1 // Bitmap Allocator. -*- C++ -*-
3 // Copyright (C) 2004 Free Software Foundation, Inc.
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)
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.
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, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
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.
30 /** @file ext/bitmap_allocator.h
31 * This file is a GNU extension to the Standard C++ Library.
32 * You should only include this header if you are using GCC 3 or later.
35 #ifndef _BITMAP_ALLOCATOR_H
36 #define _BITMAP_ALLOCATOR_H 1
38 // For std::size_t, and ptrdiff_t.
44 // For greater_equal, and less_equal.
50 // For __gthread_mutex_t, __gthread_mutex_lock and __gthread_mutex_unlock.
51 #include <bits/gthr.h>
53 // Define this to enable error checking withing the allocator
54 // itself(to debug the allocator itself).
55 //#define _BALLOC_SANITY_CHECK
57 // The constant in the expression below is the alignment required in
59 #define _BALLOC_ALIGN_BYTES 8
61 #if defined _BALLOC_SANITY_CHECK
63 #define _BALLOC_ASSERT(_EXPR) assert(_EXPR)
65 #define _BALLOC_ASSERT(_EXPR)
71 #if defined __GTHREADS
74 // If true, then the application being compiled will be using
75 // threads, so use mutexes as a synchronization primitive, else do
76 // no use any synchronization primitives.
77 bool const __threads_enabled = __gthread_active_p();
81 #if defined __GTHREADS
82 // _Mutex is an OO-Wrapper for __gthread_mutex_t. It does not allow
83 // you to copy or assign an already initialized mutex. This is used
84 // merely as a convenience for the locking classes.
87 __gthread_mutex_t _M_mut;
89 // Prevent Copying and assignment.
90 _Mutex(_Mutex const&);
91 _Mutex& operator=(_Mutex const&);
96 if (__threads_enabled)
98 #if !defined __GTHREAD_MUTEX_INIT
99 __GTHREAD_MUTEX_INIT_FUNCTION(&_M_mut);
101 __gthread_mutex_t __mtemp = __GTHREAD_MUTEX_INIT;
109 // Gthreads does not define a Mutex Destruction Function.
113 _M_get() { return &_M_mut; }
116 // _Lock is a simple manual lokcing class which allows you to
117 // manually lock and unlock a mutex associated with the lock. There
118 // is not automatic locking or unlocking happening without the
119 // programmer's explicit instructions. This class unlocks the mutex
120 // ONLY if it has not been locked. However, this check does not
121 // apply for lokcing, and wayward use may cause dead-locks.
127 // Prevent Copying and assignment.
129 _Lock& operator=(_Lock const&);
132 _Lock(_Mutex* __mptr)
133 : _M_pmt(__mptr), _M_locked(false)
139 if (__threads_enabled)
142 __gthread_mutex_lock(_M_pmt->_M_get());
149 if (__threads_enabled)
151 if (__builtin_expect(_M_locked, true))
153 __gthread_mutex_unlock(_M_pmt->_M_get());
162 // _Auto_Lock locks the associated mutex on construction, and
163 // unlocks on it's destruction. There are no checks performed, and
164 // this calss follows the RAII principle.
168 // Prevent Copying and assignment.
169 _Auto_Lock(_Auto_Lock const&);
170 _Auto_Lock& operator=(_Auto_Lock const&);
175 if (__threads_enabled)
176 __gthread_mutex_lock(_M_pmt->_M_get());
182 if (__threads_enabled)
183 __gthread_mutex_unlock(_M_pmt->_M_get());
187 _Auto_Lock(_Mutex* __mptr) : _M_pmt(__mptr)
190 ~_Auto_Lock() { this->_M_unlock(); }
196 // __mini_vector<> is to be used only for built-in types or
197 // PODs. It is a stripped down version of the full-fledged
198 // std::vector<>. Noteable differences are:
200 // 1. Not all accessor functions are present.
201 // 2. Used ONLY for PODs.
202 // 3. No Allocator template argument. Uses ::operator new() to get
203 // memory, and ::operator delete() to free it.
204 template<typename _Tp>
207 __mini_vector(const __mini_vector&);
208 __mini_vector& operator=(const __mini_vector&);
211 typedef _Tp value_type;
212 typedef _Tp* pointer;
213 typedef _Tp& reference;
214 typedef const _Tp& const_reference;
215 typedef std::size_t size_type;
216 typedef std::ptrdiff_t difference_type;
217 typedef pointer iterator;
222 pointer _M_end_of_storage;
225 _M_space_left() const throw()
226 { return _M_end_of_storage - _M_finish; }
229 allocate(size_type __n)
230 { return static_cast<pointer>(::operator new(__n * sizeof(_Tp))); }
233 deallocate(pointer __p, size_type)
234 { ::operator delete(__p); }
237 // Members used: size(), push_back(), pop_back(),
238 // insert(iterator, const_reference), erase(iterator),
239 // begin(), end(), back(), operator[].
241 __mini_vector() : _M_start(0), _M_finish(0),
250 this->deallocate(this->_M_start, this->_M_end_of_storage
258 { return _M_finish - _M_start; }
261 begin() const throw()
262 { return this->_M_start; }
266 { return this->_M_finish; }
270 { return *(this->end() - 1); }
273 operator[](const size_type __pos) const throw()
274 { return this->_M_start[__pos]; }
277 insert(iterator __pos, const_reference __x);
280 push_back(const_reference __x)
282 if (this->_M_space_left())
288 this->insert(this->end(), __x);
293 { --this->_M_finish; }
296 erase(iterator __pos) throw();
300 { this->_M_finish = this->_M_start; }
303 // Out of line function definitions.
304 template<typename _Tp>
305 void __mini_vector<_Tp>::
306 insert(iterator __pos, const_reference __x)
308 if (this->_M_space_left())
310 size_type __to_move = this->_M_finish - __pos;
311 iterator __dest = this->end();
312 iterator __src = this->end() - 1;
318 --__dest; --__src; --__to_move;
324 size_type __new_size = this->size() ? this->size() * 2 : 1;
325 iterator __new_start = this->allocate(__new_size);
326 iterator __first = this->begin();
327 iterator __start = __new_start;
328 while (__first != __pos)
331 ++__start; ++__first;
335 while (__first != this->end())
338 ++__start; ++__first;
341 this->deallocate(this->_M_start, this->size());
343 this->_M_start = __new_start;
344 this->_M_finish = __start;
345 this->_M_end_of_storage = this->_M_start + __new_size;
349 template<typename _Tp>
350 void __mini_vector<_Tp>::
351 erase(iterator __pos) throw()
353 while (__pos + 1 != this->end())
362 template<typename _Tp>
363 struct __mv_iter_traits
365 typedef typename _Tp::value_type value_type;
366 typedef typename _Tp::difference_type difference_type;
369 template<typename _Tp>
370 struct __mv_iter_traits<_Tp*>
372 typedef _Tp value_type;
373 typedef std::ptrdiff_t difference_type;
379 bits_per_block = sizeof(size_t) * bits_per_byte
382 template<typename _ForwardIterator, typename _Tp, typename _Compare>
384 __lower_bound(_ForwardIterator __first, _ForwardIterator __last,
385 const _Tp& __val, _Compare __comp)
387 typedef typename __mv_iter_traits<_ForwardIterator>::value_type
389 typedef typename __mv_iter_traits<_ForwardIterator>::difference_type
392 _DistanceType __len = __last - __first;
393 _DistanceType __half;
394 _ForwardIterator __middle;
401 if (__comp(*__middle, __val))
405 __len = __len - __half - 1;
413 template<typename _InputIterator, typename _Predicate>
414 inline _InputIterator
415 __find_if(_InputIterator __first, _InputIterator __last, _Predicate __p)
417 while (__first != __last && !__p(*__first))
422 template<typename _AddrPair>
424 __num_blocks(_AddrPair __ap)
425 { return (__ap.second - __ap.first) + 1; }
427 template<typename _AddrPair>
429 __num_bitmaps(_AddrPair __ap)
430 { return __num_blocks(__ap) / bits_per_block; }
432 // _Tp should be a pointer type.
433 template<typename _Tp>
434 class _Inclusive_between
435 : public std::unary_function<typename std::pair<_Tp, _Tp>, bool>
438 pointer _M_ptr_value;
439 typedef typename std::pair<_Tp, _Tp> _Block_pair;
442 _Inclusive_between(pointer __ptr) : _M_ptr_value(__ptr)
446 operator()(_Block_pair __bp) const throw()
448 if (std::less_equal<pointer>()(_M_ptr_value, __bp.second)
449 && std::greater_equal<pointer>()(_M_ptr_value, __bp.first))
456 // Used to pass a Functor to functions by reference.
457 template<typename _Functor>
459 : public std::unary_function<typename _Functor::argument_type,
460 typename _Functor::result_type>
465 typedef typename _Functor::argument_type argument_type;
466 typedef typename _Functor::result_type result_type;
468 _Functor_Ref(_Functor& __fref) : _M_fref(__fref)
472 operator()(argument_type __arg)
473 { return _M_fref(__arg); }
476 // _Tp should be a pointer type, and _Alloc is the Allocator for
478 template<typename _Tp>
480 : public std::unary_function<typename std::pair<_Tp, _Tp>, bool>
482 typedef typename std::pair<_Tp, _Tp> _Block_pair;
483 typedef typename balloc::__mini_vector<_Block_pair> _BPVector;
484 typedef typename _BPVector::difference_type _Counter_type;
487 _Counter_type _M_data_offset;
490 _Ffit_finder() : _M_pbitmap(0), _M_data_offset(0)
494 operator()(_Block_pair __bp) throw()
496 // Set the _rover to the last physical location bitmap,
497 // which is the bitmap which belongs to the first free
498 // block. Thus, the bitmaps are in exact reverse order of
499 // the actual memory layout. So, we count down the bimaps,
500 // which is the same as moving up the memory.
502 // If the used count stored at the start of the Bit Map headers
503 // is equal to the number of Objects that the current Block can
504 // store, then there is definitely no space for another single
505 // object, so just return false.
506 _Counter_type __diff =
507 __gnu_cxx::balloc::__num_bitmaps(__bp);
509 if (*(reinterpret_cast<size_t*>
510 (__bp.first) - (__diff + 1))
511 == __gnu_cxx::balloc::__num_blocks(__bp))
514 size_t* __rover = reinterpret_cast<size_t*>(__bp.first) - 1;
516 for (_Counter_type __i = 0; __i < __diff; ++__i)
518 _M_data_offset = __i;
521 _M_pbitmap = __rover;
531 _M_get() const throw()
532 { return _M_pbitmap; }
535 _M_offset() const throw()
536 { return _M_data_offset * bits_per_block; }
541 // _Tp should be a pointer type.
542 template<typename _Tp>
543 class _Bitmap_counter
545 typedef typename balloc::__mini_vector<typename std::pair<_Tp, _Tp> >
547 typedef typename _BPVector::size_type _Index_type;
551 size_t* _M_curr_bmap;
552 size_t* _M_last_bmap_in_block;
553 _Index_type _M_curr_index;
556 // Use the 2nd parameter with care. Make sure that such an
557 // entry exists in the vector before passing that particular
558 // index to this ctor.
559 _Bitmap_counter(_BPVector& Rvbp, long __index = -1) : _M_vbp(Rvbp)
560 { this->_M_reset(__index); }
563 _M_reset(long __index = -1) throw()
568 _M_curr_index = static_cast<_Index_type>(-1);
572 _M_curr_index = __index;
573 _M_curr_bmap = reinterpret_cast<size_t*>
574 (_M_vbp[_M_curr_index].first) - 1;
576 _BALLOC_ASSERT(__index <= (long)_M_vbp.size() - 1);
578 _M_last_bmap_in_block = _M_curr_bmap
579 - ((_M_vbp[_M_curr_index].second
580 - _M_vbp[_M_curr_index].first + 1)
581 / bits_per_block - 1);
584 // Dangerous Function! Use with extreme care. Pass to this
585 // function ONLY those values that are known to be correct,
586 // otherwise this will mess up big time.
588 _M_set_internal_bitmap(size_t* __new_internal_marker) throw()
589 { _M_curr_bmap = __new_internal_marker; }
592 _M_finished() const throw()
593 { return(_M_curr_bmap == 0); }
598 if (_M_curr_bmap == _M_last_bmap_in_block)
600 if (++_M_curr_index == _M_vbp.size())
603 this->_M_reset(_M_curr_index);
611 _M_get() const throw()
612 { return _M_curr_bmap; }
615 _M_base() const throw()
616 { return _M_vbp[_M_curr_index].first; }
619 _M_offset() const throw()
621 return bits_per_block
622 * ((reinterpret_cast<size_t*>(this->_M_base())
623 - _M_curr_bmap) - 1);
627 _M_where() const throw()
628 { return _M_curr_index; }
632 __bit_allocate(size_t* __pbmap, size_t __pos) throw()
634 size_t __mask = 1 << __pos;
640 __bit_free(size_t* __pbmap, size_t __pos) throw()
642 size_t __mask = 1 << __pos;
645 } // namespace balloc
647 // Generic Version of the bsf instruction.
649 _Bit_scan_forward(size_t __num)
650 { return static_cast<size_t>(__builtin_ctzl(__num)); }
654 typedef size_t* value_type;
655 typedef balloc::__mini_vector<value_type> vector_type;
656 typedef vector_type::iterator iterator;
658 struct _LT_pointer_compare
661 operator()(const size_t* __pui,
662 const size_t __cui) const throw()
663 { return *__pui < __cui; }
666 #if defined __GTHREADS
667 static _Mutex _S_bfl_mutex;
669 static vector_type _S_free_list;
672 _M_validate(size_t* __addr) throw()
674 const vector_type::size_type __max_size = 64;
675 if (_S_free_list.size() >= __max_size)
677 // Ok, the threshold value has been reached. We determine
678 // which block to remove from the list of free blocks.
679 if (*__addr >= *_S_free_list.back())
681 // Ok, the new block is greater than or equal to the
682 // last block in the list of free blocks. We just free
684 ::operator delete(static_cast<void*>(__addr));
689 // Deallocate the last block in the list of free lists,
690 // and insert the new one in it's correct position.
691 ::operator delete(static_cast<void*>(_S_free_list.back()));
692 _S_free_list.pop_back();
696 // Just add the block to the list of free lists unconditionally.
697 iterator __temp = __gnu_cxx::balloc::__lower_bound
698 (_S_free_list.begin(), _S_free_list.end(),
699 *__addr, _LT_pointer_compare());
701 // We may insert the new free list before _temp;
702 _S_free_list.insert(__temp, __addr);
706 _M_should_i_give(size_t __block_size,
707 size_t __required_size) throw()
709 const size_t __max_wastage_percentage = 36;
710 if (__block_size >= __required_size &&
711 (((__block_size - __required_size) * 100 / __block_size)
712 < __max_wastage_percentage))
720 _M_insert(size_t* __addr) throw()
722 #if defined __GTHREADS
723 _Auto_Lock __bfl_lock(&_S_bfl_mutex);
725 // Call _M_validate to decide what should be done with
726 // this particular free list.
727 this->_M_validate(reinterpret_cast<size_t*>(__addr) - 1);
728 // See discussion as to why this is 1!
732 _M_get(size_t __sz) throw(std::bad_alloc);
734 // This function just clears the internal Free List, and gives back
735 // all the memory to the OS.
741 // Forward declare the class.
742 template<typename _Tp>
743 class bitmap_allocator;
745 // Specialize for void:
747 class bitmap_allocator<void>
750 typedef void* pointer;
751 typedef const void* const_pointer;
753 // Reference-to-void members are impossible.
754 typedef void value_type;
755 template<typename _Tp1>
758 typedef bitmap_allocator<_Tp1> other;
762 template<typename _Tp>
763 class bitmap_allocator : private free_list
766 typedef std::size_t size_type;
767 typedef std::ptrdiff_t difference_type;
768 typedef _Tp* pointer;
769 typedef const _Tp* const_pointer;
770 typedef _Tp& reference;
771 typedef const _Tp& const_reference;
772 typedef _Tp value_type;
773 template<typename _Tp1>
776 typedef bitmap_allocator<_Tp1> other;
780 template<size_t _BSize, size_t _AlignSize>
785 modulus = _BSize % _AlignSize,
786 value = _BSize + (modulus ? _AlignSize - (modulus) : 0)
792 char __M_unused[aligned_size<sizeof(value_type),
793 _BALLOC_ALIGN_BYTES>::value];
797 typedef typename std::pair<_Alloc_block*, _Alloc_block*> _Block_pair;
800 balloc::__mini_vector<_Block_pair> _BPVector;
802 #if defined _BALLOC_SANITY_CHECK
803 // Complexity: O(lg(N)). Where, N is the number of block of size
804 // sizeof(value_type).
806 _S_check_for_free_blocks() throw()
809 __gnu_cxx::balloc::_Ffit_finder<_Alloc_block*> _FFF;
811 typedef typename _BPVector::iterator _BPiter;
813 __gnu_cxx::balloc::__find_if
814 (_S_mem_blocks.begin(), _S_mem_blocks.end(),
815 __gnu_cxx::balloc::_Functor_Ref<_FFF>(__fff));
817 _BALLOC_ASSERT(__bpi == _S_mem_blocks.end());
821 // Complexity: O(1), but internally depends upon the complexity
822 // of the function free_list::_M_get. The
823 // part where the bitmap headers are written is of worst case
824 // complexity: O(X),where X is the number of blocks of size
825 // sizeof(value_type) within the newly acquired block. Having a
828 _S_refill_pool() throw(std::bad_alloc)
830 #if defined _BALLOC_SANITY_CHECK
831 _S_check_for_free_blocks();
834 const size_t __num_bitmaps = _S_block_size / balloc::bits_per_block;
835 const size_t __size_to_allocate = sizeof(size_t)
836 + _S_block_size * sizeof(_Alloc_block)
837 + __num_bitmaps * sizeof(size_t);
840 reinterpret_cast<size_t*>
841 (this->_M_get(__size_to_allocate));
845 // The Header information goes at the Beginning of the Block.
847 std::make_pair(reinterpret_cast<_Alloc_block*>
848 (__temp + __num_bitmaps),
849 reinterpret_cast<_Alloc_block*>
850 (__temp + __num_bitmaps)
851 + _S_block_size - 1);
853 // Fill the Vector with this information.
854 _S_mem_blocks.push_back(__bp);
856 size_t __bit_mask = 0; // 0 Indicates all Allocated.
857 __bit_mask = ~__bit_mask; // 1 Indicates all Free.
859 for (size_t __i = 0; __i < __num_bitmaps; ++__i)
860 __temp[__i] = __bit_mask;
866 static _BPVector _S_mem_blocks;
867 static size_t _S_block_size;
868 static __gnu_cxx::balloc::
869 _Bitmap_counter<_Alloc_block*> _S_last_request;
870 static typename _BPVector::size_type _S_last_dealloc_index;
871 #if defined __GTHREADS
872 static _Mutex _S_mut;
877 // Complexity: Worst case complexity is O(N), but that is hardly
878 // ever hit. if and when this particular case is encountered,
879 // the next few cases are guaranteed to have a worst case
880 // complexity of O(1)! That's why this function performs very
881 // well on the average. you can consider this function to be
882 // having a complexity referred to commonly as: Amortized
885 _M_allocate_single_object() throw(std::bad_alloc)
887 #if defined __GTHREADS
888 _Auto_Lock __bit_lock(&_S_mut);
891 // The algorithm is something like this: The last_request
892 // variable points to the last accessed Bit Map. When such a
893 // condition occurs, we try to find a free block in the
894 // current bitmap, or succeeding bitmaps until the last bitmap
895 // is reached. If no free block turns up, we resort to First
898 // WARNING: Do not re-order the condition in the while
899 // statement below, because it relies on C++'s short-circuit
900 // evaluation. The return from _S_last_request->_M_get() will
901 // NOT be dereference able if _S_last_request->_M_finished()
902 // returns true. This would inevitably lead to a NULL pointer
903 // dereference if tinkered with.
904 while (_S_last_request._M_finished() == false
905 && (*(_S_last_request._M_get()) == 0))
907 _S_last_request.operator++();
910 if (__builtin_expect(_S_last_request._M_finished() == true, false))
912 // Fall Back to First Fit algorithm.
914 __gnu_cxx::balloc::_Ffit_finder<_Alloc_block*> _FFF;
916 typedef typename _BPVector::iterator _BPiter;
918 __gnu_cxx::balloc::__find_if
919 (_S_mem_blocks.begin(), _S_mem_blocks.end(),
920 __gnu_cxx::balloc::_Functor_Ref<_FFF>(__fff));
922 if (__bpi != _S_mem_blocks.end())
924 // Search was successful. Ok, now mark the first bit from
925 // the right as 0, meaning Allocated. This bit is obtained
926 // by calling _M_get() on __fff.
927 size_t __nz_bit = _Bit_scan_forward(*__fff._M_get());
928 balloc::__bit_allocate(__fff._M_get(), __nz_bit);
930 _S_last_request._M_reset(__bpi - _S_mem_blocks.begin());
932 // Now, get the address of the bit we marked as allocated.
933 pointer __ret = reinterpret_cast<pointer>
934 (__bpi->first + __fff._M_offset() + __nz_bit);
935 size_t* __puse_count =
936 reinterpret_cast<size_t*>
938 - (__gnu_cxx::balloc::__num_bitmaps(*__bpi) + 1);
945 // Search was unsuccessful. We Add more memory to the
946 // pool by calling _S_refill_pool().
949 // _M_Reset the _S_last_request structure to the first
950 // free block's bit map.
951 _S_last_request._M_reset(_S_mem_blocks.size() - 1);
953 // Now, mark that bit as allocated.
957 // _S_last_request holds a pointer to a valid bit map, that
958 // points to a free block in memory.
959 size_t __nz_bit = _Bit_scan_forward(*_S_last_request._M_get());
960 balloc::__bit_allocate(_S_last_request._M_get(), __nz_bit);
962 pointer __ret = reinterpret_cast<pointer>
963 (_S_last_request._M_base() + _S_last_request._M_offset() + __nz_bit);
965 size_t* __puse_count = reinterpret_cast<size_t*>
966 (_S_mem_blocks[_S_last_request._M_where()].first)
967 - (__gnu_cxx::balloc::
968 __num_bitmaps(_S_mem_blocks[_S_last_request._M_where()]) + 1);
974 // Complexity: O(lg(N)), but the worst case is hit quite often!
975 // I need to do something about this. I'll be able to work on
976 // it, only when I have some solid figures from a few real apps.
978 _M_deallocate_single_object(pointer __p) throw()
980 #if defined __GTHREADS
981 _Auto_Lock __bit_lock(&_S_mut);
983 _Alloc_block* __real_p = reinterpret_cast<_Alloc_block*>(__p);
985 typedef typename _BPVector::iterator _Iterator;
986 typedef typename _BPVector::difference_type _Difference_type;
988 _Difference_type __diff;
991 _BALLOC_ASSERT(_S_last_dealloc_index >= 0);
994 if (__gnu_cxx::balloc::_Inclusive_between<_Alloc_block*>
996 (_S_mem_blocks[_S_last_dealloc_index]))
998 _BALLOC_ASSERT(_S_last_dealloc_index <= _S_mem_blocks.size() - 1);
1000 // Initial Assumption was correct!
1001 __diff = _S_last_dealloc_index;
1002 __displacement = __real_p - _S_mem_blocks[__diff].first;
1008 __find_if(_S_mem_blocks.begin(),
1009 _S_mem_blocks.end(),
1011 _Inclusive_between<_Alloc_block*>(__real_p));
1013 _BALLOC_ASSERT(_iter != _S_mem_blocks.end());
1015 __diff = _iter - _S_mem_blocks.begin();
1016 __displacement = __real_p - _S_mem_blocks[__diff].first;
1017 _S_last_dealloc_index = __diff;
1020 // Get the position of the iterator that has been found.
1021 const size_t __rotate = __displacement % balloc::bits_per_block;
1023 reinterpret_cast<size_t*>
1024 (_S_mem_blocks[__diff].first) - 1;
1025 __bitmapC -= (__displacement / balloc::bits_per_block);
1027 balloc::__bit_free(__bitmapC, __rotate);
1028 size_t* __puse_count = reinterpret_cast<size_t*>
1029 (_S_mem_blocks[__diff].first)
1030 - (__gnu_cxx::balloc::__num_bitmaps(_S_mem_blocks[__diff]) + 1);
1032 _BALLOC_ASSERT(*__puse_count != 0);
1036 if (__builtin_expect(*__puse_count == 0, false))
1040 // We can safely remove this block.
1041 // _Block_pair __bp = _S_mem_blocks[__diff];
1042 this->_M_insert(__puse_count);
1043 _S_mem_blocks.erase(_S_mem_blocks.begin() + __diff);
1045 // Reset the _S_last_request variable to reflect the
1046 // erased block. We do this to protect future requests
1047 // after the last block has been removed from a particular
1048 // memory Chunk, which in turn has been returned to the
1049 // free list, and hence had been erased from the vector,
1050 // so the size of the vector gets reduced by 1.
1051 if ((_Difference_type)_S_last_request._M_where() >= __diff--)
1052 _S_last_request._M_reset(__diff);
1054 // If the Index into the vector of the region of memory
1055 // that might hold the next address that will be passed to
1056 // deallocated may have been invalidated due to the above
1057 // erase procedure being called on the vector, hence we
1058 // try to restore this invariant too.
1059 if (_S_last_dealloc_index >= _S_mem_blocks.size())
1061 _S_last_dealloc_index =(__diff != -1 ? __diff : 0);
1062 _BALLOC_ASSERT(_S_last_dealloc_index >= 0);
1068 bitmap_allocator() throw()
1071 bitmap_allocator(const bitmap_allocator&)
1074 template<typename _Tp1>
1075 bitmap_allocator(const bitmap_allocator<_Tp1>&) throw()
1078 ~bitmap_allocator() throw()
1081 // Complexity: O(1), but internally the complexity depends upon the
1082 // complexity of the function(s) _S_allocate_single_object and
1085 allocate(size_type __n)
1087 if (__builtin_expect(__n == 1, true))
1088 return this->_M_allocate_single_object();
1091 const size_type __b = __n * sizeof(value_type);
1092 return reinterpret_cast<pointer>(::operator new(__b));
1097 allocate(size_type __n, typename bitmap_allocator<void>::const_pointer)
1098 { return allocate(__n); }
1101 deallocate(pointer __p, size_type __n) throw()
1103 if (__builtin_expect(__p != 0, true))
1105 if (__builtin_expect(__n == 1, true))
1106 this->_M_deallocate_single_object(__p);
1108 ::operator delete(__p);
1113 address(reference __r) const
1117 address(const_reference __r) const
1121 max_size() const throw()
1122 { return (size_type()-1)/sizeof(value_type); }
1125 construct(pointer __p, const_reference __data)
1126 { ::new(__p) value_type(__data); }
1129 destroy(pointer __p)
1130 { __p->~value_type(); }
1133 template<typename _Tp1, typename _Tp2>
1135 operator==(const bitmap_allocator<_Tp1>&,
1136 const bitmap_allocator<_Tp2>&) throw()
1139 template<typename _Tp1, typename _Tp2>
1141 operator!=(const bitmap_allocator<_Tp1>&,
1142 const bitmap_allocator<_Tp2>&) throw()
1145 // Static member definitions.
1146 template<typename _Tp>
1147 typename bitmap_allocator<_Tp>::_BPVector
1148 bitmap_allocator<_Tp>::_S_mem_blocks;
1150 template<typename _Tp>
1151 size_t bitmap_allocator<_Tp>::_S_block_size =
1152 2 * balloc::bits_per_block;
1154 template<typename _Tp>
1155 typename __gnu_cxx::bitmap_allocator<_Tp>::_BPVector::size_type
1156 bitmap_allocator<_Tp>::_S_last_dealloc_index = 0;
1158 template<typename _Tp>
1159 __gnu_cxx::balloc::_Bitmap_counter
1160 <typename bitmap_allocator<_Tp>::_Alloc_block*>
1161 bitmap_allocator<_Tp>::_S_last_request(_S_mem_blocks);
1163 #if defined __GTHREADS
1164 template<typename _Tp>
1166 bitmap_allocator<_Tp>::_S_mut;
1174 // LocalWords: namespace GTHREADS bool const gthread endif Mutex mutex