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|
cpu gameboy
option +list
option list-labels,all
option output-file,gb.rom
option output-format,gameboy
option gameboy-irq,vbl,vbl_code
VRAM equ $8000
SCRN equ $9800
OAM equ $fe00
LCDC equ $ff40
STAT equ $ff41
READY equ $ff81
XPOS equ $ff82
VBLANK macro
push af
.wait
ldh a,(LCDC)
cp $91
jr nz,wait
pop af
endm
;
; **********
; CODE START
; **********
;
org $150
di
xor a
ldh (READY),a
ld sp,$fffe
; Set LCD so only sprites show
;
ld a,$82
ldh (LCDC),a
ld a,$10
ldh (STAT),a
; Copy to VRAM
;
ld hl,VRAM
ld de,sprite
ld a,16
VBLANK
.copy
ld a,(hl+)
ld (de),a
inc de
dec a
jr nz,copy
ld a,1
ldh (READY),a
.idle
halt
nop
jr idle
vbl_code:
ldh a,(READY)
jr z,finish
ldh a,(XPOS)
inc a
ldh (XPOS),a
ld (OAM+1),a
xor a
ld (OAM),a
ld (OAM+2),a
ld (OAM+3),a
.finish
reti
sprite:
defs 16,$ff
|
