),$00	Remove the bonus, because the player is too far away, and return.
	D732	RET
Raise the player's speed when the bonus is touched.
UpdateSpeedBonus_Close	D733	CALL CheckPlayerCollision	Return if the bonus is not touching the player.
	D736	RET NC	Return if the bonus is not touching the player.
	D737	LD (IX+$00),$0C	Turn the bonus into a burst.
	D73B	LD A,$FF	Make the speed bonus last for FF frames.
	D73D	LD ($BBF5),A	Make the speed bonus last for FF frames.
	D740	LD A,$12	Raise the player's top speed to 12.
	D742	LD ($BBBE),A	Raise the player's top speed to 12.
	D745	LD HL,$0105	Start the speed bonus sound, which is sound effect 01 and has five notes.
	D748	LD ($BBF9),HL
	D74B	RET	Return.