When I run that code:
;-------------------MACRO-----------------
println MACRO info
push ax
push dx
mov ah, 09h
mov dx, offset info
int 21h
;print new line
mov dl, 10
mov ah, 02h
int 21h
mov dl, 13
mov ah, 02h
int 21h
pop dx
pop ax
ENDM
;-----------------end macro----------------
.model small
.stack 100h
.data
sourcePath db "C:\Files\lab5\text.txt"
sourceID dw 0
maxWordSize equ 50
buffer db maxWordSize + 2 dup(0)
startText db "Program is started", '$'
badSourceText db "Cannot open source file", '$'
fileNotFoundText db "File not found", '$'
errorClosingSource db "Cannot close source file", '$'
errorClosingDest db "Cannot close destination file", '$'
endText db "Program is ended", '$'
errorReadSourceText db "Error reading from source file", '$'
errorWritingDestText db "Error writing to destination file", '$'
.code
main:
mov ax, @data
mov es, ax
mov ds, ax
println startText
call openFiles
cmp ax, 0
jne endMain ;we have some error
call processingFile
cmp ax, 0
jne endMain ;we have some error
call closeFiles
cmp ax, 0
jne endMain ;we have some error
endMain:
;exit
println endText
mov ah, 4Ch
int 21h
;Result in ax: 0 if all is good, else not
openFiles PROC
push bx dx
;open source
mov ah, 3Dh ;open source file
mov al, 21h ;readonly, block write, other cannot write
mov dx, offset sourcePath
mov cx, 01h
int 21h
jb badOpenSource ;works when cf = 1
mov sourceID, ax ;save file ID
mov ax, 0 ;return value
jmp endOpenProc ;all is good
badOpenSource:
println badSourceText
cmp ax, 02h
jne errorFound
println fileNotFoundText
errorFound:
mov ax, 1
endOpenProc:
pop dx bx
ret
ENDP
;macro help processing
;bx - file ID
resetPosInFileToStart MACRO
push ax bx cx dx
mov ah, 42h
xor al ,al ;mov al, 0 - from file start
xor cx, cx
xor dx, dx
int 21h
pop dx cx bx ax
ENDM
;end macro help
processingFile PROC
push ax bx cx dx si di
mov bx, sourceID
resetPosInFileToStart
call readFromFile
cmp ax, 0
je finishProcessing
mov si, offset buffer
mov di, offset buffer
mov cx, ax ;save num of symbols in buffer
xor dx, dx
finishProcessing:
pop di si dx cx bx ax
ret
ENDP
;Result in ax: 0 if all is good, else not
closeFiles PROC
push bx cx
xor cx, cx
mov ah, 3Eh
mov bx, sourceID
int 21h
jnb goodCloseOfSource ;cf = 0
println errorClosingSource
inc cx ;now it is a counter of errors
goodCloseOfSource:
mov ax, cx ;save number of errors
pop cx bx
ret
ENDP
;reads to buffer maxWordSize symbols
;RES: ax - how much symbols we read
readFromFile PROC
push bx cx dx
mov ah, 3Fh
mov bx, sourceID
mov cx, maxWordSize
mov dx, offset buffer
int 21h
jnb goodRead ;cf = 0 - we read file
println errorReadSourceText
mov ax, 0
goodRead:
pop dx cx bx
ret
ENDP
end main
I have that output:
Program is started
Error reading from source file
Program is ended
text.txt contents:
Aenean ut scelerisque lacus, at aliquam ipsum. Aenean et tincidunt felis. Suspendisse volutpat aliquam odio at blandit. Integer vitae ligula consequat, interdum metus nec, venenatis arcu. Integer rhoncus quis felis et maximus. Praesent ac condimentum elit. Nullam a molestie ligula.
I olny want to read this file.
Compiler: TASM 16 bit with DOSBox (and FreeDOS with TASM).
OS: Windows 10 x64 (FreeDOS v1.2 on VirtualBox).
Why it doesn't works?
Update
Error code: I have an error in DOS 3Fh (int 21h)
CF = 1, AL = 05h (access denied).
But file is free.
As Jose Manuel Abarca Rodríguez said and then delete answer:
There are three possible values when opening a file :
0 = read only. 1 = write only. 2 = read/write.But in your code you are opening the file with the value 21h
;Result in ax: 0 if all is good, else not openFiles PROC push bx push dx
;open source mov ah, 3Dh ;open source file mov al, 21h ;readonly, block write, other cannot write ◄■■██ As !!! mov dx, offset sourcePath mov cx, 01h int 21h jb badOpenSource ;works when cf = 1Replace that 21h with 0, 1 or 2 :
mov al, 0
It's really works. Thank you