Chase H.Q.: Routine at 865A

865A: Draw the pre-game screen

Used by the routine at run_pregame_screen.
draw_pregame	865A	LD HL,$77D8	Address of data
dp_loop	865D	LD A,(HL)	A = *HL
	865E	AND A	Set flags
	865F	JP Z,draw_pregame_10	Jump to rendering messages only, if zero
	8662	INC HL	HL++
	8663	CP $D0	Jump if < $D0
	8665	JR C,draw_pregame_2	Jump if < $D0
	8667	CP $E0	Jump if < $E0 -- $D0..DF
	8669	JR C,draw_pregame_0	Jump if < $E0 -- $D0..DF
	866B	CP $F0	Jump if >= $F0
	866D	JR NC,draw_pregame_1	Jump if >= $F0
Otherwise handle $E0..$EF. This just seems to set a value.
	866F	SUB $E0	A -= $E0
	8671	LD ($86C9),A	Self modify draw_pregame_7 with A
	8674	JR dp_loop	Loop
Handle $D0..DF.
draw_pregame_0	8676	SUB $D0	A -= $D0
	8678	RLCA	Self modify 86C2 with A * 8
	8679	RLCA
	867A	RLCA
	867B	LD ($86C3),A
	867E	JR dp_loop	Loop
Handle $F0..FF.
draw_pregame_1	8680	LD D,A	D = A
	8681	LD E,(HL)	E = *HL++
	8682	INC HL	E = *HL++
	8683	JR dp_loop	Loop
Handle $00..$CF.
draw_pregame_2	8685	CP $1F
	8687	LD B,$01	B = 1 single tile?
	8689	JR NC,draw_pregame_3	Jump if >= $1F
	868B	LD B,A	B = A run of tiles?
	868C	LD A,(HL)	A = *HL++
	868D	INC HL	A = *HL++
Handle $1F..?
draw_pregame_3	868E	PUSH HL
	868F	SUB $1F	A -= $1F A is now a tile index
	8691	RLCA	multiply by 8 - size of tile
	8692	RLCA
	8693	RLA	why the different rotates?
	8694	PUSH BC
	8695	LD C,A	BC = A
	8696	LD B,$00	BC = A
	8698	RL B	shift in carry flag?
	869A	LD HL,$78A7	Address of base of tiles
	869D	ADD HL,BC	Point at tile we need
	869E	POP BC
	869F	EX DE,HL
label=loop_86a0
draw_pregame_4	86A0	PUSH BC
	86A1	PUSH DE
	86A2	PUSH HL
Plot a tile.
	86A3	LD B,$08	B = 8
draw_pregame_5	86A5	LD A,(DE)	HL = DE++
	86A6	LD (HL),A
	86A7	INC DE
	86A8	INC H	H++
	86A9	DJNZ draw_pregame_5	Loop
	86AB	POP BC
	86AC	LD A,B	D = (B << 2) & $20
	86AD	RLA
	86AE	RLA
	86AF	AND $20
	86B1	LD D,A
	86B2	LD A,C	E = (C & $1F) + D
	86B3	AND $1F
	86B5	ADD A,D
	86B6	LD E,A
	86B7	LD A,C	A = (C & $E0) << 1
	86B8	AND $E0
	86BA	ADD A,A
	86BB	LD D,$59	D = $59
	86BD	JR NC,draw_pregame_6
	86BF	INC D	D++
draw_pregame_6	86C0	ADD A,E	A += E
	86C1	LD E,A	E = A
	86C2	LD A,$00	A = xx Self modified
	86C4	AND A	Set flags
	86C5	JR Z,draw_pregame_7	Jump if zero
	86C7	LD (DE),A	*DE = A
draw_pregame_7	86C8	LD A,$00	A = xx Self modified
	86CA	DEC A	A--
	86CB	JR Z,draw_pregame_8	Jump if zero
	86CD	LD A,H	A = H & $0F
	86CE	AND $0F	A = H & $0F
	86D0	JR NZ,draw_pregame_9	Jump if non-zero
	86D2	LD A,H	H -= $10
	86D3	SUB $10
	86D5	LD H,A
	86D6	LD A,L	L += $20
	86D7	ADD A,$20
	86D9	LD L,A
	86DA	JR draw_pregame_9
draw_pregame_8	86DC	LD H,B	HL = BC
	86DD	LD L,C	HL = BC
	86DE	INC L	L++
draw_pregame_9	86DF	POP DE
	86E0	POP BC
	86E1	DJNZ draw_pregame_4	Loop loop_86a0 while B
	86E3	EX DE,HL
	86E4	POP HL
	86E5	JP dp_loop	Loop
draw_pregame_10	86E8	LD B,$04	4 messages to print
	86EA	LD HL,$7798	Address of pre_game_messages
draw_pregame_11	86ED	LD A,$04	Flags TBD
	86EF	DEC HL	HL--
	86F0	CALL print_message	Call print_message
	86F3	DJNZ draw_pregame_11	Loop while B > 0
	86F5	RET	Return