Offset value

[lcontador]

I´m tried to open a file to write in it, but in every place that I look for, they say to me that I need enter with the off set value, like in the bellow example .

mov ax,3d02h
mov dx,offset cs:fname ; DX=*FileName
int 21h ; DOS/FileOpen
jc errorlbl ; Jump On Errors

mov word ptr [offset cs:fname],ax ; BX=Handle
mov bx,ax

mov ax,4200h
xor cx,cx ; Segment
mov dx,23ceh ; Offset
int 21h ; DOS/FileSeekSet
jc errorlbl ; Error !

mov ax,4000h
mov bx,word ptr [offset fname] ; BX=Handle
mov cx,6 ; Lenght
mov dx,offset patch ; Buffer
int 21h ; DOS/WriteFile
jc errorlbl

mov ax,3e00h
mov bx,word ptr [offset fname] ; BX=Handle
int 21h ; DOS/CloseFile
jc errorlbl

My answer is : How can i found the offset value of a specifie instruction ?

 

[aphrodita]

IP-Instruction Pointer,you can have it from there.
I do not think that you need anything else but to mov 3d02 in ax and offset of the string variable(your file name) in cx;and that's it. Best Regards,

aphrodita@mail.krovatka.ru {uiuc rules}

http://www.hellforge.org