(REQ) sizeof (data)

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Daemon

Joined: 08 Jul 2003
Posts: 15

Daemon 01 Jun 2004, 10:33

Hi,
is it possible to add an asm directive which would produce a number of bytes data uses ? and also, cannot produce 'times x STRUCTNAME' structure.
ex:

Code:

struc S1
{
  .data1 dd ?
  .data2 dd ?
  .data3 rb 128
}

s1 S1

mov eax,[s1.data1]
mov ecx,sizeof s1.data1 ; should asm to mov ecx,4!

I tryed to play with macros & write own 'struct' macro but... nothing.
Is there a possibility to write such a macro? with every member of structure having 'sizeof' member ?
(the code is same only mov ecx,sizeof.s1.data should be there...)

Greetz,
Daemon.

01 Jun 2004, 10:33

vid
Verbosity in development

Joined: 05 Sep 2003
Posts: 7105
Location: Slovakia

vid 01 Jun 2004, 10:55

about times x structname - this doesn't work, because structure must be preceded by label <url=http://www.decard.net/tajga.php?chapter=preproc#struc>.

Only solution i see for your problem is to overload all data definiton directives (db, dd, dq, rb, rw etc.) with structure to produce this constant (sizeof.data). They should be overloaded in struct macro, but then you would have to end definition with some "ends" or another macro, not only with "}", because overloaded directives must be purged there.

But I can't see reason for doing this, would it be worth of all that time loss?

01 Jun 2004, 10:55

Daemon

Joined: 08 Jul 2003
Posts: 15

Daemon 02 Jun 2004, 10:36

can i get an example of overloading db,dd,etc.. directives?

02 Jun 2004, 10:36

zjlcc

Joined: 23 Jul 2003
Posts: 32
Location: china

zjlcc 02 Jun 2004, 13:29

you can:

Code:

struc db [data]
{
common
  local zzz
  label zzz
  db data
  .size=$-zzz
}
struc dd [data]
{
common
  local zzz1
  label zzz1
  dd data
  .size=$-zzz1
}
struc rb [data]
{
common
  local zzz2
  label zzz2
  rb data
  .size=$-zzz2
}
macro DB field,var
{
   field db var
   field#.#size=$-field
}  
macro DD field,var
{
   field dd var
   field#.#size=$-field
}  
macro RB field,var
{
   field rb var
   field#.#size=$-field
}  
struc S1 
{
  .data1 db ? 
  .data2 dd ? 
  .data3 rb 128 
} 
s1 S1 

struc S2 
{ 
  DB .data1,? 
  DD .data2,? 
  RB .data3,128 
} 
s2 S2
............
mov eax,s1.data1.size
mov ecx,s1.data2.size
mov ecx,s1.data3.size
nop
mov ecx,s2.data1.size
mov ecx,s2.data2.size
mov ecx,s2.data3.size

02 Jun 2004, 13:29

Daemon

Joined: 08 Jul 2003
Posts: 15

Daemon 08 Jun 2004, 03:30

And what about

Code:

mov eax,s1.size

???

i think sizeof directive must be added as a preprocessor directive; then we'll have every data size defined.

Greetz,

Daemon

08 Jun 2004, 03:30

vid
Verbosity in development

Joined: 05 Sep 2003
Posts: 7105
Location: Slovakia

vid 08 Jun 2004, 16:59

surely not preprocessor directive, preprocessor does only string manipulation, nothing with directives (only it's own), size of data, expressions (5*sizeof.data) etc.

I don't like that idea, it would produce too much unneeded overhead. Why do you need to have size of dword variable defined (in assembly, where you must know if to put it into dword register)? And how many structure definitions you have, is it that problem to write sizeof. constant yourself for every "rb" in strucutre? Remember, trying to save *typing* usually isn't right solution.

08 Jun 2004, 16:59

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