1/* Implement POWERSET runtime actions for CHILL. 2 Copyright (C) 1992,1993 Free Software Foundation, Inc. 3 Author: Wilfried Moser, et al 4 5This file is part of GNU CC. 6 7GNU CC is free software; you can redistribute it and/or modify 8it under the terms of the GNU General Public License as published by 9the Free Software Foundation; either version 2, or (at your option) 10any later version. 11 12GNU CC is distributed in the hope that it will be useful, 13but WITHOUT ANY WARRANTY; without even the implied warranty of 14MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15GNU General Public License for more details. 16 17You should have received a copy of the GNU General Public License 18along with GNU CC; see the file COPYING. If not, write to 19the Free Software Foundation, 59 Temple Place - Suite 330, 20Boston, MA 02111-1307, USA. */ 21 22/* As a special exception, if you link this library with other files, 23 some of which are compiled with GCC, to produce an executable, 24 this library does not by itself cause the resulting executable 25 to be covered by the GNU General Public License. 26 This exception does not however invalidate any other reasons why 27 the executable file might be covered by the GNU General Public License. */ 28 29#define __CHILL_LIB__ 30 31#include <stdio.h> 32#include "powerset.h" 33 34/* 35 * function __ffsetclrpowerset 36 * 37 * parameters: 38 * ps powerset 39 * bitlength length of powerset 40 * 41 * returns: 42 * int -1 .. nothing found 43 * >=0 .. index of first true bit found 44 * exceptions: 45 * none 46 */ 47 48int 49__ffsetclrpowerset (ps, bitlength, first_bit) 50 SET_WORD *ps; 51 unsigned long bitlength; 52 int first_bit; 53{ 54 register int bitno; 55 56 if (first_bit >= bitlength) 57 return -1; 58 59#ifndef USE_CHARS 60 if (bitlength <= SET_CHAR_SIZE) 61 { 62 for (bitno = first_bit; bitno < bitlength; bitno++) 63 if (GET_BIT_IN_CHAR (*((SET_CHAR *)ps), bitno)) 64 break; 65 return bitno == bitlength ? -1 : bitno; 66 } 67 else if (bitlength <= SET_SHORT_SIZE) 68 { 69 for (bitno = first_bit; bitno < bitlength; bitno++) 70 if (GET_BIT_IN_SHORT (*((SET_SHORT *)ps), bitno)) 71 break; 72 return bitno == bitlength ? -1 : bitno; 73 } 74 else 75#endif 76 { 77 unsigned int words_to_skip = (unsigned) first_bit / SET_WORD_SIZE; 78 unsigned long cnt = words_to_skip * SET_WORD_SIZE; 79 SET_WORD *p = ps + words_to_skip; 80 SET_WORD *endp = ps + BITS_TO_WORDS(bitlength); 81 SET_WORD c; 82 first_bit = (unsigned) first_bit % (unsigned) SET_WORD_SIZE; 83 84 c = *p++; 85 if (c) 86 { 87 for (bitno = first_bit; bitno < SET_WORD_SIZE; bitno++) 88 if (GET_BIT_IN_WORD(c, bitno)) 89 goto found; 90 } 91 cnt += SET_WORD_SIZE; 92 93 while (p < endp) 94 { 95 if ((c = *p++)) 96 { 97 /* found a bit set .. calculate which */ 98 for (bitno = 0; bitno < SET_WORD_SIZE; bitno++) 99 if (GET_BIT_IN_WORD(c, bitno)) 100 goto found; 101 } 102 cnt += SET_WORD_SIZE; 103 } 104 return -1; 105 found: 106 bitno += cnt; 107 return bitno >= bitlength ? -1 : bitno; 108 } 109} 110