Chase H.Q.: Routine at B549

B549: Routine at B549

Used by the routine at main_loop_24.
sub_b549	B549	LD A,$00	A = <self modified>
	B54B	AND A	Set flags
	B54C	RET Z	Return if zero
	B54D	DEC A	A--
	B54E	LD ($B54A),A	Self modify 'LD A' above
	B551	RLCA	Double A
	B552	LD E,A	DE = A
	B553	LD D,$00	DE = A
	B555	LD ($B571),DE	Self modify 'LD HL' below
	B559	LD B,$03	3 iterations
	B55B	LD HL,$0000	HL = <self modified> by B503
sub_b549_0	B55E	PUSH BC	Preserve BC
	B55F	LD E,(HL)	DE = wordat(HL); HL += 2
	B560	INC HL
	B561	LD D,(HL)
	B562	INC HL
	B563	PUSH HL	Preserve HL
	B564	LD A,(DE)	A = (*DE + 1) & 3
	B565	INC A
	B566	AND $03
	B568	LD (DE),A	*DE = A
	B569	RLCA	A <<= 2
	B56A	RLCA	A <<= 2
	B56B	LD C,A	C = A
	B56C	RLCA	A <<= 1
	B56D	ADD A,C	C += A
	B56E	LD C,A	C += A
	B56F	INC DE	DE++
	B570	LD HL,$0000	HL = <self modified>
	B573	LD B,H	B = H
	B574	ADD HL,DE	HL += DE
	B575	LD D,(HL)	DE = wordat(HL)
	B576	INC HL
	B577	LD E,(HL)
	B578	LD HL,$CEAA	HL -> bitmap_debris_1/2/3/4
	B57B	ADD HL,BC	HL -> bitmap_debris_1/2/3/4
	B57C	LD BC,$0601	B = height, C = ?
	B57F	EXX	Bank
	B580	LD BC,$0000	B = 0
	B583	LD E,$01	E = 1
	B585	EXX	Unbank
	B586	CALL sub_b67c_4	Presumably plotting the debris
	B589	POP HL	Restore HL
	B58A	POP BC	Restore BC
	B58B	DJNZ sub_b549_0	Loop
	B58D	RET	Return