/* Implement POWERSET runtime actions for CHILL.
   Copyright (C) 1992,1993 Free Software Foundation, Inc.
   Author: Wilfried Moser, et al

This file is part of GNU CC.

GNU CC 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.

GNU CC 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 GNU CC; see the file COPYING.  If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */

#define __CHILL_LIB__

#include <stdio.h>
#include "powerset.h"


/*
 * function __cardpowerset
 *
 * parameters:
 *	ps		powerset
 *	bitlength	length of powerset
 *
 * returns:
 *	long		number of set bits
 *
 * exceptions:
 *  none
 *
 * abstract:
 *  returns the number of set bit's in a powerset
 *
 */

/* bit_count[I] is number of '1' bits in I. */
static
const unsigned char __four_bit_count[16] = {
    0, 1, 1, 2,
    1, 2, 2, 3,
    1, 2, 2, 3,
    2, 3, 3, 4 };

long
__cardpowerset (ps, bitlength)
     SET_WORD      *ps;
     unsigned long  bitlength;
{
  unsigned long	count = 0;
  if (bitlength <= SET_CHAR_SIZE)
    {
      register SET_CHAR	c = *((SET_CHAR *)ps);
      /* count 4 bits at a time. */
      while (c > 0)
	{
	  count += __four_bit_count[c & 15];
	  c >>= 4;
	}
      return count;
    }
  else if (bitlength <= SET_SHORT_SIZE)
    {
      register SET_SHORT c = *((SET_SHORT *)ps);
      /* count 4 bits at a time. */
      while (c > 0)
	{
	  count += __four_bit_count[c & 15];
	  c >>= 4;
	}
      return count;
    }
  else
    {
      register SET_WORD	*p = ps;
      SET_WORD *endp = p + BITS_TO_WORDS(bitlength);
    
      while (p < endp)
	{
	  register SET_WORD c = *p++;
	  /* count 4 bits at a time. */
	  while (c > 0)
	    {
	      count += __four_bit_count[c & 15];
	      c >>= 4;
	    }
	}
      return (count);
    }
}