warshall.c revision 1.9 
1/*	$OpenBSD: warshall.c,v 1.9 2009/10/27 23:59:50 deraadt 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#include "defs.h"
37
38void transitive_closure(unsigned int *, int);
39
40void
41transitive_closure(unsigned int *R, int n)
42{
43    int rowsize;
44    unsigned i;
45    unsigned *rowj;
46    unsigned *rp;
47    unsigned *rend;
48    unsigned *ccol;
49    unsigned *relend;
50    unsigned *cword;
51    unsigned *rowi;
52
53    rowsize = WORDSIZE(n);
54    relend = R + n*rowsize;
55
56    cword = R;
57    i = 0;
58    rowi = R;
59    while (rowi < relend)
60    {
61	ccol = cword;
62	rowj = R;
63
64	while (rowj < relend)
65	{
66	    if (*ccol & (1 << i))
67	    {
68		rp = rowi;
69		rend = rowj + rowsize;
70		while (rowj < rend)
71		    *rowj++ |= *rp++;
72	    }
73	    else
74	    {
75		rowj += rowsize;
76	    }
77
78	    ccol += rowsize;
79	}
80
81	if (++i >= BITS_PER_WORD)
82	{
83	    i = 0;
84	    cword++;
85	}
86
87	rowi += rowsize;
88    }
89}
90
91void
92reflexive_transitive_closure(unsigned int *R, int n)
93{
94    int rowsize;
95    unsigned i;
96    unsigned *rp;
97    unsigned *relend;
98
99    transitive_closure(R, n);
100
101    rowsize = WORDSIZE(n);
102    relend = R + n*rowsize;
103
104    i = 0;
105    rp = R;
106    while (rp < relend)
107    {
108	*rp |= (1 << i);
109	if (++i >= BITS_PER_WORD)
110	{
111	    i = 0;
112	    rp++;
113	}
114
115	rp += rowsize;
116    }
117}
118