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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 "config.h"
#include <stdio.h>
#include "powerset.h"
/*
* function __flsetclrpowerset
*
* parameters:
* ps powerset
* bitlength length of powerset
*
* returns:
* int -1 .. nothing found
* >= 0 .. index of last set bit
* exceptions:
* none
*
* abstract:
* Find last bit set in a powerset and return the corresponding value
* in *out and clear this bit. Return 0 for no more found, else 1.
*
*/
int
__flsetclrpowerset (ps, bitlength, first_bit)
SET_WORD *ps;
unsigned long bitlength;
int first_bit;
{
register int bitno;
#ifndef USE_CHARS
if (bitlength <= SET_CHAR_SIZE)
{
for (bitno = bitlength - 1; bitno >= first_bit; bitno--)
if (GET_BIT_IN_CHAR (*((SET_CHAR *)ps), bitno))
break;
return bitno < first_bit ? -1 : bitno;
}
else if (bitlength <= SET_SHORT_SIZE)
{
for (bitno = bitlength - 1; bitno >= first_bit; bitno--)
if (GET_BIT_IN_SHORT (*((SET_SHORT *)ps), bitno))
break;
return bitno < first_bit ? -1 : bitno;
}
else
#endif
{
SET_WORD *p, c;
bitno = bitlength - 1;
if (bitno < first_bit)
return -1;
p = &ps[(unsigned) bitno / SET_WORD_SIZE];
c = *p;
if (((unsigned) bitlength % SET_WORD_SIZE) != 0)
MASK_UNUSED_WORD_BITS(&c, (unsigned) bitlength % SET_WORD_SIZE);
if (c)
goto found;
else
bitno -= ((unsigned) bitno % SET_WORD_SIZE) + 1;
while (bitno >= first_bit)
{
c = *--p;
if (c)
goto found;
bitno -= SET_WORD_SIZE;
}
return -1;
found:
for (; bitno >= first_bit; bitno--)
{
if (GET_BIT_IN_WORD (c, (unsigned) bitno % SET_WORD_SIZE))
return bitno;
}
return -1;
}
}
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