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/* bit.c --
* Created: Thu Sep 28 18:09:30 1995 by faith@cs.unc.edu
* Revised: Mon Sep 23 16:23:51 1996 by faith@cs.unc.edu
* Copyright 1995, 1996 Rickard E. Faith (faith@cs.unc.edu)
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Library General Public License as published
* by the Free Software Foundation; either version 2 of the License, or (at
* your option) any later version.
*
* This library 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* $Id: bit.c,v 1.6 1999/12/23 08:43:39 faith Exp $
*
* \section{Bit manipulation routines}
*
* \intro These are a set of simple routine to manipulate bits in an
* integer.
*
*/
#include "maaP.h"
/* \doc Set |bit| in |flags|. */
__inline__ void bit_set( unsigned long *flags, int bit )
{
*flags |= (1UL << bit);
}
/* \doc Clear |bit| in |flags|. */
__inline__ void bit_clr( unsigned long *flags, int bit )
{
*flags &= ~(1UL << bit);
}
/* \doc Test |bit| in |flags|, returning non-zero if the bit is set and
zero if the bit is clear. */
__inline__ int bit_tst( unsigned long *flags, int bit )
{
return (*flags & (1UL << bit));
}
/* \doc Return a count of the number of bits set in |flags|. */
__inline__ int bit_cnt( unsigned long *flags )
{
unsigned long x = *flags;
#if SIZEOF_LONG == 4
x = (x >> 1 & 0x55555555) + (x & 0x55555555);
x = ((x >> 2) & 0x33333333) + (x & 0x33333333);
x = ((x >> 4) + x) & 0x0f0f0f0f;
x = ((x >> 8) + x);
return (x + (x >> 16)) & 0xff;
#else
#if SIZEOF_LONG == 8
x = (x >> 1 & 0x5555555555555555) + (x & 0x5555555555555555);
x = ((x >> 2) & 0x3333333333333333) + (x & 0x3333333333333333);
x = ((x >> 4) + x) & 0x0f0f0f0f0f0f0f0f;
x = ((x >> 8) + x) & 0x00ff00ff00ff00ff;
x = ((x >> 16) + x) & 0x0000ffff0000ffff;
return (x + (x >> 32)) & 0xff;
#else
err_internal( __FUNCTION__,
"Implemented for 32-bit and 64-bit longs, not %d-bit longs\n",
SIZEOF_LONG * 8 );
#endif
#endif
}
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