warshall.c

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/*************************************************************************\
* Copyright (c) 2002 The University of Chicago, as Operator of Argonne
*     National Laboratory.
* Copyright (c) 2002 The Regents of the University of California, as
*     Operator of Los Alamos National Laboratory.
* EPICS BASE is distributed subject to a Software License Agreement found
* in file LICENSE that is included with this distribution.
\*************************************************************************/
#include "defs.h"

static void
transitive_closure(unsigned int *R, int n)
{
    int rowsize;
    unsigned i;
    unsigned *rowj;
    unsigned *rp;
    unsigned *rend;
    unsigned *ccol;
    unsigned *relend;
    unsigned *cword;
    unsigned *rowi;

    rowsize = WORDSIZE(n);
    relend = R + n*rowsize;

    cword = R;
    i = 0;
    rowi = R;
    while (rowi < relend)
    {
        ccol = cword;
        rowj = R;

        while (rowj < relend)
        {
            if (*ccol & (1 << i))
            {
                rp = rowi;
                rend = rowj + rowsize;
                while (rowj < rend)
                    *rowj++ |= *rp++;
            }
            else
            {
                rowj += rowsize;
            }

            ccol += rowsize;
        }

        if (++i >= BITS_PER_WORD)
        {
            i = 0;
            cword++;
        }

        rowi += rowsize;
    }
}

void
reflexive_transitive_closure(unsigned int *R, int n)
{
    int rowsize;
    unsigned i;
    unsigned *rp;
    unsigned *relend;

    transitive_closure(R, n);

    rowsize = WORDSIZE(n);
    relend = R + n*rowsize;

    i = 0;
    rp = R;
    while (rp < relend)
    {
        *rp |= (1 << i);
        if (++i >= BITS_PER_WORD)
        {
            i = 0;
            rp++;
        }

        rp += rowsize;
    }
}