wrong behaviour of <struct frame>

wrong behaviour of <struct frame>

[alin soare]

I defined within the struct frame an integer variable

int ct;

If I define it immediately after the menu_bar_vector, it is initialized
somewhere with the pointer value of Qnil. (&Qnil)

      Only the X toolkit version uses this.  */

   Lisp_Object menu_bar_vector;
+
+    int ct;


In this case, if I change the value f->ct, emacs crashes with segmentation
fault, generated by the garbage collector. Why , as time as I initialize a
variable defined by myself ?


-----------------------------------------

If I define it at the end of struct frame, id est immediately after the
fieldforeground_pixel,

/* All display backends seem to need these two pixel values. */
  unsigned long background_pixel;
  unsigned long foreground_pixel;
+
+    int ct;
}

everything works fine in that case.

I wish to ask you to suggest me if you can, what happens when I define the var.
'ct' inside the struct frame.



Alin.

Re: wrong behaviour of <struct frame>

[Jan Djärv]

Read the comments:

   /* All Lisp_Object components must come first.
      That ensures they are all aligned normally.  */

and

   /* Beyond here, there should be no more Lisp_Object components.  */

Also see allocate_frame in alloc.c and make_frame in frame.c.

	Jan D.


alin soare skrev 2010-12-02 09.54:
> I defined within the struct frame an integer variable
>
> int ct;
>
> If I define it immediately after the menu_bar_vector, it is initialized
> somewhere with the pointer value of Qnil. (&Qnil)
>
>        Only the X toolkit version uses this.  */
>
>     Lisp_Object menu_bar_vector;
> +
> +    int ct;
>
>
> In this case, if I change the value f->ct, emacs crashes with segmentation
> fault, generated by the garbage collector. Why , as time as I initialize a
> variable defined by myself ?
>
>
> -----------------------------------------
>
> If I define it at the end of struct frame, id est immediately after the
> fieldforeground_pixel,
>
> /* All display backends seem to need these two pixel values. */
>    unsigned long background_pixel;
>    unsigned long foreground_pixel;
> +
> +    int ct;
> }
>
> everything works fine in that case.
>
> I wish to ask you to suggest me if you can, what happens when I define the var.
> 'ct' inside the struct frame.
>
>
>
> Alin.
>
>
>

Re: wrong behaviour of <struct frame>

[Alin Soare]

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>
>  /* All Lisp_Object components must come first.
>     That ensures they are all aligned normally.  */
>
> and
>
>  /* Beyond here, there should be no more Lisp_Object components.  */
>
> Also see allocate_frame in alloc.c and make_frame in frame.c.
>


Great!. Pfff, I did not see it :(.


Alin.

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Re: wrong behaviour of <struct frame>

[martin rudalics]

 > I wish to ask you to suggest me if you can, what happens when I define the var.
 > 'ct' inside the struct frame.

Lisp objects (objects handled by the GC) should appear above this line

   /* Beyond here, there should be no more Lisp_Object components.  */

and non-Lisp objects (objects not handled by the GC) below.

martin

Re: wrong behaviour of <struct frame>

[Andreas Schwab]

alin soare <as1789@gmail.com> writes:

> I defined within the struct frame an integer variable
>
> int ct;
>
> If I define it immediately after the menu_bar_vector, it is initialized
> somewhere with the pointer value of Qnil. (&Qnil)

Read the comments.

  /* All Lisp_Object components must come first.

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
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