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, 675 Mass Ave, Cambridge, MA 02139, USA.  */
  20
  21 /* As a special exception, if you link this library with other files,
  22    some of which are compiled with GCC, to produce an executable,
  23    this library does not by itself cause the resulting executable
  24    to be covered by the GNU General Public License.
  25    This exception does not however invalidate any other reasons why
  26    the executable file might be covered by the GNU General Public License.  */
  27
  28 #define __CHILL_LIB__
  29
  30 #include <stdio.h>
  31 #include "powerset.h"
  32
  33
  34 /*
  35  * function __cardpowerset
  36  *
  37  * parameters:
  38  *      ps              powerset
  39  *      bitlength       length of powerset
  40  *
  41  * returns:
  42  *      long            number of set bits
  43  *
  44  * exceptions:
  45  *  none
  46  *
  47  * abstract:
  48  *  returns the number of set bit's in a powerset
  49  *
  50  */
  51
  52 /* bit_count[I] is number of '1' bits in I. */
  53 static
  54 const unsigned char __four_bit_count[16] = {
  55     0, 1, 1, 2,
  56     1, 2, 2, 3,
  57     1, 2, 2, 3,
  58     2, 3, 3, 4 };
  59
  60 long
  61 __cardpowerset (ps, bitlength)
  62      SET_WORD      *ps;
  63      unsigned long  bitlength;
  64 {
  65   unsigned long count = 0;
  66   if (bitlength <= SET_CHAR_SIZE)
  67     {
  68       register SET_CHAR c = *((SET_CHAR *)ps);
  69       /* count 4 bits at a time. */
  70       while (c > 0)
  71         {
  72           count += __four_bit_count[c & 15];
  73           c >>= 4;
  74         }
  75       return count;
  76     }
  77   else if (bitlength <= SET_SHORT_SIZE)
  78     {
  79       register SET_SHORT c = *((SET_SHORT *)ps);
  80       /* count 4 bits at a time. */
  81       while (c > 0)
  82         {
  83           count += __four_bit_count[c & 15];
  84           c >>= 4;
  85         }
  86       return count;
  87     }
  88   else
  89     {
  90       register SET_WORD *p = ps;
  91       SET_WORD *endp = p + BITS_TO_WORDS(bitlength);
  92
  93       while (p < endp)
  94         {
  95           register SET_WORD c = *p++;
  96           /* count 4 bits at a time. */
  97           while (c > 0)
  98             {
  99               count += __four_bit_count[c & 15];
 100               c >>= 4;
 101             }
 102         }
 103       return (count);
 104     }
 105 }