/*

 * Copyright (c) 1997, 2016, 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.

 *

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 */

#ifndef SHARE_VM_UTILITIES_BITMAP_HPP

#define SHARE_VM_UTILITIES_BITMAP_HPP

#include "memory/allocation.hpp"

// Forward decl;

class BitMapClosure;

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

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

class BitMap VALUE_OBJ_CLASS_SPEC {

  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)

 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);

  // 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 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);

  // Set the map and size.

  // 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);

  }

  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_size_up(bit, BitsPerWord);

  }

  static idx_t word_align_down(idx_t bit) {

    return align_size_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();

  // Iteration support.  Returns "true" if the iteration completed, false

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

  // false).

  bool iterate(BitMapClosure* blk, idx_t leftIndex, idx_t rightIndex);

  bool iterate(BitMapClosure* blk) {

    // 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_inline (idx_t l_index, idx_t r_index) const;

  idx_t get_next_zero_offset_inline(idx_t l_index, idx_t r_index) const;

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

  // aligned to bitsizeof(bm_word_t).

  idx_t get_next_one_offset_inline_aligned_right(idx_t l_index,

                                                        idx_t r_index) const;

  // Non-inline versionsof the above.

  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());

  }

  // 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);

  // Requires the submap of "bits" starting at offset to be at least as

  // large as "this".  Modifies "this" to be the intersection of its

  // current contents and the submap of "bits" starting at "offset" of the

  // same length as "this."

  // (For expedience, currently requires the offset to be aligned to the

  // bitsize of a uintptr_t.  This should go away in the future though it

  // will probably remain a good case to optimize.)

  void set_intersection_at_offset(const BitMap& bits, idx_t offset);

  void set_from(const BitMap& bits);

  bool is_same(const BitMap& bits);

  // Test if all bits are set or cleared

  bool is_full() const;

  bool is_empty() const;

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

#ifndef PRODUCT

 public:

  // Printing

  void print_on(outputStream* st) const;

#endif

};

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

class BitMap2D VALUE_OBJ_CLASS_SPEC {

 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:

  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.

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

  idx_t size_in_bits() {

    return _map.size();

  }

  // Returns number of full slots that have been allocated

  idx_t size_in_slots() {

    // Round down

    return _map.size() / _bits_per_slot;

  }

  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);

  void clear();

};

// Closure for iterating over BitMaps

class BitMapClosure VALUE_OBJ_CLASS_SPEC {

 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_VM_UTILITIES_BITMAP_HPP