mirror of
https://github.com/sehugg/8bitworkshop.git
synced 2024-11-23 06:32:11 +00:00
322 lines
6.5 KiB
NASM
322 lines
6.5 KiB
NASM
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.include "hvsync_generator.v"
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.include "font_cp437_8x8.v"
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.include "ram.v"
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.include "tile_renderer.v"
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.include "sprite_scanline_renderer.v"
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.include "lfsr.v"
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.include "sound_generator.v"
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.include "cpu16.v"
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.include "cpu_platform.v"
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.module cpu_platform
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.arch femto16
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.org 0x8000
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.len 32768
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.define RegSwitches $fffe
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.define RegFlags $ffff
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.define KeyP1Left 1
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.define KeyP1Right 2
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.define KeyP1Up 4
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.define KeyP1Down 8
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.define KeyP1Btn1 16
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.define KeyP1Btn2 32
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.define ScreenBuffer $6000
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.define PageTable $7e00
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.define SpriteTable $7f00
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jmp Start
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Start:
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mov sp,@$6fff
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mov fx,@InitPageTable
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jsr fx
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mov ax,@$0700
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mov fx,@ClearTiles
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jsr fx
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mov fx,@DrawMaze
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jsr fx
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mov bx,@HelloWorld
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mov cx,@$0200
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mov dx,@$6001
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mov fx,@WriteString
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jsr fx
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mov fx,@ClearSprites
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jsr fx
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mov fx,@InitSprites
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jsr fx
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GameLoop:
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mov fx,@WaitVSync
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jsr fx
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mov fx,@MoveSprites
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jsr fx
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jmp GameLoop
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WaitVSync:
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mov bx,@$FFFF
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mov ax,[bx]
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and ax,#16
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bz WaitVSync
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rts
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WriteString:
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mov ax,[bx]
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bz StringDone
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xor ax,cx
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mov [dx],ax
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inc bx
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inc dx
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jmp WriteString
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StringDone:
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rts
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DrawMaze:
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mov dx,@$6080
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mov bx,@MazeData
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DrawMazeLoop:
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mov ax,[bx]
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inc bx
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mov fx,#4
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ShiftMazeChar:
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; rotate high 4 bits to low 4 bits
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asl ax
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rol ax
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rol ax
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rol ax
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mov ex,ax
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and ax,#7
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adc ax,ex
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; lookup character in table
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mov ex,ax
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and ex,#$f
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add ex,@MazeChars
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mov ex,[ex]
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; store to video buffer
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mov [dx],ex
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inc dx
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dec fx
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bnz ShiftMazeChar
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mov ax,dx
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sub ax,@$6380
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bnz DrawMazeLoop
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rts
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InitPageTable:
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mov ax,@ScreenBuffer ; screen buffer
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mov bx,@PageTable ; page table start
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mov cx,#32 ; 32 rows
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InitPTLoop:
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mov [bx],ax
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add ax,#32
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inc bx
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dec cx
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bnz InitPTLoop
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rts
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ClearTiles:
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mov bx,@ScreenBuffer
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mov cx,@$3c0
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ClearLoop:
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mov [bx],ax
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inc bx
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dec cx
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bnz ClearLoop
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rts
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ClearSprites:
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mov ax,#0
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mov cx,#$40
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mov dx,@SpriteTable
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ClearSLoop:
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mov [dx],ax
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inc dx
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dec cx
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bnz ClearSLoop
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rts
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InitSprites:
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mov bx,@SpriteInitData
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mov cx,#10
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mov dx,@SpriteTable
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InitSLoop:
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mov ax,[bx]
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mov [dx],ax
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inc bx
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inc dx
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dec cx
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bnz InitSLoop
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rts
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MoveSprites:
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mov dx,@SpriteTable
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mov cx,#5
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MoveSLoop:
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mov fx,@MoveSprite
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jsr fx
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add dx,#2
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dec cx
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bnz MoveSLoop
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rts
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MoveSprite:
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; get sprite position
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mov ax,[dx] ; x/y pos
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; get direction sprite is moving
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mov bx,[dx+1] ; direction
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rol bx
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rol bx
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rol bx
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rol bx
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rol bx
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and bx,#3 ; bx = direction (0-3)
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; is sprite in middle of a lane?
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mov ex,ax
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and ex,@$0707
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sub ex,@$0404
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bnz JustUpdatePos ; no, just move
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; is this the player?
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mov fx,dx
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sub fx,@SpriteTable
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bnz NotPlayerMove
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mov fx,@MovePlayer
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jsr fx
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NotPlayerMove:
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; make sure we don't collide with wall
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mov ex,ax
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lsr ex
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lsr ex
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lsr ex ; divide X by 8
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and ex,#31
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mov fx,ex ; fx = X/8
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mov ex,ax
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lsr ex
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lsr ex
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lsr ex
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lsr ex
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lsr ex
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lsr ex ; ex = Y/64
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and ex,@$ffe0
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or ex,fx ; ex = screen offset
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add bx,@DirectionCells
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add ex,[bx] ; add direction offset
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sub bx,@DirectionCells
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add ex,#33 ; add +1 right and +1 down
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add ex,@ScreenBuffer
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mov fx,[ex]
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and fx,@$ff00
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xor fx,@$0500
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bz ChooseNewDirection
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mov fx,#0
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mov [ex],fx ; eat dots
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JustUpdatePos:
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; update x/y position
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add bx,@DirectionXY
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add ax,[bx] ; lookup & add to x/y
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mov [dx],ax ; store x/y pos
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rts
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; Choose a new direction
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ChooseNewDirection:
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mov fx,dx
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sub fx,@SpriteTable
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bnz NotPlayer
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rts
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NotPlayer:
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inc dx
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mov bx,[dx] ; direction
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add bx,@$1000
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mov [dx],bx
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dec dx
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rts
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MovePlayer:
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mov fx,@RegSwitches
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mov fx,[fx]
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SwitchLoop:
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mov ex,#0
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lsr fx
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bcs PlyrMove
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mov ex,#2
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lsr fx
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bcs PlyrMove
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mov ex,#3
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lsr fx
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bcs PlyrMove
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mov ex,#1
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lsr fx
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bcs PlyrMove
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rts
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PlyrMove:
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mov bx,ex
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mov fx,bx
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lsr fx
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ror fx
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ror fx
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ror fx
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ror fx
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inc dx
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mov ex,[dx] ; direction
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and ex,@$0fff
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or ex,fx
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mov [dx],ex
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dec dx
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rts
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HelloWorld:
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.string HELLO WORLD
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.data 0
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SpriteInitData:
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.data $b474 $0033
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.data $8464 $0056
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.data $8474 $1067
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.data $8484 $2078
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.data $8474 $3034
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DirectionXY:
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.data -1
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.data 256
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.data 1
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.data -256
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DirectionCells:
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.data -1
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.data 32
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.data 1
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.data -32
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MazeData:
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.data $3111 $1111 $1111 $1114 $3111 $1111 $1111 $1114
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.data $2000 $0000 $0000 $0002 $2000 $0000 $0000 $0002
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.data $2031 $1114 $0311 $1402 $2031 $1140 $3111 $1402
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.data $2d51 $1116 $0511 $1605 $6051 $1160 $5111 $16d2
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.data $2000 $0000 $0000 $0000 $0000 $0000 $0000 $0002
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.data $2031 $1114 $0340 $3111 $1114 $0340 $3111 $1402
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.data $2051 $1116 $0220 $5114 $3116 $0220 $5111 $1602
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.data $2000 $0000 $0220 $0002 $2000 $0220 $0000 $0002
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.data $5111 $1114 $0251 $1402 $2031 $1620 $3111 $1116
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.data $3111 $1116 $0231 $1605 $6051 $1420 $5111 $1114
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.data $2000 $0000 $0220 $0000 $0000 $0220 $0000 $0002
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.data $2031 $1114 $0220 $3111 $1114 $0220 $3111 $1402
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.data $2051 $1116 $0560 $2ccc $ccc2 $0560 $5111 $1602
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.data $2000 $0000 $0000 $2ccc $ccc2 $0000 $0000 $0002
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.data $5111 $1114 $0340 $2ccc $ccc2 $0340 $3111 $1116
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.data $3111 $1116 $0220 $5111 $1116 $0220 $5111 $1114
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.data $2000 $0000 $0220 $0000 $0000 $0220 $0000 $0002
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.data $2031 $1114 $0251 $1403 $4031 $1620 $3111 $1402
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.data $2051 $1116 $0511 $1605 $6051 $1160 $5111 $1602
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.data $2d00 $0000 $0000 $0000 $0000 $0000 $0000 $00d2
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.data $2031 $1114 $0311 $1403 $4031 $1140 $3111 $1402
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.data $2051 $1116 $0511 $1602 $2051 $1160 $5111 $1602
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.data $2000 $0000 $0000 $0002 $2000 $0000 $0000 $0002
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.data $5111 $1111 $1111 $1116 $5111 $1111 $1111 $1116
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MazeChars:
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.data $07f9 ; empty
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.data $05c4 $05b3 ; horizvert
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.data $05da $05bf $05c0 $05d9 ; corners
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.data $05c3 $05c1 $05c2 $05b4 ; 3-way
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.data $05c5 ; 4-way
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.data $0720 ; empty (no dot)
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.data $07fe ; power pill
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.data 123 $123
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.align $10
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