std_bitset.h

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// <bitset> -*- C++ -*-

// Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 2, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING.  If not, write to the Free
// Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
// USA.

// As a special exception, you may use this file as part of a free software
// library without restriction.  Specifically, if other files instantiate
// templates or use macros or inline functions from this file, or you compile
// this file and link it with other files to produce an executable, this
// file does not by itself cause the resulting executable to be covered by
// the GNU General Public License.  This exception does not however
// invalidate any other reasons why the executable file might be covered by
// the GNU General Public License.

/*
 * Copyright (c) 1998
 * Silicon Graphics Computer Systems, Inc.
 *
 * Permission to use, copy, modify, distribute and sell this software
 * and its documentation for any purpose is hereby granted without fee,
 * provided that the above copyright notice appear in all copies and
 * that both that copyright notice and this permission notice appear
 * in supporting documentation.  Silicon Graphics makes no
 * representations about the suitability of this software for any
 * purpose.  It is provided "as is" without express or implied warranty.
 */

/** @file bitset
 *  This is a Standard C++ Library header.
 */

#ifndef _GLIBCXX_BITSET
#define _GLIBCXX_BITSET 1

#pragma GCC system_header

#include <cstddef>     // For size_t
#include <cstring>     // For memset
#include <limits>      // For numeric_limits
#include <string>
#include <bits/functexcept.h>   // For invalid_argument, out_of_range,
                                // overflow_error
#include <ostream>     // For ostream (operator<<)
#include <istream>     // For istream (operator>>)

#define _GLIBCXX_BITSET_BITS_PER_WORD  numeric_limits<unsigned long>::digits
#define _GLIBCXX_BITSET_WORDS(__n) \
 ((__n) < 1 ? 0 : ((__n) + _GLIBCXX_BITSET_BITS_PER_WORD - 1) \
                  / _GLIBCXX_BITSET_BITS_PER_WORD)

namespace _GLIBCXX_STD
{
  /**
   *  @if maint
   *  Base class, general case.  It is a class inveriant that _Nw will be
   *  nonnegative.
   *
   *  See documentation for bitset.
   *  @endif
  */
  template<size_t _Nw>
    struct _Base_bitset
    {
      typedef unsigned long _WordT;

      /// 0 is the least significant word.
      _WordT 		_M_w[_Nw];

      _Base_bitset()
      { _M_do_reset(); }

      _Base_bitset(unsigned long __val)
      {
	_M_do_reset();
	_M_w[0] = __val;
      }

      static size_t
      _S_whichword(size_t __pos )
      { return __pos / _GLIBCXX_BITSET_BITS_PER_WORD; }

      static size_t
      _S_whichbyte(size_t __pos )
      { return (__pos % _GLIBCXX_BITSET_BITS_PER_WORD) / __CHAR_BIT__; }

      static size_t
      _S_whichbit(size_t __pos )
      { return __pos % _GLIBCXX_BITSET_BITS_PER_WORD; }

      static _WordT
      _S_maskbit(size_t __pos )
      { return (static_cast<_WordT>(1)) << _S_whichbit(__pos); }

      _WordT&
      _M_getword(size_t __pos)
      { return _M_w[_S_whichword(__pos)]; }

      _WordT
      _M_getword(size_t __pos) const
      { return _M_w[_S_whichword(__pos)]; }

      _WordT&
      _M_hiword()
      { return _M_w[_Nw - 1]; }

      _WordT
      _M_hiword() const
      { return _M_w[_Nw - 1]; }

      void
      _M_do_and(const _Base_bitset<_Nw>& __x)
      {
	for (size_t __i = 0; __i < _Nw; __i++)
	  _M_w[__i] &= __x._M_w[__i];
      }

      void
      _M_do_or(const _Base_bitset<_Nw>& __x)
      {
	for (size_t __i = 0; __i < _Nw; __i++)
	  _M_w[__i] |= __x._M_w[__i];
      }

      void
      _M_do_xor(const _Base_bitset<_Nw>& __x)
      {
	for (size_t __i = 0; __i < _Nw; __i++)
	  _M_w[__i] ^= __x._M_w[__i];
      }

      void
      _M_do_left_shift(size_t __shift);

      void
      _M_do_right_shift(size_t __shift);

      void
      _M_do_flip()
      {
	for (size_t __i = 0; __i < _Nw; __i++)
	  _M_w[__i] = ~_M_w[__i];
      }

      void
      _M_do_set()
      {
	for (size_t __i = 0; __i < _Nw; __i++)
	  _M_w[__i] = ~static_cast<_WordT>(0);
      }

      void
      _M_do_reset()
      { std::memset(_M_w, 0, _Nw * sizeof(_WordT)); }

      bool
      _M_is_equal(const _Base_bitset<_Nw>& __x) const
      {
	for (size_t __i = 0; __i < _Nw; ++__i)
	  {
	    if (_M_w[__i] != __x._M_w[__i])
	      return false;
	  }
	return true;
      }

      bool
      _M_is_any() const
      {
	for (size_t __i = 0; __i < _Nw; __i++)
	  {
	    if (_M_w[__i] != static_cast<_WordT>(0))
	      return true;
	  }
	return false;
      }

      size_t
      _M_do_count() const
      {
	size_t __result = 0;
	for (size_t __i = 0; __i < _Nw; __i++)
	  __result += __builtin_popcountl(_M_w[__i]);
	return __result;
      }

      unsigned long
      _M_do_to_ulong() const;

      // find first "on" bit
      size_t
      _M_do_find_first(size_t __not_found) const;

      // find the next "on" bit that follows "prev"
      size_t
      _M_do_find_next(size_t __prev, size_t __not_found) const;
    };

  // Definitions of non-inline functions from _Base_bitset.
  template<size_t _Nw>
    void
    _Base_bitset<_Nw>::_M_do_left_shift(size_t __shift)
    {
      if (__builtin_expect(__shift != 0, 1))
	{
	  const size_t __wshift = __shift / _GLIBCXX_BITSET_BITS_PER_WORD;
	  const size_t __offset = __shift % _GLIBCXX_BITSET_BITS_PER_WORD;

	  if (__offset == 0)
	    for (size_t __n = _Nw - 1; __n >= __wshift; --__n)
	      _M_w[__n] = _M_w[__n - __wshift];
	  else
	    {
	      const size_t __sub_offset = (_GLIBCXX_BITSET_BITS_PER_WORD 
					   - __offset);
	      for (size_t __n = _Nw - 1; __n > __wshift; --__n)
		_M_w[__n] = ((_M_w[__n - __wshift] << __offset)
			     | (_M_w[__n - __wshift - 1] >> __sub_offset));
	      _M_w[__wshift] = _M_w[0] << __offset;
	    }

	  std::fill(_M_w + 0, _M_w + __wshift, static_cast<_WordT>(0));
	}
    }

  template<size_t _Nw>
    void
    _Base_bitset<_Nw>::_M_do_right_shift(size_t __shift)
    {
      if (__builtin_expect(__shift != 0, 1))
	{
	  const size_t __wshift = __shift / _GLIBCXX_BITSET_BITS_PER_WORD;
	  const size_t __offset = __shift % _GLIBCXX_BITSET_BITS_PER_WORD;
	  const size_t __limit = _Nw - __wshift - 1;

	  if (__offset == 0)
	    for (size_t __n = 0; __n <= __limit; ++__n)
	      _M_w[__n] = _M_w[__n + __wshift];
	  else
	    {
	      const size_t __sub_offset = (_GLIBCXX_BITSET_BITS_PER_WORD
					   - __offset);
	      for (size_t __n = 0; __n < __limit; ++__n)
		_M_w[__n] = ((_M_w[__n + __wshift] >> __offset)
			     | (_M_w[__n + __wshift + 1] << __sub_offset));
	      _M_w[__limit] = _M_w[_Nw-1] >> __offset;
	    }
	  
	  std::fill(_M_w + __limit + 1, _M_w + _Nw, static_cast<_WordT>(0));
	}
    }

  template<size_t _Nw>
    unsigned long
    _Base_bitset<_Nw>::_M_do_to_ulong() const
    {
      for (size_t __i = 1; __i < _Nw; ++__i)
	if (_M_w[__i])
	  __throw_overflow_error(__N("_Base_bitset::_M_do_to_ulong"));
      return _M_w[0];
    }

  template<size_t _Nw>
    size_t
    _Base_bitset<_Nw>::_M_do_find_first(size_t __not_found) const
    {
      for (size_t __i = 0; __i < _Nw; __i++)
	{
	  _WordT __thisword = _M_w[__i];
	  if (__thisword != static_cast<_WordT>(0))
	    return (__i * _GLIBCXX_BITSET_BITS_PER_WORD
		    + __builtin_ctzl(__thisword));
	}
      // not found, so return an indication of failure.
      return __not_found;
    }

  template<size_t _Nw>
    size_t
    _Base_bitset<_Nw>::_M_do_find_next(size_t __prev, size_t __not_found) const
    {
      // make bound inclusive
      ++__prev;

      // check out of bounds
      if (__prev >= _Nw * _GLIBCXX_BITSET_BITS_PER_WORD)
	return __not_found;

      // search first word
      size_t __i = _S_whichword(__prev);
      _WordT __thisword = _M_w[__i];

      // mask off bits below bound
      __thisword &= (~static_cast<_WordT>(0)) << _S_whichbit(__prev);

      if (__thisword != static_cast<_WordT>(0))
	return (__i * _GLIBCXX_BITSET_BITS_PER_WORD
		+ __builtin_ctzl(__thisword));

      // check subsequent words
      __i++;
      for (; __i < _Nw; __i++)
	{
	  __thisword = _M_w[__i];
	  if (__thisword != static_cast<_WordT>(0))
	    return (__i * _GLIBCXX_BITSET_BITS_PER_WORD
		    + __builtin_ctzl(__thisword));
	}
      // not found, so return an indication of failure.
      return __not_found;
    } // end _M_do_find_next

  /**
   *  @if maint
   *  Base class, specialization for a single word.
   *
   *  See documentation for bitset.
   *  @endif
  */
  template<>
    struct _Base_bitset<1>
    {
      typedef unsigned long _WordT;
      _WordT _M_w;

      _Base_bitset(void)
      : _M_w(0)
      { }

      _Base_bitset(unsigned long __val)
      : _M_w(__val)
      { }

      static size_t
      _S_whichword(size_t __pos )
      { return __pos / _GLIBCXX_BITSET_BITS_PER_WORD; }

      static size_t
      _S_whichbyte(size_t __pos )
      { return (__pos % _GLIBCXX_BITSET_BITS_PER_WORD) / __CHAR_BIT__; }

      static size_t
      _S_whichbit(size_t __pos )
      {  return __pos % _GLIBCXX_BITSET_BITS_PER_WORD; }

      static _WordT
      _S_maskbit(size_t __pos )
      { return (static_cast<_WordT>(1)) << _S_whichbit(__pos); }

      _WordT&
      _M_getword(size_t)
      { return _M_w; }

      _WordT
      _M_getword(size_t) const
      { return _M_w; }

      _WordT&
      _M_hiword()
      { return _M_w; }

      _WordT
      _M_hiword() const
      { return _M_w; }

      void
      _M_do_and(const _Base_bitset<1>& __x)
      { _M_w &= __x._M_w; }

      void
      _M_do_or(const _Base_bitset<1>& __x)
      { _M_w |= __x._M_w; }

      void
      _M_do_xor(const _Base_bitset<1>& __x)
      { _M_w ^= __x._M_w; }

      void
      _M_do_left_shift(size_t __shift)
      { _M_w <<= __shift; }

      void
      _M_do_right_shift(size_t __shift)
      { _M_w >>= __shift; }

      void
      _M_do_flip()
      { _M_w = ~_M_w; }

      void
      _M_do_set()
      { _M_w = ~static_cast<_WordT>(0); }

      void
      _M_do_reset()
      { _M_w = 0; }

      bool
      _M_is_equal(const _Base_bitset<1>& __x) const
      { return _M_w == __x._M_w; }

      bool
      _M_is_any() const
      { return _M_w != 0; }

      size_t
      _M_do_count() const
      { return __builtin_popcountl(_M_w); }

      unsigned long
      _M_do_to_ulong() const
      { return _M_w; }

      size_t
      _M_do_find_first(size_t __not_found) const
      {
        if (_M_w != 0)
          return __builtin_ctzl(_M_w);
        else
          return __not_found;
      }