warshall.c revision 1.7 
1/*	$OpenBSD: warshall.c,v 1.7 2003/06/03 02:56:24 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. 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 1.7 2003/06/03 02:56:24 millert Exp $";
41#endif
42#endif /* not lint */
43
44#include "defs.h"
45
46void transitive_closure(unsigned *, int);
47
48void
49transitive_closure(R, n)
50unsigned *R;
51int n;
52{
53    int rowsize;
54    unsigned i;
55    unsigned *rowj;
56    unsigned *rp;
57    unsigned *rend;
58    unsigned *ccol;
59    unsigned *relend;
60    unsigned *cword;
61    unsigned *rowi;
62
63    rowsize = WORDSIZE(n);
64    relend = R + n*rowsize;
65
66    cword = R;
67    i = 0;
68    rowi = R;
69    while (rowi < relend)
70    {
71	ccol = cword;
72	rowj = R;
73
74	while (rowj < relend)
75	{
76	    if (*ccol & (1 << i))
77	    {
78		rp = rowi;
79		rend = rowj + rowsize;
80		while (rowj < rend)
81		    *rowj++ |= *rp++;
82	    }
83	    else
84	    {
85		rowj += rowsize;
86	    }
87
88	    ccol += rowsize;
89	}
90
91	if (++i >= BITS_PER_WORD)
92	{
93	    i = 0;
94	    cword++;
95	}
96
97	rowi += rowsize;
98    }
99}
100
101void
102reflexive_transitive_closure(R, n)
103unsigned *R;
104int n;
105{
106    int rowsize;
107    unsigned i;
108    unsigned *rp;
109    unsigned *relend;
110
111    transitive_closure(R, n);
112
113    rowsize = WORDSIZE(n);
114    relend = R + n*rowsize;
115
116    i = 0;
117    rp = R;
118    while (rp < relend)
119    {
120	*rp |= (1 << i);
121	if (++i >= BITS_PER_WORD)
122	{
123	    i = 0;
124	    rp++;
125	}
126
127	rp += rowsize;
128    }
129}
130