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 /*

  * Copyright (c) 2000, 2012, Oracle and/or its affiliates. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code 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

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

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 #ifndef SHARE_VM_MEMORY_MEMREGION_HPP

 #define SHARE_VM_MEMORY_MEMREGION_HPP

 #include "memory/allocation.hpp"

 #include "utilities/debug.hpp"

 #include "utilities/globalDefinitions.hpp"

 // A very simple data structure representing a contigous region

 // region of address space.

 // Note that MemRegions are passed by value, not by reference.

 // The intent is that they remain very small and contain no

 // objects.

 class MetaWord;

 class MemRegion VALUE_OBJ_CLASS_SPEC {

   friend class VMStructs;

 private:

   HeapWord* _start;

   size_t    _word_size;

 public:

   MemRegion() : _start(NULL), _word_size(0) {};

   MemRegion(HeapWord* start, size_t word_size) :

     _start(start), _word_size(word_size) {};

   MemRegion(HeapWord* start, HeapWord* end) :

     _start(start), _word_size(pointer_delta(end, start)) {

     assert(end >= start, "incorrect constructor arguments");

   }

   MemRegion(MetaWord* start, MetaWord* end) :

     _start((HeapWord*)start), _word_size(pointer_delta(end, start)) {

     assert(end >= start, "incorrect constructor arguments");

   }

   MemRegion(const MemRegion& mr): _start(mr._start), _word_size(mr._word_size) {}

   MemRegion intersection(const MemRegion mr2) const;

   // regions must overlap or be adjacent

   MemRegion _union(const MemRegion mr2) const;

   // minus will fail a guarantee if mr2 is interior to this,

   // since there's no way to return 2 disjoint regions.

   MemRegion minus(const MemRegion mr2) const;

   HeapWord* start() const { return _start; }

   HeapWord* end() const   { return _start + _word_size; }

   HeapWord* last() const  { return _start + _word_size - 1; }

   void set_start(HeapWord* start) { _start = start; }

   void set_end(HeapWord* end)     { _word_size = pointer_delta(end, _start); }

   void set_word_size(size_t word_size) {

     _word_size = word_size;

   }

   bool contains(const MemRegion mr2) const {

     return _start <= mr2._start && end() >= mr2.end();

   }

   bool contains(const void* addr) const {

     return addr >= (void*)_start && addr < (void*)end();

   }

   bool equals(const MemRegion mr2) const {

     // first disjunct since we do not have a canonical empty set

     return ((is_empty() && mr2.is_empty()) ||

             (start() == mr2.start() && end() == mr2.end()));

   }

   size_t byte_size() const { return _word_size * sizeof(HeapWord); }

   size_t word_size() const { return _word_size; }

   bool is_empty() const { return word_size() == 0; }

 };

 // For iteration over MemRegion's.

 class MemRegionClosure : public StackObj {

 public:

   virtual void do_MemRegion(MemRegion mr) = 0;

 };

 // A ResourceObj version of MemRegionClosure

 class MemRegionClosureRO: public MemRegionClosure {

 public:

   void* operator new(size_t size, ResourceObj::allocation_type type, MEMFLAGS flags) {

         return ResourceObj::operator new(size, type, flags);

   }

   void* operator new(size_t size, Arena *arena) {

         return ResourceObj::operator new(size, arena);

   }

   void* operator new(size_t size) {

         return ResourceObj::operator new(size);

   }

   void  operator delete(void* p) {} // nothing to do

 };

 #endif // SHARE_VM_MEMORY_MEMREGION_HPP