GAME GAME GAME is what I called my first Nintendo Game Boy assembly project. The name comes from the childish assertion of its status as a game, since the project barely resembles a game at all.
The source code is really silly. I was following an old and mildly infamous tutorial, so I took a lot of liberties for my own amusement. I had the amazing idea of giving every label the most bizarre names I could come up with, leading to hits such as potato_salad.walmart and strawberry_jam.let_set. I also decided to write comments for as much code as I could, even when I had no idea what was being done. This was actually a good idea in hindsight: it made it explicit what I didn't understand (so I could learn about it in the future — not to be blindly accepted) and it helped reinforce the knowledge that I did gain. It's really funny how little I understood at this point, though.
I made another silly but good decision, which was to iterate on this and incorporate some of my own twists for a second version of GAME GAME GAME. This is a really good idea. I'd strongly encourage this when learning anything for the first time: practice what you just learned, and then extend it. Add something new. In this case, since the program involved moving a sprite around the screen, I switched the sprite to an arrow and I added functionality to make the arrow face the direction it moves (roughly — diagonal cases are not handled, with vertical movement given precedence).
The original version remained named "GAME GAME GAME v1", with the added functionality found in a separate copy named "GAME GAME GAME v2". (This might have been the first experience enticing me to start using version control, which began a little later!)
INCLUDE "gbhw.inc" ;include definitions because I'm a lazy bum
_SPR0_Y EQU _OAMRAM ;constants for the sprite's OAM because I'm still lazy
_SPR0_X EQU _OAMRAM+1 ;more OAM constants
_SPR0_NUM EQU _OAMRAM+2 ;more
_SPR0_ATT EQU _OAMRAM+3 ;don't even need this one because I won't be working with it but why not
_PAD EQU _RAM ;joypad variable goes in regular RAM
;program start
SECTION "i_like_cheese",HOME[$0100]
nop ;NO OPERATION
jp cow_says_moo ;go to the real program start
;boring ROM header stuff because I want the game to actually work
ROM_HEADER ROM_NOMBC, ROM_SIZE_32KBYTE, RAM_SIZE_0KBYTE
;the REAL program start
cow_says_moo:
nop ;NOP
di ;Disable Interrupts
ld sp, $FFFF ;LoaD the top of RAM to the stack
;some more initial settings
potato_salad:
ld a, %11100100 ;use the normal palette because we want normal colours
ld [rBGP], a ;and put it in the background palette register
ld [rOBP0], a ;also the sprite (object, OBJ) palette register
ld a, 0 ;0, that's right captain feathersword,
ld [rSCX], a ;we need to put 0 in the accumulator register for
ld [rSCY], a ;the window scroll positions!
call strawberry_jam ;for whatever reason I need to turn off the LCD
ld hl, Tiles ;sprite(tm) (and background)
ld de, _VRAM ;get the VRAM address in de
ld b, EndTiles-Tiles ;b is the data counter, it counts how much data we need to transfer
.chair_cushion:
ld a, [hl] ;data pointed to by hl goes into a (the tiles)
ld [de], a ;put that data into address pointed to by de (the VRAM)
dec b ;one less byte of data to go
jr z, .walmart ;if b is zero, go do the walmart subprocess
;if not:
inc hl ;go to the next byte of data
inc de ;go to the next byte in VRAM
jr .chair_cushion ;loop
.walmart:
;fill the background map with tile 0 (the background tile)
ld hl, _SCRN0 ;background map
ld de, 32*32 ;background map is 32x32 tiles
.z_dash_niner_niner:
ld a, 0 ;tile 0
ld [hl], a ;into _SCRN0
dec de ;counter - 1
;the 16-bit dec operation doesn't affect the flags, so I need to check manually
ld a, d ;1st (technically 2nd) half of de
or e ;logical or with 2nd (1st) half
jp z, .sleeping_foot ;if they're both zero (from the or) then it's done
;if not:
inc hl ;next!
jp .z_dash_niner_niner ;loop
.sleeping_foot:
ld hl, _OAMRAM ;next is the sprite data, which goes into OAM RAM
ld de, 40*4 ;40 sprites x 4 bytes of OAM
.tiger_fur:
ld a, 0 ;0th
ld [hl], a ;goes into OAM RAM
dec de ;-1
;check if zero
ld a, d
or e
jp z, .black_and_white
inc hl
jp .tiger_fur
.black_and_white:
;make the sprite
ld a, 84 ;y position
ld [_SPR0_Y], a
ld a, 84 ;x position
ld [_SPR0_X], a
ld a, 1 ;tile number
ld [_SPR0_NUM], a
ld a, 0 ;special attributes
ld [_SPR0_ATT], a
;DISPLAY ACTIVATE
ld a, LCDCF_ON|LCDCF_BG8000|LCDCF_BG9800|LCDCF_BGON|LCDCF_OBJ8|LCDCF_OBJON
ld [rLCDC], a
;main loop
fabric_softener:
call cloudy_mason_jar ;read the joypad input
;wait for VBlank
.knalbv_rof_tiaw:
ld a, [rLY] ;get the coord for LCDC
cp 145 ;is it 145? (the screen is 144 lines, so 145 is off it)
jr nz, .knalbv_rof_tiaw ;if it's not 145, then waste another CPU cycle (loop)
;oh look, it's 145
ld a, [_PAD] ;check the joypad
and %00010000 ;is it the right button?
call nz, stranded_wire ;if it is, then go deal with that
ld a, [_PAD]
and %00100000 ;left
call nz, water_bottle
ld a, [_PAD]
and %01000000 ;up
call nz, boston_red_sox
ld a, [_PAD]
and %10000000 ;down
call nz, ham_sandwich
ld a, [_PAD]
and %00000001 ;A button
call nz, dirty_dog
call orange_ink ;delay
jr fabric_softener ;loop
;what's that? oh you pressed a button?
;right
stranded_wire:
ld a, [_SPR0_X] ;get the sprite's x position
cp 160 ;is it on the edge?
ret z ;if it is, then forget it
inc a ;if it's not on the edge, then x goes up 1
ld [_SPR0_X], a ;store the new position in OAM
ret ;return
;left
water_bottle:
ld a, [_SPR0_X] ;get the sprite's x position
cp 8 ;is it on the edge?
ret z ;if it is, then forget it
dec a ;if it's not on the edge, then x goes down 1
ld [_SPR0_X], a ;store the new position in OAM
ret ;return
;up
boston_red_sox:
ld a, [_SPR0_Y] ;get the sprite's y position
cp 16 ;is it on the edge?
ret z ;if it is, then forget it
dec a ;if it's not on the edge, then y goes down (up) 1
ld [_SPR0_Y], a ;store the new position in OAM
ret ;return
;down
ham_sandwich:
ld a, [_SPR0_Y] ;get the sprite's y position
cp 152 ;is it on the edge?
ret z ;if it is, then forget it
inc a ;if it's not on the edge, then y goes up (down) 1
ld [_SPR0_Y], a ;store the new position in OAM
ret ;return
;A button
dirty_dog:
ld a, [_SPR0_NUM] ;I want to change the sprite tile, so get the tile number
cp 2 ;is it already 2?
jr z, .dirty_cat ;if it's already 2, then it should be changed to 1, right?
ld a, 2 ;new tile number
ld [_SPR0_NUM], a ;store it in sprite data
call orange_ink ;delay because otherwise the change would look too fast and weird
ret ;return
.dirty_cat:
ld a, 1 ;new tile number
ld [_SPR0_NUM], a
call orange_ink ;wait a bit
ret ;return
;read the joypad input
cloudy_mason_jar:
ld a, %00100000 ;read d-pad (you can only do either d-pad or buttons at a time
;for some weird reason
ld [rP1], a ;tell the GameBoy that we want to read the d-pad
;do several readings to avoid "bouncing"
ld a, [rP1]
ld a, [rP1]
ld a, [rP1]
ld a, [rP1]
and $0F ;the readings are stored in the bottom 4 bits so we only need those
swap a ;swap upper and lower bits
ld b, a ;store it in b
ld a, %00010000 ;read buttons
ld [rP1], a
;no bouncing allowed
ld a, [rP1]
ld a, [rP1]
ld a, [rP1]
ld a, [rP1]
and $0F ;top 4 bits are unused
or b ;I honestly don't know how this works because they're 8-bits
;it probably works with each bit and I guess would combine the two
cpl ;complement a
ld [_PAD], a ;put it in the joypad variable
ret ;return
;LCD shutdown?
strawberry_jam:
;not sure how this works or what is does
ld a, [rLCDC]
rlca ;essentially set the high bit in the carry flag, not sure the purpose
ret nc ;not sure the purpose of this, but I think it goes back if the carry
;is 0
.let_set:
ld a, [rLY]
cp 145
jr nz, .let_set
;hey, it's 145
;not sure what this does either
ld a, [rLCDC]
res 7, a
ld [rLCDC], a
ret ;return
;delay
orange_ink:
ld de, 5000 ;the number of times to execute the loop
.yellow_ink:
dec de ;-1
ld a, d ;is it zero?
or e
jr z, .ink_cartridge_empty
nop
jr .yellow_ink ;loop
.ink_cartridge_empty:
ret
;tiles
Tiles:
;background tile
DB $00, $FF, $00, $FF, $00, $FF, $00, $FF
DB $00, $FF, $00, $FF, $00, $FF, $00, $FF
;sprite 1
DB $3C, $3C, $7E, $42, $FF, $A5, $FF, $81
DB $FF, $A5, $FF, $99, $7E, $42, $3C, $3C
;sprite 2
DB $3C, $3C, $7E, $42, $FF, $A5, $FF, $81
DB $FF, $81, $FF, $BD, $7E, $42, $3C, $3C
EndTiles:
INCLUDE "gbhw.inc" ;include definitions because I'm a lazy bum
_SPR0_Y EQU _OAMRAM ;constants for the sprite's OAM because I'm still lazy
_SPR0_X EQU _OAMRAM+1 ;more OAM constants
_SPR0_NUM EQU _OAMRAM+2 ;more
_SPR0_ATT EQU _OAMRAM+3 ;don't even need this one because I won't be working with it but why not
_PAD EQU _RAM ;joypad variable goes in regular RAM
;program start
SECTION "i_like_cheese",HOME[$0100]
nop ;NO OPERATION
jp cow_says_moo ;go to the real program start
;boring ROM header stuff because I want the game to actually work
ROM_HEADER ROM_NOMBC, ROM_SIZE_32KBYTE, RAM_SIZE_0KBYTE
;the REAL program start
cow_says_moo:
nop ;NOP
di ;Disable Interrupts
ld sp, $FFFF ;LoaD the top of RAM to the stack
;some more initial settings
potato_salad:
ld a, %11100100 ;use the normal palette because we want normal colours
ld [rBGP], a ;and put it in the background palette register
ld a, %11010010 ;use this palette for sprites because I want white in them
ld [rOBP0], a ;store in the the sprite (object, OBJ) palette register
ld a, 0 ;0, that's right captain feathersword,
ld [rSCX], a ;we need to put 0 in the accumulator register for
ld [rSCY], a ;the window scroll positions!
call strawberry_jam ;for whatever reason I need to turn off the LCD
ld hl, Tiles ;sprite(tm) (and background)
ld de, _VRAM ;get the VRAM address in de
ld b, EndTiles-Tiles ;b is the data counter, it counts how much data we need to transfer
.chair_cushion:
ld a, [hl] ;data pointed to by hl goes into a (the tiles)
ld [de], a ;put that data into address pointed to by de (the VRAM)
dec b ;one less byte of data to go
jr z, .walmart ;if b is zero, go do the walmart subprocess
;if not:
inc hl ;go to the next byte of data
inc de ;go to the next byte in VRAM
jr .chair_cushion ;loop
.walmart:
;fill the background map with tile 0 (the background tile)
ld hl, _SCRN0 ;background map
ld de, 32*32 ;background map is 32x32 tiles
.z_dash_niner_niner:
ld a, 0 ;tile 0
ld [hl], a ;into _SCRN0
dec de ;counter - 1
;the 16-bit dec operation doesn't affect the flags, so I need to check manually
ld a, d ;1st (technically 2nd) half of de
or e ;logical or with 2nd (1st) half
jp z, .sleeping_foot ;if they're both zero (from the or) then it's done
;if not:
inc hl ;next!
jp .z_dash_niner_niner ;loop
.sleeping_foot:
ld hl, _OAMRAM ;next is the sprite data, which goes into OAM RAM
ld de, 40*4 ;40 sprites x 4 bytes of OAM
.tiger_fur:
ld a, 0 ;0th
ld [hl], a ;goes into OAM RAM
dec de ;-1
;check if zero
ld a, d
or e
jp z, .black_and_white
inc hl
jp .tiger_fur
.black_and_white:
;make the sprite
ld a, 84 ;y position
ld [_SPR0_Y], a
ld a, 84 ;x position
ld [_SPR0_X], a
ld a, 1 ;tile number
ld [_SPR0_NUM], a
ld a, 0 ;special attributes
ld [_SPR0_ATT], a
;DISPLAY ACTIVATE
ld a, LCDCF_ON|LCDCF_BG8000|LCDCF_BG9800|LCDCF_BGON|LCDCF_OBJ8|LCDCF_OBJON
ld [rLCDC], a
;main loop
fabric_softener:
call cloudy_mason_jar ;read the joypad input
;wait for VBlank
.knalbv_rof_tiaw:
ld a, [rLY] ;get the coord for LCDC
cp 145 ;is it 145? (the screen is 144 lines, so 145 is off it)
jr nz, .knalbv_rof_tiaw ;if it's not 145, then waste another CPU cycle (loop)
;oh look, it's 145
ld a, [_PAD] ;check the joypad
and %00010000 ;is it the right button?
call nz, stranded_wire ;if it is, then go deal with that
ld a, [_PAD]
and %00100000 ;left
call nz, water_bottle
ld a, [_PAD]
and %01000000 ;up
call nz, boston_red_sox
ld a, [_PAD]
and %10000000 ;down
call nz, ham_sandwich
ld a, [_PAD]
and %00000001 ;A button
call nz, dirty_dog
call orange_ink ;delay
jr fabric_softener ;loop
;what's that? oh you pressed a button?
;right
stranded_wire:
ld a, 1 ;the left/right arrow sprite
ld [_SPR0_NUM], a
ld a, [_SPR0_ATT]
res 5, a ;no x flip, facing right
ld [_SPR0_ATT], a
ld a, [_SPR0_X] ;get the sprite's x position
cp 160 ;is it on the edge?
ret z ;if it is, then forget it
inc a ;if it's not on the edge, then x goes up 1
ld [_SPR0_X], a ;store the new position in OAM
ret ;return
;left
water_bottle:
ld a, 1 ;the left/right arrow sprite
ld [_SPR0_NUM], a
ld a, [_SPR0_ATT]
set 5, a ;x flip, facing left
ld [_SPR0_ATT], a
ld a, [_SPR0_X] ;get the sprite's x position
cp 8 ;is it on the edge?
ret z ;if it is, then forget it
dec a ;if it's not on the edge, then x goes down 1
ld [_SPR0_X], a ;store the new position in OAM
ret ;return
;up
boston_red_sox:
ld a, 2 ;the up/down arrow sprite
ld [_SPR0_NUM], a
ld a, [_SPR0_ATT]
res 6, a ;no y flip, facing up
ld [_SPR0_ATT], a
ld a, [_SPR0_Y] ;get the sprite's y position
cp 16 ;is it on the edge?
ret z ;if it is, then forget it
dec a ;if it's not on the edge, then y goes down (up) 1
ld [_SPR0_Y], a ;store the new position in OAM
ret ;return
;down
ham_sandwich:
ld a, 2 ;the up/down arrow sprite
ld [_SPR0_NUM], a
ld a, [_SPR0_ATT]
set 6, a ;y flip, facing down
ld [_SPR0_ATT], a
ld a, [_SPR0_Y] ;get the sprite's y position
cp 152 ;is it on the edge?
ret z ;if it is, then forget it
inc a ;if it's not on the edge, then y goes up (down) 1
ld [_SPR0_Y], a ;store the new position in OAM
ret ;return
;A button
dirty_dog:
ld a, [_SPR0_NUM] ;I want to change the sprite tile, so get the tile number
cp 3 ;is it already 3?
jr z, .dirty_cat ;if it's already 3, then it should be changed to 2, right?
ld a, 3 ;new tile number
ld [_SPR0_NUM], a ;store it in sprite data
call orange_ink ;delay because otherwise the change would look too fast and weird
ret ;return
.dirty_cat:
ld a, 2 ;new tile number
ld [_SPR0_NUM], a
call orange_ink ;wait a bit
ret ;return
;read the joypad input
cloudy_mason_jar:
ld a, %00100000 ;read d-pad (you can only do either d-pad or buttons at a time
;for some weird reason)
ld [rP1], a ;tell the GameBoy that we want to read the d-pad
;do several readings to avoid "bouncing"
ld a, [rP1]
ld a, [rP1]
ld a, [rP1]
ld a, [rP1]
and $0F ;the readings are stored in the bottom 4 bits so we only need those
swap a ;swap upper and lower bits
ld b, a ;store it in b
ld a, %00010000 ;read buttons
ld [rP1], a
;no bouncing allowed
ld a, [rP1]
ld a, [rP1]
ld a, [rP1]
ld a, [rP1]
and $0F ;top 4 bits are unused
or b ;I honestly don't know how this works because they're 8-bits
;it probably works with each bit and I guess would combine the two
cpl ;complement a
ld [_PAD], a ;put it in the joypad variable
ret ;return
;LCD shutdown?
strawberry_jam:
;not sure how this works or what is does
ld a, [rLCDC]
rlca ;essentially set the high bit in the carry flag, not sure the purpose
ret nc ;not sure the purpose of this, but I think it goes back if the carry
;is 0
.let_set:
ld a, [rLY]
cp 145
jr nz, .let_set
;hey, it's 145
;not sure what this does either
ld a, [rLCDC]
res 7, a
ld [rLCDC], a
ret ;return
;delay
orange_ink:
ld de, 5000 ;the number of times to execute the loop
.yellow_ink:
dec de ;-1
ld a, d ;is it zero?
or e
jr z, .ink_cartridge_empty
nop
jr .yellow_ink ;loop
.ink_cartridge_empty:
ret
;tiles
Tiles:
;background tile
DB $00, $FF, $00, $FF, $00, $FF, $00, $FF
DB $00, $FF, $00, $FF, $00, $FF, $00, $FF
;sprite 1
DB $1C, $1C, $1E, $16, $FF, $F3, $FF, $81
DB $FD, $83, $FB, $F7, $16, $1E, $1C, $1C
;sprite 2
DB $3C, $3C, $76, $6E, $FB, $C7, $FD, $83
DB $FF, $E7, $3C, $24, $3C, $24, $3C, $3C
;sprite 3
DB $FF, $FF, $81, $FF, $BD, $C3, $BD, $C3
DB $BD, $C3, $BD, $C3, $81, $FF, $FF, $FF
EndTiles:
I did not write nor modify this file. I include it here only for the sake of preservation; it appears here as I had downloaded it from the aforementioned tutorial in 2019. The improved modern descendant of this file can be found on GitHub at gbdev/hardware.inc.file contents
;*
;* GBHW.INC - Gameboy Hardware definitions
;*
; Modified for GBC by David Pello http://ladecadence.net
; If all of these are already defined, don't do it again.
IF !DEF(HARDWARE_INC)
HARDWARE_INC SET 1
rev_Check_hardware_inc: MACRO
;NOTE: REVISION NUMBER CHANGES MUST BE ADDED
;TO SECOND PARAMETER IN FOLLOWING LINE.
IF \1 > 1.1 ;PUT REVISION NUMBER HERE
WARN "Version \1 or later of 'gbhw.inc' is required."
ENDC
ENDM
_HW EQU $FF00
_VRAM EQU $8000 ; $8000->$A000
_SCRN0 EQU $9800 ; $9800->$9BFF
_SCRN1 EQU $9C00 ; $9C00->$9FFF
_RAM EQU $C000 ; $C000->$DFFF
_RAM_BNK1 EQU $D000 ; $D000->$DFFF (GBC)
_HRAM EQU $F800 ; $F800->$FFFE
_OAMRAM EQU $FE00 ; $FE00->$FE9F
_AUD3WAVERAM EQU $FF30 ; $FF30->$FF3F
; --
; -- OAM flags
; --
OAMF_PRI EQU %10000000 ; Priority
OAMF_YFLIP EQU %01000000 ; Y flip
OAMF_XFLIP EQU %00100000 ; X flip
OAMF_PAL0 EQU %00000000 ; Palette number; 0,1
OAMF_PAL1 EQU %00010000 ; Palette number; 0,1
;***************************************************************************
;*
;* Custom registers
;*
;***************************************************************************
; --
; -- P1 ($FF00)
; -- Register for reading joy pad info. (R/W)
; --
rP1 EQU $FF00
P1F_5 EQU %00100000 ; P15 out port
P1F_4 EQU %00010000 ; P14 out port
P1F_3 EQU %00001000 ; P13 in port
P1F_2 EQU %00000100 ; P12 in port
P1F_1 EQU %00000010 ; P11 in port
P1F_0 EQU %00000001 ; P10 in port
; --
; -- LCDC ($FF40)
; -- LCD Control (R/W)
; --
rLCDC EQU $FF40
LCDCF_OFF EQU %00000000 ; LCD Control Operation
LCDCF_ON EQU %10000000 ; LCD Control Operation
LCDCF_WIN9800 EQU %00000000 ; Window Tile Map Display Select
LCDCF_WIN9C00 EQU %01000000 ; Window Tile Map Display Select
LCDCF_WINOFF EQU %00000000 ; Window Display
LCDCF_WINON EQU %00100000 ; Window Display
LCDCF_BG8800 EQU %00000000 ; BG & Window Tile Data Select
LCDCF_BG8000 EQU %00010000 ; BG & Window Tile Data Select
LCDCF_BG9800 EQU %00000000 ; BG Tile Map Display Select
LCDCF_BG9C00 EQU %00001000 ; BG Tile Map Display Select
LCDCF_OBJ8 EQU %00000000 ; OBJ Construction
LCDCF_OBJ16 EQU %00000100 ; OBJ Construction
LCDCF_OBJOFF EQU %00000000 ; OBJ Display
LCDCF_OBJON EQU %00000010 ; OBJ Display
LCDCF_BGOFF EQU %00000000 ; BG Display
LCDCF_BGON EQU %00000001 ; BG Display
; "Window Character Data Select" follows BG
; --
; -- STAT ($FF41)
; -- LCDC Status (R/W)
; --
rSTAT EQU $FF41
STATF_LYC EQU %01000000 ; LYCEQULY Coincidence (Selectable)
STATF_MODE10 EQU %00100000 ; Mode 10
STATF_MODE01 EQU %00010000 ; Mode 01 (V-Blank)
STATF_MODE00 EQU %00001000 ; Mode 00 (H-Blank)
STATF_LYCF EQU %00000100 ; Coincidence Flag
STATF_HB EQU %00000000 ; H-Blank
STATF_VB EQU %00000001 ; V-Blank
STATF_OAM EQU %00000010 ; OAM-RAM is used by system
STATF_LCD EQU %00000011 ; Both OAM and VRAM used by system
STATF_BUSY EQU %00000010 ; When set, VRAM access is unsafe
; --
; -- SCY ($FF42)
; -- Scroll Y (R/W)
; --
rSCY EQU $FF42
; --
; -- SCY ($FF43)
; -- Scroll X (R/W)
; --
rSCX EQU $FF43
; --
; -- LY ($FF44)
; -- LCDC Y-Coordinate (R)
; --
; -- Values range from 0->153. 144->153 is the VBlank period.
; --
rLY EQU $FF44
; --
; -- LYC ($FF45)
; -- LY Compare (R/W)
; --
; -- When LYEQUEQULYC, STATF_LYCF will be set in STAT
; --
rLYC EQU $FF45
; --
; -- DMA ($FF46)
; -- DMA Transfer and Start Address (W)
; --
rDMA EQU $FF46
; --
; -- BGP ($FF47)
; -- BG Palette Data (W)
; --
; -- Bit 7-6 - Intensity for %11
; -- Bit 5-4 - Intensity for %10
; -- Bit 3-2 - Intensity for %01
; -- Bit 1-0 - Intensity for %00
; --
rBGP EQU $FF47
; --
; -- OBP0 ($FF48)
; -- Object Palette 0 Data (W)
; --
; -- See BGP for info
; --
rOBP0 EQU $FF48
; --
; -- OBP1 ($FF49)
; -- Object Palette 1 Data (W)
; --
; -- See BGP for info
; --
rOBP1 EQU $FF49
; --
; -- SB ($FF01)
; -- Serial Transfer Data (R/W)
; --
rSB EQU $FF01
; --
; -- SC ($FF02)
; -- Serial I/O Control (R/W)
; --
rSC EQU $FF02
; --
; -- DIV ($FF04)
; -- Divider register (R/W)
; --
rDIV EQU $FF04
; --
; -- TIMA ($FF05)
; -- Timer counter (R/W)
; --
rTIMA EQU $FF05
; --
; -- TMA ($FF06)
; -- Timer modulo (R/W)
; --
rTMA EQU $FF06
; --
; -- TAC ($FF07)
; -- Timer control (R/W)
; --
rTAC EQU $FF07
TACF_START EQU %00000100
TACF_STOP EQU %00000000
TACF_4KHZ EQU %00000000
TACF_16KHZ EQU %00000011
TACF_65KHZ EQU %00000010
TACF_262KHZ EQU %00000001
; --
; -- IF ($FF0F)
; -- Interrupt Flag (R/W)
; --
; -- IE ($FFFF)
; -- Interrupt Enable (R/W)
; --
rIF EQU $FF0F
rIE EQU $FFFF
IEF_HILO EQU %00010000 ; Transition from High to Low of Pin number P10-P13
IEF_SERIAL EQU %00001000 ; Serial I/O transfer end
IEF_TIMER EQU %00000100 ; Timer Overflow
IEF_LCDC EQU %00000010 ; LCDC (see STAT)
IEF_VBLANK EQU %00000001 ; V-Blank
; --
; -- WY ($FF4A)
; -- Window Y Position (R/W)
; --
; -- 0 <EQU WY <EQU 143
; --
rWY EQU $FF4A
; --
; -- WX ($FF4B)
; -- Window X Position (R/W)
; --
; -- 7 <EQU WX <EQU 166
; --
rWX EQU $FF4B
;***************************************************************************
;*
;* Sound control registers
;*
;***************************************************************************
; --
; -- AUDVOL/NR50 ($FF24)
; -- Channel control / ON-OFF / Volume (R/W)
; --
; -- Bit 7 - Vin->SO2 ON/OFF (Vin??)
; -- Bit 6-4 - SO2 output level (volume) (# 0-7)
; -- Bit 3 - Vin->SO1 ON/OFF (Vin??)
; -- Bit 2-0 - SO1 output level (volume) (# 0-7)
; --
rNR50 EQU $FF24
rAUDVOL EQU rNR50
; --
; -- AUDTERM/NR51 ($FF25)
; -- Selection of Sound output terminal (R/W)
; --
; -- Bit 7 - Output sound 4 to SO2 terminal
; -- Bit 6 - Output sound 3 to SO2 terminal
; -- Bit 5 - Output sound 2 to SO2 terminal
; -- Bit 4 - Output sound 1 to SO2 terminal
; -- Bit 3 - Output sound 4 to SO1 terminal
; -- Bit 2 - Output sound 3 to SO1 terminal
; -- Bit 1 - Output sound 2 to SO1 terminal
; -- Bit 0 - Output sound 0 to SO1 terminal
; --
rNR51 EQU $FF25
rAUDTERM EQU rNR51
; --
; -- AUDENA/NR52 ($FF26)
; -- Sound on/off (R/W)
; --
; -- Bit 7 - All sound on/off (sets all audio regs to 0!)
; -- Bit 3 - Sound 4 ON flag (doesn't work!)
; -- Bit 2 - Sound 3 ON flag (doesn't work!)
; -- Bit 1 - Sound 2 ON flag (doesn't work!)
; -- Bit 0 - Sound 1 ON flag (doesn't work!)
; --
rNR52 EQU $FF26
rAUDENA EQU rNR52
;***************************************************************************
;*
;* SoundChannel #1 registers
;*
;***************************************************************************
; --
; -- AUD1SWEEP/NR10 ($FF10)
; -- Sweep register (R/W)
; --
; -- Bit 6-4 - Sweep Time
; -- Bit 3 - Sweep Increase/Decrease
; -- 0: Addition (frequency increases???)
; -- 1: Subtraction (frequency increases???)
; -- Bit 2-0 - Number of sweep shift (# 0-7)
; -- Sweep Time: (n*7.8ms)
; --
rNR10 EQU $FF10
rAUD1SWEEP EQU rNR10
; --
; -- AUD1LEN/NR11 ($FF11)
; -- Sound length/Wave pattern duty (R/W)
; --
; -- Bit 7-6 - Wave Pattern Duty (00:12.5% 01:25% 10:50% 11:75%)
; -- Bit 5-0 - Sound length data (# 0-63)
; --
rNR11 EQU $FF11
rAUD1LEN EQU rNR11
; --
; -- AUD1ENV/NR12 ($FF12)
; -- Envelope (R/W)
; --
; -- Bit 7-4 - Initial value of envelope
; -- Bit 3 - Envelope UP/DOWN
; -- 0: Decrease
; -- 1: Range of increase
; -- Bit 2-0 - Number of envelope sweep (# 0-7)
; --
rNR12 EQU $FF12
rAUD1ENV EQU rNR12
; --
; -- AUD1LOW/NR13 ($FF13)
; -- Frequency lo (W)
; --
rNR13 EQU $FF13
rAUD1LOW EQU rNR13
; --
; -- AUD1HIGH/NR14 ($FF14)
; -- Frequency hi (W)
; --
; -- Bit 7 - Initial (when set, sound restarts)
; -- Bit 6 - Counter/consecutive selection
; -- Bit 2-0 - Frequency's higher 3 bits
; --
rNR14 EQU $FF14
rAUD1HIGH EQU rNR14
;***************************************************************************
;*
;* SoundChannel #2 registers
;*
;***************************************************************************
; --
; -- AUD2LEN/NR21 ($FF16)
; -- Sound Length; Wave Pattern Duty (R/W)
; --
; -- see AUD1LEN for info
; --
rNR21 EQU $FF16
rAUD2LEN EQU rNR21
; --
; -- AUD2ENV/NR22 ($FF17)
; -- Envelope (R/W)
; --
; -- see AUD1ENV for info
; --
rNR22 EQU $FF17
rAUD2ENV EQU rNR22
; --
; -- AUD2LOW/NR23 ($FF18)
; -- Frequency lo (W)
; --
rNR23 EQU $FF18
rAUD2LOW EQU rNR23
; --
; -- AUD2HIGH/NR24 ($FF19)
; -- Frequency hi (W)
; --
; -- see AUD1HIGH for info
; --
rNR24 EQU $FF19
rAUD2HIGH EQU rNR24
;***************************************************************************
;*
;* SoundChannel #3 registers
;*
;***************************************************************************
; --
; -- AUD3ENA/NR30 ($FF1A)
; -- Sound on/off (R/W)
; --
; -- Bit 7 - Sound ON/OFF (1EQUON,0EQUOFF)
; --
rNR30 EQU $FF1A
rAUD3ENA EQU rNR30
; --
; -- AUD3LEN/NR31 ($FF1B)
; -- Sound length (R/W)
; --
; -- Bit 7-0 - Sound length
; --
rNR31 EQU $FF1B
rAUD3LEN EQU rNR31
; --
; -- AUD3LEVEL/NR32 ($FF1C)
; -- Select output level
; --
; -- Bit 6-5 - Select output level
; -- 00: 0/1 (mute)
; -- 01: 1/1
; -- 10: 1/2
; -- 11: 1/4
; --
rNR32 EQU $FF1C
rAUD3LEVEL EQU rNR32
; --
; -- AUD3LOW/NR33 ($FF1D)
; -- Frequency lo (W)
; --
; -- see AUD1LOW for info
; --
rNR33 EQU $FF1D
rAUD3LOW EQU rNR33
; --
; -- AUD3HIGH/NR34 ($FF1E)
; -- Frequency hi (W)
; --
; -- see AUD1HIGH for info
; --
rNR34 EQU $FF1E
rAUD3HIGH EQU rNR34
; --
; -- AUD4LEN/NR41 ($FF20)
; -- Sound length (R/W)
; --
; -- Bit 5-0 - Sound length data (# 0-63)
; --
rNR41 EQU $FF20
rAUD4LEN EQU rNR41
; --
; -- AUD4ENV/NR42 ($FF21)
; -- Envelope (R/W)
; --
; -- see AUD1ENV for info
; --
rNR42 EQU $FF21
rAUD4ENV EQU rNR42
; --
; -- AUD4POLY/NR42 ($FF22)
; -- Polynomial counter (R/W)
; --
; -- Bit 7-4 - Selection of the shift clock frequency of the (scf)
; -- polynomial counter (0000-1101)
; -- freqEQUdrf*1/2^scf (not sure)
; -- Bit 3 - Selection of the polynomial counter's step
; -- 0: 15 steps
; -- 1: 7 steps
; -- Bit 2-0 - Selection of the dividing ratio of frequencies (drf)
; -- 000: f/4 001: f/8 010: f/16 011: f/24
; -- 100: f/32 101: f/40 110: f/48 111: f/56 (fEQU4.194304 Mhz)
; --
rNR42_2 EQU $FF22
rAUD4POLY EQU rNR42_2
; --
; -- AUD4GO/NR43 ($FF23)
; -- (has wrong name and value (ff30) in Dr.Pan's doc!)
; --
; -- Bit 7 - Inital
; -- Bit 6 - Counter/consecutive selection
; --
rNR43 EQU $FF23
rAUD4GO EQU rNR43 ; silly name!
;***************************************************************************
;*
;* Cart related
;*
;***************************************************************************
ROM_NOMBC EQU 0
ROM_MBC1 EQU 1
ROM_MBC1_RAM EQU 2
ROM_MBC1_RAM_BAT EQU 3
ROM_MBC2 EQU 5
ROM_MBC2_BAT EQU 6
ROM_NOMBC_RAM EQU 8
ROM_NOMBC_RAM_BAT EQU 9
ROM_SIZE_256KBIT EQU 0
ROM_SIZE_512KBIT EQU 1
ROM_SIZE_1M EQU 2
ROM_SIZE_2M EQU 3
ROM_SIZE_4M EQU 4
ROM_SIZE_8M EQU 5
ROM_SIZE_16M EQU 6
ROM_SIZE_32KBYTE EQU 0
ROM_SIZE_64KBYTE EQU 1
ROM_SIZE_128KBYTE EQU 2
ROM_SIZE_256KBYTE EQU 3
ROM_SIZE_512KBYTE EQU 4
ROM_SIZE_1MBYTE EQU 5
ROM_SIZE_2MBYTE EQU 6
RAM_SIZE_0KBIT EQU 0
RAM_SIZE_16KBIT EQU 1
RAM_SIZE_64KBIT EQU 2
RAM_SIZE_256KBIT EQU 3
RAM_SIZE_1MBIT EQU 4
RAM_SIZE_0KBYTE EQU 0
RAM_SIZE_2KBYTE EQU 1
RAM_SIZE_8KBYTE EQU 2
RAM_SIZE_32KBYTE EQU 3
RAM_SIZE_128KBYTE EQU 4
;***************************************************************************
;*
;* Keypad related
;*
;***************************************************************************
PADF_DOWN EQU $80
PADF_UP EQU $40
PADF_LEFT EQU $20
PADF_RIGHT EQU $10
PADF_START EQU $08
PADF_SELECT EQU $04
PADF_B EQU $02
PADF_A EQU $01
PADB_DOWN EQU $7
PADB_UP EQU $6
PADB_LEFT EQU $5
PADB_RIGHT EQU $4
PADB_START EQU $3
PADB_SELECT EQU $2
PADB_B EQU $1
PADB_A EQU $0
;***************************************************************************
;*
;* Screen related
;*
;***************************************************************************
SCRN_X EQU 160 ; Width of screen in pixels
SCRN_Y EQU 144 ; Height of screen in pixels
SCRN_X_B EQU 20 ; Width of screen in bytes
SCRN_Y_B EQU 18 ; Height of screen in bytes
SCRN_VX EQU 256 ; Virtual width of screen in pixels
SCRN_VY EQU 256 ; Virtual height of screen in pixels
SCRN_VX_B EQU 32 ; Virtual width of screen in bytes
SCRN_VY_B EQU 32 ; Virtual height of screen in bytes
;***************************************************************************
;*
;* GameBoy Color registers
;*
;***************************************************************************
; GB Color detection
; Read A register after boot, a == $11 = GBC
; B register, bit 0 == 0, GBC, bit 0 == 1, GBA
REGA_GBC EQU $11
REGB_GBA EQU %00000001
; Gameboy Clock Speed
; Bit 7: Current Speed (0=Normal, 1=Double) (Read Only)
; Bit 0: Prepare Speed Switch (0=No, 1=Prepare) (Read/Write)
;
; IF KEY1_BIT7 <> DESIRED_SPEED THEN
; IE=00H ;(FFFF)=00h
; JOYP=30H ;(FF00)=30h
; KEY1=01H ;(FF4D)=01h
; STOP ;STOP
; ENDIF
rKEY1 EQU $FF4D ; Gameboy Clock Switch
GBC_IS_NORMAL_CLK EQU %00000000 ; Normal Clock ?
GBC_IS_DOUBLE_CLK EQU %10000000 ; Double Clock ?
GBC_CHANGE_CLK EQU %00000001 ; Prepare clock change
; RAM Banks
rSVBK EQU $FF70 ; Set work ram bank
WRAM_BANK0 EQU %00000000 ; Bank 0
WRAM_BANK1 EQU %00000001 ; Bank 1
WRAM_BANK2 EQU %00000010 ; Bank 2
WRAM_BANK3 EQU %00000011 ; Bank 3
WRAM_BANK4 EQU %00000100 ; Bank 4
WRAM_BANK5 EQU %00000101 ; Bank 5
WRAM_BANK6 EQU %00000110 ; Bank 6
WRAM_BANK7 EQU %00000111 ; Bank 7
; Palettes
rBGPI EQU $FF68 ; Background Palette Index
rBGPD EQU $FF69 ; Backgorund Palette Data
rOBPI EQU $FF6A ; Sprite Palette Index
rOBPD EQU $FF6B ; Sprite Palette Data
; VRAM Banks
rVRBS EQU $FF4F ; VRAM Bank Select
VRB0 EQU $00 ; VRAM Bank 0
VRB1 EQU $01 ; VRAM Bank 1
; GB Color Map attributes (VRAM Bank 1)
;
; Bit 0-2 Background Palette number (BGP0-7)
; Bit 3 Tile VRAM Bank number (0=Bank 0, 1=Bank 1)
; Bit 4 Not used
; Bit 5 Horizontal Flip (0=Normal, 1=Mirror horizontally)
; Bit 6 Vertical Flip (0=Normal, 1=Mirror vertically)
; Bit 7 BG-to-OAM Priority (0=Use OAM priority bit, 1=BG Priority)
GBCMA_PAL0 EQU %00000000 ; Pallete 0
GBCMA_PAL1 EQU %00000001 ; Pallete 1
GBCMA_PAL2 EQU %00000010 ; Pallete 2
GBCMA_PAL3 EQU %00000011 ; Pallete 3
GBCMA_PAL4 EQU %00000100 ; Pallete 4
GBCMA_PAL5 EQU %00000101 ; Pallete 5
GBCMA_PAL6 EQU %00000110 ; Pallete 6
GBCMA_PAL7 EQU %00000111 ; Pallete 7
GBCMA_BNK0 EQU %00000000 ; Bank 0
GBCMA_BNK1 EQU %00001000 ; Bank 1
GBCMA_FLPH EQU %00100000 ; Flip Horizontally
GBCMA_FLPV EQU %01000000 ; Flip Vertically
GBCMA_BKGP EQU %10000000 ; Background Priority
; VRAM DMA
rDMA1 EQU $FF51 ; DMA Source High
rDMA2 EQU $FF52 ; DMA Source Low
rDMA3 EQU $FF53 ; DMA Destination High
rDMA4 EQU $FF54 ; DMA Destination Low
rDMA5 EQU $FF55 ; DMA Length-Mode-Start
GPDMA EQU %00000000 ; rDMA5 General Purpose DMA
HBDMA EQU %10000000 ; rDMA5 HBlank DMA
DMAAT EQU %00000000 ; DMA Active (rDMA5 bit 7 = 0)
; IR Port
; Bit 0: Write Data (0=LED Off, 1=LED On) (Read/Write)
; Bit 1: Read Data (0=Receiving IR Signal, 1=Normal) (Read Only)
; Bit 6-7: Data Read Enable (0=Disable, 3=Enable) (Read/Write)
rRP EQU $FF56 ; IR Port control
;; ROM HEADERS
NINTENDO_LOGO: MACRO
;*
;* Nintendo scrolling logo
;* (Code won't work on a real GameBoy)
;* (if next six lines are altered.)
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
ENDM
ROM_HEADER: MACRO
;*
;* Nintendo scrolling logo
;* (Code won't work on a real GameBoy)
;* (if next six lines are altered.)
; 0123456789ABCDEF
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
DB "GAME GAME GAME",0 ; Cart name - 15bytes
DB 0 ; $143
DB 0,0 ; $144 - Licensee code (not important)
DB 0 ; $146 - SGB Support indicator
DB \1 ; $147 - Cart type
DB \2 ; $148 - ROM Size
DB \3 ; $149 - RAM Size
DB 1 ; $14a - Destination code
DB $33 ; $14b - Old licensee code
DB 0 ; $14c - Mask ROM version
DB 0 ; $14d - Complement check (important)
DW 0 ; $14e - Checksum (not important)
ENDM
ROM_HEADER_COLOR: MACRO
;*
;* Nintendo scrolling logo
;* (Code won't work on a real GameBoy)
;* (if next six lines are altered.)
; 0123456789ABCDEF
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
DB "EXAMPLE",0,0,0,0,0,0,0,0 ; Cart name - 15bytes
DB $80 ; $143 - GB Color support
DB 0,0 ; $144 - Licensee code (not important)
DB 0 ; $146 - SGB Support indicator
DB \1 ; $147 - Cart type
DB \2 ; $148 - ROM Size
DB \3 ; $149 - RAM Size
DB 1 ; $14a - Destination code
DB $33 ; $14b - Old licensee code
DB 0 ; $14c - Mask ROM version
DB 0 ; $14d - Complement check (important)
DW 0 ; $14e - Checksum (not important)
ENDM
ENDC ;HARDWARE_INC