106 lines
2.5 KiB
C
106 lines
2.5 KiB
C
/* Implement POWERSET runtime actions for CHILL.
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Copyright (C) 1992,1993 Free Software Foundation, Inc.
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Author: Wilfried Moser, et al
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This file is part of GNU CC.
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GNU CC is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU CC is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU CC; see the file COPYING. If not, write to
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the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
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/* As a special exception, if you link this library with other files,
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some of which are compiled with GCC, to produce an executable,
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this library does not by itself cause the resulting executable
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to be covered by the GNU General Public License.
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This exception does not however invalidate any other reasons why
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the executable file might be covered by the GNU General Public License. */
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#define __CHILL_LIB__
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#include <stdio.h>
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#include "powerset.h"
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/*
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* function __cardpowerset
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*
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* parameters:
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* ps powerset
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* bitlength length of powerset
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*
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* returns:
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* long number of set bits
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*
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* exceptions:
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* none
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*
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* abstract:
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* returns the number of set bit's in a powerset
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*
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*/
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/* bit_count[I] is number of '1' bits in I. */
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static
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const unsigned char __four_bit_count[16] = {
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0, 1, 1, 2,
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1, 2, 2, 3,
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1, 2, 2, 3,
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2, 3, 3, 4 };
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long
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__cardpowerset (ps, bitlength)
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SET_WORD *ps;
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unsigned long bitlength;
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{
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unsigned long count = 0;
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if (bitlength <= SET_CHAR_SIZE)
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{
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register SET_CHAR c = *((SET_CHAR *)ps);
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/* count 4 bits at a time. */
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while (c > 0)
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{
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count += __four_bit_count[c & 15];
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c >>= 4;
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}
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return count;
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}
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else if (bitlength <= SET_SHORT_SIZE)
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{
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register SET_SHORT c = *((SET_SHORT *)ps);
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/* count 4 bits at a time. */
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while (c > 0)
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{
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count += __four_bit_count[c & 15];
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c >>= 4;
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}
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return count;
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}
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else
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{
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register SET_WORD *p = ps;
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SET_WORD *endp = p + BITS_TO_WORDS(bitlength);
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while (p < endp)
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{
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register SET_WORD c = *p++;
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/* count 4 bits at a time. */
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while (c > 0)
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{
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count += __four_bit_count[c & 15];
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c >>= 4;
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}
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}
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return (count);
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}
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}
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