.include "header.inc"
.include "snes_init.asm"

.BANK 0 SLOT 0
.org 0
.section "Vblank"

VBlank:
    rti

.ENDS

.BANK 0 SLOT 0
.ORG 0
.section "Main"

Start:
    Snes_Init

; 16-bit xy, 8-bit a
rep #%00010000
sep #%00100000


ldx #$0000
- lda UntitledPalette.l, x
sta $2122
inx
cpx #8
bne -

lda #33
sta $2121
lda.l Palette2
sta $2122
lda.l Palette2 + 1
sta $2122

ldx #UntitledData
lda #:UntitledData
ldy #(15*16*2)

;$43X0 is DMA register X, X from 0 to 7
stx $4302 ;A address low byte
sta $4304 ;A address bank
sty $4305 ;number of bytes to transfer

lda #%00000001 ;set mode transfer words
sta $4300

lda #$18            ; $211[89]: VRAM data write
sta $4301           ; set destination

ldy #$0000
sty $2116

lda #%00000001
sta $420b ;start DMA


; write to BG1

lda #%10000000 ; VRAM writing mode
sta $2115

ldx #$4000
stx $2116 ; write to VRAM

;ugly code starts here - it writes the # shape I mentioned before.
.rept 2
   ;X|X|X
   .rept 2
     ldx #$0000 ; tile 0 ( )
     stx $2118
     ldx #$0002 ; tile 2 (|)
     stx $2118
   .endr
   ldx #$0000
   stx $2118
   ;first line finished, add BG's
   .rept 27
     stx $2118  ; X=0
   .endr
   ;beginning of 2nd line
   ;-+-+-
   .rept 2
     ldx #$0004 ; tile 4 (-)
     stx $2118
     ldx #$0006 ; tile 6 (+)
     stx $2118
   .endr
   ldx #$0004   ; tile 4 (-)
   stx $2118
   ldx #$0000
   .rept 27
     stx $2118
   .endr
.endr
.rept 2
  ldx #$0000    ; tile 0 ( )
  stx $2118
  ldx #$0002    ; tile 2 (|)
  stx $2118
.endr



; BG2 starts at $6000
ldx #$6000
stx $2116

ldx #$000c ;and contains one tile
stx $2118 ;data for VRAM write register




; set up the screen

lda #%00110000 ; 16x16 tiles, mode 0
sta $2105

lda #%01000000 ; data starts from $4000
sta $2107      ; for bg1

lda #%0110000 ; and $6000
sta $2108 ; for bg2

stz $210b	    ; BG1 and BG2 use the $0000 tiles

lda #%00000011  ; enable bg1 and 2
sta $212C

;The PPU doesn't process the top line, so we scroll down 1 line.
rep #$20        ; 16bit a
lda #$07FF      ; this is -1 for BG1
sep #$20        ; 8bit a
sta $210E       ; BG1 vert scroll
xba
sta $210E

rep #$20        ; 16bit a
lda #$FFFF      ; this is -1 for BG2
sep #$20        ; 8bit a
sta $2110       ; BG2 vert scroll
xba
sta $2110

lda #%00001111  ; enable screen, set brightness to 15
sta $2100

lda #%10000001  ; enable NMI and joypads
sta $4200




;sep #$30        ; get 8-bit registers
;stz $2121       ; write to CGRAM from $0
;lda #%10000000  ; this is
;ldx #%00111100  ; a green color
;sta $2122       ; write it
;stx $2122       ; to CGRAM
;lda #%00001111  ; turn on screen
;sta $2100       ; here


mainloop:
    jmp mainloop

.ENDS


.BANK 1 SLOT 0
.org 0
.section "TileData"

UntitledData:
    .db $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00
    .db $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00
    .db $03, $03, $03, $03, $03, $03, $03, $03, $03, $03, $03, $03, $03, $03, $03, $03
    .db $C0, $C0, $C0, $C0, $C0, $C0, $C0, $C0, $C0, $C0, $C0, $C0, $C0, $C0, $C0, $C0
    .db $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $FF, $FF, $FF, $FF
    .db $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $FF, $FF, $FF, $FF
    .db $03, $03, $03, $03, $03, $03, $03, $03, $03, $03, $03, $03, $FF, $FF, $FF, $FF
    .db $C0, $C0, $C0, $C0, $C0, $C0, $C0, $C0, $C0, $C0, $C0, $C0, $FF, $FF, $FF, $FF
    .db $00, $C0, $00, $E0, $00, $70, $00, $38, $00, $1C, $00, $0E, $00, $07, $00, $03
    .db $00, $03, $00, $07, $00, $0E, $00, $1C, $00, $38, $00, $70, $00, $E0, $00, $C0
    .db $00, $07, $00, $0F, $00, $18, $00, $30, $00, $60, $00, $C0, $00, $C0, $00, $C0
    .db $00, $E0, $00, $F0, $00, $18, $00, $0C, $00, $06, $00, $03, $00, $03, $00, $03
    .db $FC, $00, $F8, $00, $F0, $00, $E0, $00, $C0, $00, $80, $00, $00, $00, $00, $00
    .db $3F, $00, $1F, $00, $0F, $00, $07, $00, $03, $00, $01, $00, $00, $00, $00, $00
    .db $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00
    .db $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00
    .db $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00
    .db $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00
    .db $03, $03, $03, $03, $03, $03, $03, $03, $03, $03, $03, $03, $03, $03, $03, $03
    .db $C0, $C0, $C0, $C0, $C0, $C0, $C0, $C0, $C0, $C0, $C0, $C0, $C0, $C0, $C0, $C0
    .db $FF, $FF, $FF, $FF, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00
    .db $FF, $FF, $FF, $FF, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00
    .db $FF, $FF, $FF, $FF, $03, $03, $03, $03, $03, $03, $03, $03, $03, $03, $03, $03
    .db $FF, $FF, $FF, $FF, $C0, $C0, $C0, $C0, $C0, $C0, $C0, $C0, $C0, $C0, $C0, $C0
    .db $00, $03, $00, $07, $00, $0E, $00, $1C, $00, $38, $00, $70, $00, $E0, $00, $C0
    .db $00, $C0, $00, $E0, $00, $70, $00, $38, $00, $1C, $00, $0E, $00, $07, $00, $03
    .db $00, $C0, $00, $C0, $00, $C0, $00, $60, $00, $30, $00, $18, $00, $0F, $00, $07
    .db $00, $03, $00, $03, $00, $03, $00, $06, $00, $0C, $00, $18, $00, $F0, $00, $E0
    .db $00, $00, $00, $00, $80, $00, $C0, $00, $E0, $00, $F0, $00, $F8, $00, $FC, $00
    .db $00, $00, $00, $00, $01, $00, $03, $00, $07, $00, $0F, $00, $1F, $00, $3F, $00

UntitledPalette:
    .db $00, $00, $E0, $7F, $1F, $00, $FF, $03
Palette2:
    .db $E0, $7F

; 30 tiles (2 spaces)
; 480 bytes

.ENDS