1 /***********************************************************************
2 * *
3 * This software is part of the ast package *
4 * Copyright (c) 1985-2010 AT&T Intellectual Property *
5 * and is licensed under the *
6 * Common Public License, Version 1.0 *
7 * by AT&T Intellectual Property *
8 * *
9 * A copy of the License is available at *
10 * http://www.opensource.org/licenses/cpl1.0.txt *
11 * (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9) *
12 * *
13 * Information and Software Systems Research *
14 * AT&T Research *
15 * Florham Park NJ *
16 * *
17 * Glenn Fowler <gsf@research.att.com> *
18 * David Korn <dgk@research.att.com> *
19 * Phong Vo <kpv@research.att.com> *
20 * *
21 ***********************************************************************/
22 #include "dthdr.h"
23
24 /* Set attributes of a tree.
25 **
26 ** Written by Kiem-Phong Vo (09/17/2001)
27 */
28
29 #if __STD_C
treebalance(Dtlink_t * list,int size)30 static Dtlink_t* treebalance(Dtlink_t* list, int size)
31 #else
32 static Dtlink_t* treebalance(list, size)
33 Dtlink_t* list;
34 int size;
35 #endif
36 {
37 int n;
38 Dtlink_t *l, *mid;
39
40 if(size <= 2)
41 return list;
42
43 for(l = list, n = size/2 - 1; n > 0; n -= 1)
44 l = l->right;
45
46 mid = l->right; l->right = NIL(Dtlink_t*);
47 mid->left = treebalance(list, (n = size/2) );
48 mid->right = treebalance(mid->right, size - (n + 1));
49 return mid;
50 }
51
52 #if __STD_C
dttreeset(Dt_t * dt,int minp,int balance)53 int dttreeset(Dt_t* dt, int minp, int balance)
54 #else
55 int dttreeset(dt, minp, balance)
56 Dt_t* dt;
57 int minp;
58 int balance;
59 #endif
60 {
61 int size;
62
63 if(dt->meth->type != DT_OSET)
64 return -1;
65
66 size = dtsize(dt);
67
68 if(minp < 0)
69 { for(minp = 0; minp < DT_MINP; ++minp)
70 if((1 << minp) >= size)
71 break;
72 if(minp <= DT_MINP-4) /* use log(size) + 4 */
73 minp += 4;
74 }
75
76 if((dt->data->minp = minp + (minp%2)) > DT_MINP)
77 dt->data->minp = DT_MINP;
78
79 if(balance)
80 dt->data->here = treebalance(dtflatten(dt), size);
81
82 return 0;
83 }
84