warshall.c revision 1.8 
1/*	$OpenBSD: warshall.c,v 1.8 2003/06/19 16:34:53 pvalchev Exp $	*/
2/*	$NetBSD: warshall.c,v 1.4 1996/03/19 03:21:51 jtc Exp $	*/
3
4/*
5 * Copyright (c) 1989 The Regents of the University of California.
6 * All rights reserved.
7 *
8 * This code is derived from software contributed to Berkeley by
9 * Robert Paul Corbett.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 *    notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 *    notice, this list of conditions and the following disclaimer in the
18 *    documentation and/or other materials provided with the distribution.
19 * 3. Neither the name of the University nor the names of its contributors
20 *    may be used to endorse or promote products derived from this software
21 *    without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36#ifndef lint
37#if 0
38static char sccsid[] = "@(#)warshall.c	5.4 (Berkeley) 5/24/93";
39#else
40static char rcsid[] = "$OpenBSD: warshall.c,v 1.8 2003/06/19 16:34:53 pvalchev Exp $";
41#endif
42#endif /* not lint */
43
44#include "defs.h"
45
46void transitive_closure(unsigned int *, int);
47
48void
49transitive_closure(unsigned int *R, int n)
50{
51    int rowsize;
52    unsigned i;
53    unsigned *rowj;
54    unsigned *rp;
55    unsigned *rend;
56    unsigned *ccol;
57    unsigned *relend;
58    unsigned *cword;
59    unsigned *rowi;
60
61    rowsize = WORDSIZE(n);
62    relend = R + n*rowsize;
63
64    cword = R;
65    i = 0;
66    rowi = R;
67    while (rowi < relend)
68    {
69	ccol = cword;
70	rowj = R;
71
72	while (rowj < relend)
73	{
74	    if (*ccol & (1 << i))
75	    {
76		rp = rowi;
77		rend = rowj + rowsize;
78		while (rowj < rend)
79		    *rowj++ |= *rp++;
80	    }
81	    else
82	    {
83		rowj += rowsize;
84	    }
85
86	    ccol += rowsize;
87	}
88
89	if (++i >= BITS_PER_WORD)
90	{
91	    i = 0;
92	    cword++;
93	}
94
95	rowi += rowsize;
96    }
97}
98
99void
100reflexive_transitive_closure(unsigned int *R, int n)
101{
102    int rowsize;
103    unsigned i;
104    unsigned *rp;
105    unsigned *relend;
106
107    transitive_closure(R, n);
108
109    rowsize = WORDSIZE(n);
110    relend = R + n*rowsize;
111
112    i = 0;
113    rp = R;
114    while (rp < relend)
115    {
116	*rp |= (1 << i);
117	if (++i >= BITS_PER_WORD)
118	{
119	    i = 0;
120	    rp++;
121	}
122
123	rp += rowsize;
124    }
125}
126