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warshall.c
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1991-11-03
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/* Generate transitive closure of a matrix,
Copyright (C) 1984, 1989 Free Software Foundation, Inc.
This file is part of Bison, the GNU Compiler Compiler.
Bison is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
Bison is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with Bison; see the file COPYING. If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
#include <stdio.h>
#include "system.h"
#include "machine.h"
/* given n by n matrix of bits R, modify its contents
to be the transive closure of what was given. */
void
TC(R, n)
unsigned *R;
int n;
{
register int rowsize;
register unsigned mask;
register unsigned *rowj;
register unsigned *rp;
register unsigned *rend;
register unsigned *ccol;
unsigned *relend;
unsigned *cword;
unsigned *rowi;
rowsize = WORDSIZE(n) * sizeof(unsigned);
relend = (unsigned *) ((char *) R + (n * rowsize));
cword = R;
mask = 1;
rowi = R;
while (rowi < relend)
{
ccol = cword;
rowj = R;
while (rowj < relend)
{
if (*ccol & mask)
{
rp = rowi;
rend = (unsigned *) ((char *) rowj + rowsize);
while (rowj < rend)
*rowj++ |= *rp++;
}
else
{
rowj = (unsigned *) ((char *) rowj + rowsize);
}
ccol = (unsigned *) ((char *) ccol + rowsize);
}
mask <<= 1;
if (mask == 0)
{
mask = 1;
cword++;
}
rowi = (unsigned *) ((char *) rowi + rowsize);
}
}
/* Reflexive Transitive Closure. Same as TC
and then set all the bits on the diagonal of R. */
void
RTC(R, n)
unsigned *R;
int n;
{
register int rowsize;
register unsigned mask;
register unsigned *rp;
register unsigned *relend;
TC(R, n);
rowsize = WORDSIZE(n) * sizeof(unsigned);
relend = (unsigned *) ((char *) R + n*rowsize);
mask = 1;
rp = R;
while (rp < relend)
{
*rp |= mask;
mask <<= 1;
if (mask == 0)
{
mask = 1;
rp++;
}
rp = (unsigned *) ((char *) rp + rowsize);
}
}