libchill/cardps.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
  35 /*
  36  * function __cardpowerset
  37  *
  38  * parameters:
  39  *      ps              powerset
  40  *      bitlength       length of powerset
  41  *
  42  * returns:
  43  *      long            number of set bits
  44  *
  45  * exceptions:
  46  *  none
  47  *
  48  * abstract:
  49  *  returns the number of set bit's in a powerset
  50  *
  51  */
  52
  53 /* bit_count[I] is number of '1' bits in I. */
  54 static
  55 const unsigned char __four_bit_count[16] = {
  56     0, 1, 1, 2,
  57     1, 2, 2, 3,
  58     1, 2, 2, 3,
  59     2, 3, 3, 4 };
  60
  61 long
  62 __cardpowerset (ps, bitlength)
  63      SET_WORD      *ps;
  64      unsigned long  bitlength;
  65 {
  66   unsigned long count = 0;
  67   if (bitlength <= SET_CHAR_SIZE)
  68     {
  69       register SET_CHAR c = *((SET_CHAR *)ps);
  70       /* count 4 bits at a time. */
  71       while (c > 0)
  72         {
  73           count += __four_bit_count[c & 15];
  74           c >>= 4;
  75         }
  76       return count;
  77     }
  78   else if (bitlength <= SET_SHORT_SIZE)
  79     {
  80       register SET_SHORT c = *((SET_SHORT *)ps);
  81       /* count 4 bits at a time. */
  82       while (c > 0)
  83         {
  84           count += __four_bit_count[c & 15];
  85           c >>= 4;
  86         }
  87       return count;
  88     }
  89   else
  90     {
  91       register SET_WORD *p = ps;
  92       SET_WORD *endp = p + BITS_TO_WORDS(bitlength);
  93
  94       while (p < endp)
  95         {
  96           register SET_WORD c = *p++;
  97           /* count 4 bits at a time. */
  98           while (c > 0)
  99             {
 100               count += __four_bit_count[c & 15];
 101               c >>= 4;
 102             }
 103         }
 104       return (count);
 105     }
 106 }