1/***********************************************************************
2*                                                                      *
3*               This software is part of the ast package               *
4*          Copyright (c) 1985-2011 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
30static Dtlink_t* treebalance(Dtlink_t* list, int size)
31#else
32static Dtlink_t* treebalance(list, size)
33Dtlink_t*	list;
34int		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
53int dttreeset(Dt_t* dt, int minp, int balance)
54#else
55int dttreeset(dt, minp, balance)
56Dt_t*	dt;
57int	minp;
58int	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