如何在 DOSBox 下的程序集 运行 中写入文件
How to write to a file in assembly running under DOSBox
我做了一个写入文件的程序，并做了一个写入代码的标签，但是我正在填充的字符串没有被写入文件。
编写程序：
proc WriteToFile
mov ah,40h
mov bx,[filehandle]
mov cx,255
lea dx,[WriteStr]
int 21h
ret
endp WriteToFile
写标签：
WritingToFile:
mov dx,offset w
mov ah,9h
int 21h
mov dx,offset filenameStr
mov bx,dx
mov [byte ptr bx],13 ;8+1+3+1
mov ah,0Ah
int 21h
mov dx,offset filenameStr + 2
mov ah,9h
int 21h
mov [byte ptr filenameStr+2+8],0
call OpenFile
xor bx,bx
call WipeClean
mov dx,offset filereaderline
mov ah,9h
int 21h
mov dx,offset WriteStr
mov bx,dx
mov [byte ptr bx],100 ;8+1+3+1
mov ah,0Ah
int 21h
call WriteToFile
call CloseFile
call DisplayWriteStr
jmp GetCommandLetter
我发现在这个过程中：
CreatingFile:
mov dx,offset c
mov ah,9h
int 21h
mov dx,offset filenameStr
mov bx,dx
mov [byte ptr bx],13 ;8+1+3+1
mov ah,0Ah
int 21h
mov dx,offset filenameStr + 2
mov ah,9h
int 21h
mov [byte ptr filenameStr+2+8],0
call CreateFile
;
call WriteToFile -it wrote,an accident
call DisplayFileName
xor bx,bx
call CloseFile
jmp GetCommandLetter
它在文件中写了这个：
i $$$$$$$$$$$$$
HELP LIST:
-----------
Commands are:
/e-Exit
/h-help
/1-Says: 'Hello World!'
$ Error
$file name consists of 4 letters MUST!! (dont forget to add '.txt' at the end of the name: 'xmpl.txt')$
/r/ $
/c/ $
/w/ $ i $$$$$$$$$$$$$
HELP LIST:
-----------
Commands are:
/e-Exit
/h-help
/1-Says: 'Hello World!'
$ Error
$file name consists of 4 letters MUST!! (dont forget to add '.txt' at the end of the name: 'xmpl.txt')$
/r/ $
/c/ $
/w/ $ "
在它创建的文件中，我看到用于写入文件的变量是：
WriteStr db 105,0,13 dup("$")
它解释了重复的 $，我知道这个变量主要有问题，我想，我该如何更改它以及如何更改它才能正常工作？
完整代码：
IDEAL
MODEL small
STACK 100h
DATASEG
szMsg1 db "Hi! What do you want to do?",10,13,10,13,"/h-help(see all the commands)",10,13,"/e-Exit",10,13,10,13,"$"
szHelloWorld db 10,13,"Hello World!",10,13,"$"
ErrorMsg db 10,13,"Illegal Command,Try again!",10,13,"$"
filenameStr db 13,0,13 dup("$")
WriteStr db 105,0,13 dup("$")
help db 10,13,"HELP LIST:",10,13,"-----------",10,13,"Commands are:",10,13," /e-Exit",10,13," /h-help",10,13," /1-Says: 'Hello World!'",10,13,"$"
filename db ?,0
filehandle dw 0
ErrorOpenMsg db 'Error',10,13,'$'
FileNameLength db "file name consists of 4 letters MUST!! (dont forget to add '.txt' at the end of the name: 'xmpl.txt')","$"
r db 10,13,"/r/ ","$"
c db ,10,13,"/c/ ","$"
w db ,10,13,"/w/ ","$"
fileString db 255 dup (0)
space db " ","$"
CommandMsg db 10,13,"Enter your command:",10,13,"Command: ","$",10,13
filereaderline db "file's text:","$"
CODESEG
proc Exitp
mov ax, 4c00h
int 21h
endp Exitp
proc WipeClean
mov [byte ptr fileString + bx], 0
inc bx
cmp bx, 255
jb WipeClean
ret
endp WipeClean
proc OpenFile
;Open file
mov ah,3Dh
xor al,al
lea dx,[filenameStr+2]
int 21h
jc openerror
mov [filehandle],ax
ret
openerror:
mov dx,offset ErrorOpenMsg
mov ah,9h
int 21h
ret
endp OpenFile
proc CreateFile
mov ah,3ch
mov cx,00000000b
lea dx,[filenameStr+2]
int 21h
jc CreateError
mov [filehandle],ax
ret
CreateError:
mov dx,offset ErrorOpenMsg
mov ah,9h
int 21h
ret
endp CreateFile
proc ReadFile
mov ah,3fh
mov bx,[filehandle]
mov cx,255
lea dx,[fileString]
int 21h
ret
endp ReadFile
proc DeleteFile
mov ah,41h
lea dx,[filenameStr+2]
int 21h
endp DeleteFile
proc DisplayFileString
mov ah,09h
lea dx,[fileString]
int 21h
endp DisplayFileString
proc DisplayWriteStr
mov ah,09h
lea dx,[WriteStr]
int 21h
endp DisplayWriteStr
proc DisplayFileName
mov ah,09h
lea dx,[filenameStr]
int 21h
endp DisplayFileName
proc KeyStroke
xor ax,ax
int 16h
endp KeyStroke
proc WriteToFile
mov ah,40h
mov bx,[filehandle]
mov cx,255
lea dx,[WriteStr]
int 21h
ret
endp WriteToFile
proc CloseFile
mov ah,3Eh
mov bx,[filehandle]
int 21h
ret
endp CloseFile
start:
mov ax, @data
mov ds, ax
mov ah,0
mov al,2
int 10h
mov dx,offset szMsg1
mov ah,9h
int 21h
jmp GetCommandLetter
PrintLine:
mov dx, offset szHelloWorld
mov ah, 9h
int 21h
jmp GetCommandLetter
_Error:
mov dx,offset ErrorMsg
mov ah,9h
int 21h
GetCommandLetter:
mov dx,offset CommandMsg
mov ah,9h
int 21h
mov ah, 1h
int 21h
mov bl,al
mov ah, 1h
int 21h
mov bh,al
compare:
cmp bl,'/'
jne _Error
cmp bh,'h'
je _help
cmp bh,'H'
je _help
cmp bh,'1'
je PrintLine
cmp bh,'e'
je _Exitp
cmp bh,'E'
je _Exitp
mov dx,offset space
mov ah,9h
int 21h
mov dx,offset FileNameLength
mov ah,9h
int 21h
cmp bh,'c'
je CreatingFile
cmp bh,'C'
je CreatingFile
cmp bh,'r'
je GetFileName
cmp bh,'R'
je GetFileName
cmp bh,'w'
je WritingToFile
cmp bh,'W'
je WritingToFile
jmp _Error
_Exitp:
call Exitp
_help:
mov dx,offset help
mov ah,9h
int 21h
jmp GetCommandLetter
GetFileName:
mov dx,offset r
mov ah,9h
int 21h
mov dx,offset filenameStr
mov bx,dx
mov [byte ptr bx],13 ;8+1+3+1
mov ah,0Ah
int 21h
mov dx,offset filenameStr + 2
mov ah,9h
int 21h
mov [byte ptr filenameStr+2+8],0
call OpenFile
xor bx,bx
call WipeClean
call ReadFile
mov dx,offset filereaderline
mov ah,9h
int 21h
call DisplayFileString
call CloseFile
jmp GetCommandLetter
CreatingFile:
mov dx,offset c
mov ah,9h
int 21h
mov dx,offset filenameStr
mov bx,dx
mov [byte ptr bx],13 ;8+1+3+1
mov ah,0Ah
int 21h
mov dx,offset filenameStr + 2
mov ah,9h
int 21h
mov [byte ptr filenameStr+2+8],0
call CreateFile
call WriteToFile
call DisplayFileName
xor bx,bx
call CloseFile
jmp GetCommandLetter
WritingToFile:
mov dx,offset w
mov ah,9h
int 21h
mov dx,offset filenameStr
mov bx,dx
mov [byte ptr bx],13 ;8+1+3+1
mov ah,0Ah
int 21h
mov dx,offset filenameStr + 2
mov ah,9h
int 21h
mov [byte ptr filenameStr+2+8],0
call OpenFile
xor bx,bx
call WipeClean
mov dx,offset filereaderline
mov ah,9h
int 21h
mov dx,offset WriteStr
mov bx,dx
mov [byte ptr bx],100 ;8+1+3+1
mov ah,0Ah
int 21h
call WriteToFile
call CloseFile
call DisplayWriteStr
jmp GetCommandLetter
exit:
mov ax, 4c00h
int 21h
END start
在您的代码中发现错误：文件是以只读模式打开的，因此您无法写入它：
proc OpenFile
;Open file
mov ah,3Dh
mov al,2 ;<================== 0:READ ONLY, 1:WRITE ONLY, 2:READ/WRITE.
lea dx,[filenameStr+2]
int 21h
jc openerror
mov [filehandle],ax
ret
openerror:
mov dx,offset ErrorOpenMsg
mov ah,9h
int 21h
ret
endp OpenFile
我做了一个写入文件的程序，并做了一个写入代码的标签，但是我正在填充的字符串没有被写入文件。
编写程序：
proc WriteToFile
mov ah,40h
mov bx,[filehandle]
mov cx,255
lea dx,[WriteStr]
int 21h
ret
endp WriteToFile
写标签：
WritingToFile:
mov dx,offset w
mov ah,9h
int 21h
mov dx,offset filenameStr
mov bx,dx
mov [byte ptr bx],13 ;8+1+3+1
mov ah,0Ah
int 21h
mov dx,offset filenameStr + 2
mov ah,9h
int 21h
mov [byte ptr filenameStr+2+8],0
call OpenFile
xor bx,bx
call WipeClean
mov dx,offset filereaderline
mov ah,9h
int 21h
mov dx,offset WriteStr
mov bx,dx
mov [byte ptr bx],100 ;8+1+3+1
mov ah,0Ah
int 21h
call WriteToFile
call CloseFile
call DisplayWriteStr
jmp GetCommandLetter
我发现在这个过程中：
CreatingFile:
mov dx,offset c
mov ah,9h
int 21h
mov dx,offset filenameStr
mov bx,dx
mov [byte ptr bx],13 ;8+1+3+1
mov ah,0Ah
int 21h
mov dx,offset filenameStr + 2
mov ah,9h
int 21h
mov [byte ptr filenameStr+2+8],0
call CreateFile
;
call WriteToFile -it wrote,an accident
call DisplayFileName
xor bx,bx
call CloseFile
jmp GetCommandLetter
它在文件中写了这个：
i $$$$$$$$$$$$$
HELP LIST:
-----------
Commands are:
/e-Exit
/h-help
/1-Says: 'Hello World!'
$ Error
$file name consists of 4 letters MUST!! (dont forget to add '.txt' at the end of the name: 'xmpl.txt')$
/r/ $
/c/ $
/w/ $ i $$$$$$$$$$$$$
HELP LIST:
-----------
Commands are:
/e-Exit
/h-help
/1-Says: 'Hello World!'
$ Error
$file name consists of 4 letters MUST!! (dont forget to add '.txt' at the end of the name: 'xmpl.txt')$
/r/ $
/c/ $
/w/ $ "
在它创建的文件中，我看到用于写入文件的变量是：
WriteStr db 105,0,13 dup("$")
它解释了重复的 $，我知道这个变量主要有问题，我想，我该如何更改它以及如何更改它才能正常工作？
完整代码：
IDEAL
MODEL small
STACK 100h
DATASEG
szMsg1 db "Hi! What do you want to do?",10,13,10,13,"/h-help(see all the commands)",10,13,"/e-Exit",10,13,10,13,"$"
szHelloWorld db 10,13,"Hello World!",10,13,"$"
ErrorMsg db 10,13,"Illegal Command,Try again!",10,13,"$"
filenameStr db 13,0,13 dup("$")
WriteStr db 105,0,13 dup("$")
help db 10,13,"HELP LIST:",10,13,"-----------",10,13,"Commands are:",10,13," /e-Exit",10,13," /h-help",10,13," /1-Says: 'Hello World!'",10,13,"$"
filename db ?,0
filehandle dw 0
ErrorOpenMsg db 'Error',10,13,'$'
FileNameLength db "file name consists of 4 letters MUST!! (dont forget to add '.txt' at the end of the name: 'xmpl.txt')","$"
r db 10,13,"/r/ ","$"
c db ,10,13,"/c/ ","$"
w db ,10,13,"/w/ ","$"
fileString db 255 dup (0)
space db " ","$"
CommandMsg db 10,13,"Enter your command:",10,13,"Command: ","$",10,13
filereaderline db "file's text:","$"
CODESEG
proc Exitp
mov ax, 4c00h
int 21h
endp Exitp
proc WipeClean
mov [byte ptr fileString + bx], 0
inc bx
cmp bx, 255
jb WipeClean
ret
endp WipeClean
proc OpenFile
;Open file
mov ah,3Dh
xor al,al
lea dx,[filenameStr+2]
int 21h
jc openerror
mov [filehandle],ax
ret
openerror:
mov dx,offset ErrorOpenMsg
mov ah,9h
int 21h
ret
endp OpenFile
proc CreateFile
mov ah,3ch
mov cx,00000000b
lea dx,[filenameStr+2]
int 21h
jc CreateError
mov [filehandle],ax
ret
CreateError:
mov dx,offset ErrorOpenMsg
mov ah,9h
int 21h
ret
endp CreateFile
proc ReadFile
mov ah,3fh
mov bx,[filehandle]
mov cx,255
lea dx,[fileString]
int 21h
ret
endp ReadFile
proc DeleteFile
mov ah,41h
lea dx,[filenameStr+2]
int 21h
endp DeleteFile
proc DisplayFileString
mov ah,09h
lea dx,[fileString]
int 21h
endp DisplayFileString
proc DisplayWriteStr
mov ah,09h
lea dx,[WriteStr]
int 21h
endp DisplayWriteStr
proc DisplayFileName
mov ah,09h
lea dx,[filenameStr]
int 21h
endp DisplayFileName
proc KeyStroke
xor ax,ax
int 16h
endp KeyStroke
proc WriteToFile
mov ah,40h
mov bx,[filehandle]
mov cx,255
lea dx,[WriteStr]
int 21h
ret
endp WriteToFile
proc CloseFile
mov ah,3Eh
mov bx,[filehandle]
int 21h
ret
endp CloseFile
start:
mov ax, @data
mov ds, ax
mov ah,0
mov al,2
int 10h
mov dx,offset szMsg1
mov ah,9h
int 21h
jmp GetCommandLetter
PrintLine:
mov dx, offset szHelloWorld
mov ah, 9h
int 21h
jmp GetCommandLetter
_Error:
mov dx,offset ErrorMsg
mov ah,9h
int 21h
GetCommandLetter:
mov dx,offset CommandMsg
mov ah,9h
int 21h
mov ah, 1h
int 21h
mov bl,al
mov ah, 1h
int 21h
mov bh,al
compare:
cmp bl,'/'
jne _Error
cmp bh,'h'
je _help
cmp bh,'H'
je _help
cmp bh,'1'
je PrintLine
cmp bh,'e'
je _Exitp
cmp bh,'E'
je _Exitp
mov dx,offset space
mov ah,9h
int 21h
mov dx,offset FileNameLength
mov ah,9h
int 21h
cmp bh,'c'
je CreatingFile
cmp bh,'C'
je CreatingFile
cmp bh,'r'
je GetFileName
cmp bh,'R'
je GetFileName
cmp bh,'w'
je WritingToFile
cmp bh,'W'
je WritingToFile
jmp _Error
_Exitp:
call Exitp
_help:
mov dx,offset help
mov ah,9h
int 21h
jmp GetCommandLetter
GetFileName:
mov dx,offset r
mov ah,9h
int 21h
mov dx,offset filenameStr
mov bx,dx
mov [byte ptr bx],13 ;8+1+3+1
mov ah,0Ah
int 21h
mov dx,offset filenameStr + 2
mov ah,9h
int 21h
mov [byte ptr filenameStr+2+8],0
call OpenFile
xor bx,bx
call WipeClean
call ReadFile
mov dx,offset filereaderline
mov ah,9h
int 21h
call DisplayFileString
call CloseFile
jmp GetCommandLetter
CreatingFile:
mov dx,offset c
mov ah,9h
int 21h
mov dx,offset filenameStr
mov bx,dx
mov [byte ptr bx],13 ;8+1+3+1
mov ah,0Ah
int 21h
mov dx,offset filenameStr + 2
mov ah,9h
int 21h
mov [byte ptr filenameStr+2+8],0
call CreateFile
call WriteToFile
call DisplayFileName
xor bx,bx
call CloseFile
jmp GetCommandLetter
WritingToFile:
mov dx,offset w
mov ah,9h
int 21h
mov dx,offset filenameStr
mov bx,dx
mov [byte ptr bx],13 ;8+1+3+1
mov ah,0Ah
int 21h
mov dx,offset filenameStr + 2
mov ah,9h
int 21h
mov [byte ptr filenameStr+2+8],0
call OpenFile
xor bx,bx
call WipeClean
mov dx,offset filereaderline
mov ah,9h
int 21h
mov dx,offset WriteStr
mov bx,dx
mov [byte ptr bx],100 ;8+1+3+1
mov ah,0Ah
int 21h
call WriteToFile
call CloseFile
call DisplayWriteStr
jmp GetCommandLetter
exit:
mov ax, 4c00h
int 21h
END start
在您的代码中发现错误：文件是以只读模式打开的，因此您无法写入它：
proc OpenFile
;Open file
mov ah,3Dh
mov al,2 ;<================== 0:READ ONLY, 1:WRITE ONLY, 2:READ/WRITE.
lea dx,[filenameStr+2]
int 21h
jc openerror
mov [filehandle],ax
ret
openerror:
mov dx,offset ErrorOpenMsg
mov ah,9h
int 21h
ret
endp OpenFile