| /* 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, 59 Temple Place - Suite 330, |
| Boston, MA 02111-1307, USA. */ |
| |
| /* As a special exception, if you link this library with other files, |
| some of which are compiled with GCC, to produce an executable, |
| this library does not by itself cause the resulting executable |
| to be covered by the GNU General Public License. |
| This exception does not however invalidate any other reasons why |
| the executable file might be covered by the GNU General Public License. */ |
| |
| #define __CHILL_LIB__ |
| |
| #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; |
| |
| { |
| 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; |
| } |
| } |