include irvine16.inc


.data
 snakestart word ?
 forecolor byte 0ffh;;white
 backcolor byte 01010101b;;bluegreen
 
 snakelen = 14

   

 Video equ 0b800h

.code
 start proc
 mov ax, @data
 mov ds, ax
 mov ax, Video
 mov es, ax
 cld  ;;;forward
 ;set to medium resolution
 mov ax, 4
 int 10h
 
  
 background:

 mov di, 07D0h
 mov cx, 6000
 mov al, backcolor
 rep stosb
 
 mov di, 27D0h
 mov cx, 6000
 rep stosb
 
 mov snakestart, 1C20h 
  ;;;horizontal snake
  mov ecx,30
  top:

	  movzx edi, snakestart
	  mov al,forecolor ;;;white
	  call draw_snake_horiz
	  mov eax, 1000
	  call delay

	  mov al,backcolor
	  movzx edi, snakestart
	  call draw_snake_horiz
	  ; mov eax, 10000
	  ;call delay


	  inc snakestart
	  
	
	
	
 loop top
    
 ;;;;vertical snake
    add snakestart, snakelen
 mov ecx,30
   top2:
 
 	  movzx edi, snakestart
 	  mov al,forecolor ;;;white
 	  call draw_snake_vert
 	  mov eax, 1000
 	  call delay
 
 	  mov al,backcolor
 	  movzx edi, snakestart
 	  call draw_snake_vert
 	  ; mov eax, 10000
 	  ;call delay
  sub snakestart, 80
 
 	 
 	
 	
 	
 loop top2
    
 mov ah, 1
  int 21h
  mov ax, 2
  int 10h
  mov ax, 4c00h
  int 21h
start endp
 
 draw_snake_horiz proc uses ecx edi
 ;draw even lines (bottom)
 
 
 push edi
 mov ecx, 14
 rep stosb
 pop edi
 push edi
 add edi,80
 mov ecx, 14
 rep stosb
 
 
 
 ;draw odd lines (bottom)
 

 pop edi
 add edi, 2000h
 push edi
 mov ecx, 14
 rep stosb
 pop edi
 add edi,80
 mov ecx, 14
 rep stosb
 
ret
draw_snake_horiz endp

draw_snake_vert proc uses ecx edi
 ;draw even lines (bottom)
 
 
 
 ;;do 14X
 mov ecx, 14
 
 push edi
 even_vert:

 push edi
 stosb
 ;stosb
 pop edi
 sub edi,80

 loop even_vert
 
 ;draw odd lines (bottom)
 

 pop edi
 add edi, 2000h
 ;;do 14X
  mov ecx, 14
 
  odd_vert:
  push edi
 ; stosb
  stosb
  pop edi
  sub edi,80
  loop odd_vert
 
ret
draw_snake_vert endp
 
 end start