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/* List Utilities
* Copyright (C) 2009 Chris Hall (GMCH), Highwayman
*
* This file is part of GNU Zebra.
*
* GNU Zebra is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2, or (at your option) any
* later version.
*
* GNU Zebra is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GNU Zebra; see the file COPYING. If not, write to the Free
* Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
* 02111-1307, USA.
*/
#include "misc.h"
#include "list_util.h"
/*==============================================================================
* Single Base, Single Link
*/
/*------------------------------------------------------------------------------
* Deleting item
*
* Have to chase down list to find item.
*
* Note that p_prev:
*
* * starts as pointer to the base pointer and thereafter is a pointer to
* the "next" pointer in the current item.
*
* In the macro we cast &base to (void**) before passing it as p_prev.
*
* The compiler has a tendency to throw a wobbly complaining about aliasing,
* which is a complete mystery. But this all works OK, provided the
* ssl_del_func() is not inlined -- go figure.
*
* * as steps along the list p_prev points to the "next" pointer in the
* previous item.
*
* The _sl_p_next() macro adds the offset of the "next" pointer to the
* address of the given item, and returns a (void**).
*
* * at the end, assigns the item's "next" pointer to the "next" pointer
* field pointed at by p_prev.
*
* Returns: true => removed item from list
* false => item not found on list (or item == NULL)
*/
extern bool
ssl_del_func(void** p_prev, void* item, size_t link_offset)
{
void* prev ;
if (item == NULL)
return false ;
while ((prev = *p_prev) != item)
{
if (prev == NULL)
return false ;
p_prev = _sl_p_next(prev, link_offset) ;
} ;
*p_prev = _sl_next(item, link_offset) ;
return true ;
} ;
/*------------------------------------------------------------------------------
* Appending item
*
* Have to chase down list to find item to insert after.
*
* See notes on p_prev above.
*/
extern void
ssl_append_func(void** p_prev, void* item, size_t link_offset)
{
void* prev ;
while ((prev = *p_prev) != NULL)
p_prev = _sl_p_next(prev, link_offset) ;
*p_prev = item ;
} ;
/*==============================================================================
* Double Base, Single Link
*/
/*------------------------------------------------------------------------------
* Deleting item
*
* Have to chase down list to find item.
*
* Note that p_this:
*
* * starts as pointer to the base pointer, so should really be void**,
* but that causes all sorts of problems with strict-aliasing.
*
* So: have to cast to (void**) before dereferencing to get the address
* of the first item on the list.
*
* * as steps along the list p_this points to the "next pointer" in the
* previous item.
*
* The _sl_p_next() macro adds the offset of the "next pointer" to the
* address of the this item.
*
* * at the end, assigns the item's "next pointer" to the "next pointer"
* field pointed at by p_this.
*
* Note again the cast to (void**).
*
* Returns: true => removed item from list
* false => item not found on list (or item == NULL)
*/
extern bool
dsl_del_func(struct dl_void_base_pair* p_base, void* item, size_t link_offset)
{
void* this ;
void** p_this ;
if (item == NULL)
return false ;
p_this = &p_base->head ;
while ((this = *p_this) != item)
{
if (this == NULL)
return false ;
p_this = _sl_p_next(this, link_offset) ;
} ;
*p_this = _sl_next(item, link_offset) ;
if (item == p_base->tail)
p_base->tail = *p_this ;
return true ;
} ;
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