/*

 * Copyright 1997-2006 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 *

 */

// 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)

  // Puts the given value at the given offset, using resize() to size

  // the bitmap appropriately if needed using factor-of-two expansion.

  void at_put_grow(idx_t index, bool value);

 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() 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) 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, ~(uintptr_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, statistics.

  void verify_index(idx_t index) const;

  void verify_range(idx_t beg_index, idx_t end_index) const;

  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);

 public:

  // Constructs a bitmap with no map, and size 0.

  BitMap() : _map(NULL), _size(0) {}

  // Constructs a bitmap with the given map and size.

  BitMap(bm_word_t* map, idx_t size_in_bits);

  // Constructs an empty bitmap of the given size (that is, this clears the

  // new bitmap).  Allocates the map array in resource area if

  // "in_resource_area" is true, else in the C heap.

  BitMap(idx_t size_in_bits, bool in_resource_area = true);

  // Set the map and size.

  void set_map(bm_word_t* map)      { _map = map; }

  void set_size(idx_t size_in_bits) { _size = size_in_bits; }

  // Allocates necessary data structure, either in the resource area

  // or in the C heap, as indicated by "in_resource_area."

  // Preserves state currently in bit map by copying data.

  // Zeros any newly-addressable bits.

  // If "in_resource_area" is false, frees the current map.

  // (Note that this assumes that all calls to "resize" on the same BitMap

  // use the same value for "in_resource_area".)

  void resize(idx_t size_in_bits, bool in_resource_area = true);

  // Accessing

  idx_t size() const                    { return _size; }

  idx_t size_in_words() const           {

    return word_index(size() + 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);

  void clear_bit(idx_t bit);

  // Atomically set or clear the specified bit.

  bool par_set_bit(idx_t bit);

  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);

  // It performs the union operation between subsets of equal length

  // of two bitmaps (the target bitmap of the method and the

  // from_bitmap) and stores the result to the target bitmap.  The

  // from_start_index represents the first bit index of the subrange

  // of the from_bitmap.  The to_start_index is the equivalent of the

  // target bitmap. Both indexes should be word-aligned, i.e. they

  // should correspond to the first bit on a bitmap word (it's up to

  // the caller to ensure this; the method does check it).  The length

  // of the subset is specified with word_num and it is in number of

  // bitmap words. The caller should ensure that this is at least 2

  // (smaller ranges are not support to save extra checks).  Again,

  // this is checked in the method.

  //

  // Atomicity concerns: it is assumed that any contention on the

  // target bitmap with other threads will happen on the first and

  // last words; the ones in between will be "owned" exclusively by

  // the calling thread and, in fact, they will already be 0. So, the

  // method performs a CAS on the first word, copies the next

  // word_num-2 words, and finally performs a CAS on the last word.

  void mostly_disjoint_range_union(BitMap* from_bitmap,

                                   idx_t   from_start_index,

                                   idx_t   to_start_index,

                                   size_t  word_num);

  // 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(BitMap bits);

  void set_difference(BitMap bits);

  void set_intersection(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(BitMap bits);

  bool set_difference_with_result(BitMap bits);

  bool set_intersection_with_result(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(BitMap bits, idx_t offset);

  void set_from(BitMap bits);

  bool is_same(BitMap bits);

  // Test if all bits are set or cleared

  bool is_full() const;

  bool is_empty() 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:

  BitMap _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(bm_word_t* map, idx_t size_in_slots, idx_t 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);

  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) {

    verify_bit_within_slot_index(bit_within_slot_index);

    return (bit_index(slot_index, bit_within_slot_index) < size_in_bits());

  }

  bool at(idx_t slot_index, idx_t bit_within_slot_index) const {

    verify_bit_within_slot_index(bit_within_slot_index);

    return _map.at(bit_index(slot_index, bit_within_slot_index));

  }

  void set_bit(idx_t slot_index, idx_t bit_within_slot_index) {

    verify_bit_within_slot_index(bit_within_slot_index);

    _map.set_bit(bit_index(slot_index, bit_within_slot_index));

  }

  void clear_bit(idx_t slot_index, idx_t bit_within_slot_index) {

    verify_bit_within_slot_index(bit_within_slot_index);

    _map.clear_bit(bit_index(slot_index, bit_within_slot_index));

  }

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

    verify_bit_within_slot_index(bit_within_slot_index);

    _map.at_put(bit_index(slot_index, bit_within_slot_index), value);

  }

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

    verify_bit_within_slot_index(bit_within_slot_index);

    _map.at_put_grow(bit_index(slot_index, bit_within_slot_index), 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;

};