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

 *

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 * 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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#ifndef SHARE_GC_G1_G1CARDTABLE_HPP

#define SHARE_GC_G1_G1CARDTABLE_HPP

#include "gc/g1/g1RegionToSpaceMapper.hpp"

#include "gc/shared/cardTable.hpp"

#include "oops/oopsHierarchy.hpp"

#include "utilities/macros.hpp"

class G1CardTable;

class G1RegionToSpaceMapper;

class G1CardTableChangedListener : public G1MappingChangedListener {

 private:

  G1CardTable* _card_table;

 public:

  G1CardTableChangedListener() : _card_table(NULL) { }

  void set_card_table(G1CardTable* card_table) { _card_table = card_table; }

  virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);

};

class G1CardTable : public CardTable {

  friend class VMStructs;

  friend class G1CardTableChangedListener;

  G1CardTableChangedListener _listener;

public:

  enum G1CardValues {

    g1_young_gen = CT_MR_BS_last_reserved << 1,

    // During evacuation we use the card table to consolidate the cards we need to

    // scan for roots onto the card table from the various sources. Further it is

    // used to record already completely scanned cards to avoid re-scanning them

    // when incrementally evacuating the old gen regions of a collection set.

    // This means that already scanned cards should be preserved.

    //

    // The merge at the start of each evacuation round simply sets cards to dirty

    // that are clean; scanned cards are set to 0x1.

    //

    // This means that the LSB determines what to do with the card during evacuation

    // given the following possible values:

    //

    // 11111111 - clean, do not scan

    // 00000001 - already scanned, do not scan

    // 00000000 - dirty, needs to be scanned.

    //

    g1_card_already_scanned = 0x1

  };

  static const size_t WordAllClean = SIZE_MAX;

  static const size_t WordAllDirty = 0;

  STATIC_ASSERT(BitsPerByte == 8);

  static const size_t WordAlreadyScanned = (SIZE_MAX / 255) * g1_card_already_scanned;

  G1CardTable(MemRegion whole_heap): CardTable(whole_heap, /* scanned concurrently */ true), _listener() {

    _listener.set_card_table(this);

  }

  static CardValue g1_young_card_val() { return g1_young_gen; }

  void verify_g1_young_region(MemRegion mr) PRODUCT_RETURN;

  void g1_mark_as_young(const MemRegion& mr);

  size_t index_for_cardvalue(CardValue const* p) const {

    return pointer_delta(p, _byte_map, sizeof(CardValue));

  }

  // Change Clean cards in a (large) area on the card table as Dirty, preserving

  // already scanned cards. Assumes that most cards in that area are Clean.

  // Mark the given range of cards as Scanned. All of these cards must be Dirty.

  inline void mark_as_scanned(size_t start_card_index, size_t num_cards);

  inline uint region_idx_for(CardValue* p);

  static size_t compute_size(size_t mem_region_size_in_words) {

    size_t number_of_slots = (mem_region_size_in_words / card_size_in_words);

    return ReservedSpace::allocation_align_size_up(number_of_slots);

  }

  // Returns how many bytes of the heap a single byte of the Card Table corresponds to.

  static size_t heap_map_factor() { return card_size; }

  void initialize() {}

  void initialize(G1RegionToSpaceMapper* mapper);

  virtual void resize_covered_region(MemRegion new_region) { ShouldNotReachHere(); }

  virtual bool is_in_young(oop obj) const;

};

#endif // SHARE_GC_G1_G1CARDTABLE_HPP