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/* 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);
}
}
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