libchill/flsetps.c

   1 /* Implement POWERSET runtime actions for CHILL.
   2    Copyright (C) 1992,1993 Free Software Foundation, Inc.
   3    Author: Wilfried Moser, et al
   4
   5 This file is part of GNU CC.
   6
   7 GNU CC is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 2, or (at your option)
  10 any later version.
  11
  12 GNU CC is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GNU CC; see the file COPYING.  If not, write to
  19 the Free Software Foundation, 59 Temple Place - Suite 330,
  20 Boston, 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 extern void __cause_ex1 (char *exname, char *file, int lineno);
  35
  36 /*
  37  * function __flsetpowerset
  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             largest enumeration value
  48  * exceptions:
  49  *      "empty"         if set is empty
  50  *
  51  * abstract:
  52  *  Find last bit set in a powerset and return the corresponding value.
  53  *
  54  */
  55 long
  56 __flsetpowerset (ps, bitlength, minval, filename, lineno)
  57      SET_WORD      *ps;
  58      unsigned long  bitlength;
  59      long           minval;
  60      char          *filename;
  61      int            lineno;
  62 {
  63   unsigned long bitno;
  64
  65   if (bitlength <= SET_CHAR_SIZE)
  66     {
  67       SET_CHAR cset = *((SET_CHAR *)ps);
  68       if (cset != 0)
  69         {
  70           /* found a bit set .. calculate which */
  71           for (bitno = SET_CHAR_SIZE; bitno >= 1; bitno--)
  72             if (GET_BIT_IN_CHAR (cset, bitno - 1))
  73               break;
  74           /* return its index */
  75           return bitno + minval - 1;
  76         }
  77     }
  78   else if (bitlength <= SET_SHORT_SIZE)
  79     {
  80       SET_SHORT sset = *((SET_SHORT *)ps);
  81       if (sset != 0)
  82         {
  83           /* found a bit set .. calculate which */
  84           for (bitno = SET_SHORT_SIZE; bitno >= 1; bitno--)
  85             if (GET_BIT_IN_SHORT (sset, bitno - 1))
  86               break;
  87           /* return its index */
  88           return bitno + minval - 1;
  89         }
  90     }
  91   else /* set composed of array of one or more WORDs */
  92     {
  93       SET_WORD  *endp = ps;
  94       SET_WORD  *p = ps + BITS_TO_WORDS(bitlength) - 1;
  95       unsigned long cnt;
  96
  97       /* FIXME: bitorder problems? */
  98       for (cnt = ((bitlength - 1) / SET_WORD_SIZE) * SET_WORD_SIZE;
  99            p >= endp; p--, cnt -= SET_WORD_SIZE)
 100         {
 101           SET_WORD c = *p;
 102           if (c)
 103             {
 104               /* found a bit set .. calculate which */
 105               for (bitno = SET_WORD_SIZE; bitno >= 1; bitno--)
 106                 if (GET_BIT_IN_WORD (c, bitno - 1))
 107                   break;
 108               return cnt + bitno + minval - 1;
 109             }
 110         }
 111     }
 112   /* no bits found - raise exception */
 113   __cause_ex1 ("empty", filename, lineno);
 114 }