[M3devel] m3gap.... it's an alignment issue

[Jay K]

Or make all field references be via function calls to C.
Very good option imho.
Like how I access DIR->d_name.


 - Jay

----------------------------------------
> From: jay.krell at cornell.edu
> To: dragisha at m3w.org; m3devel at elegosoft.com
> Subject: RE: [M3devel] m3gap.... it's an alignment issue
> Date: Fri, 8 Oct 2010 18:36:44 +0000
>
>
> I may have broken this, a while ago. I may have relaxed all the alignments long ago.
> We have very little interfacing with C now and most of that is with our own C,
> where I avoid small types.
> We have had at least temporary problems related to our rules being sort of too strict.
>   The need for -munaligned-double or such. (which reminds me I should try that again).
>   Where our rules were ok but gcc's default for to align stuff more.
>   Where our layout and gcc's didn't agree.
>
> How bad would it be to generate or write a C layer that copies stuff into "idealized" structs?
>   Where the types are all INTEGER or LONGINT or pointers.
>
>  - Jay
>
> ----------------------------------------
> > From: dragisha at m3w.org
> > To: m3devel at elegosoft.com
> > Date: Fri, 8 Oct 2010 16:17:00 +0200
> > Subject: Re: [M3devel] m3gap.... it's an alignment issue
> >
> > WindowStar is
> > TYPE
> > Window = RECORD
> > user_data: void_star
> > END;
> > WindowStar = UNTRACED REF Window;
> >
> > and this whole record is
> > typedef struct {
> > GdkEventType type;
> > GdkWindow *window;
> > gint8 send_event;
> > guint32 time;
> > guint state;
> > guint keyval;
> > gint length;
> > gchar *string;
> > guint16 hardware_keycode;
> > guint8 group;
> > guint is_modifier : 1;
> > } GdkEventKey;
> >
> > in C.
> >
> > It's Modula-3 BYTESIZE is 64, and C sizeof() is 56. window field is aligned at 8 bytes (thank you Jay for m3gap 8_56!) and C's GdkWindow * is aligned at 4 bytes.
> >
> > As I don't use window field I'll split it in two placeholder int's, but this is, IMO, interesting point.
> >
> > dd
> >
> > On Tue, 2010-10-05 at 15:32 +0200, Dragiša Durić wrote:
> > > EventKey = RECORD
> > > type: EventType;
> > > window: WindowStar;
> > > send_event: char;
> > > time: unsigned_long_int;
> > > state: unsigned_int;
> > > keyval: unsigned_int;
> > > length: int;
> > > string: char_star;
> > > hardware_keycode: unsigned_short_int;
> > > group: unsigned_char;
> > > END;
> > >
> > > also with m3gdb....
> > >
> > > (m3gdb) p event
> > > $1 = {4type = 8 '\b', _m3gap_8_56 = {}, window = 0x0,
> > > send_event = 0 '\000',
> > --
> > Dragiša Durić
> >
>