Please!! sizeof.(structure) implement directly into Fasm!!

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Dragontamer

Joined: 24 Aug 2003
Posts: 84

Dragontamer 23 Aug 2004, 12:30

Overloading the struc operator works... most of the time. But when i want to have a constructor for my structure, then it is impossible to define sizeof.(structure) into a macro, or at least very troublesome.

For example, lets say i have

Code:

struc point x,y {
  .x dd x
  .y dd y
}

I'd like the ability to just have sizeof.point to say 8 automatically, without me having to write a macro that defines .size and stuff.

This would be most useful when putting structures into dynamic memory or into the stack. Such as
add esp, sizeof.point*3 + 4*3 + 2*1 ; 3 points, 3 doublewords, one word

Thank you for listening / debating.

And yes, i know the work around macro, but it does have its limitations.

23 Aug 2004, 12:30

pelaillo
Missing in inaction

Joined: 19 Jun 2003
Posts: 878
Location: Colombia

pelaillo 23 Aug 2004, 12:38

Hi Dragontamer,
the macros are flexible, for example, I never use sizeof.thing but instead the form thing.size that I find nicer.

In order to start a debating, it would be interesting to have examples for limitations of struct macro in order to solve (if possible) each one of them.

23 Aug 2004, 12:38

Dragontamer

Joined: 24 Aug 2003
Posts: 84

Dragontamer 23 Aug 2004, 13:02

Ok, then how to allocate memory on the stack? Or how to allocate memory from malloc call?

sizeof.point is much cleaner than
mypoint.size

Especially if there aren't any handy points around to steal size from.

For example:
I wish to do:

Code:

function:
push ebp
mov ebp, esp
sub esp, (amount of space to allocate)
virtual at esp
  point1 point
  x dd ?
  y dd ?
end virtual

;function
mov esp, ebp
pop ebp
ret

Or a better example

Code:

push sizeof.point
call malloc
add esp, 4

True, i can just do push mypoint.size, however, it makes more sense to do sizeof.point IMO.

23 Aug 2004, 13:02

Tomasz Grysztar

Joined: 16 Jun 2003
Posts: 8351
Location: Kraków, Poland

Tomasz Grysztar 23 Aug 2004, 13:14

This is the flexibility of structure macros that disallows the "sizeof"-like features to be build in. Suppose you have such structure:

Code:

struc mystruct string,cptrs
 {
   .String db string,0
   .Pointers rd cptrs
 }

What would the sizeof.mystruct mean, then?

You can try to adapt "struct" macro for the structures with parameters, but you still have to allow the structure to accept empty parameters for it to work:

Code:

macro struct [def]
{
   common
   struc def {
}

macro struct_helper name
{
   virtual at 0
   name name
   sizeof.#name = $ - name
   name equ sizeof.#name
   end virtual
}

ends fix } struct_helper

struct point x,y
  .x dd x+0
  .y dd y+0
ends point

push sizeof.point

There are also other, much more complex macro solutions.

Last edited by Tomasz Grysztar on 12 Jun 2005, 09:33; edited 1 time in total

23 Aug 2004, 13:14

Dragontamer

Joined: 24 Aug 2003
Posts: 84

Dragontamer 23 Aug 2004, 13:22

Well, that makes sense...
I guess i'll just have to settle with doing mypoint.size for now.

23 Aug 2004, 13:22

pelaillo
Missing in inaction

Joined: 19 Jun 2003
Posts: 878
Location: Colombia

pelaillo 23 Aug 2004, 18:24

Dragontamer wrote:

I guess i'll just have to settle with doing mypoint.size for now.

Or sizeof.point if you prefer. That's the standard way as Privalov have indicated.

23 Aug 2004, 18:24

vid
Verbosity in development

Joined: 05 Sep 2003
Posts: 7105
Location: Slovakia

vid 23 Aug 2004, 20:13

dragontamer: keep in mind "struc" is same as "macro", only with all names starting with "." character prepended by structure name. It is not like HLL strucgture definition.

23 Aug 2004, 20:13

fasm9

Joined: 19 Jun 2003
Posts: 439

fasm9 24 Aug 2004, 03:14

HLL structure means "compiler",
While assembler is assembler.

parsing, more-higher-abstraction, bison, flex, RTL(reigster transfer language), treecc, BNF, machine code generation, microcode, regex..

so means not only "sugar-syntax".

--
PS: *_< at least, In my short knowledge. Smile

24 Aug 2004, 03:14

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