/*

 * Copyright (c) 1997, 2019, 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

 * questions.

 *

 */

#ifndef SHARE_UTILITIES_BITMAP_HPP

#define SHARE_UTILITIES_BITMAP_HPP

#include "memory/allocation.hpp"

#include "utilities/align.hpp"

// Forward decl;

class BitMapClosure;

// Operations for bitmaps represented as arrays of unsigned integers.

// Bit offsets are numbered from 0 to size-1.

// The "abstract" base BitMap class.

//

// The constructor and destructor are protected to prevent

// creation of BitMap instances outside of the BitMap class.

//

// The BitMap class doesn't use virtual calls on purpose,

// this ensures that we don't get a vtable unnecessarily.

//

// The allocation of the backing storage for the BitMap are handled by

// the subclasses. BitMap doesn't allocate or delete backing storage.

class BitMap {

  friend class BitMap2D;

 public:

  typedef size_t idx_t;         // Type used for bit and word indices.

  typedef uintptr_t bm_word_t;  // Element type of array that represents

                                // the bitmap.

  // Hints for range sizes.

  typedef enum {

    unknown_range, small_range, large_range

  } RangeSizeHint;

 private:

  bm_word_t* _map;     // First word in bitmap

  idx_t      _size;    // Size of bitmap (in bits)

  // Helper for get_next_{zero,one}_bit variants.

  // - flip designates whether searching for 1s or 0s.  Must be one of

  //   find_{zeros,ones}_flip.

  // - aligned_right is true if r_index is a priori on a bm_word_t boundary.

  template<bm_word_t flip, bool aligned_right>

  inline idx_t get_next_bit_impl(idx_t l_index, idx_t r_index) const;

  // Values for get_next_bit_impl flip parameter.

  static const bm_word_t find_ones_flip = 0;

  static const bm_word_t find_zeros_flip = ~(bm_word_t)0;

  // Threshold for performing small range operation, even when large range

  // operation was requested. Measured in words.

  static const size_t small_range_words = 32;

 protected:

  // Return the position of bit within the word that contains it (e.g., if

  // bitmap words are 32 bits, return a number 0 <= n <= 31).

  static idx_t bit_in_word(idx_t bit) { return bit & (BitsPerWord - 1); }

  // Return a mask that will select the specified bit, when applied to the word

  // containing the bit.

  static bm_word_t bit_mask(idx_t bit) { return (bm_word_t)1 << bit_in_word(bit); }

  // Return the index of the word containing the specified bit.

  static idx_t word_index(idx_t bit)  { return bit >> LogBitsPerWord; }

  // Return the bit number of the first bit in the specified word.

  static idx_t bit_index(idx_t word)  { return word << LogBitsPerWord; }

  // Return the array of bitmap words, or a specific word from it.

  bm_word_t* map()                 { return _map; }

  const bm_word_t* map() const     { return _map; }

  bm_word_t  map(idx_t word) const { return _map[word]; }

  // Return a pointer to the word containing the specified bit.

  bm_word_t* word_addr(idx_t bit)             { return map() + word_index(bit); }

  const bm_word_t* word_addr(idx_t bit) const { return map() + word_index(bit); }

  // Set a word to a specified value or to all ones; clear a word.

  void set_word  (idx_t word, bm_word_t val) { _map[word] = val; }

  void set_word  (idx_t word)            { set_word(word, ~(bm_word_t)0); }

  void clear_word(idx_t word)            { _map[word] = 0; }

  // Utilities for ranges of bits.  Ranges are half-open [beg, end).

  // Ranges within a single word.

  bm_word_t inverted_bit_mask_for_range(idx_t beg, idx_t end) const;

  void  set_range_within_word      (idx_t beg, idx_t end);

  void  clear_range_within_word    (idx_t beg, idx_t end);

  void  par_put_range_within_word  (idx_t beg, idx_t end, bool value);

  // Ranges spanning entire words.

  void      set_range_of_words         (idx_t beg, idx_t end);

  void      clear_range_of_words       (idx_t beg, idx_t end);

  void      set_large_range_of_words   (idx_t beg, idx_t end);

  void      clear_large_range_of_words (idx_t beg, idx_t end);

  static void clear_range_of_words(bm_word_t* map, idx_t beg, idx_t end);

  static bool is_small_range_of_words(idx_t beg_full_word, idx_t end_full_word);

  // The index of the first full word in a range.

  idx_t word_index_round_up(idx_t bit) const;

  // Verification.

  void verify_index(idx_t index) const NOT_DEBUG_RETURN;

  void verify_range(idx_t beg_index, idx_t end_index) const NOT_DEBUG_RETURN;

  // Statistics.

  static const idx_t* _pop_count_table;

  static void init_pop_count_table();

  static idx_t num_set_bits(bm_word_t w);

  static idx_t num_set_bits_from_table(unsigned char c);

  // Allocation Helpers.

  // Allocates and clears the bitmap memory.

  template <class Allocator>

  static bm_word_t* allocate(const Allocator&, idx_t size_in_bits, bool clear = true);

  // Reallocates and clears the new bitmap memory.

  template <class Allocator>

  static bm_word_t* reallocate(const Allocator&, bm_word_t* map, idx_t old_size_in_bits, idx_t new_size_in_bits, bool clear = true);

  // Free the bitmap memory.

  template <class Allocator>

  static void free(const Allocator&, bm_word_t* map, idx_t size_in_bits);

  // Protected functions, that are used by BitMap sub-classes that support them.

  // Resize the backing bitmap memory.

  //

  // Old bits are transfered to the new memory

  // and the extended memory is cleared.

  template <class Allocator>

  void resize(const Allocator& allocator, idx_t new_size_in_bits, bool clear);

  // Set up and clear the bitmap memory.

  //

  // Precondition: The bitmap was default constructed and has

  // not yet had memory allocated via resize or (re)initialize.

  template <class Allocator>

  void initialize(const Allocator& allocator, idx_t size_in_bits, bool clear);

  // Set up and clear the bitmap memory.

  //

  // Can be called on previously initialized bitmaps.

  template <class Allocator>

  void reinitialize(const Allocator& allocator, idx_t new_size_in_bits, bool clear);

  // Set the map and size.

  void update(bm_word_t* map, idx_t size) {

    _map = map;

    _size = size;

  }

  // Protected constructor and destructor.

  BitMap(bm_word_t* map, idx_t size_in_bits) : _map(map), _size(size_in_bits) {}

  ~BitMap() {}

 public:

  // Pretouch the entire range of memory this BitMap covers.

  void pretouch();

  // Accessing

  static idx_t calc_size_in_words(size_t size_in_bits) {

    return word_index(size_in_bits + BitsPerWord - 1);

  }

  static idx_t calc_size_in_bytes(size_t size_in_bits) {

    return calc_size_in_words(size_in_bits) * BytesPerWord;

  }

  idx_t size() const          { return _size; }

  idx_t size_in_words() const { return calc_size_in_words(size()); }

  idx_t size_in_bytes() const { return calc_size_in_bytes(size()); }

  bool at(idx_t index) const {

    verify_index(index);

    return (*word_addr(index) & bit_mask(index)) != 0;

  }

  // Align bit index up or down to the next bitmap word boundary, or check

  // alignment.

  static idx_t word_align_up(idx_t bit) {

    return align_up(bit, BitsPerWord);

  }

  static idx_t word_align_down(idx_t bit) {

    return align_down(bit, BitsPerWord);

  }

  static bool is_word_aligned(idx_t bit) {

    return word_align_up(bit) == bit;

  }

  // Set or clear the specified bit.

  inline void set_bit(idx_t bit);

  inline void clear_bit(idx_t bit);

  // Atomically set or clear the specified bit.

  inline bool par_set_bit(idx_t bit);

  inline bool par_clear_bit(idx_t bit);

  // Put the given value at the given offset. The parallel version

  // will CAS the value into the bitmap and is quite a bit slower.

  // The parallel version also returns a value indicating if the

  // calling thread was the one that changed the value of the bit.

  void at_put(idx_t index, bool value);

  bool par_at_put(idx_t index, bool value);

  // Update a range of bits.  Ranges are half-open [beg, end).

  void set_range   (idx_t beg, idx_t end);

  void clear_range (idx_t beg, idx_t end);

  void set_large_range   (idx_t beg, idx_t end);

  void clear_large_range (idx_t beg, idx_t end);

  void at_put_range(idx_t beg, idx_t end, bool value);

  void par_at_put_range(idx_t beg, idx_t end, bool value);

  void at_put_large_range(idx_t beg, idx_t end, bool value);

  void par_at_put_large_range(idx_t beg, idx_t end, bool value);

  // Update a range of bits, using a hint about the size.  Currently only

  // inlines the predominant case of a 1-bit range.  Works best when hint is a

  // compile-time constant.

  void set_range(idx_t beg, idx_t end, RangeSizeHint hint);

  void clear_range(idx_t beg, idx_t end, RangeSizeHint hint);

  void par_set_range(idx_t beg, idx_t end, RangeSizeHint hint);

  void par_clear_range  (idx_t beg, idx_t end, RangeSizeHint hint);

  // Clearing

  void clear_large();

  inline void clear();

  // if the iteration terminated early (because the closure "blk" returned

  // false).

    // call the version that takes an interval

    return iterate(blk, 0, size());

  }

  // Looking for 1's and 0's at indices equal to or greater than "l_index",

  // stopping if none has been found before "r_index", and returning

  // "r_index" (which must be at most "size") in that case.

  idx_t get_next_one_offset (idx_t l_index, idx_t r_index) const;

  idx_t get_next_zero_offset(idx_t l_index, idx_t r_index) const;

  idx_t get_next_one_offset(idx_t offset) const {

    return get_next_one_offset(offset, size());

  }

  idx_t get_next_zero_offset(idx_t offset) const {

    return get_next_zero_offset(offset, size());

  }

  // Like "get_next_one_offset", except requires that "r_index" is

  // aligned to bitsizeof(bm_word_t).

  idx_t get_next_one_offset_aligned_right(idx_t l_index, idx_t r_index) const;

  // Returns the number of bits set in the bitmap.

  idx_t count_one_bits() const;

  // Set operations.

  void set_union(const BitMap& bits);

  void set_difference(const BitMap& bits);

  void set_intersection(const BitMap& bits);

  // Returns true iff "this" is a superset of "bits".

  bool contains(const BitMap& bits) const;

  // Returns true iff "this and "bits" have a non-empty intersection.

  bool intersects(const BitMap& bits) const;

  // Returns result of whether this map changed

  // during the operation

  bool set_union_with_result(const BitMap& bits);

  bool set_difference_with_result(const BitMap& bits);

  bool set_intersection_with_result(const BitMap& bits);

  void set_from(const BitMap& bits);

  bool is_same(const BitMap& bits) const;

  // Test if all bits are set or cleared

  bool is_full() const;

  bool is_empty() const;

  void write_to(bm_word_t* buffer, size_t buffer_size_in_bytes) const;

  void print_on_error(outputStream* st, const char* prefix) const;

#ifndef PRODUCT

 public:

  // Printing

  void print_on(outputStream* st) const;

#endif

};

// A concrete implementation of the the "abstract" BitMap class.

//

// The BitMapView is used when the backing storage is managed externally.

class BitMapView : public BitMap {

 public:

  BitMapView() : BitMap(NULL, 0) {}

  BitMapView(bm_word_t* map, idx_t size_in_bits) : BitMap(map, size_in_bits) {}

};

// A BitMap with storage in a ResourceArea.

class ResourceBitMap : public BitMap {

 public:

  ResourceBitMap() : BitMap(NULL, 0) {}

  // Conditionally clears the bitmap memory.

  ResourceBitMap(idx_t size_in_bits, bool clear = true);

  // Resize the backing bitmap memory.

  //

  // Old bits are transfered to the new memory

  // and the extended memory is cleared.

  void resize(idx_t new_size_in_bits);

  // Set up and clear the bitmap memory.

  //

  // Precondition: The bitmap was default constructed and has

  // not yet had memory allocated via resize or initialize.

  void initialize(idx_t size_in_bits);

  // Set up and clear the bitmap memory.

  //

  // Can be called on previously initialized bitmaps.

  void reinitialize(idx_t size_in_bits);

};

// A BitMap with storage in a specific Arena.

class ArenaBitMap : public BitMap {

 public:

  // Clears the bitmap memory.

  ArenaBitMap(Arena* arena, idx_t size_in_bits);

 private:

  // Don't allow copy or assignment.

  ArenaBitMap(const ArenaBitMap&);

  ArenaBitMap& operator=(const ArenaBitMap&);

};

// A BitMap with storage in the CHeap.

class CHeapBitMap : public BitMap {

 private:

  // Don't allow copy or assignment, to prevent the

  // allocated memory from leaking out to other instances.

  CHeapBitMap(const CHeapBitMap&);

  CHeapBitMap& operator=(const CHeapBitMap&);

  // NMT memory type

  MEMFLAGS _flags;

 public:

  CHeapBitMap(MEMFLAGS flags = mtInternal) : BitMap(NULL, 0), _flags(flags) {}

  // Clears the bitmap memory.

  CHeapBitMap(idx_t size_in_bits, MEMFLAGS flags = mtInternal, bool clear = true);

  ~CHeapBitMap();

  // Resize the backing bitmap memory.

  //

  // Old bits are transfered to the new memory

  // and the extended memory is (optionally) cleared.

  void resize(idx_t new_size_in_bits, bool clear = true);

  // Set up and (optionally) clear the bitmap memory.

  //

  // Precondition: The bitmap was default constructed and has

  // not yet had memory allocated via resize or initialize.

  void initialize(idx_t size_in_bits, bool clear = true);

  // Set up and (optionally) clear the bitmap memory.

  //

  // Can be called on previously initialized bitmaps.

  void reinitialize(idx_t size_in_bits, bool clear = true);

};

// Convenience class wrapping BitMap which provides multiple bits per slot.

class BitMap2D {

 public:

  typedef BitMap::idx_t idx_t;          // Type used for bit and word indices.

  typedef BitMap::bm_word_t bm_word_t;  // Element type of array that

                                        // represents the bitmap.

 private:

  ResourceBitMap _map;

  idx_t          _bits_per_slot;

  idx_t bit_index(idx_t slot_index, idx_t bit_within_slot_index) const {

    return slot_index * _bits_per_slot + bit_within_slot_index;

  }

  void verify_bit_within_slot_index(idx_t index) const {

    assert(index < _bits_per_slot, "bit_within_slot index out of bounds");

  }

 public:

  // Construction. bits_per_slot must be greater than 0.

  BitMap2D(idx_t bits_per_slot) :

      _map(), _bits_per_slot(bits_per_slot) {}

  // Allocates necessary data structure in resource area. bits_per_slot must be greater than 0.

  BitMap2D(idx_t size_in_slots, idx_t bits_per_slot) :

      _map(size_in_slots * bits_per_slot), _bits_per_slot(bits_per_slot) {}

  idx_t size_in_bits() {

    return _map.size();

  }

  bool is_valid_index(idx_t slot_index, idx_t bit_within_slot_index);

  bool at(idx_t slot_index, idx_t bit_within_slot_index) const;

  void set_bit(idx_t slot_index, idx_t bit_within_slot_index);

  void clear_bit(idx_t slot_index, idx_t bit_within_slot_index);

  void at_put(idx_t slot_index, idx_t bit_within_slot_index, bool value);

  void at_put_grow(idx_t slot_index, idx_t bit_within_slot_index, bool value);

};

// Closure for iterating over BitMaps

class BitMapClosure {

 public:

  // Callback when bit in map is set.  Should normally return "true";

  // return of false indicates that the bitmap iteration should terminate.

  virtual bool do_bit(BitMap::idx_t offset) = 0;

};

#endif // SHARE_UTILITIES_BITMAP_HPP