Chase H.Q.: Routine at B549

B549: Draws the debris

Used by the routine at animate_hero_car.
draw_debris	B549	LD A,$00	A = <self modified>
	B54B	AND A	Set flags
	B54C	RET Z	Return if zero -- no debris?
	B54D	DEC A	Decrement
	B54E	LD ($B54A),A	Self modify 'LD A' above
	B551	RLCA	DE = A * 2 -- builds an offset
	B552	LD E,A
	B553	LD D,$00
	B555	LD ($B571),DE	Self modify 'LD HL' below
	B559	LD B,$03	3 iterations
	B55B	LD HL,$0000	HL = <self modified> by B503 -- an entry in debris_table_ce33
dd_loop	B55E	PUSH BC	Preserve BC
	B55F	LD E,(HL)	Load an address
	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 -- writes back into table
	B569	RLCA	C = A * 12
	B56A	RLCA
	B56B	LD C,A
	B56C	RLCA
	B56D	ADD A,C
	B56E	LD C,A
	B56F	INC DE	DE++ -- advance to next byte in table
	B570	LD HL,$0000	HL = <self modified> above
	B573	LD B,H	B = H -- H is zero so BC = C
	B574	ADD HL,DE	HL += DE -- DE is ptr to table, HL is offset
	B575	LD D,(HL)	DE = wordat(HL)
	B576	INC HL
	B577	LD E,(HL)
	B578	LD HL,$CEAA	Address of bitmap_debris_1/2/3/4
	B57B	ADD HL,BC	Address of 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 draw_part_entry2	Presumably plotting the debris
	B589	POP HL	Restore HL
	B58A	POP BC	Restore BC
	B58B	DJNZ dd_loop	Loop to dd_loop
	B58D	RET	Return