> > Another possibility is a macro like
> >
> > #define field_at_offset(base, offset, type) \
> > ((type) (((char *) (base)) + (offset)))
> >
> > so that you can do
> >
> > *field_at_offset(void **, elm, (entry) + QTAILQ_NEXT_OFFSET) = NULL;
> > *field_at_offset(void ***, elm, (entry) + QTAILQ_PREV_OFFSET) =
> > *field_at_offset(void ***, head, QTAILQ_LAST_OFFSET);
> > **field_at_offset(void ***, head, QTAILQ_LAST_OFFSET) = (elm);
> > *field_at_offset(void ***, head, QTAILQ_LAST_OFFSET) =
> > field_at_offset(void **, elm, (entry) + QTAILQ_NEXT_OFFSET);
>
> The thing is that we don't know type at all. So only the offset values
> is used. This is intended for QTAILQ of any type.
Sure, my code is identical to yours---just with more macros for readability,
and a little more type-safe. Another possibility:
#define QTAILQ_RAW_NEXT(elm, entry) \
(*field_at_offset(void **, elm, (entry) + QTAILQ_NEXT_OFFSET))
#define QTAILQ_RAW_PREV(elm, entry) \
(*field_at_offset(void ***, elm, (entry) + QTAILQ_PREV_OFFSET))
#define QTAILQ_RAW_LAST(head) \
(*field_at_offset(void ***, head, QTAILQ_LAST_OFFSET))
QTAILQ_RAW_NEXT(elm, entry) = NULL;
QTAILQ_RAW_PREV(elm, entry) = QTAILQ_RAW_LAST(head);
*QTAILQ_RAW_LAST(head) = (elm);
QTAILQ_RAW_LAST(head) = &QTAILQ_RAW_NEXT(elm, entry);
Thanks,
Paolo
> Thanks,
> Jianjun
>
> >
> > or something like that (note that I've always used the same type for
> > next and last, by the way).
> >
> > Paolo
> >
>
>
