160 lines
3.2 KiB
NASM
160 lines
3.2 KiB
NASM
.include "header.inc"
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.include "snes_init.asm"
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.include "my_custom.asm"
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.BANK 0 SLOT 0
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.org 0
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.section "Vblank"
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VBlank:
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rti
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.ENDS
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.BANK 0 SLOT 0
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.ORG 0
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.section "Main"
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.MACRO Video_Port_Control
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;VRAM transfer, word-access, increment by 1
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lda #%10000000
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sta $2115
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.ENDM
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;assumes 8-bit a, 16-bit xy
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.MACRO Load_Block_to_VRAM ARGS SOURCE DEST SIZE
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Video_Port_Control
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ldx #DEST
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stx $2116 ; $2116/2117 is 2byte address for VRAM upload/download. most significant bit must be 0
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lda #:SOURCE ; source bank
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ldx #SOURCE ; source offset
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ldy #SIZE
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stx $4302 ; store data offset into DMA control register
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sta $4304 ; store bank into DMA source bank
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sty $4305 ; store size of block
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lda #$01
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sta $4300 ; set DMA mode (word, normal increment)
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lda #$18
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sta $4301 ; set destination register (VRAM write register) - add value to $2100 to get destination address
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; i.e. this is writing to $2118, which when written writes a byte to VRAM
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lda #$01
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sta $420b ; and start the transfer
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.ENDM
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Start:
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Snes_Init
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Set_A_8_XY_16
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Load_Palette_Color $00, $00
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Load_Palette_Color $00, $00
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Load_Palette_Color $00, $00
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Load_Palette_Color $ff, $0a
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Set_Screen_Brightness %00001111
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lda #%00000000 ; 8x8 for all 4 backgrounds, no priority flip, Mode: 4 colors/tile w/ 32 palettes
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sta $2105 ; store to screen mode register
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; size (last argument) depends on color mode
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; location is beginning of VRAM
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Load_Block_to_VRAM Tiles, $0000, (8*2*2),
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; put character data at VRAM $0000, tile data at $0400
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lda #$04
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sta $2107 ; BG1 tile map location (upper 6 bits)
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lda #$00
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sta $210b ; BG1 character location ($1000 word intervals - can't go over $8000 b/c size of VRAM)
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; main screen designation
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lda #%00000001
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sta $212c ; enable bkg 1,
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ldx #$0400 ; load $0400 (VRAM address of tile data)
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TileLoadLoop:
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stx $2116 ; store VRAM address of tile data to VRAM address word-sized register
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lda #$01 ; smile tile
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sta $2118 ;store tile map entry to the address specified in $2116 - this increments or not based on 2115
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inx
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stx $2116
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lda #$00 ; blank tile
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sta $2118
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inx
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cpx #$0780 ; $400 - $780 seems to be limit of snes screen tile memory
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bne TileLoadLoop
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lda #%10000001 ; enable NMI and joypads
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sta $4200
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mainloop:
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Spin_Loop $02
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Reset_Palette_Offset
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Load_Palette_Color $00, $00
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Load_Palette_Color $00, $00
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Load_Palette_Color $00, $00
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Load_Palette_Color $ff, $0a
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Spin_Loop $02
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Reset_Palette_Offset
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Load_Palette_Color $ff, $a0
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Load_Palette_Color $00, $00
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Load_Palette_Color $00, $00
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Load_Palette_Color $ff, $0a
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jmp mainloop
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.ENDS
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.BANK 1 SLOT 0
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.org 0
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.section "TileData"
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Tiles:
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;blank tile
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.db $00, $00, $00, $00, $00, $00, $00, $00
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.db $00, $00, $00, $00, $00, $00, $00, $00
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;face
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.db %00000000
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.db %00000000
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.db %11000011
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.db %11000011
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.db %11000011
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.db %11000011
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.db %00111000
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.db %00111000
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.db %00111000
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.db %00111000
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.db %10000001
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.db %10000001
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.db %01000010
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.db %01000010
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.db %00111100
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.db %00111100
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.ENDS
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