Thread: Assembly newbie question

  1. #1
    Android geek@02's Avatar
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    Assembly newbie question

    Code:
    ....
           mov     dx,OFFSET FNAME 
           mov     ax,3D02H            
           int     21H
           jc      FOK_NZEND           
    
           mov     bx,ax               
           push    bx                  
           mov     cx,5               
           mov     dx,OFFSET START_IMAGE       
           mov     ah,3FH              
           int     21H
    
           pop     bx                  
           mov     ah,3EH
           int     21H                 
    
           mov     ax,WORD PTR [FSIZE] 
           add     ax,OFFSET ENDPROG - OFFSET PROG   
           jc      FOK_NZEND           
           cmp     BYTE PTR [START_IMAGE],0E9H   
           jnz     FOK_ZEND            
           cmp     WORD PTR [START_IMAGE+3],4956H   
           jnz     FOK_ZEND            
    ....
    Hi im trying to learn assembly.
    Above lines are intended to assembled with TASM. but im using NASM and when i assemble them with nasm, i get errors for lines with OFFSET, WORD PTR and BYTE PTR. How can fix the code to assemble it with nasm. (when i just delete above statements (eg. mov dx, FNAME) thoes errors dont show up, but is it right to do that?)

    thanx.
    GameJolt: https://gamejolt.com/@KasunL
    Game Development Youtube:
    https://is.gd/XyhYoP
    Amateur IT Blog: http://everything-geeky.blogspot.com/



    (and, sorry for my amateur English)

  2. #2
    Kernel hacker
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    OFFSET means "the address of within the current segment". I think you can just remove that all together - it will be obvious if it works or not.

    WORD PTR, etc, you need to put the size without ptr inside the [], e.g. [word: blah] will access blah as a word.

    See the NASM manual: http://nasm.sourceforge.net/doc/nasmdoc0.html

    --
    Mats
    Compilers can produce warnings - make the compiler programmers happy: Use them!
    Please don't PM me for help - and no, I don't do help over instant messengers.

  3. #3
    Android geek@02's Avatar
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    worked. thanks.
    GameJolt: https://gamejolt.com/@KasunL
    Game Development Youtube:
    https://is.gd/XyhYoP
    Amateur IT Blog: http://everything-geeky.blogspot.com/



    (and, sorry for my amateur English)

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