/*

 * 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.

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 */

// 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 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(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) {

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

  }

  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

};