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Index > Compiler Internals > Request/suggestion for zero length structure fields

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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 17248
Location: In your JS exploiting you and your system
revolution
When using the fasm package STRUCT.INC, I tried to do this:
Code:
struct foo_header
       field1 rd 1
 field2 dd ?
...
  var_data rb 0  ;a field indicating where data starts
ends    


It errors due to the last field generating the line "foo_header.var_data db 0 dup (?)".

With the standard assembler (not macro) struc we can do this easily:
Code:
struc foo_header {
     .field1 rd 1
        .field2 dd ?
...
 .var_data rb 0  ;a field indicating where data starts
}    


But the is no equivalent way to do this using the macro version.

There are two ways to solve this.
1) Modify the macros in STRUCT.INC like this:
Code:
macro struct name
...
   struc rb count \{ define field@struct .,rb,count   ;modified here
                   fields@struct equ fields@struct,field@struct \}
   struc rw count \{ define field@struct .,rw,count ;modified here
                   fields@struct equ fields@struct,field@struct \}
   struc rd count \{ define field@struct .,rd,count ;modified here
                   fields@struct equ fields@struct,field@struct \}
   struc rp count \{ define field@struct .,rp,count ;modified here
                   fields@struct equ fields@struct,field@struct \}
   struc rq count \{ define field@struct .,rq,count ;modified here
                   fields@struct equ fields@struct,field@struct \}
   struc rt count \{ define field@struct .,rt,count ;modified here
...    
or, 2) Modify the assembler to allow zero duplications like "db 0 dup (?)".

So ... my request/suggestion is to change the setup in the next version using either of these two solutions. I think the preferred option is the first where STRUCT.INC is changed.
Post 12 Feb 2008, 16:28
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vid
Verbosity in development


Joined: 05 Sep 2003
Posts: 7105
Location: Slovakia
vid
in standard struc, just use label, no? not sure about STRUCT, never used it Smile
Post 12 Feb 2008, 16:37
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 17248
Location: In your JS exploiting you and your system
revolution
vid wrote:
in standard struc, just use label, no? not sure about STRUCT, never used it Smile
Can't use label because it is not correctly initialised, it would always be zero. The struct macro is generated inside a virtual block and only initialised after the ends, that is also why you can't put code inside the struct whereas for struc you can put code.
Post 12 Feb 2008, 16:47
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 17248
Location: In your JS exploiting you and your system
revolution
*BUMP*

I think my suggestion above has been forgotten about Sad
Post 20 Dec 2008, 12:37
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kempis



Joined: 12 Jun 2008
Posts: 49
kempis
What about

Code:
macro struct name
...
   macro label ...
...    
Post 20 Dec 2008, 13:53
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 17248
Location: In your JS exploiting you and your system
revolution
What about it?
Post 20 Dec 2008, 13:58
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kempis



Joined: 12 Jun 2008
Posts: 49
kempis
Code:
...
macro label var\{ define field@struct var,:,
                  fields@struct equ fields@struct,field@struct
...     
Post 21 Dec 2008, 07:32
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 17248
Location: In your JS exploiting you and your system
revolution
Okay, sure, that can be added also for unsized labels. We also need to add "purge label".
Post 21 Dec 2008, 08:39
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