Chase H.Q.: Routine at B9F4

B9F4: Routine at B9F4

Used by the routines at main_loop, cpu_driver and escape_scene.
main_loop_12	B9F4	LD A,($A240)	Load road_buffer_offset into A [as byte]
	B9F7	ADD A,$40	Add 64 so it's the lanes data offset
	B9F9	LD E,A	DE = $EE00 \| A
	B9FA	LD D,$EE	DE = $EE00 \| A
	B9FC	LD BC,$16E1	B=20, C=$E1 -- counter, mask
	B9FF	LD L,$00	Counter/Index
Suspect this is counting the distance to road split.
main_loop_12_0	BA01	LD A,(DE)	Load a lanes byte
	BA02	AND C	Jump if (byte & $E1) == $E1
	BA03	CP C
	BA04	JP Z,main_loop_12_3
	BA07	INC E	Advance to next lanes byte (wrapping around)
	BA08	INC L	Increment counter
	BA09	DJNZ main_loop_12_0	Loop while B
No road split found?
	BA0B	CALL $CBD6	[road is still rendered if this is NOPped, but road is in wrong position]
	BA0E	LD ($BA4E),SP	Self modify return path
	BA12	LD SP,$EC30	must be data
	BA15	LD A,$30
main_loop_12_1	BA17	LD HL,$BA36	Self modify BA35 to load $EA30
	BA1A	LD DE,$BA40	Self modify BA3F to load $EB30
	BA1D	LD BC,$BA45	Self modify BA44 to load $E930
main_loop_12_2	BA20	LD (HL),A
	BA21	LD (DE),A
	BA22	LD (BC),A
	BA23	LD ($BA29),A	Self modify BA27 to load ($E800 \| A)
	BA26	EXX	Bank
	BA27	LD DE,($E800)	Self modified
	BA2B	POP HL
	BA2C	SBC HL,DE
	BA2E	SRA H
	BA30	RR L
	BA32	LD B,H	BC = HL
	BA33	LD C,L	BC = HL
	BA34	ADD HL,DE
	BA35	LD ($EA00),HL
	BA38	LD D,B	DE = BC
	BA39	LD E,C	DE = BC
	BA3A	SRA B
	BA3C	RR C
	BA3E	ADD HL,BC
	BA3F	LD ($EB00),HL
	BA42	SBC HL,DE
	BA44	LD ($E900),HL
	BA47	INC A	A += 2
	BA48	INC A	A += 2
	BA49	EXX	Unbank
	BA4A	JP NZ,main_loop_12_2	Loop while A > 0 ?
ml12_exit	BA4D	LD SP,$0000	Restore original SP
	BA50	RET	Return
Handle road split.
main_loop_12_3	BA51	LD A,L
	BA52	LD ($A266),A	split_road_countdown = A
	BA55	LD H,$E3
	BA57	LD A,$60	Set split_road visible
	BA59	LD ($A265),A	Set split_road visible
	BA5C	SUB (HL)
	BA5D	CPL	A = ~A + $69
	BA5E	ADD A,$69	A = ~A + $69
	BA60	PUSH AF
	BA61	LD HL,($A267)	HL = var_a267
	BA64	LD A,(DE)	A = *DE & 4
	BA65	AND $04	A = *DE & 4
	BA67	JR NZ,main_loop_12_9
	BA69	LD A,($A269)	A = var_a269 - 1
	BA6C	DEC A	A = var_a269 - 1
	BA6D	JR Z,main_loop_12_6	Jump if zero
	BA6F	NEG	A = -A
	BA71	LD ($A269),A	var_a269 = A
	BA74	LD DE,($A26C)	Get road position
	BA78	LD A,$01	A = 1
	BA7A	DEC D	D--
	BA7B	JP M,main_loop_12_5
	BA7E	JP NZ,main_loop_12_4
	BA81	LD A,E	A = E
	BA82	CP $0C
	BA84	LD A,$01
	BA86	JR C,main_loop_12_5	Jump if E < 12
main_loop_12_4	BA88	DEC A	A--
main_loop_12_5	BA89	LD ($A249),A	Set fork_taken to A
	BA8C	INC A	A++
	BA8D	PUSH HL
	BA8E	LD HL,$A226	Address of correct_fork
	BA91	CP (HL)	Match?
	BA92	LD HL,$9941	-> Tony: "LET'S GO. MR. DRIVER." <STOP>
	BA95	JR Z,ml12_chatter	Jump to ml12_chatter if correct fork was taken
Incorrect fork was taken.
	BA97	LD A,$5F
	BA99	LD ($A195),A	A195 is horz position of perp car
Add a bonus of (40,000 + 10,000 * level number) for going the wrong way...?
	BA9C	LD A,($8007)	A = wanted_stage_number + 4
	BA9F	ADD A,$04	A = wanted_stage_number + 4
	BAA1	LD D,A	Set top digits
	BAA2	XOR A	Clear low digit
	BAA3	LD E,A	Clear middle digits
	BAA4	CALL bonus	Call bonus
	BAA7	LD HL,$98D0	-> Raymond: "WHAT ARE YOU DOING MAN!!" / "THE BAD GUYS ARE GOING THE OTHER WAY." <STOP>
ml12_chatter	BAAA	LD A,$14	Set priority to 20
	BAAC	CALL chatter	Call chatter (priority 20)
	BAAF	POP HL
main_loop_12_6	BAB0	LD A,($A254)	Load another_spawning_flag
	BAB3	AND A
	BAB4	JR Z,main_loop_12_8	Jump if zero
	BAB6	LD C,A	C = A
	BAB7	LD A,($A16D)	A = var_a16d
	BABA	ADD A,C	A += C
	BABB	LD C,A	C = A
	BABC	SUB $02	A -= 2
	BABE	JR C,main_loop_12_7
	BAC0	LD C,A	C = A
	BAC1	LD DE,$0010	DE = 16
	BAC4	ADD HL,DE	HL += DE
	BAC5	LD ($A267),HL	var_a267 = HL
main_loop_12_7	BAC8	LD A,C
	BAC9	LD ($A16D),A	var_a16d = A
main_loop_12_8	BACC	LD A,($A16D)	A = var_a16d
	BACF	RRA
	BAD0	LD A,($A23F)	A = fast_counter
	BAD3	RLA	A ROR 4
	BAD4	RLA
	BAD5	RLA
	BAD6	RLA
	BAD7	AND $0F	A &= $0F
	BAD9	SUB $10	A -= 16
	BADB	LD E,A	DE = $FF00 \| A
	BADC	LD D,$FF	DE = $FF00 \| A
	BADE	ADD HL,DE	HL += DE
main_loop_12_9	BADF	PUSH HL
	BAE0	LD A,($A249)	Jump if fork_taken was 1 (right fork taken)
	BAE3	DEC A
	BAE4	JR Z,main_loop_12_10
Left fork was taken.
	BAE6	CALL $CBD6
	BAE9	POP DE
	BAEA	LD HL,($A26C)	Get road position
	BAED	PUSH HL
	BAEE	ADD HL,DE
	BAEF	LD ($A26C),HL	Set road position
	BAF2	CALL $CBCE
	BAF5	JR main_loop_12_11
Right fork was taken.
main_loop_12_10	BAF7	CALL $CBCE
	BAFA	POP DE
	BAFB	LD HL,($A26C)	Get road position
	BAFE	PUSH HL
	BAFF	SBC HL,DE
	BB01	LD ($A26C),HL	Set road position
	BB04	CALL $CBD6
main_loop_12_11	BB07	POP HL
	BB08	LD ($A26C),HL	Get road position
	BB0B	POP BC
	BB0C	LD ($BA4E),SP
	BB10	LD SP,$EC30
	BB13	LD A,$30
	BB15	LD HL,$BB38
	BB18	LD DE,$BB40
main_loop_12_12	BB1B	LD (HL),A
	BB1C	LD (DE),A
	BB1D	LD ($BB2F),A
	BB20	LD ($BB44),A
	BB23	LD ($BB47),A
	BB26	LD ($BB4F),A
	BB29	LD ($BB57),A
	BB2C	EXX
	BB2D	LD DE,($E800)
	BB31	POP HL
	BB32	ADD HL,DE
	BB33	SRA H
	BB35	RR L
	BB37	LD ($EA00),HL
	BB3A	ADD HL,DE
	BB3B	SRA H
	BB3D	RR L
	BB3F	LD ($E900),HL
	BB42	LD DE,($ED00)
	BB46	LD HL,($EB00)
	BB49	ADD HL,DE
	BB4A	SRA H
	BB4C	RR L
	BB4E	LD ($EB00),HL
	BB51	ADD HL,DE
	BB52	SRA H
	BB54	RR L
	BB56	LD ($EC00),HL
	BB59	INC A
	BB5A	INC A
	BB5B	EXX
	BB5C	DJNZ main_loop_12_12
	BB5E	AND A
	BB5F	JP Z,ml12_exit
	BB62	LD H,$EC
	BB64	LD L,A
	BB65	LD SP,HL
	BB66	JP main_loop_12_1