蛇组装8086：无法正确移动

Question

 
.model small 
.data 

;variables needed for snake body 


head db '@', '$' ;head and body symbols 
tail db ' ', '$' ;tail part set color to black 

snake_length db 3 ; 1-2 body 3 tail 
copy_snake_length db ? ;for loop 
sEnd db ? 

head_col db 40 ;starting col for snake 
head_row db 12 ;starting row for snake 

; snake movement algorithm 
; always copy the coordinates of the symbol in front. 
copy_col db ? 
copy_row db ? 


delaytime db 1 
;variable for control keys 
input db ? 
.stack 100h 
.code 

;to delay time 
delay proc 
    mov ah, 00 
    int 1Ah 
    mov bx, dx 

jmp_delay: 
    int 1Ah 
    sub dx, bx 
    cmp dl, delaytime 
    jl jmp_delay 
    ret 

delay endp 

;make snake head go to the right 

righty proc 
    cmp head_col,79 
    je resetposl 

    zero: 
    inc head_col 
    jmp rightyie 

    resetposl: 
    mov head_col, 0 


    rightyie: 
    mov dl,head_col 
    mov dh,head_row 
    xor bh, bh 

    mov ah, 02h 
    int 10h 
    ret 
righty endp 

startgame proc 

    mov dh, 12 ;row 
    mov dl, 40 ;column 
    xor bh, bh 
    mov ah, 02h 
    int 10h 

    mov dx, offset head 
      mov ah, 09h 
       int 21h 
ret 
startgame endp 


mov cl, head_row 
mov copy_row,cl 

mov cl, head_col 
mov copy_col, cl 

;print head 
mov dh, head_row 
mov dl, head_col 
xor bh, bh 
mov ah, 02h 
int 10h 
mov dx, offset head 
mov ah, 09h 
int 21h 





main proc 
    mov ax, @data 
    mov ds, ax 

    ;set video mode 
    mov al, 03h 
    mov ah, 00h 
    int 10h 

    ;clear screen 
    ;only need it once (reason no need to use function) 
    mov ax, 0600h 
    mov bh, 07h 
    xor cx, cx 
    mov dx, 184fh 
    int 10h 

    mov cx, 3200h ;stop cursor blinking 
    mov ah, 01h 
    int 10h 

;set start head snake in the middle of the screen 
    call startgame 


;control 
mov ah,00h 
int 16h 
mov input, 'd' 

;to change direction or to keep on going 
getinput: 
mov ah, 01h 
int 16h 
jz key 
mov ah,00h 
int 16h 
mov input,al 

;control keys 
key: 
;cmp input, 'w' 
;je w 
;cmp input, 's' 
;je s 
;cmp input, 'a' 
;je a 

cmp input, 'd' 
je d 

jne rak 


d: 

    mov cl, head_row 
    mov copy_row,cl 
    mov cl, head_col 
    mov copy_col, cl 

    mov dh, head_row 
    mov dl, head_col 
    xor bh, bh 
    mov ah, 02h 
    int 10h  

    mov al, tail 
    mov bh, 0 
    mov bl, 000h 
    mov cx, 1 
    mov ah, 09h 
    int 10h 

mov cl, snake_length 
mov copy_snake_length, cl 
dec copy_snake_length 

mov bl,0 

printbody: 
mov al, head_row 
mov copy_row,al 
mov al, head_col 
mov copy_col, al 

call righty 

;print head 
;coordinates 
    mov dh, head_row 
    mov dl, head_col 
    xor bh, bh 
    mov ah, 02h 
    int 10h 
;printing "@" 
    mov dx, offset head 
    mov ah, 09h 
    int 21h 

; inc copy_col to update the head. 
inc copy_col 
mov al,copy_col 
mov head_col,al 

inc bl 
; now loop to print other characters 
cmp bl,copy_snake_length 

jl printbody 
dec head_col 
jmp rak 






rak: 
call delay 
jmp getinput 


mov ax, 4c00h 
int 21h 
main endp 
end main 

如果您想尝试一下代码，请按d移动字符。

的问题是，当它到达最后一栏，我用右手的功能想改变head_col为0，这样它看起来像它到达屏幕的结束。不幸的是，它忽略了在最后一个字符山坳80然后继续打印，但下一排。

然后，当它到达第13行的末尾时，它不会在col 0处留下字符，但仍然沿着另一个行向下，并且在3继续打印后，似乎它会回到原始行，然后当它达到了起点，它不再打印任何东西。

Answer 1

问题是，当它到达最后一列时，我的函数正确地假设将head_col更改为0，以便它看起来像到达屏幕的末端。不幸的是，它忽略了在最后一个字符山坳80然后继续打印，但下一排。

您正在使用DOS功能9来显示您的蛇，但忘记DOS提前光标。你不应该输入第80列。将79的限制更改为78，并查看问题是否消失。或者使用BIOS功能9显示蛇头。你已经将它用于snaketail。