warshall.c revision 1.10 
1/* $OpenBSD: warshall.c,v 1.10 2014/03/13 00:56:39 tedu 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		ccol = cword;
61		rowj = R;
62
63		while (rowj < relend) {
64			if (*ccol & (1 << i)) {
65				rp = rowi;
66				rend = rowj + rowsize;
67				while (rowj < rend)
68					*rowj++ |= *rp++;
69			} else {
70				rowj += rowsize;
71			}
72
73			ccol += rowsize;
74		}
75
76		if (++i >= BITS_PER_WORD) {
77			i = 0;
78			cword++;
79		}
80		rowi += rowsize;
81	}
82}
83
84void
85reflexive_transitive_closure(unsigned int *R, int n)
86{
87	int rowsize;
88	unsigned i;
89	unsigned *rp;
90	unsigned *relend;
91
92	transitive_closure(R, n);
93
94	rowsize = WORDSIZE(n);
95	relend = R + n * rowsize;
96
97	i = 0;
98	rp = R;
99	while (rp < relend) {
100		*rp |= (1 << i);
101		if (++i >= BITS_PER_WORD) {
102			i = 0;
103			rp++;
104		}
105		rp += rowsize;
106	}
107}
108