MS-DOS 16ビットマシンコード:199バイト
このサイトを使用してデコードし、「koch.com」ファイルとして保存し、WinXPコマンドプロンプトから実行します。
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更新
読みやすいアセンブラバージョンを次に示します。
  ; L-System Description
  ;
  ; Alphabet : F
  ; Constants : +, -
  ; Axiom : F++F++F
  ; Production rules: F -> F-F++F-F 
  ;
  ; Register usage:
  ;                             _        _
  ; bp = direction: 0 = ->, 1 = /|, 2 = |\, 3 = <-, 4 = |/_, 5 = _\|
  ; cl = min y, ch = max y
  ; bl = x (unsigned)
  ; bh = y (signed)
  ; si = max level
  ; clear data
  mov al,20h
  add dh,al
  mov ds,dx
  mov es,dx
  mov cx,di
  rep stosb
  mov ax,'__'
  mov dx,'/\'
  ; initialise variables
  mov bp,Direction0
  xor bx,bx
  mov si,4
  call MoveForward
  call TurnRight
  call TurnRight
  call MoveForward
  call TurnRight
  call TurnRight
  call MoveForward
  mov dh,cl
  xor dl,dl
  mov bl,79
OutputLoop:
  mov bh,dh
  mov w [bx],0a0dh
  mov b [bx+2],24h
  mov ah,9
  int 21h
  inc dh
  cmp dh,ch
  jle OutputLoop  
  ret
Direction0:
  dw MoveRight
  dw MoveUpRight
  dw MoveUpLeft
  dw MoveLeft
  dw MoveDownLeft
  dw MoveDownRight
Direction6:
MoveRight:
  mov w [bx],ax
  add bl,2
  ret
MoveUpRight:
  mov b [bx],dh
  inc bl
  jmp DecBHCheckY
MoveUpLeft:
  dec bl
  mov b [bx],dl
DecBHCheckY:  
  dec bh
  jmp CheckY
MoveLeft:
  dec bl  
  cmp b [bx],20h
  jne MoveLeftAgain
  mov [bx],al
MoveLeftAgain:
  dec bl  
  mov [bx],al
  ret
MoveDownLeft:
  add bx,255
  mov b [bx],dh
  jmp CheckY
MoveDownRight:
  inc bh
  mov b [bx],dl
  inc bl
CheckY:
  cmp bh,ch
  jle NoMaxChange
  mov ch,bh
NoMaxChange:  
  cmp bh,cl
  jge NoMinChange
  mov cl,bh
NoMinChange:  
  ret
TurnRight:
  add bp,8
TurnLeft:
  add bp,2
  cmp bp,Direction6
  jb ret
  sub bp,12
  ret
MoveForward:
  dec si
  push [bp]
  jz DontRecurse
  pop di
  call MoveForward
  call TurnLeft
  call MoveForward
  call TurnRight
  call TurnRight
  call MoveForward
  call TurnLeft
  call MoveForward
DontRecurse:
  inc si
  ret