INCLUDE "hardware.inc"
INCLUDE "sprobjs_lib.asm"

SECTION "Header", ROM0[$100]

	jp Init

	ds $150 - @, 0 ; Make room for the header

SECTION "Init", ROM0
Init:
	; Shut down audio circuitry
	ld a, 0
	ld [rNR52], a

	; Do not turn the LCD off outside of VBlank
WaitVBlank:
	ld a, [rLY]
	cp 144
	jp c, WaitVBlank

	; Turn the LCD off
	ld a, 0
	ld [rLCDC], a

	; Initialize Sprite Object Library
	call InitSprObjLib

	; Reset hardware OAM
	xor a, a
	ld b, 160
	ld hl, _OAMRAM
.resetOAM
	ld [hli], a
	dec b
	jr nz, .resetOAM

	; Copy cat sprite
	ld de, GfxCat
	ld hl, $8000
	ld bc, GfxCat.end - GfxCat
	call Memcopy

	; Reset positions
	ld hl, wSimplePosition
	ld a, 8
	ld [hl], a

	ld hl, wMetaspritePosition
	ld a, 0
	ld [wMetaspritePosition], a
	ld a, $80
	ld [wMetaspritePosition + 1], a

	; Copy the tile data
	ld de, Tiles
	ld hl, $9000
	ld bc, TilesEnd - Tiles
	call Memcopy

	; Copy the tilemap
	ld de, Tilemap
	ld hl, $9800
	ld bc, TilemapEnd - Tilemap
	call Memcopy
	
	; Turn the LCD on
	ld a, LCDCF_ON | LCDCF_BGON | LCDCF_OBJON | LCDCF_OBJ8
	ld [rLCDC], a

	; During the first (blank) frame, initialize display registers
	ld a, %11100100
	ld [rBGP], a
	ld [rOBP0], a
	ld [rOBP1], a

	; Enable vblank interrupt
	ld a, IEF_VBLANK
	ldh [rIE], a
	; Clear interrupt register to 0
	xor a, a
	ldh [rIF], a
	; Enable interrupts 
	ei

Main:
	call ResetShadowOAM

	ld de, $0100
	ld c, 8
	ld b, 16
	call RenderSimpleSprite

	ld hl, wSimplePosition
	inc [hl]

	ld bc, (96.0 >> 12) & $FFFF
	ld a, [wMetaspritePosition]
	ld e, a
	ld a, [wMetaspritePosition + 1]
	ld d, a
	ld hl, CatMetasprite
	call RenderMetasprite

	ldh a, [hFrameCounter]
	inc a
	ldh [hFrameCounter], a 

	halt
	nop

	jp Main

Memcopy::
	dec bc
	inc b
	inc c
.loop:
	ld a, [de]
	ld [hli], a
	inc de
	dec c
	jr nz, .loop
	dec b
	jr nz, .loop
	ret


SECTION "VBlank Interrupt", ROM0[$0040]
VBlankInterrupt:
	; Store registers to prevent clobbering
	push af
	push bc
	push de
	push hl
	jp VBlankHandler

SECTION "VBlank Handler", ROM0
VBlankHandler:
	ldh a, [hFrameCounter]

	/*
	bit 5, a

	ld a, %11100100

	jr z, .skipCpl
	cpl ; Invert a
.skipCpl:
	ldh [rBGP], a
	*/

	ld a, HIGH(wShadowOAM)
	call hOAMDMA

	; Reset registers to orignal state
	pop hl
	pop de
	pop bc
	pop af
	reti

SECTION "Frame Counter", HRAM
hFrameCounter: 
	db


SECTION "Tile data", ROM0

Tiles:
	db $00,$ff, $00,$ff, $00,$ff, $00,$ff, $00,$ff, $00,$ff, $00,$ff, $00,$ff
	db $00,$ff, $00,$80, $00,$80, $00,$80, $00,$80, $00,$80, $00,$80, $00,$80
	db $00,$ff, $00,$7e, $00,$7e, $00,$7e, $00,$7e, $00,$7e, $00,$7e, $00,$7e
	db $00,$ff, $00,$01, $00,$01, $00,$01, $00,$01, $00,$01, $00,$01, $00,$01
	db $00,$ff, $00,$00, $00,$00, $00,$00, $00,$00, $00,$00, $00,$00, $00,$00
	db $00,$ff, $00,$7f, $00,$7f, $00,$7f, $00,$7f, $00,$7f, $00,$7f, $00,$7f
	db $00,$ff, $03,$fc, $00,$f8, $00,$f0, $00,$e0, $20,$c0, $00,$c0, $40,$80
	db $00,$ff, $c0,$3f, $00,$1f, $00,$0f, $00,$07, $04,$03, $00,$03, $02,$01
	db $00,$80, $00,$80, $7f,$80, $00,$80, $00,$80, $7f,$80, $7f,$80, $00,$80
	db $00,$7e, $2a,$7e, $d5,$7e, $2a,$7e, $54,$7e, $ff,$00, $ff,$00, $00,$00
	db $00,$01, $00,$01, $ff,$01, $00,$01, $01,$01, $fe,$01, $ff,$01, $00,$01
	db $00,$80, $80,$80, $7f,$80, $80,$80, $00,$80, $ff,$80, $7f,$80, $80,$80
	db $00,$7f, $2a,$7f, $d5,$7f, $2a,$7f, $55,$7f, $ff,$00, $ff,$00, $00,$00
	db $00,$ff, $aa,$ff, $55,$ff, $aa,$ff, $55,$ff, $fa,$07, $fd,$07, $02,$07
	db $00,$7f, $2a,$7f, $d5,$7f, $2a,$7f, $55,$7f, $aa,$7f, $d5,$7f, $2a,$7f
	db $00,$ff, $80,$ff, $00,$ff, $80,$ff, $00,$ff, $80,$ff, $00,$ff, $80,$ff
	db $40,$80, $00,$80, $7f,$80, $00,$80, $00,$80, $7f,$80, $7f,$80, $00,$80
	db $00,$3c, $02,$7e, $85,$7e, $0a,$7e, $14,$7e, $ab,$7e, $95,$7e, $2a,$7e
	db $02,$01, $00,$01, $ff,$01, $00,$01, $01,$01, $fe,$01, $ff,$01, $00,$01
	db $00,$ff, $80,$ff, $50,$ff, $a8,$ff, $50,$ff, $a8,$ff, $54,$ff, $a8,$ff
	db $7f,$80, $7f,$80, $7f,$80, $7f,$80, $7f,$80, $7f,$80, $7f,$80, $7f,$80
	db $ff,$00, $ff,$00, $ff,$00, $ab,$7e, $d5,$7e, $ab,$7e, $d5,$7e, $ab,$7e
	db $ff,$01, $fe,$01, $ff,$01, $fe,$01, $ff,$01, $fe,$01, $ff,$01, $fe,$01
	db $7f,$80, $ff,$80, $7f,$80, $ff,$80, $7f,$80, $ff,$80, $7f,$80, $ff,$80
	db $ff,$00, $ff,$00, $ff,$00, $aa,$7f, $d5,$7f, $aa,$7f, $d5,$7f, $aa,$7f
	db $f8,$07, $f8,$07, $f8,$07, $80,$ff, $00,$ff, $aa,$ff, $55,$ff, $aa,$ff
	db $7f,$80, $7f,$80, $7f,$80, $7f,$80, $7f,$80, $ff,$80, $7f,$80, $ff,$80
	db $d5,$7f, $aa,$7f, $d5,$7f, $aa,$7f, $d5,$7f, $aa,$7f, $d5,$7f, $aa,$7f
	db $d5,$7e, $ab,$7e, $d5,$7e, $ab,$7e, $d5,$7e, $ab,$7e, $d5,$7e, $eb,$3c
	db $54,$ff, $aa,$ff, $54,$ff, $aa,$ff, $54,$ff, $aa,$ff, $54,$ff, $aa,$ff
	db $7f,$80, $7f,$80, $7f,$80, $7f,$80, $7f,$80, $7f,$80, $7f,$80, $00,$ff
	db $d5,$7e, $ab,$7e, $d5,$7e, $ab,$7e, $d5,$7e, $ab,$7e, $d5,$7e, $2a,$ff
	db $ff,$01, $fe,$01, $ff,$01, $fe,$01, $ff,$01, $fe,$01, $ff,$01, $80,$ff
	db $7f,$80, $ff,$80, $7f,$80, $ff,$80, $7f,$80, $ff,$80, $7f,$80, $aa,$ff
	db $ff,$00, $ff,$00, $ff,$00, $ff,$00, $ff,$00, $ff,$00, $ff,$00, $2a,$ff
	db $ff,$01, $fe,$01, $ff,$01, $fe,$01, $fe,$01, $fe,$01, $fe,$01, $80,$ff
	db $7f,$80, $ff,$80, $7f,$80, $7f,$80, $7f,$80, $7f,$80, $7f,$80, $00,$ff
	db $fe,$01, $fe,$01, $fe,$01, $fe,$01, $fe,$01, $fe,$01, $fe,$01, $80,$ff
	db $3f,$c0, $3f,$c0, $3f,$c0, $1f,$e0, $1f,$e0, $0f,$f0, $03,$fc, $00,$ff
	db $fd,$03, $fc,$03, $fd,$03, $f8,$07, $f9,$07, $f0,$0f, $c1,$3f, $82,$ff
	db $55,$ff, $2a,$7e, $54,$7e, $2a,$7e, $54,$7e, $2a,$7e, $54,$7e, $00,$7e
	db $01,$ff, $00,$01, $01,$01, $00,$01, $01,$01, $00,$01, $01,$01, $00,$01
	db $54,$ff, $ae,$f8, $50,$f0, $a0,$e0, $60,$c0, $80,$c0, $40,$80, $40,$80
	db $55,$ff, $00,$00, $00,$00, $00,$00, $00,$00, $00,$00, $00,$00, $00,$00
	db $55,$ff, $6a,$1f, $05,$0f, $02,$07, $05,$07, $02,$03, $03,$01, $02,$01
	db $54,$ff, $80,$80, $00,$80, $80,$80, $00,$80, $80,$80, $00,$80, $00,$80
	db $55,$ff, $2a,$1f, $0d,$07, $06,$03, $01,$03, $02,$01, $01,$01, $00,$01
	db $55,$ff, $2a,$7f, $55,$7f, $2a,$7f, $55,$7f, $2a,$7f, $55,$7f, $00,$7f
	db $55,$ff, $aa,$ff, $55,$ff, $aa,$ff, $55,$ff, $aa,$ff, $55,$ff, $00,$ff
	db $15,$ff, $00,$00, $00,$00, $00,$00, $00,$00, $00,$00, $00,$00, $00,$00
	db $55,$ff, $6a,$1f, $0d,$07, $06,$03, $01,$03, $02,$01, $03,$01, $00,$01
	db $54,$ff, $a8,$ff, $54,$ff, $a8,$ff, $50,$ff, $a0,$ff, $40,$ff, $00,$ff
	db $00,$7e, $2a,$7e, $d5,$7e, $2a,$7e, $54,$7e, $ab,$76, $dd,$66, $22,$66
	db $00,$7c, $2a,$7e, $d5,$7e, $2a,$7e, $54,$7c, $ff,$00, $ff,$00, $00,$00
	db $00,$01, $00,$01, $ff,$01, $02,$01, $07,$01, $fe,$03, $fd,$07, $0a,$0f
	db $00,$7c, $2a,$7e, $d5,$7e, $2a,$7e, $54,$7e, $ab,$7e, $d5,$7e, $2a,$7e
	db $00,$ff, $a0,$ff, $50,$ff, $a8,$ff, $54,$ff, $a8,$ff, $54,$ff, $aa,$ff
	db $dd,$62, $bf,$42, $fd,$42, $bf,$40, $ff,$00, $ff,$00, $f7,$08, $ef,$18
	db $ff,$00, $ff,$00, $ff,$00, $ab,$7c, $d5,$7e, $ab,$7e, $d5,$7e, $ab,$7e
	db $f9,$07, $fc,$03, $fd,$03, $fe,$01, $ff,$01, $fe,$01, $ff,$01, $fe,$01
	db $d5,$7e, $ab,$7e, $d5,$7e, $ab,$7e, $d5,$7e, $ab,$7e, $d5,$7e, $ab,$7c
	db $f7,$18, $eb,$1c, $d7,$3c, $eb,$3c, $d5,$3e, $ab,$7e, $d5,$7e, $2a,$ff
	db $ff,$01, $fe,$01, $ff,$01, $fe,$01, $ff,$01, $fe,$01, $ff,$01, $a2,$ff
	db $7f,$c0, $bf,$c0, $7f,$c0, $bf,$e0, $5f,$e0, $af,$f0, $57,$fc, $aa,$ff
	db $ff,$01, $fc,$03, $fd,$03, $fc,$03, $f9,$07, $f0,$0f, $c1,$3f, $82,$ff
	db $55,$ff, $2a,$ff, $55,$ff, $2a,$ff, $55,$ff, $2a,$ff, $55,$ff, $00,$ff
	db $45,$ff, $a2,$ff, $41,$ff, $82,$ff, $41,$ff, $80,$ff, $01,$ff, $00,$ff
	db $54,$ff, $aa,$ff, $54,$ff, $aa,$ff, $54,$ff, $aa,$ff, $54,$ff, $00,$ff
	db $15,$ff, $2a,$ff, $15,$ff, $0a,$ff, $15,$ff, $0a,$ff, $01,$ff, $00,$ff
	db $01,$ff, $80,$ff, $01,$ff, $80,$ff, $01,$ff, $80,$ff, $01,$ff, $00,$ff
TilesEnd:

SECTION "Tilemap", ROM0

Tilemap:
	db $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00,  0,0,0,0,0,0,0,0,0,0,0,0
	db $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00,  0,0,0,0,0,0,0,0,0,0,0,0
	db $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00,  0,0,0,0,0,0,0,0,0,0,0,0
	db $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00,  0,0,0,0,0,0,0,0,0,0,0,0
	db $00, $00, $01, $02, $03, $01, $04, $03, $01, $05, $00, $01, $05, $00, $06, $04, $07, $00, $00, $00,  0,0,0,0,0,0,0,0,0,0,0,0
	db $00, $00, $08, $09, $0a, $0b, $0c, $0d, $0b, $0e, $0f, $08, $0e, $0f, $10, $11, $12, $13, $00, $00,  0,0,0,0,0,0,0,0,0,0,0,0
	db $00, $00, $14, $15, $16, $17, $18, $19, $1a, $1b, $0f, $14, $1b, $0f, $14, $1c, $16, $1d, $00, $00,  0,0,0,0,0,0,0,0,0,0,0,0
	db $00, $00, $1e, $1f, $20, $21, $22, $23, $24, $22, $25, $1e, $22, $25, $26, $22, $27, $1d, $00, $00,  0,0,0,0,0,0,0,0,0,0,0,0
	db $00, $00, $01, $28, $29, $2a, $2b, $2c, $2d, $2b, $2e, $2d, $2f, $30, $2d, $31, $32, $33, $00, $00,  0,0,0,0,0,0,0,0,0,0,0,0
	db $00, $00, $08, $34, $0a, $0b, $11, $0a, $0b, $35, $36, $0b, $0e, $0f, $08, $37, $0a, $38, $00, $00,  0,0,0,0,0,0,0,0,0,0,0,0
	db $00, $00, $14, $39, $16, $17, $1c, $16, $17, $3a, $3b, $17, $1b, $0f, $14, $3c, $16, $1d, $00, $00,  0,0,0,0,0,0,0,0,0,0,0,0
	db $00, $00, $1e, $3d, $3e, $3f, $22, $27, $21, $1f, $20, $21, $22, $25, $1e, $22, $40, $1d, $00, $00,  0,0,0,0,0,0,0,0,0,0,0,0
	db $00, $00, $00, $41, $42, $43, $44, $30, $33, $41, $45, $43, $41, $30, $43, $41, $30, $33, $00, $00,  0,0,0,0,0,0,0,0,0,0,0,0
	db $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00,  0,0,0,0,0,0,0,0,0,0,0,0
	db $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00,  0,0,0,0,0,0,0,0,0,0,0,0
	db $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00,  0,0,0,0,0,0,0,0,0,0,0,0
	db $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00,  0,0,0,0,0,0,0,0,0,0,0,0
	db $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00,  0,0,0,0,0,0,0,0,0,0,0,0
TilemapEnd:

SECTION "Graphics", ROM0
GfxCat:
  INCBIN "cat.2bpp"
.end::

CatMetasprite:
  db 16, 8, 0, 0
  db 12, 16, 0, 0
  db 20, 20, 0, 0
  db 24, 12, 0, 0
  db 128

SECTION "Position Vars", WRAM0
; 8-bit X position
wSimplePosition:
  ds 1

; Q12.4 fixed-point X posiition
wMetaspritePosition:
  dw

; Q4.4 fixed-point velocity
wMetaspriteVelocity::
  db