simple "union" macro

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Tomasz Grysztar

Joined: 16 Jun 2003
Posts: 8353
Location: Kraków, Poland

Tomasz Grysztar 29 Aug 2004, 16:08

Quite simple but may be useful:

Code:

macro union [def]
 { common size@union = 0
          origin@union = $
   forward virtual
            def
            if $-origin@union > size@union
             size@union = $-origin@union
            end if
           end virtual
   common rb size@union }

Example of usage:

Code:

union first dd ?, second db ?,  third rw 3

Can be used in structures, too.

29 Aug 2004, 16:08

Foamplast

Joined: 07 May 2004
Posts: 36
Location: Saratov, Russia

Foamplast 02 Sep 2004, 21:04

Can you explain using the '@' symbol?

02 Sep 2004, 21:04

Tomasz Grysztar

Joined: 16 Jun 2003
Posts: 8353
Location: Kraków, Poland

Tomasz Grysztar 02 Sep 2004, 21:12

It's just a character inside the label, it has no special meaning.

02 Sep 2004, 21:12

vid
Verbosity in development

Joined: 05 Sep 2003
Posts: 7105
Location: Slovakia

vid 03 Sep 2004, 19:22

it's no preprocessor, parser or assembly time operator, so it's character just like any else.

03 Sep 2004, 19:22

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20339
Location: In your JS exploiting you and your system

revolution 13 Sep 2004, 02:39

I tried the following (changing the macro to struc)

Code:

struc union [def]
 { common size@union = 0
          origin@union = $
   forward virtual
            def
            if $-origin@union > size@union
             size@union = $-origin@union
            end if
           end virtual
   common rb size@union }

struc uretin
{
.ddHelp         dd      ?
.ddBegin        dd      ?
}

struc wimsad
{
.dwTest         dd      ?
}

struc kolp
{
.ddStart  dd      ?
.ddStop   dd      ?
.ddMode   dd      ?
.data     union     .strUretin    uretin,\
                    .strWimsad    wimsad
.lpszText dd      ?
}

k       kolp

        mov     eax,[k.strUretin]       ;This line should fail - but okay
        mov     eax,[k.data.strUretin]  ;This line should work - but fails

The label ".data" seems to be forgotten.

Fasm gives an error message if the union structure is put back to macro.

Any way I can solve this?

13 Sep 2004, 02:39

S.T.A.S.

Joined: 09 Jan 2004
Posts: 173
Location: Ru#27

S.T.A.S. 13 Sep 2004, 20:45

The problem is because of special meaning of dot symbol inside 'struc' statement.
The right code should be:

Code:

struc union [def]
 { common size@union = 0
          origin@union = $
   forward virtual
            .#def           ; plase dot here 
            if $-origin@union > size@union
             size@union = $-origin@union
            end if
           end virtual
   common rb size@union }


struc kolp
{
.ddStart  dd      ?
.ddStop   dd      ?
.ddMode   dd      ?
.data     union     strUretin    uretin,\ ; note: there's no dot
                    strWimsad    wimsad
.lpszText dd      ?
}

13 Sep 2004, 20:45

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20339
Location: In your JS exploiting you and your system

revolution 14 Sep 2004, 02:15

Aha, you got it. Thanks.

14 Sep 2004, 02:15

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