lkml.org 
[lkml]   [2002]   [Sep]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH][2.5] Single linked lists for Linux, overly complicated v2
Hi,

Thanks for copying me. That one almost got lost!

On Thu, 26 Sep 2002, Zach Brown wrote:
> #define TSLIST_DECLARE(type, name) \
> type *name = NULL

OK, but I'd rather use typeof() which enhances possibilities. (Imagine
code which wouldn't know the type of something arbitrary passed.)

> #define TSLIST_MEMBER_INIT(member) \
> NULL

I'd prefer { .next = NULL; }
> #define INIT_TSLIST_MEMBER(member) \
> do { \
> (member)->_slist_next = NULL; \
> } while (0)

I'd still prefer calling the field ->next.

> #define tslist_on_list(_head,_elem) \
> ( (_elem)->_slist_next != NULL || _head == _elem )

That doesn't give me whether the elem is on _that_ list.

> #define tslist_add(_head, _elem) \
> do { \
> BUG_ON(tslist_on_list(_head, _elem)); \
> (_elem)->_slist_next = (_head); \
> (_head) = (_elem); \
> } while(0)

That's adding to front. One should be aware of that. The other add is

#define slist_add(_new_in, _head_in) \
do { \
typeof(_head_in) _head = (_head_in), \
_new = (_new_in); \
_new->next = _head->next; \
_head->next = _new; \
} while (0)
> #define tslist_pop(_head) \
> ({ \
> typeof(_head) _ret = _head; \
> if ( _head ) { \
> _ret = _head; \
> _head = _head->_slist_next; \
> _ret->_slist_next = NULL; \
> } \
> _ret; \
> })

Okay with me, except for the below reason.

> #define __tslist_walk_del(_start, _elem) \
> do { \
> typeof(_start) _pos, _prev = _start; \
> for (; _prev && (_pos = _prev->_slist_next) ; \
> _prev = _pos ) { \
> if ( _pos != _elem ) \
> continue; \
> _prev->_slist_next = (_elem)->_slist_next;\
> (_elem)->_slist_next = NULL; \
> break; \
> } \
> } while (0)

This looks overly complicated. Why not something like while, but this
weird for construct?

> #define tslist_del(_head, _elem) \
> do { \
> if ( _head == _elem ) { \
> _head = (_elem)->_slist_next; \
> (_elem)->_slist_next = NULL; \
> } else { \
> __tslist_walk_del(_head, _elem); \
> } \
> } while (0)

OK with me, I'll apply it to my version. Coming soon.

> #define tslist_for_each(_pos, _head) \
> for ( _pos = _head ; _pos ; _pos = _pos->_slist_next )

That lacks the prefetch feature at all.

The issue overall is that you still evaluate the arguments more than once.
That's what Nikita mentioned: you might end up somewhere outlandish.

Wait -- I'll do that.

Thunder
--
assert(typeof((fool)->next) == typeof(fool)); /* wrong */
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:29    [from the cache]
©2003-2011 Jasper Spaans