AIV_Gameboy_FirstChallenge.asm

SECTION "Setup", ROM0[$100]

JP start

SECTION "Main", ROM0[$150]

start:
	LD SP, $FFFE
	CALL clear_vram
	CALL clear_oam

	LD HL, $8000

	LD BC, tile_quad
	CALL set_tile

	LD BC, tile_block
	CALL set_tile

	LD BC, tile_hlines
	CALL set_tile

	LD BC, tile_blank
	CALL set_tile

	LD BC, tile_block
	CALL set_tile

	LD BC, tile_cross
	CALL set_tile

	LD BC, window_map
	LD DE, 1024
	LD HL, $9C00
	CALL load_map

	XOR A
	LD [$FF42], A
	LD [$FF43], A

	LD A, 100
	LD [$FF4A], A
	LD [$FF4B], A

	CALL sprite_palette0

	LD A, 30
	LD [sprite_y], A
	LD [sprite_x], A

	LD A, [sprite_y]
	LD [$FE00], A
	LD A, [sprite_x]
	LD [$FE01], A
	LD A, 5
	LD [$FE02], A
	LD A, 0
	LD [$FE03], A

	CALL turn_on_lcd

gameloop:
	LD A, [$FF44]
	CP $90
	CALL Z, in_vblank

	LD A, [$FF44]
	CP $48
	JP NC, scroll_x

	CALL wait_hblank
	LD A, [sprite_y]
	LD [$FE00], A
	LD A, [sprite_x]
	LD [$FE01], A
	CALL white_palette
	XOR A
	LD [$FF43], A
	CALL wait_non_hblank
	JP gameloop

scroll_x:
	CALL wait_hblank
	CALL black_palette
	LD A, [scroll_var]
	LD [$FF43], A
	CALL wait_non_hblank
	JP gameloop

in_vblank:
	LD A, $20
	LD [$FF00], A
	LD A, [$FF00]
	LD A, [$FF00]
	LD A, [$FF00]
	LD A, [$FF00]
	LD A, [$FF00]
	BIT 0, A
	JP NZ, left
	LD HL, $FF4B
	INC [HL]
left:
	BIT 1, A
	JP NZ, up
	LD HL, $FF4B
	DEC [HL]
up:
	BIT 2, A
	JP NZ, down
	LD HL, $FF4A
	DEC [HL]
down:
	BIT 3, A
	JP NZ, half_bottom_scroll
	LD HL, $FF4A
	INC [HL]

half_bottom_scroll:
	LD A, [scroll_var]
	INC A
	LD [scroll_var],A

	LD HL, sprite_y
	INC [HL]
	LD HL, sprite_x
	INC [HL]

	RET

wait_vblank:
	LD A, [$FF44]
	CP $90
	JP NZ, wait_vblank
	RET

wait_hblank:
	LD A, [$FF41]
	AND $03
	JP NZ, wait_hblank
	RET

wait_non_hblank:
	LD A, [$FF41]
	AND $03
	JP Z, wait_non_hblank
	RET

turn_off_lcd:
	CALL wait_vblank
	XOR A
	LD [$FF40], A
	RET

turn_on_lcd:
	LD A, $f3
	LD [$FF40], A
	RET

clear_vram:
	CALL turn_off_lcd
	XOR A
	LD HL, $9FFF
clear_vram_loop:
	LD [HL-], A
	BIT 7, H
	JP NZ, clear_vram_loop
	RET

black_palette:
	LD A, $03
	LD [$FF47], A
	RET

white_palette:
	LD A, $C0
	LD [$FF47], A
	RET

sprite_palette0:
	LD A, $e4
	LD [$FF48], A
	RET

clear_oam:
	LD HL, $FE00
clear_oam_loop:
	XOR A
	LD [HL+], A
	LD A, $A0
	CP A, L
	JP NZ, clear_oam_loop
	RET

set_tile:
	LD D, 0
set_tile_loop:
	LD A, [BC]
	LD [HL+], A
	INC BC
	INC D
	LD A, D
	CP $10
	JP NZ, set_tile_loop
	RET

load_map:
	LD A, [BC]
	LD [HL+], A
	INC BC
	DEC DE
	LD A,D
	OR E
	JP NZ, load_map
	RET

tile_quad:
DB $FF,$FF,$81,$81,$81,$81,$81,$81,$81,$81,$81,$81,$81,$81,$FF,$FF

tile_block:
DB $FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF

tile_hlines:
DB $FF,$FF,$00,$00,$FF,$FF,$00,$00,$FF,$FF,$00,$00,$FF,$FF,$00,$00

tile_blank:
DB $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00

tile_cross:
DB $18,$00,$18,$00,$18,$00,$FF,$FF,$FF,$FF,$00,$18,$00,$18,$00,$18

window_map:
DB 3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4
DB 4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3
DB 3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4
DB 4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3
DB 3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4
DB 4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3
DB 3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4
DB 4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3
DB 3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4
DB 4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3
DB 3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4
DB 4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3
DB 3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4
DB 4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3
DB 3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4
DB 4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3
DB 3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4
DB 4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3
DB 3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4
DB 4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3
DB 3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4
DB 4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3
DB 3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4
DB 4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3
DB 3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4
DB 4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3
DB 3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4
DB 4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3
DB 3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4
DB 4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3
DB 3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4
DB 4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3,4,3

SECTION "VARIABLES", WRAM0
scroll_var:
DS 1
sprite_y:
DS 1
sprite_x:
DS 1