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
34extern void __cause_ex1 (char *exname, char *file, int lineno);
35
36/*
37 * function __ffsetpowerset
38 *
39 * parameters:
40 *	ps		powerset
41 *	bitlength	length of powerset
42 *      minval          set low bound
43 *      filename        caller's file name
44 *      lineno          caller's line number
45 *
46 * returns:
47 *	int		enum value of lowest member of powerset
48 *
49 * exceptions:
50 *      "empty" if the set is empty
51 *
52 * abstract:
53 *  Find first bit set in a powerset and return the corresponding value.
54 *
55 */
56long
57__ffsetpowerset (ps, bitlength, minval, filename, lineno)
58     SET_WORD      *ps;
59     unsigned long  bitlength;
60     long           minval;
61     char          *filename;
62     int            lineno;
63{
64  unsigned long bitno;
65
66  if (bitlength <= SET_CHAR_SIZE)
67    {
68      SET_CHAR cset = *((SET_CHAR *)ps);
69      if (cset != 0)
70	{
71	  /* found a bit set .. calculate which */
72	  for (bitno = 0; bitno < SET_CHAR_SIZE; bitno++)
73	    if (GET_BIT_IN_CHAR (cset, bitno))
74	      break;
75	  /* return its index */
76	  return bitno + minval;
77	}
78    }
79  else if (bitlength <= SET_SHORT_SIZE)
80    {
81      SET_SHORT sset = *((SET_SHORT *)ps);
82      if (sset != 0)
83	{
84	  /* found a bit set .. calculate which */
85	  for (bitno = 0; bitno < SET_SHORT_SIZE; bitno++)
86	    if (GET_BIT_IN_SHORT (sset, bitno))
87	      break;
88	  /* return its index */
89	  return bitno + minval;
90	}
91    }
92  else /* set composed of array of one or more WORDs */
93    {
94      SET_WORD *p    = ps;
95      SET_WORD *endp = ps + BITS_TO_WORDS(bitlength);
96      unsigned long    cnt;
97
98      /* FIXME: bitorder problems? */
99      for (cnt = 0; p < endp; p++, cnt += SET_WORD_SIZE)
100	{
101	  SET_WORD c = *p;
102
103	  if (c)
104	    {
105	      /* found a bit set .. calculate which */
106	      for (bitno = 0; bitno < SET_WORD_SIZE; bitno++)
107		if (GET_BIT_IN_WORD (c, bitno))
108		  break;
109	      /* return its index */
110	      return cnt + bitno + minval;
111	    }
112	}
113    }
114  /* no bits found - raise exception */
115  __cause_ex1 ("empty", filename, lineno);
116}
117