Read / Write to file

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adroit

Joined: 21 Feb 2010
Posts: 252

adroit 27 Feb 2010, 03:53

How do I write data to a file, that the user input into the console? Also, how do I read data from that file, and use the information in my program?

Here's a algorithm:

PROMPT "Enter name here: "
READ Name
STORE Name in File.txt
READ data from File.txt
PRINT data from text
;End-Of-Line

And now if the user input: John Doe, the program will store that into File.txt then read the data from that text file (which is John Doe), and then Print the data on screen

_________________
meshnix

27 Feb 2010, 03:53

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20335
Location: In your JS exploiting you and your system

revolution 27 Feb 2010, 03:56

MeshNix: Do you have a list of the DOS int 0x21 services?

http://en.wikipedia.org/wiki/MS-DOS_API

27 Feb 2010, 03:56

adroit

Joined: 21 Feb 2010
Posts: 252

adroit 27 Feb 2010, 20:48

Sort of!
Thanks!

27 Feb 2010, 20:48

cthug

Joined: 03 Apr 2009
Posts: 36
Location: /home/Australia

cthug 28 Feb 2010, 11:03

This is more complete and includes other Interrupts: Interrupt Jump Table.

28 Feb 2010, 11:03

edfed

Joined: 20 Feb 2006
Posts: 4333
Location: Now

edfed 28 Feb 2010, 13:14

to read data from DOS files, i recommend to use this code:

Code:

fptr:
.off=0
.seg=2
.size=4
DOSread:
.call=0
.ptr=4
.name=8
.handle=12
        push eax ebx ecx edx edi esi ds
        mov edi,[esi+.ptr]
        mov edx,[esi+.name]   ; load the asciiz filename pointer
        mov edx,[edx]
        mov ax,3d00h         ; DOS open file
        int 21h
        jc .error             ; carry, then error
        mov [esi+.handle],ax
        mov bx,ax
        mov ax,[edi+fptr.seg]
        mov ds,ax
        mov dx,[edi+fptr.off] ; at [ds:dx]
        mov ah,3fh            ; will we load
        mov cx,0ffffh         ; ffffh bytes
        int 21h               ; from the file.
        jc .error             ; carry then error
        pop ds                ; restore ds
        mov [edi+fptr.size],eax   ; how long is the file, in bytes
        mov bx,[esi+.handle]
        mov ah,3eh            ; DOS close file
        int 21h
        jc .error
@@:
        pop esi edi edx ecx ebx eax
        ret
.error:
        mov word[esi+.handle],0
        mov eax,0
        jmp @b

it will open file withhandle, read from handle, and close file.
then, multiple file openings/ reopening are possible with a minimal effort.

28 Feb 2010, 13:14

adroit

Joined: 21 Feb 2010
Posts: 252

adroit 01 Mar 2010, 02:59

Ok. Thanks. I'll test it out and post

01 Mar 2010, 02:59

typedef

Joined: 25 Jul 2010
Posts: 2909
Location: 0x77760000

typedef 17 Aug 2010, 19:56

Just a question. I see people doing this. What does it do, whats its purpose ?

Quote:

Code:

push eax ebx ecx edx edi esi ds

17 Aug 2010, 19:56

edfed

Joined: 20 Feb 2006
Posts: 4333
Location: Now

edfed 17 Aug 2010, 20:34

it is because every registers can be modified in the function.
and it is writen one by one because sometimes, pushes are added or deleted during modifications.

and to avoid particular precautions in user code, everything is saved.

i hope people answered your question. Wink

17 Aug 2010, 20:34

typedef

Joined: 25 Jul 2010
Posts: 2909
Location: 0x77760000

typedef 17 Aug 2010, 20:48

yeah, thanks people.

*thought* Man, people are peoplelish *thought*

17 Aug 2010, 20:48

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