1 files changed, 132 insertions, 0 deletions
diff --git a/common/ring.h b/common/ring.h
new file mode 100644
index 00000000..4c177132
--- /dev/null
+++ b/common/ring.h
@@ -0,0 +1,132 @@
+/*
+   Copyright (C) 2009 Red Hat, Inc.
+
+   This program 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 of
+   the License, or (at your option) any later version.
+
+   This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef _H_RING2
+#define _H_RING2
+
+typedef struct Ring RingItem;
+typedef struct Ring {
+    RingItem *prev;
+    RingItem *next;
+} Ring;
+
+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;
+}
+
+#endif
+