warshall.c revision 87234 
1/*
2 * Copyright (c) 1989 The Regents of the University of California.
3 * All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Robert Paul Corbett.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 *    must display the following acknowledgement:
18 *	This product includes software developed by the University of
19 *	California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 *    may be used to endorse or promote products derived from this software
22 *    without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 */
36
37#include <sys/cdefs.h>
38
39__FBSDID("$FreeBSD: head/usr.bin/yacc/warshall.c 87234 2001-12-02 21:24:03Z markm $");
40
41#ifndef lint
42static char const sccsid[] = "@(#)warshall.c	5.4 (Berkeley) 5/24/93";
43#endif
44
45#include "defs.h"
46
47static void transitive_closure __P((unsigned *, int));
48
49static void
50transitive_closure(R, n)
51unsigned *R;
52int n;
53{
54    int rowsize;
55    unsigned i;
56    unsigned *rowj;
57    unsigned *rp;
58    unsigned *rend;
59    unsigned *ccol;
60    unsigned *relend;
61    unsigned *cword;
62    unsigned *rowi;
63
64    rowsize = WORDSIZE(n);
65    relend = R + n*rowsize;
66
67    cword = R;
68    i = 0;
69    rowi = R;
70    while (rowi < relend)
71    {
72	ccol = cword;
73	rowj = R;
74
75	while (rowj < relend)
76	{
77	    if (*ccol & (1 << i))
78	    {
79		rp = rowi;
80		rend = rowj + rowsize;
81		while (rowj < rend)
82		    *rowj++ |= *rp++;
83	    }
84	    else
85	    {
86		rowj += rowsize;
87	    }
88
89	    ccol += rowsize;
90	}
91
92	if (++i >= BITS_PER_WORD)
93	{
94	    i = 0;
95	    cword++;
96	}
97
98	rowi += rowsize;
99    }
100}
101
102void
103reflexive_transitive_closure(R, n)
104unsigned *R;
105int n;
106{
107    int rowsize;
108    unsigned i;
109    unsigned *rp;
110    unsigned *relend;
111
112    transitive_closure(R, n);
113
114    rowsize = WORDSIZE(n);
115    relend = R + n*rowsize;
116
117    i = 0;
118    rp = R;
119    while (rp < relend)
120    {
121	*rp |= (1 << i);
122	if (++i >= BITS_PER_WORD)
123	{
124	    i = 0;
125	    rp++;
126	}
127
128	rp += rowsize;
129    }
130}
131