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// Bitmap Allocator. -*- C++ -*-
 
// Copyright (C) 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.
 
/** @file ext/bitmap_allocator.h
 *  This file is a GNU extension to the Standard C++ Library.
 */
 
#ifndef _BITMAP_ALLOCATOR_H
#define _BITMAP_ALLOCATOR_H 1
 
// For std::size_t, and ptrdiff_t.
#include <cstddef>
 
// For __throw_bad_alloc().
#include <bits/functexcept.h>
 
// For std::pair.
#include <utility>
 
// For greater_equal, and less_equal.
#include <functional>
 
// For operator new.
#include <new>
 
// For __gthread_mutex_t, __gthread_mutex_lock and __gthread_mutex_unlock.
#include <bits/gthr.h>
 
// Define this to enable error checking withing the allocator
// itself(to debug the allocator itself).
//#define _BALLOC_SANITY_CHECK
 
/** @brief The constant in the expression below is the alignment
 * required in bytes.
 */
#define _BALLOC_ALIGN_BYTES 8
 
#if defined _BALLOC_SANITY_CHECK
#include <cassert>
#define _BALLOC_ASSERT(_EXPR) assert(_EXPR)
#else
#define _BALLOC_ASSERT(_EXPR)
#endif
 
 
namespace __gnu_cxx
{
#if defined __GTHREADS
  namespace
  {
    /** @brief  If true, then the application being compiled will be
     *  using threads, so use mutexes as a synchronization primitive,
     *  else do no use any synchronization primitives.
     */
    bool const __threads_enabled = __gthread_active_p();
  }
#endif
 
#if defined __GTHREADS
  /** @class  _Mutex bitmap_allocator.h bitmap_allocator.h
   *
   *  @brief  _Mutex is an OO-Wrapper for __gthread_mutex_t.
   *
   *  It does not allow you to copy or assign an already initialized
   *  mutex. This is used merely as a convenience for the locking
   *  classes.
   */
  class _Mutex
  {
    __gthread_mutex_t _M_mut;
 
    // Prevent Copying and assignment.
    _Mutex(_Mutex const&);
    _Mutex& operator=(_Mutex const&);
 
  public:
    _Mutex()
    {
      if (__threads_enabled)
        {
#if !defined __GTHREAD_MUTEX_INIT
          __GTHREAD_MUTEX_INIT_FUNCTION(&_M_mut);
#else
          __gthread_mutex_t __mtemp = __GTHREAD_MUTEX_INIT;
          _M_mut = __mtemp;
#endif
        }
    }
 
    ~_Mutex()
    {
      // Gthreads does not define a Mutex Destruction Function.
    }
 
    __gthread_mutex_t*
    _M_get() { return &_M_mut; }
  };
 
  /** @class  _Lock bitmap_allocator.h bitmap_allocator.h
   *
   *  @brief  _Lock is a simple manual locking class which allows you to
   *  manually lock and unlock a mutex associated with the lock.
   *
   *  There is no automatic locking or unlocking happening without the
   *  programmer's explicit instructions. This class unlocks the mutex
   *  ONLY if it has not been locked. However, this check does not
   *  apply for locking, and wayward use may cause dead-locks.
   */
  class _Lock
  {
    _Mutex* _M_pmt;
    bool _M_locked;
 
    // Prevent Copying and assignment.
    _Lock(_Lock const&);
    _Lock& operator=(_Lock const&);
 
  public:
    _Lock(_Mutex* __mptr)
    : _M_pmt(__mptr), _M_locked(false)
    { }
 
    void
    _M_lock()
    {
      if (__threads_enabled)
        {
          _M_locked = true;
          __gthread_mutex_lock(_M_pmt->_M_get());
        }
    }
 
    void
    _M_unlock()
    {
      if (__threads_enabled)
        {
          if (__builtin_expect(_M_locked, true))
            {
              __gthread_mutex_unlock(_M_pmt->_M_get());
              _M_locked = false;
            }
        }
    }
 
    ~_Lock() { }
  };
 
  /** @class  _Auto_Lock bitmap_allocator.h bitmap_allocator.h
   *
   *  @brief  _Auto_Lock locks the associated mutex on construction, and
   *  unlocks on destruction.
   *
   *  There are no checks performed, and this class follows the RAII
   *  principle.
   */
  class _Auto_Lock
  {
    _Mutex* _M_pmt;
    // Prevent Copying and assignment.
    _Auto_Lock(_Auto_Lock const&);
    _Auto_Lock& operator=(_Auto_Lock const&);
 
    void
    _M_lock()
    {
      if (__threads_enabled)
        __gthread_mutex_lock(_M_pmt->_M_get());
    }
 
    void
    _M_unlock()
    {
      if (__threads_enabled)
        __gthread_mutex_unlock(_M_pmt->_M_get());
    }
 
  public:
    _Auto_Lock(_Mutex* __mptr) : _M_pmt(__mptr)
    { this->_M_lock(); }
 
    ~_Auto_Lock() { this->_M_unlock(); }
  };
#endif 
 
  namespace balloc
  {
    /** @class  __mini_vector bitmap_allocator.h bitmap_allocator.h
     *
     *  @brief  __mini_vector<> is a stripped down version of the
     *  full-fledged std::vector<>.
     *
     *  It is to be used only for built-in types or PODs. Notable
     *  differences are:
     *
     *  @detail
     *  1. Not all accessor functions are present.
     *  2. Used ONLY for PODs.
     *  3. No Allocator template argument. Uses ::operator new() to get
     *  memory, and ::operator delete() to free it.
     *  Caveat: The dtor does NOT free the memory allocated, so this a
     *  memory-leaking vector!
     */
    template<typename _Tp>
      class __mini_vector
      {
        __mini_vector(const __mini_vector&);
        __mini_vector& operator=(const __mini_vector&);
 
      public:
        typedef _Tp value_type;
        typedef _Tp* pointer;
        typedef _Tp& reference;
        typedef const _Tp& const_reference;
        typedef std::size_t size_type;
        typedef std::ptrdiff_t difference_type;
        typedef pointer iterator;
 
      private:
        pointer _M_start;
        pointer _M_finish;
        pointer _M_end_of_storage;
 
        size_type
        _M_space_left() const throw()
        { return _M_end_of_storage - _M_finish; }
 
        pointer
        allocate(size_type __n)
        { return static_cast<pointer>(::operator new(__n * sizeof(_Tp))); }
 
        void
        deallocate(pointer __p, size_type)
        { ::operator delete(__p); }
 
      public:
        // Members used: size(), push_back(), pop_back(),
        // insert(iterator, const_reference), erase(iterator),
        // begin(), end(), back(), operator[].
 
        __mini_vector() : _M_start(0), _M_finish(0),
                          _M_end_of_storage(0)
        { }
 
#if 0
        ~__mini_vector()
        {
          if (this->_M_start)
            {
              this->deallocate(this->_M_start, this->_M_end_of_storage
                               - this->_M_start);
            }
        }
#endif
 
        size_type
        size() const throw()
        { return _M_finish - _M_start; }
 
        iterator
        begin() const throw()
        { return this->_M_start; }
 
        iterator
        end() const throw()
        { return this->_M_finish; }
 
        reference
        back() const throw()
        { return *(this->end() - 1); }
 
        reference
        operator[](const size_type __pos) const throw()
        { return this->_M_start[__pos]; }
 
        void
        insert(iterator __pos, const_reference __x);
 
        void
        push_back(const_reference __x)
        {
          if (this->_M_space_left())
            {
              *this->end() = __x;
              ++this->_M_finish;
            }
          else
            this->insert(this->end(), __x);
        }
 
        void
        pop_back() throw()
        { --this->_M_finish; }
 
        void
        erase(iterator __pos) throw();
 
        void
        clear() throw()
        { this->_M_finish = this->_M_start; }
      };
 
    // Out of line function definitions.
    template<typename _Tp>
      void __mini_vector<_Tp>::
      insert(iterator __pos, const_reference __x)
      {
        if (this->_M_space_left())
          {
            size_type __to_move = this->_M_finish - __pos;
            iterator __dest = this->end();
            iterator __src = this->end() - 1;
 
            ++this->_M_finish;
            while (__to_move)
              {
                *__dest = *__src;
                --__dest; --__src; --__to_move;
              }
            *__pos = __x;
          }
        else
          {
            size_type __new_size = this->size() ? this->size() * 2 : 1;
            iterator __new_start = this->allocate(__new_size);
            iterator __first = this->begin();
            iterator __start = __new_start;
            while (__first != __pos)
              {
                *__start = *__first;
                ++__start; ++__first;
              }
            *__start = __x;
            ++__start;
            while (__first != this->end())
              {
                *__start = *__first;
                ++__start; ++__first;
              }
            if (this->_M_start)
              this->deallocate(this->_M_start, this->size());
 
            this->_M_start = __new_start;
            this->_M_finish = __start;
            this->_M_end_of_storage = this->_M_start + __new_size;
          }
      }
 
    template<typename _Tp>
      void __mini_vector<_Tp>::
      erase(iterator __pos) throw()
      {
        while (__pos + 1 != this->end())
          {
            *__pos = __pos[1];
            ++__pos;
          }
        --this->_M_finish;
      }
 
 
    template<typename _Tp>
      struct __mv_iter_traits
      {
        typedef typename _Tp::value_type value_type;
        typedef typename _Tp::difference_type difference_type;
      };
 
    template<typename _Tp>
      struct __mv_iter_traits<_Tp*>
      {
        typedef _Tp value_type;
        typedef std::ptrdiff_t difference_type;
      };
 
    enum
      {
        bits_per_byte = 8,
        bits_per_block = sizeof(size_t) * size_t(bits_per_byte)
      };
 
    template<typename _ForwardIterator, typename _Tp, typename _Compare>
      _ForwardIterator
      __lower_bound(_ForwardIterator __first, _ForwardIterator __last,
                    const _Tp& __val, _Compare __comp)
      {
        typedef typename __mv_iter_traits<_ForwardIterator>::value_type
          _ValueType;
        typedef typename __mv_iter_traits<_ForwardIterator>::difference_type
          _DistanceType;
 
        _DistanceType __len = __last - __first;
        _DistanceType __half;
        _ForwardIterator __middle;
 
        while (__len > 0)
          {
            __half = __len >> 1;
            __middle = __first;
            __middle += __half;
            if (__comp(*__middle, __val))
              {
                __first = __middle;
                ++__first;
                __len = __len - __half - 1;
              }
            else
              __len = __half;
          }
        return __first;
      }
 
    template<typename _InputIterator, typename _Predicate>
      inline _InputIterator
      __find_if(_InputIterator __first, _InputIterator __last, _Predicate __p)
      {
        while (__first != __last && !__p(*__first))
          ++__first;
        return __first;
      }
 
    /** @brief The number of Blocks pointed to by the address pair
     *  passed to the function.
     */
    template<typename _AddrPair>
      inline size_t
      __num_blocks(_AddrPair __ap)
      { return (__ap.second - __ap.first) + 1; }
 
    /** @brief The number of Bit-maps pointed to by the address pair
     *  passed to the function.
     */
    template<typename _AddrPair>
      inline size_t
      __num_bitmaps(_AddrPair __ap)
      { return __num_blocks(__ap) / size_t(bits_per_block); }
 
    // _Tp should be a pointer type.
    template<typename _Tp>
      class _Inclusive_between
      : public std::unary_function<typename std::pair<_Tp, _Tp>, bool>
      {
        typedef _Tp pointer;
        pointer _M_ptr_value;
        typedef typename std::pair<_Tp, _Tp> _Block_pair;
 
      public:
        _Inclusive_between(pointer __ptr) : _M_ptr_value(__ptr)
        { }
 
        bool
        operator()(_Block_pair __bp) const throw()
        {
          if (std::less_equal<pointer>()(_M_ptr_value, __bp.second)
              && std::greater_equal<pointer>()(_M_ptr_value, __bp.first))
            return true;
          else
            return false;
        }
      };
 
    // Used to pass a Functor to functions by reference.
    template<typename _Functor>
      class _Functor_Ref
      : public std::unary_function<typename _Functor::argument_type,
                                   typename _Functor::result_type>
      {
        _Functor& _M_fref;
 
      public:
        typedef typename _Functor::argument_type argument_type;
        typedef typename _Functor::result_type result_type;
 
        _Functor_Ref(_Functor& __fref) : _M_fref(__fref)
        { }
 
        result_type
        operator()(argument_type __arg)
        { return _M_fref(__arg); }
      };
 
    /** @class  _Ffit_finder bitmap_allocator.h bitmap_allocator.h
     *
     *  @brief  The class which acts as a predicate for applying the
     *  first-fit memory allocation policy for the bitmap allocator.
     */
    // _Tp should be a pointer type, and _Alloc is the Allocator for
    // the vector.
    template<typename _Tp>
      class _Ffit_finder
      : public std::unary_function<typename std::pair<_Tp, _Tp>, bool>
      {
        typedef typename std::pair<_Tp, _Tp> _Block_pair;
        typedef typename balloc::__mini_vector<_Block_pair> _BPVector;
        typedef typename _BPVector::difference_type _Counter_type;
 
        size_t* _M_pbitmap;
        _Counter_type _M_data_offset;
 
      public:
        _Ffit_finder() : _M_pbitmap(0), _M_data_offset(0)
        { }
 
        bool
        operator()(_Block_pair __bp) throw()
        {
          // Set the _rover to the last physical location bitmap,
          // which is the bitmap which belongs to the first free
          // block. Thus, the bitmaps are in exact reverse order of
          // the actual memory layout. So, we count down the bimaps,
          // which is the same as moving up the memory.
 
          // If the used count stored at the start of the Bit Map headers
          // is equal to the number of Objects that the current Block can
          // store, then there is definitely no space for another single
          // object, so just return false.
          _Counter_type __diff =
            __gnu_cxx::balloc::__num_bitmaps(__bp);
 
          if (*(reinterpret_cast<size_t*>
                (__bp.first) - (__diff + 1))
              == __gnu_cxx::balloc::__num_blocks(__bp))
            return false;
 
          size_t* __rover = reinterpret_cast<size_t*>(__bp.first) - 1;
 
          for (_Counter_type __i = 0; __i < __diff; ++__i)
            {
              _M_data_offset = __i;
              if (*__rover)
                {
                  _M_pbitmap = __rover;
                  return true;
                }
              --__rover;
            }
          return false;
        }
 
 
        size_t*
        _M_get() const throw()
        { return _M_pbitmap; }
 
        _Counter_type
        _M_offset() const throw()
        { return _M_data_offset * size_t(bits_per_block); }
      };
 
 
    /** @class  _Bitmap_counter bitmap_allocator.h bitmap_allocator.h
     *
     *  @brief  The bitmap counter which acts as the bitmap
     *  manipulator, and manages the bit-manipulation functions and
     *  the searching and identification functions on the bit-map.
     */
    // _Tp should be a pointer type.
    template<typename _Tp>
      class _Bitmap_counter
      {
        typedef typename balloc::__mini_vector<typename std::pair<_Tp, _Tp> >
        _BPVector;
        typedef typename _BPVector::size_type _Index_type;
        typedef _Tp pointer;
 
        _BPVector& _M_vbp;
        size_t* _M_curr_bmap;
        size_t* _M_last_bmap_in_block;
        _Index_type _M_curr_index;
 
      public:
        // Use the 2nd parameter with care. Make sure that such an
        // entry exists in the vector before passing that particular
        // index to this ctor.
        _Bitmap_counter(_BPVector& Rvbp, long __index = -1) : _M_vbp(Rvbp)
        { this->_M_reset(__index); }
 
        void
        _M_reset(long __index = -1) throw()
        {
          if (__index == -1)
            {
              _M_curr_bmap = 0;
              _M_curr_index = static_cast<_Index_type>(-1);
              return;
            }
 
          _M_curr_index = __index;
          _M_curr_bmap = reinterpret_cast<size_t*>
            (_M_vbp[_M_curr_index].first) - 1;
 
          _BALLOC_ASSERT(__index <= (long)_M_vbp.size() - 1);
 
          _M_last_bmap_in_block = _M_curr_bmap
            - ((_M_vbp[_M_curr_index].second
                - _M_vbp[_M_curr_index].first + 1)
               / size_t(bits_per_block) - 1);
        }
 
        // Dangerous Function! Use with extreme care. Pass to this
        // function ONLY those values that are known to be correct,
        // otherwise this will mess up big time.
        void
        _M_set_internal_bitmap(size_t* __new_internal_marker) throw()
        { _M_curr_bmap = __new_internal_marker; }
 
        bool
        _M_finished() const throw()
        { return(_M_curr_bmap == 0); }
 
        _Bitmap_counter&
        operator++() throw()
        {
          if (_M_curr_bmap == _M_last_bmap_in_block)
            {
              if (++_M_curr_index == _M_vbp.size())
                _M_curr_bmap = 0;
              else
                this->_M_reset(_M_curr_index);
            }
          else
            --_M_curr_bmap;
          return *this;
        }
 
        size_t*
        _M_get() const throw()
        { return _M_curr_bmap; }
 
        pointer
        _M_base() const throw()
        { return _M_vbp[_M_curr_index].first; }
 
        _Index_type
        _M_offset() const throw()
        {
          return size_t(bits_per_block)
            * ((reinterpret_cast<size_t*>(this->_M_base())
                - _M_curr_bmap) - 1);
        }
 
        _Index_type
        _M_where() const throw()
        { return _M_curr_index; }
      };
 
    /** @brief  Mark a memory address as allocated by re-setting the
     *  corresponding bit in the bit-map.
     */
    inline void
    __bit_allocate(size_t* __pbmap, size_t __pos) throw()
    {
      size_t __mask = 1 << __pos;
      __mask = ~__mask;
      *__pbmap &= __mask;
    }
 
    /** @brief  Mark a memory address as free by setting the
     *  corresponding bit in the bit-map.
     */
    inline void
    __bit_free(size_t* __pbmap, size_t __pos) throw()
    {
      size_t __mask = 1 << __pos;
      *__pbmap |= __mask;
    }
  } // namespace balloc
 
  /** @brief  Generic Version of the bsf instruction.
   */
  inline size_t
  _Bit_scan_forward(size_t __num)
  { return static_cast<size_t>(__builtin_ctzl(__num)); }
 
  /** @class  free_list bitmap_allocator.h bitmap_allocator.h
   *
   *  @brief  The free list class for managing chunks of memory to be
   *  given to and returned by the bitmap_allocator.
   */
  class free_list
  {
    typedef size_t* value_type;
    typedef balloc::__mini_vector<value_type> vector_type;
    typedef vector_type::iterator iterator;
 
    struct _LT_pointer_compare
    {
      bool
      operator()(const size_t* __pui,
                 const size_t __cui) const throw()
      { return *__pui < __cui; }
    };
 
#if defined __GTHREADS
    _Mutex*
    _M_get_mutex()
    {
      static _Mutex _S_mutex;
      return &_S_mutex;
    }
#endif
 
    vector_type&
    _M_get_free_list()
    {
      static vector_type _S_free_list;
      return _S_free_list;
    }
 
    /** @brief  Performs validation of memory based on their size.
     *
     *  @param  __addr The pointer to the memory block to be
     *  validated.
     *
     *  @detail  Validates the memory block passed to this function and
     *  appropriately performs the action of managing the free list of
     *  blocks by adding this block to the free list or deleting this
     *  or larger blocks from the free list.
     */
    void
    _M_validate(size_t* __addr) throw()
    {
      vector_type& __free_list = _M_get_free_list();
      const vector_type::size_type __max_size = 64;
      if (__free_list.size() >= __max_size)
        {
          // Ok, the threshold value has been reached.  We determine
          // which block to remove from the list of free blocks.
          if (*__addr >= *__free_list.back())
            {
              // Ok, the new block is greater than or equal to the
              // last block in the list of free blocks. We just free
              // the new block.
              ::operator delete(static_cast<void*>(__addr));
              return;
            }
          else
            {
              // Deallocate the last block in the list of free lists,
              // and insert the new one in it's correct position.
              ::operator delete(static_cast<void*>(__free_list.back()));
              __free_list.pop_back();
            }
        }
 
      // Just add the block to the list of free lists unconditionally.
      iterator __temp = __gnu_cxx::balloc::__lower_bound
        (__free_list.begin(), __free_list.end(),
         *__addr, _LT_pointer_compare());
 
      // We may insert the new free list before _temp;
      __free_list.insert(__temp, __addr);
    }
 
    /** @brief  Decides whether the wastage of memory is acceptable for
     *  the current memory request and returns accordingly.
     *
     *  @param __block_size The size of the block available in the free
     *  list.
     *
     *  @param __required_size The required size of the memory block.
     *
     *  @return true if the wastage incurred is acceptable, else returns
     *  false.
     */
    bool
    _M_should_i_give(size_t __block_size,
                     size_t __required_size) throw()
    {
      const size_t __max_wastage_percentage = 36;
      if (__block_size >= __required_size &&
          (((__block_size - __required_size) * 100 / __block_size)
           < __max_wastage_percentage))
        return true;
      else
        return false;
    }
 
  public:
    /** @brief This function returns the block of memory to the
     *  internal free list.
     *
     *  @param  __addr The pointer to the memory block that was given
     *  by a call to the _M_get function.
     */
    inline void
    _M_insert(size_t* __addr) throw()
    {
#if defined __GTHREADS
      _Auto_Lock __bfl_lock(_M_get_mutex());
#endif
      // Call _M_validate to decide what should be done with
      // this particular free list.
      this->_M_validate(reinterpret_cast<size_t*>(__addr) - 1);
      // See discussion as to why this is 1!
    }
 
    /** @brief  This function gets a block of memory of the specified
     *  size from the free list.
     *
     *  @param  __sz The size in bytes of the memory required.
     *
     *  @return  A pointer to the new memory block of size at least
     *  equal to that requested.
     */
    size_t*
    _M_get(size_t __sz) throw(std::bad_alloc);
 
    /** @brief  This function just clears the internal Free List, and
     *  gives back all the memory to the OS.
     */
    void
    _M_clear();
  };
 
 
  // Forward declare the class.
  template<typename _Tp>
    class bitmap_allocator;
 
  // Specialize for void:
  template<>
    class bitmap_allocator<void>
    {
    public:
      typedef void*       pointer;
      typedef const void* const_pointer;
 
      // Reference-to-void members are impossible.
      typedef void  value_type;
      template<typename _Tp1>
        struct rebind
        {
          typedef bitmap_allocator<_Tp1> other;
        };
    };
 
  template<typename _Tp>
    class bitmap_allocator : private free_list
    {
    public:
      typedef std::size_t    size_type;
      typedef std::ptrdiff_t difference_type;
      typedef _Tp*        pointer;
      typedef const _Tp*  const_pointer;
      typedef _Tp&        reference;
      typedef const _Tp&  const_reference;
      typedef _Tp         value_type;
      template<typename _Tp1>
        struct rebind
        {
          typedef bitmap_allocator<_Tp1> other;
        };
 
    private:
      template<size_t _BSize, size_t _AlignSize>
        struct aligned_size
        {
          enum
            {
              modulus = _BSize % _AlignSize,
              value = _BSize + (modulus ? _AlignSize - (modulus) : 0)
            };
        };
 
      struct _Alloc_block
      {
        char __M_unused[aligned_size<sizeof(value_type),
                        _BALLOC_ALIGN_BYTES>::value];
      };
 
 
      typedef typename std::pair<_Alloc_block*, _Alloc_block*> _Block_pair;
 
      typedef typename
      balloc::__mini_vector<_Block_pair> _BPVector;
 
#if defined _BALLOC_SANITY_CHECK
      // Complexity: O(lg(N)). Where, N is the number of block of size
      // sizeof(value_type).
      void
      _S_check_for_free_blocks() throw()
      {
        typedef typename
          __gnu_cxx::balloc::_Ffit_finder<_Alloc_block*> _FFF;
        _FFF __fff;
        typedef typename _BPVector::iterator _BPiter;
        _BPiter __bpi =
          __gnu_cxx::balloc::__find_if
          (_S_mem_blocks.begin(), _S_mem_blocks.end(),
           __gnu_cxx::balloc::_Functor_Ref<_FFF>(__fff));
 
        _BALLOC_ASSERT(__bpi == _S_mem_blocks.end());
      }
#endif
 
      /** @brief  Responsible for exponentially growing the internal
       *  memory pool.
       *
       *  @throw  std::bad_alloc. If memory can not be allocated.
       *
       *  @detail  Complexity: O(1), but internally depends upon the
       *  complexity of the function free_list::_M_get. The part where
       *  the bitmap headers are written has complexity: O(X),where X
       *  is the number of blocks of size sizeof(value_type) within
       *  the newly acquired block. Having a tight bound.
       */
      void
      _S_refill_pool() throw(std::bad_alloc)
      {
#if defined _BALLOC_SANITY_CHECK
        _S_check_for_free_blocks();
#endif
 
        const size_t __num_bitmaps = (_S_block_size
                                      / size_t(balloc::bits_per_block));
        const size_t __size_to_allocate = sizeof(size_t)
          + _S_block_size * sizeof(_Alloc_block)
          + __num_bitmaps * sizeof(size_t);
 
        size_t* __temp =
          reinterpret_cast<size_t*>
          (this->_M_get(__size_to_allocate));
        *__temp = 0;
        ++__temp;
 
        // The Header information goes at the Beginning of the Block.
        _Block_pair __bp =
          std::make_pair(reinterpret_cast<_Alloc_block*>
                         (__temp + __num_bitmaps),
                         reinterpret_cast<_Alloc_block*>
                         (__temp + __num_bitmaps)
                         + _S_block_size - 1);
 
        // Fill the Vector with this information.
        _S_mem_blocks.push_back(__bp);
 
        size_t __bit_mask = 0; // 0 Indicates all Allocated.
        __bit_mask = ~__bit_mask; // 1 Indicates all Free.
 
        for (size_t __i = 0; __i < __num_bitmaps; ++__i)
          __temp[__i] = __bit_mask;
 
        _S_block_size *= 2;
      }
 
 
      static _BPVector _S_mem_blocks;
      static size_t _S_block_size;
      static __gnu_cxx::balloc::
      _Bitmap_counter<_Alloc_block*> _S_last_request;
      static typename _BPVector::size_type _S_last_dealloc_index;
#if defined __GTHREADS
      static _Mutex _S_mut;
#endif
 
    public:
 
      /** @brief  Allocates memory for a single object of size
       *  sizeof(_Tp).
       *
       *  @throw  std::bad_alloc. If memory can not be allocated.
       *
       *  @detail  Complexity: Worst case complexity is O(N), but that
       *  is hardly ever hit. If and when this particular case is
       *  encountered, the next few cases are guaranteed to have a
       *  worst case complexity of O(1)!  That's why this function
       *  performs very well on average. You can consider this
       *  function to have a complexity referred to commonly as:
       *  Amortized Constant time.
       */
      pointer
      _M_allocate_single_object() throw(std::bad_alloc)
      {
#if defined __GTHREADS
        _Auto_Lock __bit_lock(&_S_mut);
#endif
 
        // The algorithm is something like this: The last_request
        // variable points to the last accessed Bit Map. When such a
        // condition occurs, we try to find a free block in the
        // current bitmap, or succeeding bitmaps until the last bitmap
        // is reached. If no free block turns up, we resort to First
        // Fit method.
 
        // WARNING: Do not re-order the condition in the while
        // statement below, because it relies on C++'s short-circuit
        // evaluation. The return from _S_last_request->_M_get() will
        // NOT be dereference able if _S_last_request->_M_finished()
        // returns true. This would inevitably lead to a NULL pointer
        // dereference if tinkered with.
        while (_S_last_request._M_finished() == false
               && (*(_S_last_request._M_get()) == 0))
          {
            _S_last_request.operator++();
          }
 
        if (__builtin_expect(_S_last_request._M_finished() == true, false))
          {
            // Fall Back to First Fit algorithm.
            typedef typename
              __gnu_cxx::balloc::_Ffit_finder<_Alloc_block*> _FFF;
            _FFF __fff;
            typedef typename _BPVector::iterator _BPiter;
            _BPiter __bpi =
              __gnu_cxx::balloc::__find_if
              (_S_mem_blocks.begin(), _S_mem_blocks.end(),
               __gnu_cxx::balloc::_Functor_Ref<_FFF>(__fff));
 
            if (__bpi != _S_mem_blocks.end())
              {
                // Search was successful. Ok, now mark the first bit from
                // the right as 0, meaning Allocated. This bit is obtained
                // by calling _M_get() on __fff.
                size_t __nz_bit = _Bit_scan_forward(*__fff._M_get());
                balloc::__bit_allocate(__fff._M_get(), __nz_bit);
 
                _S_last_request._M_reset(__bpi - _S_mem_blocks.begin());
 
                // Now, get the address of the bit we marked as allocated.
                pointer __ret = reinterpret_cast<pointer>
                  (__bpi->first + __fff._M_offset() + __nz_bit);
                size_t* __puse_count =
                  reinterpret_cast<size_t*>
                  (__bpi->first)
                  - (__gnu_cxx::balloc::__num_bitmaps(*__bpi) + 1);
 
                ++(*__puse_count);
                return __ret;
              }
            else
              {
                // Search was unsuccessful. We Add more memory to the
                // pool by calling _S_refill_pool().
                _S_refill_pool();
 
                // _M_Reset the _S_last_request structure to the first
                // free block's bit map.
                _S_last_request._M_reset(_S_mem_blocks.size() - 1);
 
                // Now, mark that bit as allocated.
              }
          }
 
        // _S_last_request holds a pointer to a valid bit map, that
        // points to a free block in memory.
        size_t __nz_bit = _Bit_scan_forward(*_S_last_request._M_get());
        balloc::__bit_allocate(_S_last_request._M_get(), __nz_bit);
 
        pointer __ret = reinterpret_cast<pointer>
          (_S_last_request._M_base() + _S_last_request._M_offset() + __nz_bit);
 
        size_t* __puse_count = reinterpret_cast<size_t*>
          (_S_mem_blocks[_S_last_request._M_where()].first)
          - (__gnu_cxx::balloc::
             __num_bitmaps(_S_mem_blocks[_S_last_request._M_where()]) + 1);
 
        ++(*__puse_count);
        return __ret;
      }
 
      /** @brief  Deallocates memory that belongs to a single object of
       *  size sizeof(_Tp).
       *
       *  @detail  Complexity: O(lg(N)), but the worst case is not hit
       *  often!  This is because containers usually deallocate memory
       *  close to each other and this case is handled in O(1) time by
       *  the deallocate function.
       */
      void
      _M_deallocate_single_object(pointer __p) throw()
      {
#if defined __GTHREADS
        _Auto_Lock __bit_lock(&_S_mut);
#endif
        _Alloc_block* __real_p = reinterpret_cast<_Alloc_block*>(__p);
 
        typedef typename _BPVector::iterator _Iterator;
        typedef typename _BPVector::difference_type _Difference_type;
 
        _Difference_type __diff;
        long __displacement;
 
        _BALLOC_ASSERT(_S_last_dealloc_index >= 0);
 
 
        if (__gnu_cxx::balloc::_Inclusive_between<_Alloc_block*>
            (__real_p)
            (_S_mem_blocks[_S_last_dealloc_index]))
          {
            _BALLOC_ASSERT(_S_last_dealloc_index <= _S_mem_blocks.size() - 1);
 
            // Initial Assumption was correct!
            __diff = _S_last_dealloc_index;
            __displacement = __real_p - _S_mem_blocks[__diff].first;
          }
        else
          {
            _Iterator _iter =
              __gnu_cxx::balloc::
              __find_if(_S_mem_blocks.begin(),
                        _S_mem_blocks.end(),
                        __gnu_cxx::balloc::
                        _Inclusive_between<_Alloc_block*>(__real_p));
 
            _BALLOC_ASSERT(_iter != _S_mem_blocks.end());
 
            __diff = _iter - _S_mem_blocks.begin();
            __displacement = __real_p - _S_mem_blocks[__diff].first;
            _S_last_dealloc_index = __diff;
          }
 
        // Get the position of the iterator that has been found.
        const size_t __rotate = (__displacement
                                 % size_t(balloc::bits_per_block));
        size_t* __bitmapC =
          reinterpret_cast<size_t*>
          (_S_mem_blocks[__diff].first) - 1;
        __bitmapC -= (__displacement / size_t(balloc::bits_per_block));
 
        balloc::__bit_free(__bitmapC, __rotate);
        size_t* __puse_count = reinterpret_cast<size_t*>
          (_S_mem_blocks[__diff].first)
          - (__gnu_cxx::balloc::__num_bitmaps(_S_mem_blocks[__diff]) + 1);
 
        _BALLOC_ASSERT(*__puse_count != 0);
 
        --(*__puse_count);
 
        if (__builtin_expect(*__puse_count == 0, false))
          {
            _S_block_size /= 2;
 
            // We can safely remove this block.
            // _Block_pair __bp = _S_mem_blocks[__diff];
            this->_M_insert(__puse_count);
            _S_mem_blocks.erase(_S_mem_blocks.begin() + __diff);
 
            // Reset the _S_last_request variable to reflect the
            // erased block. We do this to protect future requests
            // after the last block has been removed from a particular
            // memory Chunk, which in turn has been returned to the
            // free list, and hence had been erased from the vector,
            // so the size of the vector gets reduced by 1.
            if ((_Difference_type)_S_last_request._M_where() >= __diff--)
              _S_last_request._M_reset(__diff);
 
            // If the Index into the vector of the region of memory
            // that might hold the next address that will be passed to
            // deallocated may have been invalidated due to the above
            // erase procedure being called on the vector, hence we
            // try to restore this invariant too.
            if (_S_last_dealloc_index >= _S_mem_blocks.size())
              {
                _S_last_dealloc_index =(__diff != -1 ? __diff : 0);
                _BALLOC_ASSERT(_S_last_dealloc_index >= 0);
              }
          }
      }
 
    public:
      bitmap_allocator() throw()
      { }
 
      bitmap_allocator(const bitmap_allocator&)
      { }
 
      template<typename _Tp1>
        bitmap_allocator(const bitmap_allocator<_Tp1>&) throw()
        { }
 
      ~bitmap_allocator() throw()
      { }
 
      pointer
      allocate(size_type __n)
      {
        if (__builtin_expect(__n > this->max_size(), false))
          std::__throw_bad_alloc();
 
        if (__builtin_expect(__n == 1, true))
          return this->_M_allocate_single_object();
        else
          {
            const size_type __b = __n * sizeof(value_type);
            return reinterpret_cast<pointer>(::operator new(__b));
          }
      }
 
      pointer
      allocate(size_type __n, typename bitmap_allocator<void>::const_pointer)
      { return allocate(__n); }
 
      void
      deallocate(pointer __p, size_type __n) throw()
      {
        if (__builtin_expect(__p != 0, true))
          {
            if (__builtin_expect(__n == 1, true))
              this->_M_deallocate_single_object(__p);
            else
              ::operator delete(__p);
          }
      }
 
      pointer
      address(reference __r) const
      { return &__r; }
 
      const_pointer
      address(const_reference __r) const
      { return &__r; }
 
      size_type
      max_size() const throw()
      { return size_type(-1) / sizeof(value_type); }
 
      void
      construct(pointer __p, const_reference __data)
      { ::new(__p) value_type(__data); }
 
      void
      destroy(pointer __p)
      { __p->~value_type(); }
    };
 
  template<typename _Tp1, typename _Tp2>
    bool
    operator==(const bitmap_allocator<_Tp1>&,
               const bitmap_allocator<_Tp2>&) throw()
    { return true; }
 
  template<typename _Tp1, typename _Tp2>
    bool
    operator!=(const bitmap_allocator<_Tp1>&,
               const bitmap_allocator<_Tp2>&) throw()
  { return false; }
 
  // Static member definitions.
  template<typename _Tp>
    typename bitmap_allocator<_Tp>::_BPVector
    bitmap_allocator<_Tp>::_S_mem_blocks;
 
  template<typename _Tp>
    size_t bitmap_allocator<_Tp>::_S_block_size =
    2 * size_t(balloc::bits_per_block);
 
  template<typename _Tp>
    typename __gnu_cxx::bitmap_allocator<_Tp>::_BPVector::size_type
    bitmap_allocator<_Tp>::_S_last_dealloc_index = 0;
 
  template<typename _Tp>
    __gnu_cxx::balloc::_Bitmap_counter
  <typename bitmap_allocator<_Tp>::_Alloc_block*>
    bitmap_allocator<_Tp>::_S_last_request(_S_mem_blocks);
 
#if defined __GTHREADS
  template<typename _Tp>
    __gnu_cxx::_Mutex
    bitmap_allocator<_Tp>::_S_mut;
#endif
 
 
}
 
#endif 
 
//  LocalWords:  namespace GTHREADS bool const gthread endif Mutex mutex
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[/] [scarts/] [trunk/] [toolchain/] [scarts-gcc/] [gcc-4.1.1/] [libstdc++-v3/] [include/] [ext/] [bitmap_allocator.h] - Blame information for rev 17

Line No.	Rev	Author	Line
1	17	jlechner	`// Bitmap Allocator. -- C++ --`
2
3			`// Copyright (C) 2004, 2005 Free Software Foundation, Inc.`
4			`//`
5			`// This file is part of the GNU ISO C++ Library. This library is free`
6			`// software; you can redistribute it and/or modify it under the`
7			`// terms of the GNU General Public License as published by the`
8			`// Free Software Foundation; either version 2, or (at your option)`
9			`// any later version.`
10
11			`// This library is distributed in the hope that it will be useful,`
12			`// but WITHOUT ANY WARRANTY; without even the implied warranty of`
13			`// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the`
14			`// GNU General Public License for more details.`
15
16			`// You should have received a copy of the GNU General Public License along`
17			`// with this library; see the file COPYING. If not, write to the Free`
18			`// Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,`
19			`// USA.`
20
21			`// As a special exception, you may use this file as part of a free software`
22			`// library without restriction. Specifically, if other files instantiate`
23			`// templates or use macros or inline functions from this file, or you compile`
24			`// this file and link it with other files to produce an executable, this`
25			`// file does not by itself cause the resulting executable to be covered by`
26			`// the GNU General Public License. This exception does not however`
27			`// invalidate any other reasons why the executable file might be covered by`
28			`// the GNU General Public License.`
29
30			`/** @file ext/bitmap_allocator.h`
31			`* This file is a GNU extension to the Standard C++ Library.`
32			`*/`
33
34			`#ifndef _BITMAP_ALLOCATOR_H`
35			`#define _BITMAP_ALLOCATOR_H 1`
36
37			`// For std::size_t, and ptrdiff_t.`
38			`#include <cstddef>`
39
40			`// For __throw_bad_alloc().`