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GameBoy Color Boot ROM Disassembly
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GameBoy Color Boot ROM Disassembly
; GameBoy Color Boot ROM Disassembly
; Dumped by Costis
; Commenting by Randy Mongenel (Duo)
; WORK-IN-PROGRESS VERSION 09-27-2009
; ===========================================================================
; Segment type: Pure code
SECTION "ROM", CODE
; =============== S U B R O U T I N E =======================================
; Set Top-Down Stack starting position in cpu-internal HiRAM area.
sub_0000:
ld sp, $FFFE
ld a, 2 ; Set Work RAM Bank 2
jp System_Setup ; Set Work RAM Bank from A
; ---------------------------------------------------------------------------
HDMA_1: db $D3, 0,$98,$A0,$12
HDMA_2: db $D3, 0,$80, 0,$40
db $1E
db $53 ; S
db $D0 ; Ð
db 0
db $1F
db $42 ; B
db $1C
db 0
db $14
db $2A ; *
db $4D ; M
db $19
db $8C ; Œ
db $7E ; ~
db 0
db $7C ; |
db $31 ; 1
db $6E ; n
db $4A ; J
db $45 ; E
db $52 ; R
db $4A ; J
db 0
db 0
db $FF
db $53 ; S
db $1F
db $7C ; |
db $FF
db 3
db $1F
db 0
db $FF
db $1F
db $A7 ; §
db 0
db $EF ; ï
db $1B
db $1F
db 0
db $EF ; ï
db $1B
db 0
db $7C ; |
db 0
db 0
db $FF
db 3
Nintendo_Logo: db $CE,$ED,$66,$66,$CC, $D, 0, $B, 3,$73, 0,$83, 0
db $C, 0, $D, 0, 8,$11,$1F,$88,$89, 0, $E,$DC,$CC
db $6E,$E6,$DD,$DD,$D9,$99,$BB,$BB,$67,$63,$6E, $E,$EC
db $CC,$DD,$DC,$99,$9F,$BB,$B9,$33,$3E
R_Tile: db $3C,$42,$B9,$A5,$B9,$A5,$42,$3C ; (R) tile, compressed to 8 bytes
db $58 ; X
db $43 ; C
; ---------------------------------------------------------------------------
System_Setup: ; CODE XREF: sub_0000+5j
ld [Reg_SVBK], a ; Set Work RAM Bank from A
ld a, $FC ; 'ü' ; Set DMG Mode BG Palette to BLACK BLACK BLACK WHITE
ld [Reg_BGP], a ; |
call Setup_Sound
call Clear_8KB_at_8000_Aligned ; Falls through to Clear function below
ld h, $D0 ; 'Ð'
call Clear_8KB_at_HL_Aligned ; Fill 8KB at HL with zeroes (7-byte TINY version)
;
; Input:
; HL = Pointer to start of area to clear
;
; Note: HL must be aligned to xx000000, due to 8KB Counter check method (bit 5,h = done?)
ld hl, $FE00 ; Clear A0 bytes of OAM at FE00 (all of it)
ld c, $A0 ; ' ' ; |
xor a
loc_0093: ; CODE XREF: sub_0000+95j
ldi [hl], a ; |
dec c ; |
jr nz, loc_0093 ; |
Load_Logo_into_RAM_VRAM: ; Cartridge ROM Location of Nintendo Logo bytes
ld de, $104
ld hl, $8010
ld c, h
loc_009E: ; CODE XREF: sub_0000+ABj
ld a, [de] ; get header logo byte
ld [c], a ; copy it to FF80+
inc c
call Scale_Graphic_Byte_2X_Nibble1 ; 2x scales nintendo logo graphic data for display on LCD
call Scale_Graphic_Byte_2X_Nibble2 ; must be called after 1 to work right
inc de
ld a, e
cp $34 ; '4'
jr nz, loc_009E ; get header logo byte
Copy_R_Tile_To_VRAM: ; address of R tile ($0072)
ld de, $72 ; 'r'
ld b, 8 ; size of R tile (8 bytes 2x vertical compressed tile)
_copy_r_tile_loop: ; CODE XREF: sub_0000+B7j
ld a, [de] ; get tile byte
inc de ; increment pointer
ldi [hl], a ; store tile byte at (HL)
inc hl ; skip compressed byte by incrementing destination pointer again (after the previous LDI)
dec b ; decrement length counter
jr nz, _copy_r_tile_loop ; get tile byte
call Load_GameBoy_Check_Header
ld a, 1
ld [Reg_VBK], a ; VRAM Bank 1
ld a, $91 ; '‘'
ld [Reg_LCDC], a ; $91 = LCD ON | Window OFF | Char 8000 | BG 9800 | BG ON | OBJ OFF
ld hl, $98B2
ld b, $4E ; 'N'
ld c, $44 ; 'D'
call sub_0291 ; Input:
; HL = VRAM Map Address
; B = ?
; C = ?
xor a
ld [Reg_VBK], a
ld c, $80 ; '€'
ld hl, $42 ; 'B'
ld b, $18
loc_00D8: ; CODE XREF: sub_0000+DFj
ld a, [c]
inc c
cp [hl]
loc_00DB: ; CODE XREF: sub_0000:loc_00DBj
jr nz, @
inc hl
dec b
jr nz, loc_00D8
ld hl, $134 ; Cartridge ROM Header Game Title
ld b, $19 ; Add up Game Title data for checksum check
ld a, b ; from 0134 to 014C (title, manufacturer, cart type, version codes)
loc_00E7: ; CODE XREF: sub_0000+EAj
add a, [hl]
inc l
dec b
jr nz, loc_00E7
add a, [hl] ; Add Complement Checksum at 014D to summed header data. If result = 0, then header is valid
FAIL_LOOP: ; CODE XREF: sub_0000:FAIL_LOOPj
jr nz, @ ; if Complement Checksum != 0, then check failed. Stop execution by jumping to self.
call Load_VRAM_and_Palettes ; If checksum = 0 then success, setup graphics and Palettes and Commit System type and boot cartridge
jr Commit_System_and_Boot_Cart
; ---------------------------------------------------------------------------
db 0
db 0
; ---------------------------------------------------------------------------
Commit_System_and_Boot_Cart: ; CODE XREF: sub_0000+F2j
call Set_System_Mode
xor a ; Set work ram bank to 0 (0/1 are both bank 1)
ld [Reg_SVBK], a ; |
ld a, $11
ld [Reg_BLCK], a ; Disable boot ROM
; End of function sub_0000
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loc_0137: ; DATA XREF: Load_GameBoy_Check_Header:loc_04BBr
nop
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loc_0143: ; DATA XREF: Set_System_Mode+3r
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; =============== S U B R O U T I N E =======================================
; Falls through to Clear function below
Clear_8KB_at_8000_Aligned: ; CODE XREF: sub_0000+85p
; Load_GameBoy_Check_Header+4p
ld hl, $8000
; End of function Clear_8KB_at_8000_Aligned
; =============== S U B R O U T I N E =======================================
; Fill 8KB at HL with zeroes (7-byte TINY version)
;
; Input:
; HL = Pointer to start of area to clear
;
; Note: HL must be aligned to xx000000, due to 8KB Counter check method (bit 5,h = done?)
Clear_8KB_at_HL_Aligned: ; CODE XREF: sub_0000+8Ap
xor a
_clear_8kb_loop: ; CODE XREF: Clear_8KB_at_HL_Aligned+4j
ldi [hl], a ; if HL < $2000, loop back
bit 5, h
jr z, _clear_8kb_loop ; if HL < $2000, loop back
ret
; End of function Clear_8KB_at_HL_Aligned
; =============== S U B R O U T I N E =======================================
; Copy bytes from Pointer in HL to Pointer in DE
;
; Input:
; HL = Source Address
; DE = Destination Address
; C = copy length
;
; Output:
; HL = HL + C
; DE = DE + C
; C = 0
Copy_C_bytes_from_HL_to_DE: ; CODE XREF: Copy_C_bytes_from_HL_to_DE+4j
; Load_HDMA_HL+5p ...
ldi a, [hl]
ld [de], a
inc de
dec c
jr nz, Copy_C_bytes_from_HL_to_DE ; |
ret
; End of function Copy_C_bytes_from_HL_to_DE
; =============== S U B R O U T I N E =======================================
; Wait until LCD VBlank Interrupt is flagged.
;
; Input: None.
; Output: None.
Wait_for_next_VBLANK: ; CODE XREF: sub_0291p sub_0291+2Bp ...
push hl
ld hl, $FF0F
res 0, [hl]
_wait_vblank_loop: ; CODE XREF: Wait_for_next_VBLANK+8j
bit 0, [hl] ; wait until hardware goes into vblank mode and sets the vblank flag (bit 0 of FF0F)
jr z, _wait_vblank_loop ; wait until hardware goes into vblank mode and sets the vblank flag (bit 0 of FF0F)
pop hl
ret
; End of function Wait_for_next_VBLANK
; =============== S U B R O U T I N E =======================================
; Input:
; D003 = Last Keypad state
;
; Output:
; Bit Format: D, U, L, R, ST, SEL, B, A
; D003 = New Keypad state
; D004 = Keys changed since last read?
Read_Keypad: ; CODE XREF: DMG_Manual_Color_Selectp
ld de, $FF00 ; Pad register
ld hl, $D003 ; D003 = Copy of keys last/currently pressed
ld c, $F ; button mask
ld a, $30 ; '0' ; Reset Keypad
ld [de], a ; |
ld a, $20 ; ' ' ; Enable D-PAD bits
ld [de], a ; |
ld a, [de] ; Get pad bits
cpl ; Invert Pad bits
and c ; mask off upper control bits, leaving only lower pad bits
swap a ; swap d-pad bits to upper 4 bits
ld b, a ; store d-pad bits in B
ld a, $10 ; Enable Button (A,B,Select,Start) bits
ld [de], a ; |
ld a, [de] ; Get button bits
cpl ; invert button bits
and c ; mask off control bits, leaving only button bits
or b ; merge button bits with d-pad bits
ld c, a ; store complete button reading in C
ld a, [hl] ; get data from D003
xor c ; XOR with last keypad reading. Changed bits since last reading will be 1 in A.
and $F0 ; 'ð' ; Isolate D-Pad bits, clear button bits
ld b, a ; save dpad bits in B
ldi a, [hl] ; get last keypad reading again and increment pointer to D004
xor c ; XOR current keypad reading with last keypad reading. Changed bits are 1 in A
and c ; AND changed bits with current keypad data to get bits which have turned ON since last reading
or b ; combine with saved Dpad reading.
; At this point, we have the ability to HOLD the d-pad while changing A or B buttons to change the palette
ldd [hl], a
ld b, a
ld a, c
ld [hl], a
ld a, $30 ; '0'
ld [de], a
ret
; End of function Read_Keypad
; =============== S U B R O U T I N E =======================================
; Input:
; HL = Pointer to OBJ Palette Data
; B = Size in bytes of OBJ Palette Data to load
; D = 256-byte offset from end of OBJ palette to start of BG Palette
; E = Size in bytes of BG Palette Data to load
Load_BG_OBJ_Palettes: ; CODE XREF: Setup_Color_Palettes_1+Cp
; Set_System_Mode+22p
ld a, $80 ; '€'
ld [Reg_BCPS], a ; BG Palette Selection
ld [Reg_OCPS], a ; setup BG and OBJ color palette registers to accept entries in sequence
ld c, $6B ; 'k' ; $6B is register for OBJ Palette Data
loc_0252: ; CODE XREF: Load_BG_OBJ_Palettes+Bj
ldi a, [hl] ; Load next palette data byte from HL into C, increment HL pointer
ld [c], a
dec b ; B palette bytes to load into OBJ palette registers
jr nz, loc_0252 ; Load next palette data byte from HL into C, increment HL pointer
ld c, d
add hl, bc ; Next Palette is D+1 bytes from previous
ld b, e
ld c, $69 ; 'i'
loc_025C: ; CODE XREF: Load_BG_OBJ_Palettes+15j
ldi a, [hl]
ld [c], a
dec b ; B palette bytes to load into BG Palette registers
jr nz, loc_025C
ret
; End of function Load_BG_OBJ_Palettes
; =============== S U B R O U T I N E =======================================
Setup_Color_Palettes_1: ; CODE XREF: sub_0291+3p
; Load_VRAM_and_Palettes+8p ...
push bc
push de
push hl ; save registers
ld hl, $D800 ; RAM location of palettes to use
ld b, 1 ; Length of OBJ palette to load
ld d, $3F ; '?' ; Offset to BG palette start
ld e, $40 ; '@' ; Length of BG Palette
call Load_BG_OBJ_Palettes ; Input:
; HL = Pointer to OBJ Palette Data
; B = Size in bytes of OBJ Palette Data to load
; D = 256-byte offset from end of OBJ palette to start of BG Palette
; E = Size in bytes of BG Palette Data to load
pop hl ; restore saved registers
pop de
pop bc
ret
; End of function Setup_Color_Palettes_1
; =============== S U B R O U T I N E =======================================
Setup_Sound: ; CODE XREF: sub_0000+82p
ld a, $80 ; '€'
ld [unk_FF26], a ; Enable sound system, all channels OFF
ld [unk_FF11], a ; Sound wave duty 50%
ld a, $F3 ; 'ó'
ld [unk_FF12], a ; Init Envelope
ld [unk_FF25], a ; Set enabled soudn channels
ld a, $77 ; 'w'
ld [unk_FF24], a ; Set full volume
ld hl, $FF30 ; Setup 00 FF repeating waveform in wave RAM
xor a
ld c, $10
_loop_clear_wave_data: ; CODE XREF: Setup_Sound+19j
ldi [hl], a
cpl
dec c
jr nz, _loop_clear_wave_data
ret
; End of function Setup_Sound
; =============== S U B R O U T I N E =======================================
; Input:
; HL = VRAM Map Address
; B = ?
; C = ?
sub_0291: ; CODE XREF: sub_0000+CBp sub_0291+83j ...
call Wait_for_next_VBLANK ; |
call Setup_Color_Palettes_1
ld a, c
cp $38 ; '8'
jr nz, loc_02B0
push hl
xor a
ld [Reg_VBK], a
ld hl, $99A7
ld a, $38 ; '8'
loc_02A5: ; CODE XREF: sub_0291+18j
ldi [hl], a
inc a
cp $3F ; '?'
jr nz, loc_02A5
ld a, 1
ld [Reg_VBK], a
pop hl
loc_02B0: ; CODE XREF: sub_0291+9j
push bc
push hl
ld hl, $143 ; GBC flag bit check
bit 7, [hl]
call z, DMG_Manual_Color_Select ; if Cartridge Header CGB flag is NOT present, call 0589
pop hl
pop bc
call Wait_for_next_VBLANK ; |
ld a, c
sub $30 ; '0'
jp nc, loc_0306
ld a, c
cp 1
jp z, loc_0306
ld a, l
cp $D1 ; 'Ñ'
jr z, loc_02F1
push bc
ld b, 3
loc_02D3: ; CODE XREF: sub_0291+59j
ld c, 1
loc_02D5: ; CODE XREF: sub_0291+52j
ld d, 3
loc_02D7: ; CODE XREF: sub_0291+4Cj
ld a, [hl]
and $F8 ; 'ø'
or c
ldi [hl], a ; write palette data to screen for color sweep
dec d
jr nz, loc_02D7
inc c
ld a, c
cp 6
jr nz, loc_02D5
ld de, $11
add hl, de
dec b
jr nz, loc_02D3
ld de, $FFA1
add hl, de
pop bc
loc_02F1: ; CODE XREF: sub_0291+3Dj
inc b
ld a, b
ld e, $83 ; 'ƒ'
cp $62 ; 'b'
jr z, loc_02FF
ld e, $C1 ; 'Á'
cp $64 ; 'd'
jr nz, loc_0306
loc_02FF: ; CODE XREF: sub_0291+66j
ld a, e
ld [unk_FF13], a
ld a, $87 ; '‡'
ld [unk_FF14], a
loc_0306: ; CODE XREF: sub_0291+31j sub_0291+37j ...
ld a, [byte_C000+$1002]
cp 0
jr z, loc_0317
dec a
ld [byte_C000+$1002], a
ld a, c
cp 1
jp z, sub_0291 ; Input:
; HL = VRAM Map Address
; B = ?
; C = ?
loc_0317: ; CODE XREF: sub_0291+7Aj
dec c
jp nz, sub_0291 ; Input:
; HL = VRAM Map Address
; B = ?
; C = ?
ret
; End of function sub_0291
; =============== S U B R O U T I N E =======================================
Load_VRAM_and_Palettes: ; CODE XREF: sub_0000+EFp
ld c, $26 ; '&'
loc_031E: ; CODE XREF: Load_VRAM_and_Palettes+Cj
call Strange_D840_Counter
call Wait_for_next_VBLANK ; Wait until LCD VBlank Interrupt is flagged.
;
; Input: None.
; Output: None.
call Setup_Color_Palettes_1
dec c
jr nz, loc_031E
call Wait_for_next_VBLANK ; Wait until LCD VBlank Interrupt is flagged.
;
; Input: None.
; Output: None.
ld a, 1
ld [Reg_VBK], a ; VRAM Bank 1
call Load_HDMA_0008 ; Copy 288 Map bytes from D300 to 98A0 (char map)
call Load_HDMA_HL ; Copy 64 CHARs from D300 to 8000
xor a
ld [Reg_VBK], a ; VRAM Bank 0
call Load_HDMA_0008
ret
; End of function Load_VRAM_and_Palettes
; =============== S U B R O U T I N E =======================================
Load_HDMA_0008: ; CODE XREF: Load_VRAM_and_Palettes+15p
; Load_VRAM_and_Palettes+1Ep
ld hl, 8
; End of function Load_HDMA_0008
; =============== S U B R O U T I N E =======================================
Load_HDMA_HL: ; CODE XREF: Load_VRAM_and_Palettes+18p
ld de, $FF51
ld c, 5 ; Copies 5 bytes of HDMA control data from HL into HDMA registers
call Copy_C_bytes_from_HL_to_DE ; Copy bytes from Pointer in HL to Pointer in DE
;
; Input:
; HL = Source Address
; DE = Destination Address
; C = copy length
;
; Output:
; HL = HL + C
; DE = DE + C
; C = 0
ret
; End of function Load_HDMA_HL
; =============== S U B R O U T I N E =======================================
Strange_D840_Counter: ; CODE XREF: Load_VRAM_and_Palettes:loc_031Ep
push bc
push de ; save BC, DE, HL registers
push hl
ld hl, $D840 ; RAM structure ??
ld c, $20 ; ' '
loc_0352: ; CODE XREF: Strange_D840_Counter+3Fj
ld a, [hl] ; get data from RAM
and $1F ; clear upper 3 bits
cp $1F ; if lower 5 bits are all 1, then skip
jr z, loc_035A ; |
inc a ; else inc A
loc_035A: ; CODE XREF: Strange_D840_Counter+Dj
ld d, a
ldi a, [hl] ; get next RAM byte
rlca
rlca
rlca ; rotate left 3 bits
and 7
ld b, a
ldd a, [hl]
rlca
rlca
rlca
and $18
or b
cp $1F
jr z, loc_036E
inc a
loc_036E: ; CODE XREF: Strange_D840_Counter+21j
rrca
rrca
rrca
ld b, a
and $E0 ; 'à'
or d
ldi [hl], a
ld a, b
and 3
ld e, a
ld a, [hl]
rrca
rrca
and $1F
cp $1F
jr z, loc_0384
inc a
loc_0384: ; CODE XREF: Strange_D840_Counter+37j
rlca
rlca
or e
ldi [hl], a
dec c ; loop $20 times
jr nz, loc_0352 ; get data from RAM
pop hl
pop de
pop bc
ret
; End of function Strange_D840_Counter
; =============== S U B R O U T I N E =======================================
Copy_Cart_Logo_Data_Add_Checksum: ; CODE XREF: Load_GameBoy_Check_Header+1Bp
; Load_GameBoy_Check_Header+22p
ld c, 0
loc_0391: ; CODE XREF: Copy_Cart_Logo_Data_Add_Checksum+34j
ld a, [de]
and $F0 ; 'ð'
bit 1, c
jr z, loc_039A
swap a
loc_039A: ; CODE XREF: Copy_Cart_Logo_Data_Add_Checksum+7j
ld b, a
inc hl
ld a, [hl]
or b
ldi [hl], a
ld a, [de]
and $F
bit 1, c
jr nz, loc_03A8
swap a
loc_03A8: ; CODE XREF: Copy_Cart_Logo_Data_Add_Checksum+15j
ld b, a
inc hl
ld a, [hl]
or b
ldi [hl], a
inc de
bit 0, c
jr z, loc_03BF
push de
ld de, $FFF8
bit 1, c
jr z, loc_03BD
ld de, 8
loc_03BD: ; CODE XREF: Copy_Cart_Logo_Data_Add_Checksum+29j
add hl, de
pop de
loc_03BF: ; CODE XREF: Copy_Cart_Logo_Data_Add_Checksum+21j
inc c
ld a, c
cp $18
jr nz, loc_0391
ret
; End of function Copy_Cart_Logo_Data_Add_Checksum
; =============== S U B R O U T I N E =======================================
Scale_Graphic_Byte_2X_Nibble1: ; CODE XREF: sub_0000+A1p
ld b, a ; save logo byte to B
; End of function Scale_Graphic_Byte_2X_Nibble1
; =============== S U B R O U T I N E =======================================
Scale_Graphic_Byte_2X_Nibble2: ; CODE XREF: sub_0000+A4p
push de ; save header logo pointer
ld d, 4 ; D = bit counter to scale
loc_03CA: ; CODE XREF: Scale_Graphic_Byte_2X_Nibble2+Bj
ld e, b ; DE = 40,logo_byte
rl b ; scale Nintendo logo horizontally 2x
rla ; |
rl e ; |
rla ; |
dec d ; |
jr nz, loc_03CA ; |
pop de ; restore logo pointer
ldi [hl], a ; scale nintendo logo vertically 2x by storing the byte 2x at HL (tile memory)
inc hl ; |
ldi [hl], a ; |
inc hl ; |
ret
; End of function Scale_Graphic_Byte_2X_Nibble2
; =============== S U B R O U T I N E =======================================
; Draws the basic map for the Nintendo(r) logo in DMG style centered.
Copy_Nintendo_Logo_Map: ; CODE XREF: Set_System_Mode+30p
ld a, $19
ld [byte_9800+$110], a ; BG MAP ? Bottom of Y graphic gets (R) character from cart logo
ld hl, $992F
loc_03E2: ; CODE XREF: Copy_Nintendo_Logo_Map+13j
ld c, $C
loc_03E4: ; CODE XREF: Copy_Nintendo_Logo_Map+Fj
dec a
jr z, locret_03EF
ldd [hl], a
dec c
jr nz, loc_03E4
ld l, $F
jr loc_03E2
; ---------------------------------------------------------------------------
locret_03EF: ; CODE XREF: Copy_Nintendo_Logo_Map+Bj
ret
; End of function Copy_Nintendo_Logo_Map
; =============== S U B R O U T I N E =======================================
Load_GameBoy_Check_Header: ; CODE XREF: sub_0000+B9p
ld a, 1
ld [Reg_VBK], a ; Set Video Bank 1
call Clear_8KB_at_8000_Aligned ; Falls through to Clear function below
ld de, $607
ld hl, $8080
ld c, $C0 ; 'À'
loc_03FF: ; CODE XREF: Load_GameBoy_Check_Header+16j
ld a, [de] ; decompress vertically squashed GameBoy logo data
ldi [hl], a
inc hl
ldi [hl], a
inc hl
inc de
dec c
jr nz, loc_03FF ; decompress vertically squashed GameBoy logo data
ld de, $104 ; address of Cartridge Logo data
call Copy_Cart_Logo_Data_Add_Checksum
ld bc, $FFA8 ; subtract 88 from HL
add hl, bc
call Copy_Cart_Logo_Data_Add_Checksum
ld bc, $FFF8
add hl, bc ; Subtract 8 from HL
ld de, $72 ; 'r' ; data at $0072 8-byte vertically compressed (R) tile
ld c, 8
_copy_r_tile_loop2: ; CODE XREF: Load_GameBoy_Check_Header+33j
inc hl
ld a, [de] ; copy (R) tile from 0072 to vram
ldi [hl], a
inc de
dec c
jr nz, _copy_r_tile_loop2
@@loc_setup_attributes: ; Map 0 location of top left corner of "GAMEBOY" Graphic
ld hl, $98C2
ld b, 8
ld a, 8
loc_042C: ; CODE XREF: Load_GameBoy_Check_Header+47j
ld c, $10 ; map data line length
loc_042E: ; CODE XREF: Load_GameBoy_Check_Header+40j
ldi [hl], a ; fill map attribute bytes with $8
dec c
jr nz, loc_042E ; fill map attribute bytes with $8
ld de, $10 ; next map row
add hl, de ; |
dec b
jr nz, loc_042C ; fill 8 lines worth
Draw_GAMEBOY_Logo_Map:
xor a
ld [Reg_VBK], a ; VRAM Bank 0
ld hl, $98C2 ; Map 0 location of top left corner of "GAMEBOY" Graphic
ld a, 8
loc_0441: ; CODE XREF: Load_GameBoy_Check_Header+62j
ldi [hl], a ; Fill Map rectangle from 2,6 to 11,8 with 08-37 (map data for GAMEBOY logo)
inc a ; |
cp $18
jr nz, loc_0449
ld l, $E2 ; 'â'
loc_0449: ; CODE XREF: Load_GameBoy_Check_Header+55j
cp $28 ; '('
jr nz, loc_0450
ld hl, $9902
loc_0450: ; CODE XREF: Load_GameBoy_Check_Header+5Bj
cp $38 ; '8'
jr nz, loc_0441 ; Done with logo fill
Addr_0454: ; Create structures with data at 08D8
ld hl, $8D8 ; FF, FF, xx, xx, 00, 00, XX, XX
; FF, FF, xx, xx, 00, 00, XX, XX
; FF, FF, xx, xx, 00, 00, XX, XX
; FF, FF, xx, xx, 00, 00, XX, XX
; FF, FF, xx, xx, 00, 00, XX, XX
; FF, FF, xx, xx, 00, 00, XX, XX
; FF, FF, xx, xx, 00, 00, XX, XX
; FF, FF, xx, xx, 00, 00, XX, XX
;
ld de, $D840
ld b, 8
loc_045C: ; CODE XREF: Load_GameBoy_Check_Header+80j
ld a, $FF
ld [de], a
inc de
ld [de], a
inc de
ld c, 2
call Copy_C_bytes_from_HL_to_DE ; |
ld a, 0
ld [de], a
inc de
ld [de], a
inc de
inc de
inc de
dec b
jr nz, loc_045C
call Setup_Color_Palettes_1
ld hl, $14B ; Cartridge Header Data Magic Number static $33
ld a, [hl]
cp $33 ; '3'
jr nz, loc_0488
ld l, $44 ; 'D'
ld e, $30 ; '0'
ldi a, [hl]
cp e
jr nz, loc_04CE
inc e
jr loc_048C
; ---------------------------------------------------------------------------
loc_0488: ; CODE XREF: Load_GameBoy_Check_Header+8Bj
ld l, $4B ; 'K'
ld e, 1
loc_048C: ; CODE XREF: Load_GameBoy_Check_Header+96j
ldi a, [hl]
cp e
jr nz, loc_04CE
ld l, $34 ; '4'
ld bc, $10
loc_0495: ; CODE XREF: Load_GameBoy_Check_Header+A9j
ldi a, [hl]
add a, b
ld b, a
dec c
jr nz, loc_0495
ld [byte_C000+$1000], a
ld hl, $6C7
ld c, 0
loc_04A3: ; CODE XREF: Load_GameBoy_Check_Header+BBj
ldi a, [hl]
cp b
jr z, loc_04AF
inc c
ld a, c
cp $4F ; 'O'
jr nz, loc_04A3
jr loc_04CE
; ---------------------------------------------------------------------------
loc_04AF: ; CODE XREF: Load_GameBoy_Check_Header+B5j
ld a, c
sub $41 ; 'A'
jr c, loc_04D0
ld hl, $716
ld d, 0
ld e, a
add hl, de
loc_04BB: ; CODE XREF: Load_GameBoy_Check_Header+DCj
ld a, [loc_0137]
ld d, a
ld a, [hl]
cp d
jr z, loc_04D0
ld de, $E
add hl, de
ld a, c
add a, e
ld c, a
sub $5E ; '^'
jr c, loc_04BB
loc_04CE: ; CODE XREF: Load_GameBoy_Check_Header+93j
; Load_GameBoy_Check_Header+9Ej ...
ld c, 0
loc_04D0: ; CODE XREF: Load_GameBoy_Check_Header+C2j
; Load_GameBoy_Check_Header+D1j
ld hl, $733
ld b, 0
add hl, bc
ld a, [hl]
and $1F
ld [byte_C000+$1008], a
ld a, [hl]
and $E0 ; 'à'
rlca
rlca
rlca
ld [byte_C000+$100B], a
call sub_04E9
ret
; End of function Load_GameBoy_Check_Header
; =============== S U B R O U T I N E =======================================
sub_04E9: ; CODE XREF: Load_GameBoy_Check_Header+F5p
; DMG_Manual_Color_Select+40p
ld de, $791
ld hl, $D900
ld a, [byte_C000+$100B]
ld b, a
ld c, $1E
loc_04F5: ; CODE XREF: sub_04E9+33j
bit 0, b
jr nz, loc_04FB
inc de
inc de
loc_04FB: ; CODE XREF: sub_04E9+Ej
ld a, [de]
ldi [hl], a
jr nz, loc_0501
dec de
dec de
loc_0501: ; CODE XREF: sub_04E9+14j
bit 1, b
jr nz, loc_0507
inc de
inc de
loc_0507: ; CODE XREF: sub_04E9+1Aj
ld a, [de]
ldi [hl], a
inc de
inc de
jr nz, loc_050F
dec de
dec de
loc_050F: ; CODE XREF: sub_04E9+22j
bit 2, b
jr z, loc_0518
dec de
dec hl
ld a, [de]
ldi [hl], a
inc de
loc_0518: ; CODE XREF: sub_04E9+28j
ld a, [de]
ldi [hl], a
inc de
dec c
jr nz, loc_04F5
ld hl, $D900
ld de, $DA00
call Dictionary_Decompress_HL_to_DE ; This routine uses an index list ($60 long) at HL with a dictionary of 8-byte-long words at $07E8,
; and copies the words in index sequence to DE.
; Index is a byte offset, not a word offset, eg: index $80 is at $07E8+$80, not $80 * 8 byte word size.
ret
; End of function sub_04E9
; =============== S U B R O U T I N E =======================================
sub_0528: ; CODE XREF: DMG_Manual_Color_Select+43p
ld hl, $12
ld a, [byte_C000+$1005]
rlca
rlca
ld b, 0
ld c, a
add hl, bc
ld de, $D840
ld b, 8
loc_0539: ; CODE XREF: sub_0528+1Fj
push hl
ld c, 2
call Copy_C_bytes_from_HL_to_DE ; Copy bytes from Pointer in HL to Pointer in DE
;
; Input:
; HL = Source Address
; DE = Destination Address
; C = copy length
;
; Output:
; HL = HL + C
; DE = DE + C
; C = 0
inc de
inc de
inc de
inc de
inc de
inc de
pop hl
dec b
jr nz, loc_0539
ld de, $D842
ld c, 2
call Copy_C_bytes_from_HL_to_DE ; Copy bytes from Pointer in HL to Pointer in DE
;
; Input:
; HL = Source Address
; DE = Destination Address
; C = copy length
;
; Output:
; HL = HL + C
; DE = DE + C
; C = 0
ld de, $D84A
ld c, 2
call Copy_C_bytes_from_HL_to_DE ; Copy bytes from Pointer in HL to Pointer in DE
;
; Input:
; HL = Source Address
; DE = Destination Address
; C = copy length
;
; Output:
; HL = HL + C
; DE = DE + C
; C = 0
dec hl
dec hl
ld de, $D844
ld c, 2
call Copy_C_bytes_from_HL_to_DE ; Copy bytes from Pointer in HL to Pointer in DE
;
; Input:
; HL = Source Address
; DE = Destination Address
; C = copy length
;
; Output:
; HL = HL + C
; DE = DE + C
; C = 0
ret
; End of function sub_0528
; =============== S U B R O U T I N E =======================================
; This routine uses an index list ($60 long) at HL with a dictionary of 8-byte-long words at $07E8,
; and copies the words in index sequence to DE.
; Index is a byte offset, not a word offset, eg: index $80 is at $07E8+$80, not $80 * 8 byte word size.
Dictionary_Decompress_HL_to_DE: ; CODE XREF: sub_04E9+3Bp
ld c, $60 ; '`'
loc_0566: ; CODE XREF: Dictionary_Decompress_HL_to_DE+14j
ldi a, [hl]
push hl
push bc
ld hl, $7E8 ; Large table
ld b, 0
ld c, a
add hl, bc
ld c, 8
call Copy_C_bytes_from_HL_to_DE ; Copy bytes from Pointer in HL to Pointer in DE
;
; Input:
; HL = Source Address
; DE = Destination Address
; C = copy length
;
; Output:
; HL = HL + C
; DE = DE + C
; C = 0
pop bc
pop hl
dec c
jr nz, loc_0566
ret
; End of function Dictionary_Decompress_HL_to_DE
; =============== S U B R O U T I N E =======================================
HL_plus_D008_times_24: ; CODE XREF: Set_System_Mode+19p
ld a, [byte_C000+$1008]
ld de, $18 ; HL = HL + 24*[D008]
inc a
loc_0582: ; CODE XREF: HL_plus_D008_times_24+Bj
dec a
jr z, locret_0588
add hl, de
jr nz, loc_0582
locret_0588: ; CODE XREF: HL_plus_D008_times_24+8j
ret
; End of function HL_plus_D008_times_24
; =============== S U B R O U T I N E =======================================
DMG_Manual_Color_Select: ; CODE XREF: sub_0291+26p
call Read_Keypad ; |
ld a, b ; Keypad data is left in B
and $FF
jr z, loc_05A0 ; If no buttons pressed, then skip to return
ld hl, $8E4 ; Address of Color_Palette_KeyPad
ld b, 0
loc_0596: ; CODE XREF: DMG_Manual_Color_Select+15j
ldi a, [hl]
cp c
jr z, loc_05A2
inc b
ld a, b
cp $C
jr nz, loc_0596
loc_05A0: ; CODE XREF: DMG_Manual_Color_Select+6j
jr locret_05CF
; ---------------------------------------------------------------------------
loc_05A2: ; CODE XREF: DMG_Manual_Color_Select+Fj
ld a, b
ld [byte_C000+$1005], a
ld a, $1E
ld [byte_C000+$1002], a
ld de, $B
add hl, de
ld d, [hl]
ld a, d
and $1F
ld e, a
ld hl, $D008
ldd a, [hl]
ldi [hl], a
ld a, e
ld [hl], a
ld a, d
and $E0 ; 'à'
rlca
rlca
rlca
ld e, a
ld hl, $D00B
ldd a, [hl]
ldi [hl], a
ld a, e
ld [hl], a
call sub_04E9
call sub_0528
locret_05CF: ; CODE XREF: DMG_Manual_Color_Select:loc_05A0j
ret
; End of function DMG_Manual_Color_Select
; =============== S U B R O U T I N E =======================================
Set_System_Mode: ; CODE XREF: sub_0000:Commit_System_and_Boot_Cartp
call Wait_for_next_VBLANK ; Wait until LCD VBlank Interrupt is flagged.
;
; Input: None.
; Output: None.
ld a, [loc_0143] ; Cartridge ROM Compatability Flag (CGB = $80)
bit 7, a
jr z, Set_System_Mode_DMG ; If DMG, skip over FF4C part
ld [Reg_LCDMODE], a ; This unknown register is at the tail end of the LCD register space. It may possibly lockdown advanced color hardware features from being accessed by a game in DMG mode. This could be tested.
; The CGB boot ROM sets this to $80 if a CGB game is inserted, or $04 if a DMG game is inserted.
jr locret_0606
; ---------------------------------------------------------------------------
Set_System_Mode_DMG: ; CODE XREF: Set_System_Mode+8j
ld a, 4
ld [Reg_LCDMODE], a ; This unknown register is at the tail end of the LCD register space. It may possibly lockdown advanced color hardware features from being accessed by a game in DMG mode. This could be tested.
; The CGB boot ROM sets this to $80 if a CGB game is inserted, or $04 if a DMG game is inserted.
ld a, 1
ld [Reg_PAL_LOCK], a ; Unknown lockout register? Color palette lockout?
ld hl, $DA00
call HL_plus_D008_times_24
ld b, $10
ld d, 0
ld e, 8
call Load_BG_OBJ_Palettes ; Input:
; HL = Pointer to OBJ Palette Data
; B = Size in bytes of OBJ Palette Data to load
; D = 256-byte offset from end of OBJ palette to start of BG Palette
; E = Size in bytes of BG Palette Data to load
ld hl, $7A ; 'z'
ld a, [byte_C000+$1000]
ld b, a
ld c, 2
loc_05FE: ; CODE XREF: Set_System_Mode+34j
ldi a, [hl]
cp b
call z, Copy_Nintendo_Logo_Map ; Draws the basic map for the Nintendo(r) logo in DMG style centered.
dec c
jr nz, loc_05FE
locret_0606: ; CODE XREF: Set_System_Mode+Cj
ret
; End of function Set_System_Mode
; ---------------------------------------------------------------------------
GameBoy_Logo: db 1, $F,$3F,$7E,$FF,$FF,$C0, 0,$C0,$F0,$F1, 3,$7C
db $FC,$FE,$FE, 3, 7, 7, $F,$E0,$E0,$F0,$F0,$1E,$3E
db $7E,$FE, $F, $F,$1F,$1F,$FF,$FF, 0, 0, 1, 1, 1
db 3,$FF,$FF,$E1,$E0,$C0,$F0,$F9,$FB,$1F,$7F,$F8,$E0
db $F3,$FD,$3E,$1E,$E0,$F0,$F9,$7F,$3E,$7C,$F8,$E0,$F8
db $F0,$F0,$F8, 0, 0,$7F,$7F, 7, $F,$9F,$BF,$9E,$1F
db $FF,$FF, $F,$1E,$3E,$3C,$F1,$FB,$7F,$7F,$FE,$DE,$DF
db $9F,$1F,$3F,$3E,$3C,$F8,$F8, 0, 0, 3, 3, 7, 7
db $FF,$FF,$C1,$C0,$F3,$E7,$F7,$F3,$C0,$C0,$C0,$C0,$1F
db $1F,$1E,$3E,$3F,$1F,$3E,$3E,$80, 0, 0, 0,$7C,$1F
db 7, 0, $F,$FF,$FE, 0,$7C,$F8,$F0, 0,$1F, $F, $F
db 0,$7C,$F8,$F8, 0,$3F,$3E,$1C, 0, $F, $F, $F, 0
db $7C,$FF,$FF, 0, 0,$F8,$F8, 0, 7, $F, $F, 0,$81
db $FF,$FF, 0,$F3,$E1,$80, 0,$E0,$FF,$7F, 0,$FC,$F0
db $C0, 0,$3E,$7C,$7C, 0, 0, 0, 0, 0
Addr_06C7: db 0,$88,$16,$36,$D1,$DB,$F2,$3C,$8C,$92,$3D,$5C,$58
db $C9,$3E,$70,$1D,$59,$69,$19,$35,$A8,$14,$AA,$75,$95
db $99,$34,$6F,$15,$FF,$97,$4B,$90,$17,$10,$39,$F7,$F6
db $A2,$49,$4E,$43,$68,$E0,$8B,$F0,$CE, $C,$29,$E8,$B7
db $86,$9A,$52, 1,$9D,$71,$9C,$BD,$5D,$6D,$67,$3F,$6B
db $B3,$46,$28,$A5,$C6,$D3,$27,$61,$18,$66,$6A,$BF, $D
db $F4
Addr_0716: db $42,$45,$46,$41,$41,$52,$42,$45,$4B,$45,$4B,$20,$52
db $2D,$55,$52,$41,$52,$20,$49,$4E,$41,$49,$4C,$49,$43
db $45,$20,$52
Addr_0733: db $7C, 8,$12,$A3,$A2, 7,$87,$4B,$20,$12,$65,$A8,$16
db $A9,$86,$B1,$68,$A0,$87,$66,$12,$A1,$30,$3C,$12,$85
db $12,$64,$1B, 7, 6,$6F,$6E,$6E,$AE,$AF,$6F,$B2,$AF
db $B2,$A8,$AB,$6F,$AF,$86,$AE,$A2,$A2,$12,$AF,$13,$12
db $A1,$6E,$AF,$AF,$AD, 6,$4C,$6E,$AF,$AF,$12,$7C,$AC
db $A8,$6A,$6E,$13,$A0,$2D,$A8,$2B,$AC,$64,$AC,$6D,$87
db $BC,$60,$B4,$13,$72,$7C,$B5,$AE,$AE,$7C,$7C,$65,$A2
db $6C,$64,$85
Palette_Index: db $80,$B0,$40,$88,$20,$68,$DE, 0,$70,$DE,$20,$78,$20
db $20,$38,$20,$B0,$90,$20,$B0,$A0,$E0,$B0,$C0,$98,$B6
db $48,$80,$E0,$50,$1E,$1E,$58,$20,$B8,$E0,$88,$B0,$10
db $20, 0,$10,$20,$E0,$18,$E0,$18, 0,$18,$E0,$20,$A8
db $E0,$20,$18,$E0, 0,$20,$18,$D8,$C8,$18,$E0, 0,$E0
db $40,$28,$28,$28,$18,$E0,$60,$20,$18,$E0, 0, 0, 8
db $E0,$18,$30,$D0,$D0,$D0,$20,$E0,$E8
Palette_Dictionary:db $FF,$7F,$BF,$32,$D0, 0, 0, 0
db $9F,$63,$79,$42,$B0,$15,$CB, 4
db $FF,$7F,$31,$6E,$4A,$45, 0, 0
db $FF,$7F,$EF,$1B, 0, 2, 0, 0
db $FF,$7F,$1F,$42,$F2,$1C, 0, 0
db $FF,$7F,$94,$52,$4A,$29, 0, 0
db $FF,$7F,$FF, 3,$2F, 1, 0, 0
db $FF,$7F,$EF, 3,$D6, 1, 0, 0
db $FF,$7F,$B5,$42,$C8,$3D, 0, 0
db $74,$7E,$FF, 3,$80, 1, 0, 0
db $FF,$67,$AC,$77,$13,$1A,$6B,$2D
db $D6,$7E,$FF,$4B,$75,$21, 0, 0
db $FF,$53,$5F,$4A,$52,$7E, 0, 0
db $FF,$4F,$D2,$7E,$4C,$3A,$E0,$1C
db $ED, 3,$FF,$7F,$5F,$25, 0, 0
db $6A, 3,$1F, 2,$FF, 3,$FF,$7F
db $FF,$7F,$DF, 1,$12, 1, 0, 0
db $1F,$23,$5F, 3,$F2, 0, 9, 0
db $FF,$7F,$EA, 3,$1F, 1, 0, 0
db $9F,$29,$1A, 0, $C, 0, 0, 0
db $FF,$7F,$7F, 2,$1F, 0, 0, 0
db $FF,$7F,$E0, 3, 6, 2,$20, 1
db $FF,$7F,$EB,$7E,$1F, 0, 0,$7C
db $FF,$7F,$FF,$3F, 0,$7E,$1F, 0
db $FF,$7F,$FF, 3,$1F, 0, 0, 0
db $FF, 3,$1F, 0, $C, 0, 0, 0
db $FF,$7F,$3F, 3,$93, 1, 0, 0
db 0, 0, 0,$42,$7F, 3,$FF,$7F
db $FF,$7F,$8C,$7E, 0,$7C, 0, 0
db $FF,$7F,$EF,$1B,$80,$61, 0, 0
Addr_08D8: db $FF,$7F
db 0,$7C
db $E0, 3
db $1F,$7C
db $1F, 0
db $FF, 3
Color_Palette_KeyPad:db $40,$41 ; Values used when keypad is pressed to change color palettes
db $42,$20
db $21,$22
db $80,$81
db $82,$10
db $11,$12
db $12,$B0
db $79,$B8
db $AD,$16
db $17, 7
db $BA, 5
db $7C,$13
db 0
db 0
db 0
db 0
; end of 'ROM'
; ===========================================================================
; Segment type: Regular
SECTION "VRAM_CHAR", DATA
org $8000
ds $1800
; end of 'VRAM_CHAR'
; ===========================================================================
; Segment type: Regular
SECTION "VRAM_MAP", DATA
org $9800
byte_9800: ds $800
; end of 'VRAM_MAP'
; ===========================================================================
; Segment type: Regular
SECTION "EXT_RAM", DATA
org $A000
ds $2000
; end of 'EXT_RAM'
; ===========================================================================
; Segment type: Regular
SECTION "INT_RAM", DATA
org $C000
byte_C000: ds $2000
; end of 'INT_RAM'
; ===========================================================================
; Segment type: Regular
SECTION "IO_REG", DATA
org $FF00
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
unk_FF11: ds 1
unk_FF12: ds 1
unk_FF13: ds 1
unk_FF14: ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
unk_FF24: ds 1
unk_FF25: ds 1
unk_FF26: ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
Reg_LCDC: ds 1 ; DATA XREF: sub_0000+C2w
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
Reg_BGP: ds 1 ; DATA XREF: sub_0000+80w
ds 1
ds 1
ds 1
ds 1
Reg_LCDMODE: ds 1 ; This unknown register is at the tail end of the LCD register space. It may possibly lockdown advanced color hardware features from being accessed by a game in DMG mode. This could be tested.
; The CGB boot ROM sets this to $80 if a CGB game is inserted, or $04 if a DMG game is inserted.
ds 1
ds 1
Reg_VBK: ds 1 ; DATA XREF: sub_0000+BEw sub_0000+CFw ...
Reg_BLCK: ds 1 ; DATA XREF: sub_0000+FEw
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
Reg_BCPS: ds 1 ; BG Palette Selection
Reg_BCPD: ds 1 ; BG Palette Data
Reg_OCPS: ds 1 ; OBJ Palette Selection
Reg_OCPD: ds 1 ; OBJ Palette Data
Reg_PAL_LOCK: ds 1 ; Unknown lockout register? Color palette lockout?
ds 1
ds 1
ds 1
Reg_SVBK: ds 1 ; DATA XREF: sub_0000:System_Setupw
; sub_0000+FAw
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
ds 1
; end of 'IO_REG'
; ===========================================================================
; Segment type: Regular
SECTION "HiRAM", DATA
org $FF80
ds $7F
; end of 'HiRAM'
; end of file
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