id3lib_bitset

电驴下载工具eMule0.47aVeryCD的源代码,可作分析测试也可用于P2P软件的开发研究.

/*
 * 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.
 */

#ifndef __SGI_STL_BITSET
#define __SGI_STL_BITSET

// This implementation of bitset<> has a second template parameter,
// _WordT, which defaults to unsigned long.  *YOU SHOULD NOT USE
// THIS FEATURE*.  It is experimental, and it may be removed in
// future releases.

// A bitset of size N, using words of type _WordT, will have
// N % (sizeof(_WordT) * CHAR_BIT) unused bits.  (They are the high-
// order bits in the highest word.)  It is a class invariant
// of class bitset<> that those unused bits are always zero.

// Most of the actual code isn't contained in bitset<> itself, but in the
// base class _Base_bitset.  The base class works with whole words, not with
// individual bits.  This allows us to specialize _Base_bitset for the
// important special case where the bitset is only a single word.

// The C++ standard does not define the precise semantics of operator[].
// In this implementation the const version of operator[] is equivalent
// to test(), except that it does no range checking.  The non-const version
// returns a reference to a bit, again without doing any range checking.


#include <stddef.h>     // for size_t
#include <limits.h>     // for CHAR_BIT
#include <string>
#include <stdexcept>    // for invalid_argument, out_of_range, overflow_error
#include <iostream.h>   // for istream, ostream

#define __BITS_PER_WORDT(__wt) (CHAR_BIT*sizeof(__wt))
#define __BITSET_WORDS(__n,__wt) \
 ((__n) < 1 ? 1 : ((__n) + __BITS_PER_WORDT(__wt) - 1)/__BITS_PER_WORDT(__wt))

__STL_BEGIN_NAMESPACE

#if defined(__sgi) && !defined(__GNUC__) && (_MIPS_SIM != _MIPS_SIM_ABI32)
#pragma set woff 1209
#endif

// structure to aid in counting bits
template<bool __dummy>
struct _Bit_count {
  static unsigned char _S_bit_count[256];
};

// Mapping from 8 bit unsigned integers to the index of the first one
// bit:
template<bool __dummy>
struct _First_one {
  static unsigned char _S_first_one[256];
};

//
// Base class: general case.
//

template<size_t _Nw, class _WordT>
struct _Base_bitset {
  _WordT _M_w[_Nw];                // 0 is the least significant word.

  _Base_bitset( void ) { _M_do_reset(); }

  _Base_bitset(unsigned long __val);

  static size_t _S_whichword( size_t __pos ) {
    return __pos / __BITS_PER_WORDT(_WordT);
  }
  static size_t _S_whichbyte( size_t __pos ) {
    return (__pos % __BITS_PER_WORDT(_WordT)) / CHAR_BIT;
  }
  static size_t _S_whichbit( size_t __pos ) {
    return __pos % __BITS_PER_WORDT(_WordT);
  }
  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,_WordT>& __x) {
    for ( size_t __i = 0; __i < _Nw; __i++ ) {
      _M_w[__i] &= __x._M_w[__i];
    }
  }

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

  void _M_do_xor(const _Base_bitset<_Nw,_WordT>& __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() {
    for ( size_t __i = 0; __i < _Nw; __i++ ) {
      _M_w[__i] = 0;
    }
  }

  bool _M_is_equal(const _Base_bitset<_Nw,_WordT>& __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 < __BITSET_WORDS(_Nw,_WordT); __i++ ) {
      if ( _M_w[__i] != static_cast<_WordT>(0) )
        return true;
    }
    return false;
  }

  size_t _M_do_count() const {
    size_t __result = 0;
    const unsigned char* __byte_ptr = (const unsigned char*)_M_w;
    const unsigned char* __end_ptr = (const unsigned char*)(_M_w+_Nw);

    while ( __byte_ptr < __end_ptr ) {
      __result += _Bit_count<true>::_S_bit_count[*__byte_ptr];
      __byte_ptr++;
    }
    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, class _WordT>
_Base_bitset<_Nw, _WordT>::_Base_bitset(unsigned long __val)
{
  _M_do_reset();
  const size_t __n = min(sizeof(unsigned long)*CHAR_BIT,
                         __BITS_PER_WORDT(_WordT)*_Nw);
  for(size_t __i = 0; __i < __n; ++__i, __val >>= 1)
    if ( __val & 0x1 )
      _M_getword(__i) |= _S_maskbit(__i);
}

template<size_t _Nw, class _WordT>
void _Base_bitset<_Nw, _WordT>::_M_do_left_shift(size_t __shift)
{
  if (__shift != 0) {
    const size_t __wshift = __shift / __BITS_PER_WORDT(_WordT);
    const size_t __offset = __shift % __BITS_PER_WORDT(_WordT);
    const size_t __sub_offset = __BITS_PER_WORDT(_WordT) - __offset;
    size_t __n = _Nw - 1;
    for ( ; __n > __wshift; --__n)
      _M_w[__n] = (_M_w[__n - __wshift] << __offset) |
                (_M_w[__n - __wshift - 1] >> __sub_offset);
    if (__n == __wshift)
      _M_w[__n] = _M_w[0] << __offset;
    for (size_t __n1 = 0; __n1 < __n; ++__n1)
      _M_w[__n1] = static_cast<_WordT>(0);
  }
}

template<size_t _Nw, class _WordT>
void _Base_bitset<_Nw, _WordT>::_M_do_right_shift(size_t __shift)
{
  if (__shift != 0) {
    const size_t __wshift = __shift / __BITS_PER_WORDT(_WordT);
    const size_t __offset = __shift % __BITS_PER_WORDT(_WordT);
    const size_t __sub_offset = __BITS_PER_WORDT(_WordT) - __offset;
    const size_t __limit = _Nw - __wshift - 1;
    size_t __n = 0;
    for ( ; __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;
    for (size_t __n1 = __limit + 1; __n1 < _Nw; ++__n1)
      _M_w[__n1] = static_cast<_WordT>(0);
  }
}

template<size_t _Nw, class _WordT>
unsigned long _Base_bitset<_Nw, _WordT>::_M_do_to_ulong() const
{
  const overflow_error __overflow("bitset");

  if (sizeof(_WordT) >= sizeof(unsigned long)) {
    for (size_t __i = 1; __i < _Nw; ++__i)
      if (_M_w[__i])
        __STL_THROW(__overflow);

    const _WordT __mask = static_cast<_WordT>(static_cast<unsigned long>(-1));
    if (_M_w[0] & ~__mask)
      __STL_THROW(__overflow);

    return static_cast<unsigned long>(_M_w[0] & __mask);
  }
  else {                      // sizeof(_WordT) < sizeof(unsigned long).
    const size_t __nwords =
      (sizeof(unsigned long) + sizeof(_WordT) - 1) / sizeof(_WordT);

    size_t __min_nwords = __nwords;
    if (_Nw > __nwords) {
      for (size_t __i = __nwords; __i < _Nw; ++__i)
        if (_M_w[__i])
          __STL_THROW(__overflow);
    }
    else
      __min_nwords = _Nw;

    // If unsigned long is 8 bytes and _WordT is 6 bytes, then an unsigned
    // long consists of all of one word plus 2 bytes from another word.
    const size_t __part = sizeof(unsigned long) % sizeof(_WordT);

    if (__part != 0 && __nwords <= _Nw &&
        (_M_w[__min_nwords - 1] >> ((sizeof(_WordT) - __part) * CHAR_BIT)) != 0)
      __STL_THROW(__overflow);

    unsigned long __result = 0;
    for (size_t __i = 0; __i < __min_nwords; ++__i) {
      __result |= static_cast<unsigned long>(
         _M_w[__i]) << (__i * sizeof(_WordT) * CHAR_BIT);
    }
    return __result;
  }
} // End _M_do_to_ulong

template<size_t _Nw, class _WordT>
size_t _Base_bitset<_Nw, _WordT>::_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) ) {
      // find byte within word
      for ( size_t __j = 0; __j < sizeof(_WordT); __j++ ) {
        unsigned char __this_byte
          = static_cast<unsigned char>(__thisword & (~(unsigned char)0));
        if ( __this_byte )
          return __i*__BITS_PER_WORDT(_WordT) + __j*CHAR_BIT +
            _First_one<true>::_S_first_one[__this_byte];

        __thisword >>= CHAR_BIT;
      }
    }
  }
  // not found, so return an indication of failure.
  return __not_found;
}

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

  // check out of bounds
  if ( __prev >= _Nw * __BITS_PER_WORDT(_WordT) )
    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) ) {
    // find byte within word
    // get first byte into place
    __thisword >>= _S_whichbyte(__prev) * CHAR_BIT;
    for ( size_t __j = _S_whichbyte(__prev); __j < sizeof(_WordT); __j++ ) {
      unsigned char __this_byte
        = static_cast<unsigned char>(__thisword & (~(unsigned char)0));
      if ( __this_byte )
        return __i*__BITS_PER_WORDT(_WordT) + __j*CHAR_BIT +
          _First_one<true>::_S_first_one[__this_byte];

      __thisword >>= CHAR_BIT;
    }
  }

  // check subsequent words
  __i++;
  for ( ; __i < _Nw; __i++ ) {
    _WordT __thisword = _M_w[__i];
    if ( __thisword != static_cast<_WordT>(0) ) {
      // find byte within word
      for ( size_t __j = 0; __j < sizeof(_WordT); __j++ ) {
        unsigned char __this_byte
          = static_cast<unsigned char>(__thisword & (~(unsigned char)0));
        if ( __this_byte )
          return __i*__BITS_PER_WORDT(_WordT) + __j*CHAR_BIT +
            _First_one<true>::_S_first_one[__this_byte];

        __thisword >>= CHAR_BIT;
      }
    }
  }

  // not found, so return an indication of failure.
  return __not_found;
} // end _M_do_find_next


// ------------------------------------------------------------

//
// Base class: specialization for a single word.
//