Re: All is right !
- From: "almas" <almes@xxxxxxxxxx>
- Date: Tue, 15 Apr 2008 17:15:44 +0200
Hi every body.
If you remember, i would like to remove a byte in a file.
Rod; Franck ask answers.
Now, i build a part :
The spirit is : I type lettres " F " and " A " and i put the byte "
0FAh " in the file.
So for the next step, i can identify the byte i choose.
If some body have a better code, i will appréciate.
If some body have an other way to do it, i am also interrest.
Best regards
Almas
; i type the value of an ASCII...
; it put in a Byte this ascii
; this code can be run alone.
mov si,0082h ; i suppose i begin à 82h
lodsb
cmp al,3Ah
jb chiffre_d ; d for ten : ( forty, fivety, 60 and so long)
cmp al,41h ; is it an Hexa letter ?
jb error
cmp al,46h
ja error
sub al,37h ; "A" > 0Ah "F" become 0Fh
jmp short high_size
chiffre_d:
sub al,30h ; "0" > 00h "9" become 09h
high_size:
mov cx,0010h
mul cx ; get high position ascii
xor bx,bx
xchg ax,bx ; ax into bx
lodsb
cmp al,3Ah
jb chiffre_u : U like Unit
cmp al,41h
jb error
cmp al,46h
ja error
sub al,37h
jmp short low_size
chiffre_u:
sub al,30h
low_size:
mov cx,0016
add ax,bx
mov offset hexa,ax
mov dx,offset hexa
jmp short display_it
int 20h
error:
mov dx,offset txt
display_it:
mov ah,9
int 21h
int 20h
txt db: "Use Asci2Hex" ,13,10
hexa db: ,0,0,0 ,13,10,36
"almas" <almes@xxxxxxxxxx> a écrit dans le message de news:
4803ceeb$0$877$ba4acef3@xxxxxxxxxxxxxxxxx
Hello.
I ofen need help... but, this day, i built a COm alone.
The aim : Open a file, modify bytes, write it in an other file.
Now, i just write 256 bytes, just for test.
Next step : modify particular Ascii.
Then use largers files.
Below, my usefull code.
If you have betters methods, , sure i will apprecate.
Best Regards Almas
mov ax, 3D12h
mov dx, offset input
int 21h
mov offset handle1, ax
mov bx, [offset handle1] ; A86 need this syntax !
mov ah, 3Fh
mov cx,100h ; read 256 Bytes
mov dx, offset address ; buffer
int 21h
cmp ax,0 ; End of File ?
ja continue
int 20h
continue:
mov cx,ax ; Nbr of bytes usefull if less than 256
mov offset size_byte, ax ; rescue the size
mov si, offset address ; change bytes in buffer
mloop:
add byte [si],20h
inc si ; modify here...
loop mloop
jmp short do_it
creat_fil:
mov ah,3Ch
mov dx,offset output
xor cx,cx ; attrib
int 21h
do_it:
mov ax,3D01h ; Open for Write
mov dx, offset output
int 21h
jb creat_fil ; if not exist
mov offset handle2,ax
mov bx, [offset handle2]
mov ax,4202h
xor cx,cx
xor dx,dx ; BX keeps same value
int 21h
; mov dx,ax ; size, give an offset
xor dx,dx ; begin a byte 0
mov ax,4200h
xor cx,cx
int 21h
mov ah,40h
mov cx, [offset size_byte]
mov dx, offset address
int 21h
mov ah,3Eh
int 21h ; BX keep value Handle2
mov bx, [offset handle1] ; close first file
mov ah, 3Eh
int 21h
int 20h
; data -----------
size_byte db: ,0,0,0,0
input db: "FILE.IN" ,0
output db: "FILE.OUT" ,0
handle1 db: ,0,0,0,0
handle2 db: ,0,0,0,0
address:
db: ,0,0,0,0,0,0
.
- Follow-Ups:
- Re: All is right !
- From: Wolfgang Kern
- Re: All is right !
- References:
- All is right !
- From: almas
- All is right !
- Prev by Date: Question regarding ASM Listing (Z8k)
- Next by Date: Re: [OT] there is no assembly without good food and drink :))
- Previous by thread: All is right !
- Next by thread: Re: All is right !
- Index(es):
Relevant Pages
|
|
