如何用汇编语言创建文本编辑器？

Question

到目前为止，我已经创建了一个程序来读取箭头键并在屏幕上移动光标。首先，用户必须输入 0 才能开始，并且可以在 getch() != 27 (ESC) 期间四处移动。但是，光标根本没有移动。

model tiny
.code

org 100h

program:    
mov cx, 10
mov ah, 7
int 21h
cmp al, 0 ; start
je clearS ; clear screen

start:  
mov ah, 7  ; AL = getch()
int 21h
cmp al, 27 ; ESC
je fin
cmp al, 72
je moveUp
cmp al, 75
je moveLeft
cmp al, 77
je moveRight
cmp al, 80
je moveDown

moveRight:
mov dl, posY
inc dl ; posY ++
mov posY, dl
jmp prntCrs
jmp start

moveLeft:
mov dh, posX
mov dl, posY
dec dl ; posY -- 
mov posY, dh
jmp prntCrs
jmp start

moveUp: 
mov dl, posY
mov dh, posX
dec dh ; posX -- 
mov posX, dh
jmp prntCrs ; print cursor
jmp start

moveDown:   
mov dl, posY
mov dh, posX
inc dh ; posX ++ 
mov posX, dh
jmp prntCrs        
jmp start

prntCrs:      ; print cursor
mov ah, 2h
int 10h

clearS:        ; clear screen
mov ah, 7
mov al, 25
mov ch, 0
mov cl, 0
mov dh, 24
mov dl, 79
int 10h
mov ah, 2
mov bh, 0
mov dh, 0
mov dl, 0
int 10h
jmp start

fin:int 20h 

posX db 1 dup(0) ; dh = posX -> controls row
posY db 1 dup(0) ; dl = posY -> controls column

end program

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假设我有这个：

moveDown:    
    mov dl, posX
    mov dh, posY
    cmp dh, 9           ; limit
    je stayLine    
    inc dh ; posY ++
    mov posY, dh
    add curr_line, 36   ;increment by line/string size
    jmp prntCrs

goBackLine:
    mov dl, posX
    mov dh, posY
    cmp dh, 1       ; limit    
    je stayLine
    mov dl, 37
    dec dh  
    mov posX, dl
    mov posY, dh
    sub curr_line, 36 ; go to start of last line
    add curr_char, 35 ; to go to last char of last line
    jmp prntCrs

nextLine:       
    mov dl, posX
    mov dh, posY  
    mov dl, 1
    inc dh  
    mov posX, dl
    mov posY, dh
    add curr_line, 36
    mov curr_char, 0  ; or move it to whatever dl is?
    jmp prntCrs

 posX       db 1 dup(1)     ; dl = posX -> controls column
 posY       db 1 dup(1)     ; dh = posY -> controls row
 xlimit         dw 38       ; number of columns (w/ border)
 ylimit         dw 10       ; number of rows (w/ border) 
 matrix         db 36*8 dup(42)
 curr_line  dw ?        ; pointer to current line
 curr_char  dw ?        ; pointer to current char

如何保存用户输入？

    mov si, offset ???
    add si, curr_char
    mov byte ptr [si], al
    mov cl, dl      ; to not lose value of posX
    mov dl, al      ; to be able to print
    mov ah, 2h      ; character output
    int 21h         ; display character in dl

    mov dl, cl
    inc dl          ; to move right
    mov posX, dl    ; update posX
    cmp posX, 38
    je nextline

    inc si          
    jmp writing

Answer 1

您的代码有一些重要错误：

DL 代表 X，DH 代表 Y。您没有在标签 "moveLeft"、"moveRight"、"moveUp" 和 "moveDown" 中正确使用它们。
Int 16h 更适合箭头等特殊键。
你每次按键后都在清屏，所以光标每次都会回到左上角。

这是您改进的代码，使用 EMU8086 测试（箭头指向更改）：

.model tiny
.code

org 100h

program:    
mov cx, 10
mov ah, 7
int 21h
cmp al, 0 ; start
je clearS ; clear screen

start:  
mov ah, 0      ;<==================================
int 16h        ;<==================================
cmp al, 27 ; ESC
je fin
cmp ax, 4800h  ;<==================================
je moveUp
cmp ax, 4B00h  ;<==================================
je moveLeft
cmp ax, 4D00H  ;<==================================
je moveRight
cmp ax, 5000h  ;<==================================
je moveDown
jmp start      ;<==================================

moveRight:
mov dl, posX
mov dh, posY     ;<==================================
inc dl ; posX ++
mov posX, dl
jmp prntCrs
jmp start

moveLeft:
mov dl, posX     ;<==================================
mov dh, posY     ;<==================================
dec dl ; posX -- ;<==================================
mov posX, dl     ;<==================================
jmp prntCrs
jmp start

moveUp: 
mov dl, posX     ;<==================================
mov dh, posY     ;<==================================
dec dh ; posY -- 
mov posY, dh     ;<==================================
jmp prntCrs ; print cursor
jmp start

moveDown:   
mov dl, posX     ;<==================================
mov dh, posY     ;<==================================
inc dh ; posY ++ ;<==================================
mov posY, dh     ;<==================================
jmp prntCrs        
jmp start

prntCrs:      ; print cursor
mov ah, 2h
int 10h

clearS:         ; clear screen
;mov ah, 7      ;<==================================
;mov al, 25     ;<==================================
;mov ch, 0      ;<==================================
;mov cl, 0      ;<==================================
;mov dh, 24     ;<==================================
;mov dl, 79     ;<==================================
;int 10h        ;<==================================
;mov ah, 2      ;<==================================
;mov bh, 0      ;<==================================
;mov dh, 0      ;<==================================
;mov dl, 0      ;<==================================
;int 10h        ;<==================================
jmp start

fin:int 20h 

posX db 1 dup(0) ; dh = posX -> controls row
posY db 1 dup(0) ; dl = posY -> controls column

end program

编辑：现在它显示字符，将字符添加到矩阵，并更新 curr_line 和 curr_char。我使用颜色是为了好玩。还是要防止游标不超过限制，比如不要超过0列和80列。接下来是新的代码：

.model tiny
.code

org 100h

program:    

    mov  curr_line, offset matrix
    mov  curr_char, 0

start:
;CAPTURE KEY.
    mov  ah, 0
    int  16h  

;EVALUATE KEY.    
    cmp  al, 27          ; ESC
    je   fin
    cmp  ax, 4800h       ; UP.
    je   moveUp
    cmp  ax, 4B00h       ; LEFT.
    je   moveLeft
    cmp  ax, 4D00H       ; RIGHT.
    je   moveRight
    cmp  ax, 5000h       ; DOWN.
    je   moveDown
    cmp  al, 32
    jae  any_char
    jmp  start   

;DISPLAY LETTER, DIGIT OR ANY OTHER ACCEPTABLE CHAR.
any_char:
    mov  ah, 9
    mov  bh, 0
    mov  bl, color                            
    mov  cx, 1           ; how many times display char.
    int  10h             ; display char in al.
;UPDATE CHAR IN MATRIX.    
    mov  si, curr_line   ; si points to the beginning of the line.
    add  si, curr_char   ; si points to the char in the line.
    mov  [ si ], al      ; the char is in the matrix.   

;!!! EXTREMELY IMPORTANT : PREVIOUS BLOCK DISPLAYS ONE
;CHAR, AND NEXT BLOCK MOVES CURSOR TO THE RIGHT. THAT'S
;THE NORMAL BEHAVIOR FOR ALL EDITORS. DO NOT MOVE THESE
;TWO BLOCKS, THEY MUST BE THIS WAY. IF IT'S NECESSARY
;TO MOVE THEM, ADD A JUMP FROM ONE BLOCK TO THE OTHER.

;RIGHT.
moveRight:
    inc  curr_char       ; update current char.
    mov  dl, posX
    mov  dh, posY
    inc  dl              ; posX ++
    mov  posX, dl
    jmp  prntCrs

;LEFT.
moveLeft:
    dec  curr_char       ; update current char.
    mov  dl, posX
    mov  dh, posY
    dec  dl              ; posX --
    mov  posX, dl
    jmp  prntCrs

;UP.
moveUp: 
    sub  curr_line, 80   ; update current line.
    mov  dl, posX
    mov  dh, posY
    dec  dh              ; posY -- 
    mov  posY, dh
    jmp  prntCrs         ; print cursor

;DOWN.
moveDown:   
    add  curr_line, 80   ; update current line.
    mov  dl, posX
    mov  dh, posY
    inc  dh              ; posY ++
    mov  posY, dh
    jmp  prntCrs        

prntCrs:                 ; print cursor
    mov  ah, 2h
    int  10h
    jmp  start

fin:
    int  20h 

posX      db 1 dup(0)        ; dh = posX -> controls row
posY      db 1 dup(0)        ; dl = posY -> controls column
matrix    db 80*25 dup(' ')  ; 25 lines of 80 chars each.
curr_line dw ?
curr_char dw ?
color     db 2*16+15
;FOR COLORS USE NEXT TABLE:
;

end program

如果您想保存到文件或从文件加载，矩阵将是必需的。此外，矩阵在编辑器的行数超过屏幕大小的情况下很有用，例如，如果矩阵有 100 行（矩阵 db 80*100），当用户按下键时，编辑器的第一行将消失，但是，当用户按下向上键时，可以从矩阵中重新显示第一行。

Answer 2

关于您的逻辑流程的一些要点。 moveRight:等四个函数，调整光标位置，跳转到prntCrs:使BIOS调用设置光标位置，然后运行到clearS:函数，然后跳回start:

这些函数应该 called 并在末尾有一个 ret 指令。

moveDown:   
mov dl, posY
mov dh, posX
inc dh ; posX ++ 
mov posX, dh
call prntCrs            ; call not jmp
jmp start

prntCrs:      ; print cursor
mov ah, 2h
int 10h
ret                     ; added ret

此外，在 dh 和 dl 中，您并不总是正确处理行和列，而且您的光标位置变量定义不正确

posX db 1 dup(0) ; dh = posX -> controls row
posY db 1 dup(0) ; dl = posY -> controls column

这些可以是单个字节（也更正了用法）

posX db 0        ; dl = posX  <--- swapped register names
posY db 0        ; dh = posY

最后你递增和递减了光标位置，但没有检查它的边界。仅在 > 0 时减少，仅在 < 79 时增加 PosX，在 < 24 时才增加 PosY。

如何用汇编语言创建文本编辑器？

How to create a text editor in Assembly language?

keyboard

assembly

text

text-editor

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