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106 lines
2.9 KiB
C
106 lines
2.9 KiB
C
/* Implement POWERSET runtime actions for CHILL.
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Copyright (C) 1992,1993 Free Software Foundation, Inc.
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Author: Wilfried Moser, et al
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This file is part of GNU CC.
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GNU CC is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU CC is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU CC; see the file COPYING. If not, write to
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the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
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/* As a special exception, if you link this library with other files,
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some of which are compiled with GCC, to produce an executable,
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this library does not by itself cause the resulting executable
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to be covered by the GNU General Public License.
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This exception does not however invalidate any other reasons why
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the executable file might be covered by the GNU General Public License. */
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#define __CHILL_LIB__
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#include <stdio.h>
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#include "powerset.h"
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/*
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* function __flsetclrpowerset
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*
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* parameters:
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* ps powerset
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* bitlength length of powerset
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*
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* returns:
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* int -1 .. nothing found
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* >= 0 .. index of last set bit
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* exceptions:
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* none
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*
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* abstract:
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* Find last bit set in a powerset and return the corresponding value
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* in *out and clear this bit. Return 0 for no more found, else 1.
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*
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*/
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int
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__flsetclrpowerset (ps, bitlength, first_bit)
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SET_WORD *ps;
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unsigned long bitlength;
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int first_bit;
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{
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register int bitno;
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#ifndef USE_CHARS
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if (bitlength <= SET_CHAR_SIZE)
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{
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for (bitno = bitlength - 1; bitno >= first_bit; bitno--)
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if (GET_BIT_IN_CHAR (*((SET_CHAR *)ps), bitno))
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break;
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return bitno < first_bit ? -1 : bitno;
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}
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else if (bitlength <= SET_SHORT_SIZE)
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{
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for (bitno = bitlength - 1; bitno >= first_bit; bitno--)
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if (GET_BIT_IN_SHORT (*((SET_SHORT *)ps), bitno))
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break;
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return bitno < first_bit ? -1 : bitno;
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}
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else
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#endif
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{
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SET_WORD *p, c;
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bitno = bitlength - 1;
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if (bitno < first_bit)
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return -1;
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p = &ps[(unsigned) bitno / SET_WORD_SIZE];
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c = *p;
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if (((unsigned) bitlength % SET_WORD_SIZE) != 0)
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MASK_UNUSED_WORD_BITS(&c, (unsigned) bitlength % SET_WORD_SIZE);
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if (c)
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goto found;
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else
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bitno -= ((unsigned) bitno % SET_WORD_SIZE) + 1;
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while (bitno >= first_bit)
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{
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c = *--p;
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if (c)
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goto found;
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bitno -= SET_WORD_SIZE;
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}
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return -1;
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found:
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for (; bitno >= first_bit; bitno--)
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{
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if (GET_BIT_IN_WORD (c, (unsigned) bitno % SET_WORD_SIZE))
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return bitno;
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}
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return -1;
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}
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}
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