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更多習題答案見

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預設目錄下存在 test.txt

；寫入

data segment
file db 'test.txt',0
buf db 100,?,100 dup(?)
fh dw ?

error_msg db 0dh,0ah,'error!','$' 
writer_msg db 0dh,0ah,'open file !input text:',0ah,'$' 
success_msg db 0dh,0ah,'done!','$'
data ends

stack segment stack
dw 20h dup(?)
top label word
stack ends

code segment
    assume ds:data,cs:code,ss:stack
    p proc
 
 far 

    mov ax,data
    mov ds,ax

    mov ax,stack
    mov ss,ax
    lea sp,top


    lea dx,file
    mov cx,0

    mov ah,3ch
    int 21h

    jc error
writer:
    mov fh,ax;save the code of file
    lea dx,writer_msg
    mov ah,09h
    int 21h

    lea dx,buf
    mov ah,0ah
    int 21h

    lea si,buf
    inc si




    xor ch,ch
    mov cl,[si];1
 


    inc si
    mov dx,si;2
    mov bx,fh;3

    mov ah,40h
    int 21h
    jc error

success:
    lea dx,success_msg
    mov ah,09h
    int 21h 
    jmp exit    

error:
    mov cx,16
    mov bx,ax
l1: rol bx,1
    mov dl,bl
    and dl,1
    add dl,30h
    mov ah,02h
    int 21h
    loop l1

    lea dx,error
 

    mov ah,09h
    int 21h 
exit:
    mov ah,4ch
    int 21h     

    p endp      
code ends 
    end p

； 讀取

data segment

file db 'test.txt',0
buf db 100 dup(?)
fh dw ?


error_msg db 0dh,0ah,'error!','$' 
success_msg db 0dh,0ah,'done!','$'
data ends

stack segment stack
dw 20h dup(?)
top label word
stack ends

code segment
    assume ds:data,cs:code,ss:stack
    p proc far 

    mov ax,data
    mov ds,ax

    mov ax,stack
    mov ss,ax
    lea sp,top

    ;open file
    lea dx,file
    mov al,0
    mov ah,3dh
    int 21h
    jc error
    mov fh,ax
    ;read file
    lea dx,buf  
    mov cx,100
    mov bx,fh

    mov ah,3fh  
    int 21h
    jc error

    mov cx,ax
    lea si,buf

l1: mov dl,[si]
    inc si
    mov ah,02h
    int 21h
    loop l1



    jmp exit    

error:
    lea dx,error_msg
    mov ah,09h
    int 21h



exit:
    mov ah,4ch
    int 21h     

    p endp      
code ends 
    end p

;讀取一個檔案並複製到另一個檔案txt

data segment

file db 'a\test.txt',0
buf db 100 dup(?)
fh dw ?

copyfile db 'a\copytext.txt',0
copyfh dw ?


error_msg db 0dh,0ah,'error!','$' 
success_msg db 0dh,0ah,'done!','$'
data ends

stack segment stack
dw 20h dup(?)
top label word
stack ends

code segment
    assume ds:data,cs:code,ss:stack
    p proc far 

    mov ax,data
    mov ds,ax

    mov ax,stack
    mov ss,ax
    lea sp,top

    ;open file
    lea dx,file
    mov al,0
    mov ah,3dh
    int 21h
    jc error
    mov fh,ax
    ;read file
    lea dx,buf  
    mov cx,100
    mov bx,fh

    mov ah,3fh  
    int 21h
    jc error

    ;show the read content
    mov cx,ax
    push cx;push length in stack
    lea si,buf  
l1: mov dl,[si]
    inc si
    mov ah,02h
    int 21h
    loop l1
    ;create new file 2  
    lea dx,copyfile
    mov cx,0
    mov ah,3ch
    int 21h
    jc error    
    mov copyfh,ax

    ;write to copyfile
    lea dx,buf
    mov bx,copyfh
    pop cx
    mov ah,40h
    int 21h
    jc error



    jmp exit    

error:
    lea dx,error_msg
    mov ah,09h
    int 21h



exit:
    mov ah,4ch
    int 21h     

    p endp      
code ends 
    end p