1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
|
/*
* Copyright (C) 2001 Sistina Software (UK) Limited.
*
* This file is released under the LGPL.
*/
#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 1
return ((k & 0xff) << 24 |
(k & 0xff00) << 8 |
(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;
}
|
