[fpgaboy.git] / bootrom.asm

	SECTION "a",HOME[$00]

	LD SP,$fffe		; $0000  Setup Stack

	XOR A			; $0003  Zero the memory from $8000-$9FFF (VRAM)
	LD HL,$9fff		; $0004
Addr_0007:
	LD [HLD],A		; $0007
	BIT 7,H		; $0008
	JR NZ, Addr_0007	; $000a

	LD HL,$ff26		; $000c  Setup Audio
	LD C,$11		; $000f
	LD A,$80		; $0011 
	LD [HLD],A		; $0013
	LD [C],A	; $0014
	INC C			; $0015
	LD A,$f3		; $0016
	LD [C],A	; $0018
	LD [HLD],A		; $0019
	LD A,$77		; $001a
	LD [HLD],A		; $001c

	LD A,$fc		; $001d  Setup BG palette
	LD [$FF47],A	; $001f

	LD DE,$0104		; $0021  Convert and load logo data from cart into Video RAM
	LD HL,$8010		; $0024
Addr_0027:
	LD A,[DE]		; $0027
	CALL a95		; $0028
	CALL a96		; $002b
	INC DE		; $002e
	LD A,E		; $002f
	CP $34		; $0030
	JR NZ, Addr_0027	; $0032

	LD DE,Addr_00D8		; $0034  Load 8 additional bytes into Video RAM
	LD B,$08		; $0037
Addr_0039:
	LD A,[DE]		; $0039
	INC DE		; $003a
	LD [HLI],A		; $003b
	INC HL		; $003c
	DEC B			; $003d
	JR NZ, Addr_0039	; $003e

	LD A,$19		; $0040  Setup background tilemap
	LD [$9910],A	; $0042
	LD HL,$992f		; $0045
Addr_0048:
	LD C,$0c		; $0048
Addr_004A:
	DEC A			; $004a
	JR Z, Addr_0055	; $004b
	LD [HLD],A		; $004d
	DEC C			; $004e
	JR NZ, Addr_004A	; $004f
	LD L,$0f		; $0051
	JR Addr_0048	; $0053

	; === Scroll logo on screen, and play logo sound===

Addr_0055:
	LD H,A		; $0055  Initialize scroll count, H=0
	LD A,$64		; $0056
	LD D,A		; $0058  set loop count, D=$64
	LD [$FF42],A	; $0059  Set vertical scroll register
	LD A,$91		; $005b
	LD [$FF40],A	; $005d  Turn on LCD, showing Background
	INC B			; $005f  Set B=1
Addr_0060:
	LD E,$02		; $0060
Addr_0062:
	LD C,$0c		; $0062
Addr_0064:
	LD A,[$FF44]	; $0064  wait for screen frame
	CP $90		; $0066
	JR NZ, Addr_0064	; $0068
	DEC C			; $006a
	JR NZ, Addr_0064	; $006b
	DEC E			; $006d
	JR NZ, Addr_0062	; $006e

	LD C,$13		; $0070
	INC H			; $0072  increment scroll count
	LD A,H		; $0073
	LD E,$83		; $0074
	CP $62		; $0076  $62 counts in, play sound #1
	JR Z, Addr_0080	; $0078
	LD E,$c1		; $007a
	CP $64		; $007c
	JR NZ, Addr_0086	; $007e  $64 counts in, play sound #2
Addr_0080:
	LD A,E		; $0080  play sound
	LD [C],A	; $0081
	INC C			; $0082
	LD A,$87		; $0083
	LD [C],A	; $0085
Addr_0086:
	LD A,[$FF42]	; $0086
	SUB B			; $0088
	LD [$FF42],A	; $0089  scroll logo up if B=1
	DEC D			; $008b  
	JR NZ, Addr_0060	; $008c

	DEC B			; $008e  set B=0 first time
	JR NZ, Addr_00E0	; $008f    ... next time, cause jump to "Nintendo Logo check"

	LD D,$20		; $0091  use scrolling loop to pause
	JR Addr_0060	; $0093

	; ==== Graphic routine ====

a95:	LD C,A		; $0095  "Double up" all the bits of the graphics data
a96:	LD B,$04		; $0096     and store in Video RAM
Addr_0098:
	PUSH BC		; $0098
	RL C			; $0099
	RLA			; $009b
	POP BC		; $009c
	RL C			; $009d
	RLA			; $009f
	DEC B			; $00a0
	JR NZ, Addr_0098	; $00a1
	LD [HLI],A		; $00a3
	INC HL		; $00a4
	LD [HLI],A		; $00a5
	INC HL		; $00a6
	RET			; $00a7

NintendoLogo:
	;Nintendo Logo
	DB $CE,$ED,$66,$66,$CC,$0D,$00,$0B,$03,$73,$00,$83,$00,$0C,$00,$0D 
	DB $00,$08,$11,$1F,$88,$89,$00,$0E,$DC,$CC,$6E,$E6,$DD,$DD,$D9,$99 
	DB $BB,$BB,$67,$63,$6E,$0E,$EC,$CC,$DD,$DC,$99,$9F,$BB,$B9,$33,$3E 

Addr_00D8:
	;More video data
	DB $3C,$42,$B9,$A5,$B9,$A5,$42,$3C

	; ===== Nintendo logo comparison routine =====

Addr_00E0:	
	LD HL,$0104		; $00e0	; point HL to Nintendo logo in cart
	LD DE,NintendoLogo	; $00e3	; point DE to Nintendo logo in DMG rom

Addr_00E6:
	LD A,[DE]		; $00e6
	INC DE		; $00e7
	CP [HL]		; $00e8	;compare logo data in cart to DMG rom
.fuq	JR NZ,.fuq		; $00e9	;if not a match, lock up here
	INC HL		; $00eb
	LD A,L		; $00ec
	CP $34		; $00ed	;do this for $30 bytes
	JR NZ, Addr_00E6	; $00ef

	LD B,$19		; $00f1
	LD A,B		; $00f3
Addr_00F4:
	ADD [HL]		; $00f4
	INC HL		; $00f5
	DEC B			; $00f6
	JR NZ, Addr_00F4	; $00f7
	ADD [HL]		; $00f9
.fuq:	JR NZ,.fuq		; $00fa	; if $19 + bytes from $0134-$014D  don't add to $00
						;  ... lock up

	LD A,$01		; $00fc
	LD [$FF50],A	; $00fe	;turn off DMG rom


	SECTION "b",HOME[$100]
boot:	jr .running	; $0100
	nop		; $0102
	nop		; $0103
	;Nintendo Logo	; $0104
	DB $CE,$ED,$66,$66,$CC,$0D,$00,$0B,$03,$73,$00,$83,$00,$0C,$00,$0D 
	DB $00,$08,$11,$1F,$88,$89,$00,$0E,$DC,$CC,$6E,$E6,$DD,$DD,$D9,$99 
	DB $BB,$BB,$67,$63,$6E,$0E,$EC,$CC,$DD,$DC,$99,$9F,$BB,$B9,$33,$3E
	;$0134 
	DB $00,$E7,$00,$00,$00,$00,$00,$00, $00,$00,$00,$00,$00,$00,$00,$00
	;$0144
	DB $00,$00,$00,$00,$00,$00,$00,$00, $00,$00,$00,$00,$00,$00,$00,$00
.running:
	ld a, $FF
	ld [$FF51], A
	ld a, $00
	ld [$FF25], a
.diq:	ld A, [$FF51]
	cp 0
	jr z, .diq
	ld a, 0
	LD [$FF40],A
	jp $0000
Commit	Line	Data
6bd4619b JW	1	SECTION "a",HOME[$00]
	2
	3	LD SP,$fffe ; $0000 Setup Stack
	4
	5	XOR A ; $0003 Zero the memory from $8000-$9FFF (VRAM)
	6	LD HL,$9fff ; $0004
	7	Addr_0007:
	8	LD [HLD],A ; $0007
	9	BIT 7,H ; $0008
	10	JR NZ, Addr_0007 ; $000a
	11
	12	LD HL,$ff26 ; $000c Setup Audio
	13	LD C,$11 ; $000f
	14	LD A,$80 ; $0011
	15	LD [HLD],A ; $0013
	16	LD [C],A ; $0014
	17	INC C ; $0015
	18	LD A,$f3 ; $0016
	19	LD [C],A ; $0018
	20	LD [HLD],A ; $0019
	21	LD A,$77 ; $001a
	22	LD [HLD],A ; $001c
	23
	24	LD A,$fc ; $001d Setup BG palette
	25	LD [$FF47],A ; $001f
	26
	27	LD DE,$0104 ; $0021 Convert and load logo data from cart into Video RAM
	28	LD HL,$8010 ; $0024
	29	Addr_0027:
	30	LD A,[DE] ; $0027
c279b666 JW	31	CALL a95 ; $0028
c279b666 JW	32	CALL a96 ; $002b
6bd4619b JW	33	INC DE ; $002e
	34	LD A,E ; $002f
	35	CP $34 ; $0030
	36	JR NZ, Addr_0027 ; $0032
	37
b4f3ac35	38	LD DE,Addr_00D8 ; $0034 Load 8 additional bytes into Video RAM
6bd4619b JW	39	LD B,$08 ; $0037
	40	Addr_0039:
	41	LD A,[DE] ; $0039
	42	INC DE ; $003a
	43	LD [HLI],A ; $003b
	44	INC HL ; $003c
	45	DEC B ; $003d
	46	JR NZ, Addr_0039 ; $003e
	47
	48	LD A,$19 ; $0040 Setup background tilemap
	49	LD [$9910],A ; $0042
	50	LD HL,$992f ; $0045
	51	Addr_0048:
	52	LD C,$0c ; $0048
	53	Addr_004A:
	54	DEC A ; $004a
	55	JR Z, Addr_0055 ; $004b
	56	LD [HLD],A ; $004d
	57	DEC C ; $004e
	58	JR NZ, Addr_004A ; $004f
	59	LD L,$0f ; $0051
	60	JR Addr_0048 ; $0053
	61
	62	; === Scroll logo on screen, and play logo sound===
	63
	64	Addr_0055:
	65	LD H,A ; $0055 Initialize scroll count, H=0
	66	LD A,$64 ; $0056
	67	LD D,A ; $0058 set loop count, D=$64
	68	LD [$FF42],A ; $0059 Set vertical scroll register
	69	LD A,$91 ; $005b
	70	LD [$FF40],A ; $005d Turn on LCD, showing Background
	71	INC B ; $005f Set B=1
	72	Addr_0060:
	73	LD E,$02 ; $0060
	74	Addr_0062:
	75	LD C,$0c ; $0062
	76	Addr_0064:
	77	LD A,[$FF44] ; $0064 wait for screen frame
	78	CP $90 ; $0066
	79	JR NZ, Addr_0064 ; $0068
	80	DEC C ; $006a
	81	JR NZ, Addr_0064 ; $006b
	82	DEC E ; $006d
	83	JR NZ, Addr_0062 ; $006e
	84
	85	LD C,$13 ; $0070
	86	INC H ; $0072 increment scroll count
	87	LD A,H ; $0073
	88	LD E,$83 ; $0074
	89	CP $62 ; $0076 $62 counts in, play sound #1
	90	JR Z, Addr_0080 ; $0078
	91	LD E,$c1 ; $007a
	92	CP $64 ; $007c
	93	JR NZ, Addr_0086 ; $007e $64 counts in, play sound #2
	94	Addr_0080:
	95	LD A,E ; $0080 play sound
	96	LD [C],A ; $0081
	97	INC C ; $0082
	98	LD A,$87 ; $0083
	99	LD [C],A ; $0085
	100	Addr_0086:
	101	LD A,[$FF42] ; $0086
	102	SUB B ; $0088
103	LD [$FF42],A ; $0089 scroll logo up if B=1
104	DEC D ; $008b
105	JR NZ, Addr_0060 ; $008c
106
107	DEC B ; $008e set B=0 first time
108	JR NZ, Addr_00E0 ; $008f ... next time, cause jump to "Nintendo Logo check"
109
110	LD D,$20 ; $0091 use scrolling loop to pause
111	JR Addr_0060 ; $0093
112
113	; ==== Graphic routine ====
114
c279b666 JW	115	a95: LD C,A ; $0095 "Double up" all the bits of the graphics data
c279b666 JW	116	a96: LD B,$04 ; $0096 and store in Video RAM
6bd4619b JW	117	Addr_0098:
	118	PUSH BC ; $0098
	119	RL C ; $0099
	120	RLA ; $009b
	121	POP BC ; $009c
	122	RL C ; $009d
	123	RLA ; $009f
	124	DEC B ; $00a0
	125	JR NZ, Addr_0098 ; $00a1
	126	LD [HLI],A ; $00a3
	127	INC HL ; $00a4
	128	LD [HLI],A ; $00a5
	129	INC HL ; $00a6
	130	RET ; $00a7
	131
b4f3ac35	132	NintendoLogo:
6bd4619b JW	133	;Nintendo Logo
	134	DB $CE,$ED,$66,$66,$CC,$0D,$00,$0B,$03,$73,$00,$83,$00,$0C,$00,$0D
	135	DB $00,$08,$11,$1F,$88,$89,$00,$0E,$DC,$CC,$6E,$E6,$DD,$DD,$D9,$99
	136	DB $BB,$BB,$67,$63,$6E,$0E,$EC,$CC,$DD,$DC,$99,$9F,$BB,$B9,$33,$3E
	137
	138	Addr_00D8:
	139	;More video data
	140	DB $3C,$42,$B9,$A5,$B9,$A5,$42,$3C
	141
	142	; ===== Nintendo logo comparison routine =====
	143
	144	Addr_00E0:
	145	LD HL,$0104 ; $00e0 ; point HL to Nintendo logo in cart
b4f3ac35	146	LD DE,NintendoLogo ; $00e3 ; point DE to Nintendo logo in DMG rom
6bd4619b JW	147
	148	Addr_00E6:
	149	LD A,[DE] ; $00e6
	150	INC DE ; $00e7
	151	CP [HL] ; $00e8 ;compare logo data in cart to DMG rom
	152	.fuq JR NZ,.fuq ; $00e9 ;if not a match, lock up here
	153	INC HL ; $00eb
	154	LD A,L ; $00ec
	155	CP $34 ; $00ed ;do this for $30 bytes
	156	JR NZ, Addr_00E6 ; $00ef
	157
	158	LD B,$19 ; $00f1
	159	LD A,B ; $00f3
	160	Addr_00F4:
	161	ADD [HL] ; $00f4
	162	INC HL ; $00f5
	163	DEC B ; $00f6
	164	JR NZ, Addr_00F4 ; $00f7
	165	ADD [HL] ; $00f9
	166	.fuq: JR NZ,.fuq ; $00fa ; if $19 + bytes from $0134-$014D don't add to $00
	167	; ... lock up
	168
	169	LD A,$01 ; $00fc
	170	LD [$FF50],A ; $00fe ;turn off DMG rom
b4f3ac35 JW	171
	172
	173	SECTION "b",HOME[$100]
	174	boot: jr .running ; $0100
	175	nop ; $0102
	176	nop ; $0103
	177	;Nintendo Logo ; $0104
	178	DB $CE,$ED,$66,$66,$CC,$0D,$00,$0B,$03,$73,$00,$83,$00,$0C,$00,$0D
	179	DB $00,$08,$11,$1F,$88,$89,$00,$0E,$DC,$CC,$6E,$E6,$DD,$DD,$D9,$99
	180	DB $BB,$BB,$67,$63,$6E,$0E,$EC,$CC,$DD,$DC,$99,$9F,$BB,$B9,$33,$3E
	181	;$0134
	182	DB $00,$E7,$00,$00,$00,$00,$00,$00, $00,$00,$00,$00,$00,$00,$00,$00
	183	;$0144
	184	DB $00,$00,$00,$00,$00,$00,$00,$00, $00,$00,$00,$00,$00,$00,$00,$00
	185	.running:
	186	ld a, $FF
	187	ld [$FF51], A
01878f5f JW	188	ld a, $00
01878f5f JW	189	ld [$FF25], a
09c1936c JW	190	.diq: ld A, [$FF51]
	191	cp 0
	192	jr z, .diq
01878f5f JW	193	ld a, 0
01878f5f JW	194	LD [$FF40],A
09c1936c JW	195	jp $0000
09c1936c JW	196