warshall.c revision 1.6 
1/*	$OpenBSD: warshall.c,v 1.6 2002/02/16 21:28:00 millert 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. All advertising materials mentioning features or use of this software
20 *    must display the following acknowledgement:
21 *	This product includes software developed by the University of
22 *	California, Berkeley and its contributors.
23 * 4. Neither the name of the University nor the names of its contributors
24 *    may be used to endorse or promote products derived from this software
25 *    without specific prior written permission.
26 *
27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
30 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
37 * SUCH DAMAGE.
38 */
39
40#ifndef lint
41#if 0
42static char sccsid[] = "@(#)warshall.c	5.4 (Berkeley) 5/24/93";
43#else
44static char rcsid[] = "$OpenBSD: warshall.c,v 1.6 2002/02/16 21:28:00 millert Exp $";
45#endif
46#endif /* not lint */
47
48#include "defs.h"
49
50void transitive_closure(unsigned *, int);
51
52void
53transitive_closure(R, n)
54unsigned *R;
55int n;
56{
57    int rowsize;
58    unsigned i;
59    unsigned *rowj;
60    unsigned *rp;
61    unsigned *rend;
62    unsigned *ccol;
63    unsigned *relend;
64    unsigned *cword;
65    unsigned *rowi;
66
67    rowsize = WORDSIZE(n);
68    relend = R + n*rowsize;
69
70    cword = R;
71    i = 0;
72    rowi = R;
73    while (rowi < relend)
74    {
75	ccol = cword;
76	rowj = R;
77
78	while (rowj < relend)
79	{
80	    if (*ccol & (1 << i))
81	    {
82		rp = rowi;
83		rend = rowj + rowsize;
84		while (rowj < rend)
85		    *rowj++ |= *rp++;
86	    }
87	    else
88	    {
89		rowj += rowsize;
90	    }
91
92	    ccol += rowsize;
93	}
94
95	if (++i >= BITS_PER_WORD)
96	{
97	    i = 0;
98	    cword++;
99	}
100
101	rowi += rowsize;
102    }
103}
104
105void
106reflexive_transitive_closure(R, n)
107unsigned *R;
108int n;
109{
110    int rowsize;
111    unsigned i;
112    unsigned *rp;
113    unsigned *relend;
114
115    transitive_closure(R, n);
116
117    rowsize = WORDSIZE(n);
118    relend = R + n*rowsize;
119
120    i = 0;
121    rp = R;
122    while (rp < relend)
123    {
124	*rp |= (1 << i);
125	if (++i >= BITS_PER_WORD)
126	{
127	    i = 0;
128	    rp++;
129	}
130
131	rp += rowsize;
132    }
133}
134