river-raid: Routine at 73DD

73DD: Render helicopter missile (spawn new)

Spawns a new helicopter missile from an advanced helicopter. Called when processing OBJECT_HELICOPTER_ADV in the viewport loop. Plays a sound and initializes missile trajectory. Returns immediately during GAMEPLAY_MODE_SCROLL_IN Returns if missile already active (B != 0) Plays missile launch sound via ROM BEEPER Extracts helicopter position and orientation Stores initial missile coordinates to helicopter_missile_coordinates_ptr
render_helicopter_missile	73DD	LD A,($5F68)	Return if in GAMEPLAY_MODE_SCROLL_IN.
	73E0	CP $01
	73E2	RET Z
	73E3	LD BC,($5F73)	Load missile coords from helicopter_missile_coordinates_ptr. Return if missile active (B != 0).
	73E7	LD A,B
	73E8	CP $00
	73EA	RET NZ
	73EB	LD DE,$0001	Play missile launch sound: BEEPER with DE=$0001, HL=$2800.
	73EE	LD HL,$2800
	73F1	CALL $03B5
	73F4	LD HL,($5F60)	Load current_slot_ptr, extract [D, B, C] from helicopter's slot.
	73F7	DEC HL
	73F8	LD D,(HL)
	73F9	DEC HL
	73FA	LD B,(HL)
	73FB	DEC HL
	73FC	LD C,(HL)
	73FD	LD A,C	Align X to 8-pixel boundary (AND $F8), extract orientation bit.
	73FE	AND $F8
	7400	LD C,A
	7401	LD A,D
	7402	AND $40
	7404	LD ($5F75),A	Store orientation to helicopter_missile_state. If right-facing, add offset via add_missile_x_offset.
	7407	BIT 6,A
	7409	CALL Z,add_missile_x_offset
	740C	INC B	Add 4 to Y position (INC B × 4), store to helicopter_missile_coordinates_ptr.
	740D	INC B
	740E	INC B
	740F	INC B
	7410	LD ($5F73),BC
	7414	RET