On 2000/12/15 Werner Almesberger wrote:
> LA Walsh wrote:
>
> Exception: opaque types; there one would have to go via a __ identifier,
> i.e.
>
> <public>/foo.h defines struct __foo ...;
> <public>/bar.h includes <public>/foo.h
> and uses #define FOOSIZE sizeof(struct __foo)
> <private>/foo.h either typedef struct __foo foo_t;
> or #define foo __foo /* ugly */
>
Easier: public kernel interfaces only work through pointers.
<public>/foo.h typedef struct foo foo_t;
foo_t* foo_new();
<private>/foo.h includes <public>/foo.h
struct foo { ............... };
and uses #define FOOSIZE sizeof(foo_t)
Drawback: public access is slow (always through foo_set_xxxx_field(foo_t*))
private access from kernel or modules is fast (foo_t->x = ...)
Advantage: kernel can change, foo_t internals can change and it is binary
compatible. Even public headers can be kernel version
independent.
Too kind-of-classroom-not-real-world-useless-thing ?
All depends on public access needing full fast paths...
--
Juan Antonio Magallon Lacarta #> cd /pub
mailto:[EMAIL PROTECTED] #> more beer
Linux werewolf 2.2.19-pre1 #1 SMP Fri Dec 15 22:25:20 CET 2000 i686
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