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/* -*- Mode: C; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/*
Copyright (C) 2009 Red Hat, Inc.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
#ifndef _H_RING2
#define _H_RING2
#include <stddef.h>
typedef struct Ring RingItem;
typedef struct Ring {
RingItem *prev;
RingItem *next;
} Ring;
#ifndef ASSERT
# define ASSERT(X)
#endif
static inline void ring_init(Ring *ring)
{
ring->next = ring->prev = ring;
}
static inline void ring_item_init(RingItem *item)
{
item->next = item->prev = NULL;
}
static inline int ring_item_is_linked(RingItem *item)
{
return !!item->next;
}
static inline int ring_is_empty(Ring *ring)
{
ASSERT(ring->next != NULL && ring->prev != NULL);
return ring == ring->next;
}
static inline void ring_add(Ring *ring, RingItem *item)
{
ASSERT(ring->next != NULL && ring->prev != NULL);
ASSERT(item->next == NULL && item->prev == NULL);
item->next = ring->next;
item->prev = ring;
ring->next = item->next->prev = item;
}
static inline void ring_add_after(RingItem *item, RingItem *pos)
{
ring_add(pos, item);
}
static inline void ring_add_before(RingItem *item, RingItem *pos)
{
ring_add(pos->prev, item);
}
static inline void __ring_remove(RingItem *item)
{
item->next->prev = item->prev;
item->prev->next = item->next;
item->prev = item->next = 0;
}
static inline void ring_remove(RingItem *item)
{
ASSERT(item->next != NULL && item->prev != NULL);
ASSERT(item->next != item);
__ring_remove(item);
}
static inline RingItem *ring_get_head(Ring *ring)
{
RingItem *ret;
ASSERT(ring->next != NULL && ring->prev != NULL);
if (ring_is_empty(ring)) {
return NULL;
}
ret = ring->next;
return ret;
}
static inline RingItem *ring_get_tail(Ring *ring)
{
RingItem *ret;
ASSERT(ring->next != NULL && ring->prev != NULL);
if (ring_is_empty(ring)) {
return NULL;
}
ret = ring->prev;
return ret;
}
static inline RingItem *ring_next(Ring *ring, RingItem *pos)
{
RingItem *ret;
ASSERT(ring->next != NULL && ring->prev != NULL);
ASSERT(pos);
ASSERT(pos->next != NULL && pos->prev != NULL);
ret = pos->next;
return (ret == ring) ? NULL : ret;
}
static inline RingItem *ring_prev(Ring *ring, RingItem *pos)
{
RingItem *ret;
ASSERT(ring->next != NULL && ring->prev != NULL);
ASSERT(pos);
ASSERT(pos->next != NULL && pos->prev != NULL);
ret = pos->prev;
return (ret == ring) ? NULL : ret;
}
static inline unsigned int ring_get_length(Ring *ring)
{
RingItem *i;
unsigned int ret = 0;
for (i = ring_get_head(ring);
i != NULL;
i = ring_next(ring, i))
ret++;
return ret;
}
#endif
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