Chase H.Q.: Routine at C2E7

C2E7: Routine at C2E7

Used by the routine at draw_road.
C2E7	LD A,IYl	A = IY.low
C2E9	CP $13	Compare to 19
C2EB	JP NC,$C43B	Jump if >= 19
C2EE	EX AF,AF'	Bank
C2EF	LD A,(IX+$00)	A = IX[0]
C2F2	LD L,A	L = A
C2F3	AND $0C	A &= 12
C2F5	JP Z,$C43B	Jump if zero
C2F8	DEC IY	IY--
C2FA	BIT 5,L	Bit 5 of L set?
C2FC	JR Z,$C305	Jump if clear
C2FE	BIT 7,L	Bit 7 of L set?
C300	LD H,$EC	H = $EC
C302	JR NZ,$C305	Jump if set
C304	DEC H	H = $EB
C305	BIT 4,L	Bit 4 of L set?
C307	JP Z,$C37E	Jump if clear
C30A	EX AF,AF'	Bank
C30B	CP $02	Compare to 2
C30D	JP NC,$C357	Jump if >= 2
C310	EX AF,AF'	Bank
C311	CP $04	Compare to 4
C313	LD A,$20	A = 32
C315	LD C,(IY+$01)	C = IY[1]
C318	JR NZ,$C31E	Jump if != 4
C31A	XOR A	A = 0
C31B	LD C,(IY+$02)	C = IY[2]
C31E	LD ($C346),A	Self modify 'ADD A,x' @ C345
C321	LD A,(IY+$00)	A = IY[0]
C324	SUB C	A -= C
C325	JP C,$C439	Jump if A was <= C
C328	JP Z,$C439	Jump if A was <= C
C32B	LD C,A	C = A
C32C	ADD A,A	A <<= 1
C32D	LD B,A	B = A
C32E	LD A,$60	L = ~(($60 - IY[0]) << 1)
C330	SUB (IY+$00)
C333	ADD A,A
C334	CPL
C335	LD L,A
C336	LD SP,HL	-- why are we copying to SP with no push/pop nearby?
C337	LD D,(HL)	D = *HL
C338	DEC L	L--
C339	LD E,(HL)	E = *HL
C33A	SUB B	A -= B
C33B	LD L,A	L = A
C33C	DEC H	H--
C33D	LD A,($A23F)	A = fast_counter
C340	RRA	A ROR 3
C341	RRA
C342	RRA
C343	AND $1C	A &= 28
C345	ADD A,$00	A += <self modified>
C347	LD ($C352),HL	Self modify 'LD HL,x' @ C351 below
C34A	EX DE,HL	Swap
C34B	LD E,A	DE = A
C34C	LD D,$00	DE = A
C34E	SBC HL,DE	HL -= DE
C350	EX DE,HL	Swap
C351	LD HL,$0000	HL = <self modified>
C354	JP $C3EE	Jump
Another case.
C357	EX AF,AF'	Bank
C358	CP $04	Compare to 4
C35A	JP NZ,$C439	Jump if non-zero
C35D	LD A,(IY+$00)	A = IY[0] - IY[2]
C360	SUB (IY+$02)	A = IY[0] - IY[2]
C363	JP C,$C439	Jump if IY[0] was <= IY[2]
C366	JP Z,$C439	Jump if IY[0] was <= IY[2]
C369	LD C,A	C = A
C36A	ADD A,A	A <<= 1
C36B	LD B,A	B = A
C36C	LD A,$60	L = ~(($60 - IY[0]) << 1)
C36E	SUB (IY+$00)
C371	ADD A,A
C372	CPL
C373	LD L,A
C374	LD SP,HL	-- this again
C375	LD D,(HL)	D = *HL
C376	DEC L	L--
C377	LD E,(HL)	E = *HL
C378	SUB B	A -= B
C379	LD L,A	L = A
C37A	DEC H	H--
C37B	JP $C3EE	Jump
C37E	EX AF,AF'	Bank/unbank
C37F	CP $02	Compare to 2
This entry point is used by the routine at diamond_zoom_in_mask.
C381	JP NC,$C3CA	Jump if A >= 2
C384	EX AF,AF'	Bank/unbank
C385	CP $04	Compare to 4
C387	LD A,$20	A = 32
C389	LD C,(IY+$01)	C = IY[1]
C38C	JR NZ,$C392	Jump if non-zero
C38E	XOR A	X = 0
C38F	LD C,(IY+$02)	C = IY[2]
C392	LD ($C3BE),A	Self modify 'ADD A,x' @ C3BD below
C395	LD A,(IY+$00)	A = IY[0]
C398	SUB C	A -= C
C399	JP C,$C439	Jump if A was >= C
C39C	JP Z,$C439	Jump if A was >= C
C39F	LD C,A	C = A << 1
C3A0	ADD A,A	C = A << 1
C3A1	LD B,A	B = A
C3A2	LD A,$60	L = ~(($60 - IY[0]) << 1)
C3A4	SUB (IY+$00)
C3A7	ADD A,A
C3A8	CPL
C3A9	LD L,A
C3AA	LD SP,HL	-- this again
C3AB	DEC H	H--
C3AC	LD D,(HL)	D = *HL
C3AD	DEC L	L--
C3AE	LD E,(HL)	E = *HL
C3AF	SUB B	A -= B
C3B0	LD L,A	L = A
C3B1	INC H	H++
C3B2	LD ($C3C5),HL	Self modify 'LD HL,x' @ C3C4 below
C3B5	LD A,($A23F)	A = fast_counter
C3B8	RRA	A ROR 3
C3B9	RRA
C3BA	RRA
C3BB	AND $1C	A &= 28
C3BD	ADD A,$00	A += <self modified>
C3BF	LD L,A	HL = A
C3C0	LD H,$00	HL = A
C3C2	ADD HL,DE	HL += DE
C3C3	EX DE,HL	Swap
C3C4	LD HL,$0000	HL = <self modified>
C3C7	JP $C3EE	Jump
C3CA	EX AF,AF'	Swap
C3CB	CP $04	Compare to 4
C3CD	JR NZ,$C439	Jump if non-zero
C3CF	LD A,(IY+$00)	A = IY[0] - IY[2]
C3D2	SUB (IY+$02)	A = IY[0] - IY[2]
C3D5	JP C,$C439	Jump if IY[0] was <= IY[2]
C3D8	JP Z,$C439	Jump if IY[0] was <= IY[2]
C3DB	LD C,A	C = A
C3DC	ADD A,A	A <<= 1
C3DD	LD B,A	B = A
C3DE	LD A,$60	L = ~(($60 - IY[0]) << 1)
C3E0	SUB (IY+$00)
C3E3	ADD A,A
C3E4	CPL
C3E5	LD L,A
C3E6	LD SP,HL	-- this again
C3E7	DEC H	H--
C3E8	LD D,(HL)	D = *HL
C3E9	DEC L	L--
C3EA	LD E,(HL)	E = *HL
C3EB	SUB B	A -= B
C3EC	LD L,A	L = A
C3ED	INC H	H++
Continuation point.
C3EE	LD A,(HL)	A = *HL
C3EF	DEC L	L--
C3F0	LD L,(HL)	L = *HL
C3F1	LD H,A	H = A
C3F2	AND A	Set flags
C3F3	SBC HL,DE	HL -= DE
C3F5	LD A,L	A = L
C3F6	JP M,$C401	Jump if negative
C3F9	AND A	Set flags
C3FA	JP P,$C407	Jump if positive
C3FD	LD A,$7F	A = 127
C3FF	JR $C407	Jump
Negative case.
C401	AND A	Set flags
C402	JP M,$C407	Jump if negative
C405	LD A,$81	A = $81
Positive case.
C407	INC SP	SP++
C408	BIT 5,(IX+$00)	Bit 5 of IX[0] set?
C40C	JR Z,$C413	Jump if clear
C40E	LD HL,$FF00	HL = $FF00
C411	ADD HL,SP	HL += SP
C412	LD SP,HL	SP = HL
C413	LD L,A	L = A
C414	LD B,C	B = C
C415	LD A,C	A = C
C416	BIT 7,L	Bit 7 of L set?
C418	JR Z,$C426	Jump if clear
C41A	LD A,L	A = L
C41B	NEG	A = -A
C41D	LD L,A	L = A
C41E	LD A,B	A = B
C41F	CP L	Compare to L
C420	LD A,$1B	A = 'DEC DE'
C422	JR C,$C441	Jump if A was < L
C424	JR $C42B	Jump
C426	CP L	Compare to L
C427	LD A,$13	A = 'INC DE'
C429	JR C,$C441	Jump if A was < L
C42B	LD ($C435),A	Self modify instruction at C435
C42E	LD A,B	A = B
C42F	RRA	A >>= 1
Divider?
C430	ADD A,L	A = L
C431	CP C	Compare to C
C432	JR C,$C436	Jump if A < C
C434	SUB C	A -= C
C435	INC DE	<self modified instruction> DE++ or DE--
C436	PUSH DE	Stack DE
C437	DJNZ $C430	Loop
C439	INC IY	IY++
C43B	LD HL,$C534	Pointer to routine which called function will store at instruction C4B2
C43E	JP dr_c54d	Jump
C441	LD ($C445),A	Self modify instruction at C445
C444	XOR A	A = 0
C445	INC DE	<self modified instruction> DE++ or DE--
C446	ADD A,C	A += C
C447	JR C,$C44C	Jump if carry
C449	CP L	Compare to L
C44A	JR C,$C445	Jump if A < L
C44C	SUB L	A -= L
C44D	PUSH DE	Stack DE
C44E	DJNZ $C445	Loop
C450	JR $C439	Jump to exit