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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 __ffsetclrpowerset
*
* parameters:
* ps powerset
* bitlength length of powerset
*
* returns:
* int -1 .. nothing found
* >=0 .. index of first true bit found
* exceptions:
* none
*/
int
__ffsetclrpowerset (ps, bitlength, first_bit)
SET_WORD *ps;
unsigned long bitlength;
int first_bit;
{
register int bitno;
if (first_bit >= bitlength)
return -1;
#ifndef USE_CHARS
if (bitlength <= SET_CHAR_SIZE)
{
for (bitno = first_bit; bitno < bitlength; bitno++)
if (GET_BIT_IN_CHAR (*((SET_CHAR *)ps), bitno))
break;
return bitno == bitlength ? -1 : bitno;
}
else if (bitlength <= SET_SHORT_SIZE)
{
for (bitno = first_bit; bitno < bitlength; bitno++)
if (GET_BIT_IN_SHORT (*((SET_SHORT *)ps), bitno))
break;
return bitno == bitlength ? -1 : bitno;
}
else
#endif
{
unsigned int words_to_skip = (unsigned) first_bit / SET_WORD_SIZE;
unsigned long cnt = words_to_skip * SET_WORD_SIZE;
SET_WORD *p = ps + words_to_skip;
SET_WORD *endp = ps + BITS_TO_WORDS(bitlength);
SET_WORD c;
first_bit = (unsigned) first_bit % (unsigned) SET_WORD_SIZE;
c = *p++;
if (c)
{
for (bitno = first_bit; bitno < SET_WORD_SIZE; bitno++)
if (GET_BIT_IN_WORD(c, bitno))
goto found;
}
cnt += SET_WORD_SIZE;
while (p < endp)
{
if ((c = *p++))
{
/* found a bit set .. calculate which */
for (bitno = 0; bitno < SET_WORD_SIZE; bitno++)
if (GET_BIT_IN_WORD(c, bitno))
goto found;
}
cnt += SET_WORD_SIZE;
}
return -1;
found:
bitno += cnt;
return bitno >= bitlength ? -1 : bitno;
}
}
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