usr.bin/yacc/warshall.c

   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  * $FreeBSD: src/usr.bin/yacc/warshall.c,v 1.6 1999/08/28 01:08:04 peter Exp $
  37  * $DragonFly: src/usr.bin/yacc/warshall.c,v 1.4 2004/04/07 20:43:24 cpressey Exp $
  38  *
  39  * @(#)warshall.c       5.4 (Berkeley) 5/24/93
  40  */
  41
  42 #include "defs.h"
  43
  44 static void transitive_closure(unsigned *, int);
  45
  46 static void
  47 transitive_closure(unsigned *R, int n)
  48 {
  49     int rowsize;
  50     unsigned i;
  51     unsigned *rowj;
  52     unsigned *rp;
  53     unsigned *rend;
  54     unsigned *ccol;
  55     unsigned *relend;
  56     unsigned *cword;
  57     unsigned *rowi;
  58
  59     rowsize = WORDSIZE(n);
  60     relend = R + n*rowsize;
  61
  62     cword = R;
  63     i = 0;
  64     rowi = R;
  65     while (rowi < relend)
  66     {
  67         ccol = cword;
  68         rowj = R;
  69
  70         while (rowj < relend)
  71         {
  72             if (*ccol & (1 << i))
  73             {
  74                 rp = rowi;
  75                 rend = rowj + rowsize;
  76                 while (rowj < rend)
  77                     *rowj++ |= *rp++;
  78             }
  79             else
  80             {
  81                 rowj += rowsize;
  82             }
  83
  84             ccol += rowsize;
  85         }
  86
  87         if (++i >= BITS_PER_WORD)
  88         {
  89             i = 0;
  90             cword++;
  91         }
  92
  93         rowi += rowsize;
  94     }
  95 }
  96
  97 void
  98 reflexive_transitive_closure(unsigned *R, int n)
  99 {
 100     int rowsize;
 101     unsigned i;
 102     unsigned *rp;
 103     unsigned *relend;
 104
 105     transitive_closure(R, n);
 106
 107     rowsize = WORDSIZE(n);
 108     relend = R + n*rowsize;
 109
 110     i = 0;
 111     rp = R;
 112     while (rp < relend)
 113     {
 114         *rp |= (1 << i);
 115         if (++i >= BITS_PER_WORD)
 116         {
 117             i = 0;
 118             rp++;
 119         }
 120
 121         rp += rowsize;
 122     }
 123 }