Chase H.Q.: Routine at A7F3

A7F3: Spawns cars

Used by the routines at main_loop and cpu_driver.
spawn_cars	A7F3	LD A,($A230)	Return if perp_caught_stage or stop_car_spawning flags are set
	A7F6	LD C,A
	A7F7	LD A,($A225)
	A7FA	OR C
	A7FB	RET NZ
	A7FC	LD A,($A254)	Load another_spawning_flag
	A7FF	AND A	Return if another_spawning_flag was zero
	A800	RET Z	Return if another_spawning_flag was zero
	A801	NEG	A = <self modified> - another_spawning_flag
	A803	ADD A,$14	A = <self modified> - another_spawning_flag
	A805	LD ($A804),A	Self modify above
	A808	RET C	Return if carry?
Start spawning cars.
	A809	CALL rng	Call rng
	A80C	AND $0F	C = A & 15
	A80E	LD C,A	C = A & 15
	A80F	LD A,($A22E)	Load sighted_flag
	A812	AND A	Set flags
	A813	LD A,($5D1A)	Load car_spawn_rate
	A816	JR Z,spawn_cars_0	Jump to spawn_cars_0 if sighted_flag was zero
	A818	ADD A,$19	A += 25 -- boost factor/rate when perp sighted
spawn_cars_0	A81A	ADD A,C	A += C -- add random factor (0..15)
	A81B	LD ($A804),A	Self modify above
	A81E	LD BC,$0500	BC = $0500
	A821	LD IX,$A19C	IX = &hazards[1]
	A825	LD DE,$0014	DE = 20 -- stride of hazards
sc_loop	A828	RLC (IX+$00)	If the hazard is not active jump to sc_fill_in
	A82C	JR NC,sc_fill_in	If the hazard is not active jump to sc_fill_in
	A82E	LD A,(IX+$0F)	A = IX[15]
	A831	RLA
	A832	JP NC,spawn_cars_1
	A835	RL C
spawn_cars_1	A837	ADD IX,DE	IX += DE
	A839	DJNZ sc_loop	Loop to sc_loop while B
	A83B	RET	Return
sc_fill_in	A83C	BIT 2,C
	A83E	RET NZ
	A83F	PUSH IX	DE = IX
	A841	POP DE	DE = IX
	A842	LD BC,$0014	BC = 20
	A845	LD HL,$A623	Point HL at hazard_template
	A848	LDIR	Copy hazard_template
	A84A	LD C,$14	Buffer offset of 20 for get_spawn_lanes
	A84C	CALL get_spawn_lanes	Call get_spawn_lanes -- Gets car spawning positions (B = min, C = max?)
	A84F	CALL rng	Call rng
	A852	AND $03	A = (A & 3) + B
	A854	ADD A,B	A = (A & 3) + B
	A855	CP C	If A >= C A = C
	A856	JR C,spawn_cars_2
	A858	LD A,C
spawn_cars_2	A859	LD (IX+$11),A	IX[17] = A
	A85C	LD (IX+$12),A	IX[18] = A
	A85F	LD HL,$A7E6	A = $A7E6[A]
	A862	LD B,$00
	A864	LD C,A
	A865	ADD HL,BC
	A866	LD A,(HL)
	A867	LD (IX+$05),A	IX[5] = A
	A86A	LD A,($A22E)	Load sighted_flag
	A86D	AND A	Set flags
	A86E	LD A,$04	A = 4
	A870	JR Z,spawn_cars_3
	A872	ADD A,A	A <<= 1
spawn_cars_3	A873	LD C,A	HL += A
	A874	ADD HL,BC	HL += A
	A875	LD A,(HL)	IX[13] = *HL
	A876	LD (IX+$0D),A	IX[13] = *HL
	A879	CALL rng	Call rng
	A87C	AND $06	C = A & 6
	A87E	LD C,A	C = A & 6
	A87F	LD A,($A22E)	Load sighted_flag
	A882	AND A	Set flags
	A883	JR Z,spawn_cars_4
	A885	LD A,$06	A = 6
	A887	CP C
	A888	JR NZ,spawn_cars_4
	A88A	DEC C	C--
	A88B	DEC C	C--
spawn_cars_4	A88C	LD B,$00	B = 0
	A88E	LD HL,$5D12	HL = &lods_vehicles (first of the generic car LODs)
	A891	ADD HL,BC	HL += BC
	A892	LD A,(HL)	wordat(IX+9) = HL
	A893	INC HL
	A894	LD (IX+$09),A
	A897	LD A,(HL)
	A898	LD (IX+$0A),A
	A89B	RET	Return