o Trivial binary tree

diff --git a/include/.symlinks b/include/.symlinks
index be45176796521cb2f74e8fc5aead456b0a69e7cb..7882084d7ec98e030a18998fc380f12cce73c660 100644 (file)
--- a/include/.symlinks
+++ b/include/.symlinks
@@ -1,6 +1,7 @@
 ../lib/activate/activate.h
 ../lib/config/config.h
 ../lib/datastruct/bitset.h
+../lib/datastruct/btree.h
 ../lib/datastruct/hash.h
 ../lib/datastruct/list.h
 ../lib/datastruct/lvm-types.h

diff --git a/lib/Makefile.in b/lib/Makefile.in
index 7d3ffbfe03c0515e9cb1f6bf0e1f48ae6d00d2d2..a171123a802f2709da30a0d229117d7082d9ff0c 100644 (file)
--- a/lib/Makefile.in
+++ b/lib/Makefile.in
@@ -12,8 +12,8 @@ SOURCES=\
        activate/activate.c \
        config/config.c \
        datastruct/bitset.c \
+       datastruct/btree.c \
        datastruct/hash.c \
-       device/btree.c \
        device/dev-cache.c \
        device/dev-io.c \
        device/device.c \

diff --git a/lib/datastruct/btree.c b/lib/datastruct/btree.c
new file mode 100644 (file)
index 0000000..6392a64
--- /dev/null
+++ b/lib/datastruct/btree.c
@@ -0,0 +1,130 @@
+/*
+ * Copyright (C) 2001 Sistina Software (UK) Limited.
+ *
+ * This file is released under the GPL.
+ */
+
+#include "btree.h"
+#include "log.h"
+
+struct node {
+       uint32_t key;
+       struct node *l, *r, *p;
+
+       void *data;
+};
+
+struct btree {
+       struct pool *mem;
+       struct node *root;
+};
+
+struct btree *btree_create(struct pool *mem)
+{
+       struct btree *t = pool_alloc(mem, sizeof(*t));
+
+       if (t) {
+               t->mem = mem;
+               t->root = NULL;
+       }
+
+       return t;
+}
+
+/*
+ * Shuffle the bits in a key, to try and remove
+ * any ordering.
+ */
+static uint32_t _shuffle(uint32_t k)
+{
+#if 0
+       return ((k & 0xff) << 24 |
+               (k & 0xff00) << 16 |
+               (k & 0xff0000) >> 8 |
+               (k & 0xff000000) >> 24);
+#else
+       return k;
+#endif
+}
+
+struct node **_lookup(struct node **c, uint32_t key, struct node **p)
+{
+       *p = NULL;
+       while (*c) {
+               *p = *c;
+               if ((*c)->key == key)
+                       break;
+
+               if (key < (*c)->key)
+                       c = &(*c)->l;
+
+               else
+                       c = &(*c)->r;
+       }
+
+       return c;
+}
+
+void *btree_lookup(struct btree *t, uint32_t k)
+{
+       uint32_t key = _shuffle(k);
+       struct node *p, **c = _lookup(&t->root, key, &p);
+       return (*c) ? (*c)->data : NULL;
+}
+
+int btree_insert(struct btree *t, uint32_t k, void *data)
+{
+       uint32_t key = _shuffle(k);
+       struct node *p, **c = _lookup(&t->root, key, &p), *n;
+
+       if (!*c) {
+               if (!(n = pool_alloc(t->mem, sizeof(*n)))) {
+                       stack;
+                       return 0;
+               }
+
+               n->key = key;
+               n->data = data;
+               n->l = n->r = NULL;
+               n->p = p;
+
+               *c = n;
+       }
+
+       return 1;
+}
+
+void *btree_get_data(struct btree_iter *it)
+{
+       return ((struct node *) it)->data;
+}
+
+static inline struct node *_left(struct node *n)
+{
+       while (n->l)
+               n = n->l;
+       return n;
+}
+
+struct btree_iter *btree_first(struct btree *t)
+{
+       if (!t->root)
+               return NULL;
+
+       return (struct btree_iter *) _left(t->root);
+}
+
+struct btree_iter *btree_next(struct btree_iter *it)
+{
+       struct node *n = (struct node *) it;
+       uint32_t k = n->key;
+
+       if (n->r)
+               return (struct btree_iter *) _left(n->r);
+
+       do
+               n = n->p;
+       while (n && k > n->key);
+
+       return (struct btree_iter *) n;
+}

diff --git a/lib/datastruct/btree.h b/lib/datastruct/btree.h
new file mode 100644 (file)
index 0000000..4ae8770
--- /dev/null
+++ b/lib/datastruct/btree.h
@@ -0,0 +1,26 @@
+/*
+ * Copyright (C) 2001 Sistina Software (UK) Limited.
+ *
+ * This file is released under the GPL.
+ */
+
+#ifndef _LVM_BTREE_H
+#define _LVM_BTREE_H
+
+#include "lvm-types.h"
+#include "pool.h"
+
+struct btree;
+
+struct btree *btree_create(struct pool *mem);
+
+void *btree_lookup(struct btree *t, uint32_t k);
+int btree_insert(struct btree *t, uint32_t k, void *data);
+
+struct btree_iter;
+void *btree_get_data(struct btree_iter *it);
+
+struct btree_iter *btree_first(struct btree *t);
+struct btree_iter *btree_next(struct btree_iter *it);
+
+#endif