Adding upstream version 2.6.12.upstream/2.6.12upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 847 insertions, 0 deletions

diff --git a/include/import/ebmbtree.h b/include/import/ebmbtree.h
new file mode 100644
index 0000000..0e23539
--- /dev/null
+++ b/include/import/ebmbtree.h
@@ -0,0 +1,847 @@
+/*
+ * Elastic Binary Trees - macros and structures for Multi-Byte data nodes.
+ * Version 6.0.6
+ * (C) 2002-2011 - Willy Tarreau <w@1wt.eu>
+ *
+ * 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, version 2.1
+ * exclusively.
+ *
+ * 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef _EBMBTREE_H
+#define _EBMBTREE_H
+
+#include <string.h>
+#include "ebtree.h"
+
+/* Return the structure of type <type> whose member <member> points to <ptr> */
+#define ebmb_entry(ptr, type, member) container_of(ptr, type, member)
+
+/*
+ * Exported functions and macros.
+ * Many of them are always inlined because they are extremely small, and
+ * are generally called at most once or twice in a program.
+ */
+
+/* Return leftmost node in the tree, or NULL if none */
+static forceinline struct ebmb_node *ebmb_first(struct eb_root *root)
+{
+	return ebmb_entry(eb_first(root), struct ebmb_node, node);
+}
+
+/* Return rightmost node in the tree, or NULL if none */
+static forceinline struct ebmb_node *ebmb_last(struct eb_root *root)
+{
+	return ebmb_entry(eb_last(root), struct ebmb_node, node);
+}
+
+/* Return next node in the tree, or NULL if none */
+static forceinline struct ebmb_node *ebmb_next(struct ebmb_node *ebmb)
+{
+	return ebmb_entry(eb_next(&ebmb->node), struct ebmb_node, node);
+}
+
+/* Return previous node in the tree, or NULL if none */
+static forceinline struct ebmb_node *ebmb_prev(struct ebmb_node *ebmb)
+{
+	return ebmb_entry(eb_prev(&ebmb->node), struct ebmb_node, node);
+}
+
+/* Return next leaf node within a duplicate sub-tree, or NULL if none. */
+static inline struct ebmb_node *ebmb_next_dup(struct ebmb_node *ebmb)
+{
+	return ebmb_entry(eb_next_dup(&ebmb->node), struct ebmb_node, node);
+}
+
+/* Return previous leaf node within a duplicate sub-tree, or NULL if none. */
+static inline struct ebmb_node *ebmb_prev_dup(struct ebmb_node *ebmb)
+{
+	return ebmb_entry(eb_prev_dup(&ebmb->node), struct ebmb_node, node);
+}
+
+/* Return next node in the tree, skipping duplicates, or NULL if none */
+static forceinline struct ebmb_node *ebmb_next_unique(struct ebmb_node *ebmb)
+{
+	return ebmb_entry(eb_next_unique(&ebmb->node), struct ebmb_node, node);
+}
+
+/* Return previous node in the tree, skipping duplicates, or NULL if none */
+static forceinline struct ebmb_node *ebmb_prev_unique(struct ebmb_node *ebmb)
+{
+	return ebmb_entry(eb_prev_unique(&ebmb->node), struct ebmb_node, node);
+}
+
+/* Delete node from the tree if it was linked in. Mark the node unused. Note
+ * that this function relies on a non-inlined generic function: eb_delete.
+ */
+static forceinline void ebmb_delete(struct ebmb_node *ebmb)
+{
+	eb_delete(&ebmb->node);
+}
+
+/* The following functions are not inlined by default. They are declared
+ * in ebmbtree.c, which simply relies on their inline version.
+ */
+struct ebmb_node *ebmb_lookup(struct eb_root *root, const void *x, unsigned int len);
+struct ebmb_node *ebmb_insert(struct eb_root *root, struct ebmb_node *new, unsigned int len);
+struct ebmb_node *ebmb_lookup_longest(struct eb_root *root, const void *x);
+struct ebmb_node *ebmb_lookup_prefix(struct eb_root *root, const void *x, unsigned int pfx);
+struct ebmb_node *ebmb_insert_prefix(struct eb_root *root, struct ebmb_node *new, unsigned int len);
+
+/* start from a valid leaf and find the next matching prefix that's either a
+ * duplicate, or immediately shorter than the node's current one and still
+ * matches it. The purpose is to permit a caller that is not satisfied with a
+ * result provided by ebmb_lookup_longest() to evaluate the next matching
+ * entry. Given that shorter keys are necessarily attached to nodes located
+ * above the current one, it's sufficient to restart from the current leaf and
+ * go up until we find a shorter prefix, or a non-matching one.
+ */
+static inline struct ebmb_node *ebmb_lookup_shorter(struct ebmb_node *start)
+{
+	eb_troot_t *t = start->node.leaf_p;
+	struct ebmb_node *node;
+
+	/* first, chcek for duplicates */
+	node = ebmb_next_dup(start);
+	if (node)
+		return node;
+
+	while (1) {
+		if (eb_gettag(t) == EB_LEFT) {
+			/* Walking up from left branch. We must ensure that we never
+			 * walk beyond root.
+			 */
+			if (unlikely(eb_clrtag((eb_untag(t, EB_LEFT))->b[EB_RGHT]) == NULL))
+				return NULL;
+			node = container_of(eb_root_to_node(eb_untag(t, EB_LEFT)), struct ebmb_node, node);
+		} else {
+			/* Walking up from right branch, so we cannot be below
+			 * root. However, if we end up on a node with an even
+			 * and positive bit, this is a cover node, which mandates
+			 * that the left branch only contains cover values, so we
+			 * must descend it.
+			 */
+			node = container_of(eb_root_to_node(eb_untag(t, EB_RGHT)), struct ebmb_node, node);
+			if (node->node.bit > 0 && !(node->node.bit & 1))
+				return ebmb_entry(eb_walk_down(t, EB_LEFT), struct ebmb_node, node);
+		}
+
+		/* Note that <t> cannot be NULL at this stage */
+		t = node->node.node_p;
+
+		/* this is a node attached to a deeper (and possibly different)
+		 * leaf, not interesting for us.
+		 */
+		if (node->node.pfx >= start->node.pfx)
+			continue;
+
+		if (check_bits(start->key, node->key, 0, node->node.pfx) == 0)
+			break;
+	}
+	return node;
+}
+
+/* The following functions are less likely to be used directly, because their
+ * code is larger. The non-inlined version is preferred.
+ */
+
+/* Delete node from the tree if it was linked in. Mark the node unused. */
+static forceinline void __ebmb_delete(struct ebmb_node *ebmb)
+{
+	__eb_delete(&ebmb->node);
+}
+
+/* Find the first occurrence of a key of a least <len> bytes matching <x> in the
+ * tree <root>. The caller is responsible for ensuring that <len> will not exceed
+ * the common parts between the tree's keys and <x>. In case of multiple matches,
+ * the leftmost node is returned. This means that this function can be used to
+ * lookup string keys by prefix if all keys in the tree are zero-terminated. If
+ * no match is found, NULL is returned. Returns first node if <len> is zero.
+ */
+static forceinline struct ebmb_node *__ebmb_lookup(struct eb_root *root, const void *x, unsigned int len)
+{
+	struct ebmb_node *node;
+	eb_troot_t *troot;
+	int pos, side;
+	int node_bit;
+
+	troot = root->b[EB_LEFT];
+	if (unlikely(troot == NULL))
+		goto ret_null;
+
+	if (unlikely(len == 0))
+		goto walk_down;
+
+	pos = 0;
+	while (1) {
+		if (eb_gettag(troot) == EB_LEAF) {
+			node = container_of(eb_untag(troot, EB_LEAF),
+					    struct ebmb_node, node.branches);
+			if (eb_memcmp(node->key + pos, x, len) != 0)
+				goto ret_null;
+			else
+				goto ret_node;
+		}
+		node = container_of(eb_untag(troot, EB_NODE),
+				    struct ebmb_node, node.branches);
+
+		node_bit = node->node.bit;
+		if (node_bit < 0) {
+			/* We have a dup tree now. Either it's for the same
+			 * value, and we walk down left, or it's a different
+			 * one and we don't have our key.
+			 */
+			if (eb_memcmp(node->key + pos, x, len) != 0)
+				goto ret_null;
+			else
+				goto walk_left;
+		}
+
+		/* OK, normal data node, let's walk down. We check if all full
+		 * bytes are equal, and we start from the last one we did not
+		 * completely check. We stop as soon as we reach the last byte,
+		 * because we must decide to go left/right or abort.
+		 */
+		node_bit = ~node_bit + (pos << 3) + 8; // = (pos<<3) + (7 - node_bit)
+		if (node_bit < 0) {
+			/* This surprising construction gives better performance
+			 * because gcc does not try to reorder the loop. Tested to
+			 * be fine with 2.95 to 4.2.
+			 */
+			while (1) {
+				if (node->key[pos++] ^ *(unsigned char*)(x++))
+					goto ret_null;  /* more than one full byte is different */
+				if (--len == 0)
+					goto walk_left; /* return first node if all bytes matched */
+				node_bit += 8;
+				if (node_bit >= 0)
+					break;
+			}
+		}
+
+		/* here we know that only the last byte differs, so node_bit < 8.
+		 * We have 2 possibilities :
+		 *   - more than the last bit differs => return NULL
+		 *   - walk down on side = (x[pos] >> node_bit) & 1
+		 */
+		side = *(unsigned char *)x >> node_bit;
+		if (((node->key[pos] >> node_bit) ^ side) > 1)
+			goto ret_null;
+		side &= 1;
+		troot = node->node.branches.b[side];
+	}
+ walk_left:
+	troot = node->node.branches.b[EB_LEFT];
+ walk_down:
+	while (eb_gettag(troot) != EB_LEAF)
+		troot = (eb_untag(troot, EB_NODE))->b[EB_LEFT];
+	node = container_of(eb_untag(troot, EB_LEAF),
+			    struct ebmb_node, node.branches);
+ ret_node:
+	return node;
+ ret_null:
+	return NULL;
+}
+
+/* Insert ebmb_node <new> into subtree starting at node root <root>.
+ * Only new->key needs be set with the key. The ebmb_node is returned.
+ * If root->b[EB_RGHT]==1, the tree may only contain unique keys. The
+ * len is specified in bytes. It is absolutely mandatory that this length
+ * is the same for all keys in the tree. This function cannot be used to
+ * insert strings.
+ */
+static forceinline struct ebmb_node *
+__ebmb_insert(struct eb_root *root, struct ebmb_node *new, unsigned int len)
+{
+	struct ebmb_node *old;
+	unsigned int side;
+	eb_troot_t *troot, **up_ptr;
+	eb_troot_t *root_right;
+	int diff;
+	int bit;
+	eb_troot_t *new_left, *new_rght;
+	eb_troot_t *new_leaf;
+	int old_node_bit;
+
+	side = EB_LEFT;
+	troot = root->b[EB_LEFT];
+	root_right = root->b[EB_RGHT];
+	if (unlikely(troot == NULL)) {
+		/* Tree is empty, insert the leaf part below the left branch */
+		root->b[EB_LEFT] = eb_dotag(&new->node.branches, EB_LEAF);
+		new->node.leaf_p = eb_dotag(root, EB_LEFT);
+		new->node.node_p = NULL; /* node part unused */
+		return new;
+	}
+
+	/* The tree descent is fairly easy :
+	 *  - first, check if we have reached a leaf node
+	 *  - second, check if we have gone too far
+	 *  - third, reiterate
+	 * Everywhere, we use <new> for the node node we are inserting, <root>
+	 * for the node we attach it to, and <old> for the node we are
+	 * displacing below <new>. <troot> will always point to the future node
+	 * (tagged with its type). <side> carries the side the node <new> is
+	 * attached to below its parent, which is also where previous node
+	 * was attached.
+	 */
+
+	bit = 0;
+	while (1) {
+		if (unlikely(eb_gettag(troot) == EB_LEAF)) {
+			/* insert above a leaf */
+			old = container_of(eb_untag(troot, EB_LEAF),
+					    struct ebmb_node, node.branches);
+			new->node.node_p = old->node.leaf_p;
+			up_ptr = &old->node.leaf_p;
+			goto check_bit_and_break;
+		}
+
+		/* OK we're walking down this link */
+		old = container_of(eb_untag(troot, EB_NODE),
+				   struct ebmb_node, node.branches);
+		old_node_bit = old->node.bit;
+
+		if (unlikely(old->node.bit < 0)) {
+			/* We're above a duplicate tree, so we must compare the whole value */
+			new->node.node_p = old->node.node_p;
+			up_ptr = &old->node.node_p;
+		check_bit_and_break:
+			bit = equal_bits(new->key, old->key, bit, len << 3);
+			break;
+		}
+
+		/* Stop going down when we don't have common bits anymore. We
+		 * also stop in front of a duplicates tree because it means we
+		 * have to insert above. Note: we can compare more bits than
+		 * the current node's because as long as they are identical, we
+		 * know we descend along the correct side.
+		 */
+
+		bit = equal_bits(new->key, old->key, bit, old_node_bit);
+		if (unlikely(bit < old_node_bit)) {
+			/* The tree did not contain the key, so we insert <new> before the
+			 * node <old>, and set ->bit to designate the lowest bit position in
+			 * <new> which applies to ->branches.b[].
+			 */
+			new->node.node_p = old->node.node_p;
+			up_ptr = &old->node.node_p;
+			break;
+		}
+		/* we don't want to skip bits for further comparisons, so we must limit <bit>.
+		 * However, since we're going down around <old_node_bit>, we know it will be
+		 * properly matched, so we can skip this bit.
+		 */
+		bit = old_node_bit + 1;
+
+		/* walk down */
+		root = &old->node.branches;
+		side = old_node_bit & 7;
+		side ^= 7;
+		side = (new->key[old_node_bit >> 3] >> side) & 1;
+		troot = root->b[side];
+	}
+
+	new_left = eb_dotag(&new->node.branches, EB_LEFT);
+	new_rght = eb_dotag(&new->node.branches, EB_RGHT);
+	new_leaf = eb_dotag(&new->node.branches, EB_LEAF);
+
+	new->node.bit = bit;
+
+	/* Note: we can compare more bits than the current node's because as
+	 * long as they are identical, we know we descend along the correct
+	 * side. However we don't want to start to compare past the end.
+	 */
+	diff = 0;
+	if (((unsigned)bit >> 3) < len)
+		diff = cmp_bits(new->key, old->key, bit);
+
+	if (diff == 0) {
+		new->node.bit = -1; /* mark as new dup tree, just in case */
+
+		if (likely(eb_gettag(root_right))) {
+			/* we refuse to duplicate this key if the tree is
+			 * tagged as containing only unique keys.
+			 */
+			return old;
+		}
+
+		if (eb_gettag(troot) != EB_LEAF) {
+			/* there was already a dup tree below */
+			struct eb_node *ret;
+			ret = eb_insert_dup(&old->node, &new->node);
+			return container_of(ret, struct ebmb_node, node);
+		}
+		/* otherwise fall through */
+	}
+
+	if (diff >= 0) {
+		new->node.branches.b[EB_LEFT] = troot;
+		new->node.branches.b[EB_RGHT] = new_leaf;
+		new->node.leaf_p = new_rght;
+		*up_ptr = new_left;
+	}
+	else {
+		new->node.branches.b[EB_LEFT] = new_leaf;
+		new->node.branches.b[EB_RGHT] = troot;
+		new->node.leaf_p = new_left;
+		*up_ptr = new_rght;
+	}
+
+	/* Ok, now we are inserting <new> between <root> and <old>. <old>'s
+	 * parent is already set to <new>, and the <root>'s branch is still in
+	 * <side>. Update the root's leaf till we have it. Note that we can also
+	 * find the side by checking the side of new->node.node_p.
+	 */
+
+	root->b[side] = eb_dotag(&new->node.branches, EB_NODE);
+	return new;
+}
+
+
+/* Find the first occurrence of the longest prefix matching a key <x> in the
+ * tree <root>. It's the caller's responsibility to ensure that key <x> is at
+ * least as long as the keys in the tree. Note that this can be ensured by
+ * having a byte at the end of <x> which cannot be part of any prefix, typically
+ * the trailing zero for a string. If none can be found, return NULL.
+ */
+static forceinline struct ebmb_node *__ebmb_lookup_longest(struct eb_root *root, const void *x)
+{
+	struct ebmb_node *node;
+	eb_troot_t *troot, *cover;
+	int pos, side;
+	int node_bit;
+
+	troot = root->b[EB_LEFT];
+	if (unlikely(troot == NULL))
+		return NULL;
+
+	cover = NULL;
+	pos = 0;
+	while (1) {
+		if ((eb_gettag(troot) == EB_LEAF)) {
+			node = container_of(eb_untag(troot, EB_LEAF),
+					    struct ebmb_node, node.branches);
+			if (check_bits(x - pos, node->key, pos, node->node.pfx))
+				goto not_found;
+
+			return node;
+		}
+		node = container_of(eb_untag(troot, EB_NODE),
+				    struct ebmb_node, node.branches);
+
+		node_bit = node->node.bit;
+		if (node_bit < 0) {
+			/* We have a dup tree now. Either it's for the same
+			 * value, and we walk down left, or it's a different
+			 * one and we don't have our key.
+			 */
+			if (check_bits(x - pos, node->key, pos, node->node.pfx))
+				goto not_found;
+
+			troot = node->node.branches.b[EB_LEFT];
+			while (eb_gettag(troot) != EB_LEAF)
+				troot = (eb_untag(troot, EB_NODE))->b[EB_LEFT];
+			node = container_of(eb_untag(troot, EB_LEAF),
+					    struct ebmb_node, node.branches);
+			return node;
+		}
+
+		node_bit >>= 1; /* strip cover bit */
+		node_bit = ~node_bit + (pos << 3) + 8; // = (pos<<3) + (7 - node_bit)
+		if (node_bit < 0) {
+			/* This uncommon construction gives better performance
+			 * because gcc does not try to reorder the loop. Tested to
+			 * be fine with 2.95 to 4.2.
+			 */
+			while (1) {
+				x++; pos++;
+				if (node->key[pos-1] ^ *(unsigned char*)(x-1))
+					goto not_found; /* more than one full byte is different */
+				node_bit += 8;
+				if (node_bit >= 0)
+					break;
+			}
+		}
+
+		/* here we know that only the last byte differs, so 0 <= node_bit <= 7.
+		 * We have 2 possibilities :
+		 *   - more than the last bit differs => data does not match
+		 *   - walk down on side = (x[pos] >> node_bit) & 1
+		 */
+		side = *(unsigned char *)x >> node_bit;
+		if (((node->key[pos] >> node_bit) ^ side) > 1)
+			goto not_found;
+
+		if (!(node->node.bit & 1)) {
+			/* This is a cover node, let's keep a reference to it
+			 * for later. The covering subtree is on the left, and
+			 * the covered subtree is on the right, so we have to
+			 * walk down right.
+			 */
+			cover = node->node.branches.b[EB_LEFT];
+			troot = node->node.branches.b[EB_RGHT];
+			continue;
+		}
+		side &= 1;
+		troot = node->node.branches.b[side];
+	}
+
+ not_found:
+	/* Walk down last cover tree if it exists. It does not matter if cover is NULL */
+	return ebmb_entry(eb_walk_down(cover, EB_LEFT), struct ebmb_node, node);
+}
+
+
+/* Find the first occurrence of a prefix matching a key <x> of <pfx> BITS in the
+ * tree <root>. It's the caller's responsibility to ensure that key <x> is at
+ * least as long as the keys in the tree. Note that this can be ensured by
+ * having a byte at the end of <x> which cannot be part of any prefix, typically
+ * the trailing zero for a string. If none can be found, return NULL.
+ */
+static forceinline struct ebmb_node *__ebmb_lookup_prefix(struct eb_root *root, const void *x, unsigned int pfx)
+{
+	struct ebmb_node *node;
+	eb_troot_t *troot;
+	int pos, side;
+	int node_bit;
+
+	troot = root->b[EB_LEFT];
+	if (unlikely(troot == NULL))
+		return NULL;
+
+	pos = 0;
+	while (1) {
+		if ((eb_gettag(troot) == EB_LEAF)) {
+			node = container_of(eb_untag(troot, EB_LEAF),
+					    struct ebmb_node, node.branches);
+			if (node->node.pfx != pfx)
+				return NULL;
+			if (check_bits(x - pos, node->key, pos, node->node.pfx))
+				return NULL;
+			return node;
+		}
+		node = container_of(eb_untag(troot, EB_NODE),
+				    struct ebmb_node, node.branches);
+
+		node_bit = node->node.bit;
+		if (node_bit < 0) {
+			/* We have a dup tree now. Either it's for the same
+			 * value, and we walk down left, or it's a different
+			 * one and we don't have our key.
+			 */
+			if (node->node.pfx != pfx)
+				return NULL;
+			if (check_bits(x - pos, node->key, pos, node->node.pfx))
+				return NULL;
+
+			troot = node->node.branches.b[EB_LEFT];
+			while (eb_gettag(troot) != EB_LEAF)
+				troot = (eb_untag(troot, EB_NODE))->b[EB_LEFT];
+			node = container_of(eb_untag(troot, EB_LEAF),
+					    struct ebmb_node, node.branches);
+			return node;
+		}
+
+		node_bit >>= 1; /* strip cover bit */
+		node_bit = ~node_bit + (pos << 3) + 8; // = (pos<<3) + (7 - node_bit)
+		if (node_bit < 0) {
+			/* This uncommon construction gives better performance
+			 * because gcc does not try to reorder the loop. Tested to
+			 * be fine with 2.95 to 4.2.
+			 */
+			while (1) {
+				x++; pos++;
+				if (node->key[pos-1] ^ *(unsigned char*)(x-1))
+					return NULL; /* more than one full byte is different */
+				node_bit += 8;
+				if (node_bit >= 0)
+					break;
+			}
+		}
+
+		/* here we know that only the last byte differs, so 0 <= node_bit <= 7.
+		 * We have 2 possibilities :
+		 *   - more than the last bit differs => data does not match
+		 *   - walk down on side = (x[pos] >> node_bit) & 1
+		 */
+		side = *(unsigned char *)x >> node_bit;
+		if (((node->key[pos] >> node_bit) ^ side) > 1)
+			return NULL;
+
+		if (!(node->node.bit & 1)) {
+			/* This is a cover node, it may be the entry we're
+			 * looking for. We already know that it matches all the
+			 * bits, let's compare prefixes and descend the cover
+			 * subtree if they match.
+			 */
+			if ((unsigned short)node->node.bit >> 1 == pfx)
+				troot = node->node.branches.b[EB_LEFT];
+			else
+				troot = node->node.branches.b[EB_RGHT];
+			continue;
+		}
+		side &= 1;
+		troot = node->node.branches.b[side];
+	}
+}
+
+
+/* Insert ebmb_node <new> into a prefix subtree starting at node root <root>.
+ * Only new->key and new->pfx need be set with the key and its prefix length.
+ * Note that bits between <pfx> and <len> are theoretically ignored and should be
+ * zero, as it is not certain yet that they will always be ignored everywhere
+ * (eg in bit compare functions).
+ * The ebmb_node is returned.
+ * If root->b[EB_RGHT]==1, the tree may only contain unique keys. The
+ * len is specified in bytes.
+ */
+static forceinline struct ebmb_node *
+__ebmb_insert_prefix(struct eb_root *root, struct ebmb_node *new, unsigned int len)
+{
+	struct ebmb_node *old;
+	unsigned int side;
+	eb_troot_t *troot, **up_ptr;
+	eb_troot_t *root_right;
+	int diff;
+	int bit;
+	eb_troot_t *new_left, *new_rght;
+	eb_troot_t *new_leaf;
+	int old_node_bit;
+
+	side = EB_LEFT;
+	troot = root->b[EB_LEFT];
+	root_right = root->b[EB_RGHT];
+	if (unlikely(troot == NULL)) {
+		/* Tree is empty, insert the leaf part below the left branch */
+		root->b[EB_LEFT] = eb_dotag(&new->node.branches, EB_LEAF);
+		new->node.leaf_p = eb_dotag(root, EB_LEFT);
+		new->node.node_p = NULL; /* node part unused */
+		return new;
+	}
+
+	len <<= 3;
+	if (len > new->node.pfx)
+		len = new->node.pfx;
+
+	/* The tree descent is fairly easy :
+	 *  - first, check if we have reached a leaf node
+	 *  - second, check if we have gone too far
+	 *  - third, reiterate
+	 * Everywhere, we use <new> for the node node we are inserting, <root>
+	 * for the node we attach it to, and <old> for the node we are
+	 * displacing below <new>. <troot> will always point to the future node
+	 * (tagged with its type). <side> carries the side the node <new> is
+	 * attached to below its parent, which is also where previous node
+	 * was attached.
+	 */
+
+	bit = 0;
+	while (1) {
+		if (unlikely(eb_gettag(troot) == EB_LEAF)) {
+			/* Insert above a leaf. Note that this leaf could very
+			 * well be part of a cover node.
+			 */
+			old = container_of(eb_untag(troot, EB_LEAF),
+					    struct ebmb_node, node.branches);
+			new->node.node_p = old->node.leaf_p;
+			up_ptr = &old->node.leaf_p;
+			goto check_bit_and_break;
+		}
+
+		/* OK we're walking down this link */
+		old = container_of(eb_untag(troot, EB_NODE),
+				   struct ebmb_node, node.branches);
+		old_node_bit = old->node.bit;
+		/* Note that old_node_bit can be :
+		 *   < 0    : dup tree
+		 *   = 2N   : cover node for N bits
+		 *   = 2N+1 : normal node at N bits
+		 */
+
+		if (unlikely(old_node_bit < 0)) {
+			/* We're above a duplicate tree, so we must compare the whole value */
+			new->node.node_p = old->node.node_p;
+			up_ptr = &old->node.node_p;
+		check_bit_and_break:
+			/* No need to compare everything if the leaves are shorter than the new one. */
+			if (len > old->node.pfx)
+				len = old->node.pfx;
+			bit = equal_bits(new->key, old->key, bit, len);
+			break;
+		}
+
+		/* WARNING: for the two blocks below, <bit> is counted in half-bits */
+
+		bit = equal_bits(new->key, old->key, bit, old_node_bit >> 1);
+		bit = (bit << 1) + 1; // assume comparisons with normal nodes
+
+		/* we must always check that our prefix is larger than the nodes
+		 * we visit, otherwise we have to stop going down. The following
+		 * test is able to stop before both normal and cover nodes.
+		 */
+		if (bit >= (new->node.pfx << 1) && (new->node.pfx << 1) < old_node_bit) {
+			/* insert cover node here on the left */
+			new->node.node_p = old->node.node_p;
+			up_ptr = &old->node.node_p;
+			new->node.bit = new->node.pfx << 1;
+			diff = -1;
+			goto insert_above;
+		}
+
+		if (unlikely(bit < old_node_bit)) {
+			/* The tree did not contain the key, so we insert <new> before the
+			 * node <old>, and set ->bit to designate the lowest bit position in
+			 * <new> which applies to ->branches.b[]. We know that the bit is not
+			 * greater than the prefix length thanks to the test above.
+			 */
+			new->node.node_p = old->node.node_p;
+			up_ptr = &old->node.node_p;
+			new->node.bit = bit;
+			diff = cmp_bits(new->key, old->key, bit >> 1);
+			goto insert_above;
+		}
+
+		if (!(old_node_bit & 1)) {
+			/* if we encounter a cover node with our exact prefix length, it's
+			 * necessarily the same value, so we insert there as a duplicate on
+			 * the left. For that, we go down on the left and the leaf detection
+			 * code will finish the job.
+			 */
+			if ((new->node.pfx << 1) == old_node_bit) {
+				root = &old->node.branches;
+				side = EB_LEFT;
+				troot = root->b[side];
+				continue;
+			}
+
+			/* cover nodes are always walked through on the right */
+			side = EB_RGHT;
+			bit = old_node_bit >> 1; /* recheck that bit */
+			root = &old->node.branches;
+			troot = root->b[side];
+			continue;
+		}
+
+		/* we don't want to skip bits for further comparisons, so we must limit <bit>.
+		 * However, since we're going down around <old_node_bit>, we know it will be
+		 * properly matched, so we can skip this bit.
+		 */
+		old_node_bit >>= 1;
+		bit = old_node_bit + 1;
+
+		/* walk down */
+		root = &old->node.branches;
+		side = old_node_bit & 7;
+		side ^= 7;
+		side = (new->key[old_node_bit >> 3] >> side) & 1;
+		troot = root->b[side];
+	}
+
+	/* Right here, we have 4 possibilities :
+	 * - the tree does not contain any leaf matching the
+	 *   key, and we have new->key < old->key. We insert
+	 *   new above old, on the left ;
+	 *
+	 * - the tree does not contain any leaf matching the
+	 *   key, and we have new->key > old->key. We insert
+	 *   new above old, on the right ;
+	 *
+	 * - the tree does contain the key with the same prefix
+	 *   length. We add the new key next to it as a first
+	 *   duplicate (since it was alone).
+	 *
+	 * The last two cases can easily be partially merged.
+	 *
+	 * - the tree contains a leaf matching the key, we have
+	 *   to insert above it as a cover node. The leaf with
+	 *   the shortest prefix becomes the left subtree and
+	 *   the leaf with the longest prefix becomes the right
+	 *   one. The cover node gets the min of both prefixes
+	 *   as its new bit.
+	 */
+
+	/* first we want to ensure that we compare the correct bit, which means
+	 * the largest common to both nodes.
+	 */
+	if (bit > new->node.pfx)
+		bit = new->node.pfx;
+	if (bit > old->node.pfx)
+		bit = old->node.pfx;
+
+	new->node.bit = (bit << 1) + 1; /* assume normal node by default */
+
+	/* if one prefix is included in the second one, we don't compare bits
+	 * because they won't necessarily match, we just proceed with a cover
+	 * node insertion.
+	 */
+	diff = 0;
+	if (bit < old->node.pfx && bit < new->node.pfx)
+		diff = cmp_bits(new->key, old->key, bit);
+
+	if (diff == 0) {
+		/* Both keys match. Either it's a duplicate entry or we have to
+		 * put the shortest prefix left and the largest one right below
+		 * a new cover node. By default, diff==0 means we'll be inserted
+		 * on the right.
+		 */
+		new->node.bit--; /* anticipate cover node insertion */
+		if (new->node.pfx == old->node.pfx) {
+			new->node.bit = -1; /* mark as new dup tree, just in case */
+
+			if (unlikely(eb_gettag(root_right))) {
+				/* we refuse to duplicate this key if the tree is
+				 * tagged as containing only unique keys.
+				 */
+				return old;
+			}
+
+			if (eb_gettag(troot) != EB_LEAF) {
+				/* there was already a dup tree below */
+				struct eb_node *ret;
+				ret = eb_insert_dup(&old->node, &new->node);
+				return container_of(ret, struct ebmb_node, node);
+			}
+			/* otherwise fall through to insert first duplicate */
+		}
+		/* otherwise we just rely on the tests below to select the right side */
+		else if (new->node.pfx < old->node.pfx)
+			diff = -1; /* force insertion to left side */
+	}
+
+ insert_above:
+	new_left = eb_dotag(&new->node.branches, EB_LEFT);
+	new_rght = eb_dotag(&new->node.branches, EB_RGHT);
+	new_leaf = eb_dotag(&new->node.branches, EB_LEAF);
+
+	if (diff >= 0) {
+		new->node.branches.b[EB_LEFT] = troot;
+		new->node.branches.b[EB_RGHT] = new_leaf;
+		new->node.leaf_p = new_rght;
+		*up_ptr = new_left;
+	}
+	else {
+		new->node.branches.b[EB_LEFT] = new_leaf;
+		new->node.branches.b[EB_RGHT] = troot;
+		new->node.leaf_p = new_left;
+		*up_ptr = new_rght;
+	}
+
+	root->b[side] = eb_dotag(&new->node.branches, EB_NODE);
+	return new;
+}
+
+
+
+#endif /* _EBMBTREE_H */
+